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Journal articles on the topic 'Free-living protozoa'

Author: Grafiati

Published: 4 June 2021

Last updated: 1 February 2022

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1

Baré, Julie, Kurt Houf, Tine Verstraete, Mario Vaerewijck, and Koen Sabbe. "Persistence of Free-Living Protozoan Communities across Rearing Cycles in Commercial Poultry Houses." Applied and Environmental Microbiology 77, no. 5 (January 14, 2011): 1763–69. http://dx.doi.org/10.1128/aem.01756-10.

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ABSTRACTThe introduction and survival of zoonotic bacterial pathogens in poultry farming have been linked to bacterial association with free-living protozoa. To date, however, no information is available on the persistence of protozoan communities in these environments across consecutive rearing cycles and how it is affected by farm- and habitat-specific characteristics and management strategies. We therefore investigated the spatial and temporal dynamics of free-living protozoa in three habitats (pipeline, water, and miscellaneous samples) in three commercial poultry houses across three rearing cycles by using the molecular fingerprinting technique denaturing gradient gel electrophoresis (DGGE). Our study provides strong evidence for the long-term (ca. 6-month) persistence of protozoa in broiler houses across consecutive rearing cycles. Various free-living protozoa (flagellates, ciliates, and amoebae), including known vectors of bacterial pathogens, were observed during the down periods in between rearing cycles. In addition, multivariate analysis and variation partitioning showed that the protozoan community structure in the broiler houses showed almost no change across rearing cycles and remained highly habitat and farm specific. Unlike in natural environments, protozoan communities inside broiler houses are therefore not seasonal. Our results imply that currently used biosecurity measures (cleaning and disinfection) applied during the down periods are not effective against many protozoans and therefore cannot prevent potential cross-contamination of bacterial pathogens via free-living protozoa between rearing cycles.

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2

Salt, George W. "Free-Living Protozoa in Natural Communities." Ecology 68, no. 4 (August 1987): 1133–34. http://dx.doi.org/10.2307/1938398.

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3

Goertz, Hans-Dieter. "Microbial Infections in Free-Living Protozoa." Critical Reviews™ in Immunology 30, no. 1 (2010): 95–106. http://dx.doi.org/10.1615/critrevimmunol.v30.i1.70.

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4

Finlay, B. J., and J. Laybourn-Parry. "A Functional Biology of Free-Living Protozoa." Journal of Animal Ecology 54, no. 2 (June 1985): 678. http://dx.doi.org/10.2307/4513.

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5

Sanders, Robert W. "Free-living freshwater protozoa-a colour guide." Limnology and Oceanography 44, no. 1 (January 1999): 234–35. http://dx.doi.org/10.4319/lo.1999.44.1.0234.

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6

Laskowski-Arce, Michelle A., and Kim Orth. "Acanthamoeba castellanii Promotes the Survival of Vibrio parahaemolyticus." Applied and Environmental Microbiology 74, no. 23 (October 10, 2008): 7183–88. http://dx.doi.org/10.1128/aem.01332-08.

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ABSTRACT Vibrio parahaemolyticus is a food-borne pathogen that naturally inhabits both marine and estuarine environments. Free-living protozoa exist in similar aquatic environments and function to control bacterial numbers by grazing on free-living bacteria. Protozoa also play an important role in the survival and spread of some pathogenic species of bacteria. We investigated the interaction between the protozoan Acanthamoeba castellanii and the bacterium Vibrio parahaemolyticus. We found that Acanthamoeba castellanii does not prey on Vibrio parahaemolyticus but instead secretes a factor that promotes the survival of Vibrio parahaemolyticus in coculture. These studies suggest that protozoa may provide a survival advantage to an extracellular pathogen in the environment.

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7

Fenchel, Tom. "Free-Living Freshwater Protozoa: A Colour Guide.D. J. Patterson." Quarterly Review of Biology 73, no. 2 (June 1998): 230. http://dx.doi.org/10.1086/420255.

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8

Valster, Rinske M., Bart A. Wullings, Geo Bakker, Hauke Smidt, and Dick van der Kooij. "Free-Living Protozoa in Two Unchlorinated Drinking Water Supplies, Identified by Phylogenic Analysis of 18S rRNA Gene Sequences." Applied and Environmental Microbiology 75, no. 14 (May 22, 2009): 4736–46. http://dx.doi.org/10.1128/aem.02629-08.

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ABSTRACT Free-living protozoan communities in water supplies may include hosts for Legionella pneumophila and other undesired bacteria, as well as pathogens. This study aimed at identifying free-living protozoa in two unchlorinated groundwater supplies, using cultivation-independent molecular approaches. For this purpose, samples (<20°C) of treated water, distributed water, and distribution system biofilms were collected from supply A, with a low concentration of natural organic matter (NOM) (<0.5 ppm of C), and from supply B, with a high NOM concentration (7.9 ppm of C). Eukaryotic communities were studied using terminal restriction fragment length polymorphism and clone library analyses of partial 18S rRNA gene fragments and a Hartmannella vermiformis-specific quantitative PCR (qPCR). In both supplies, highly diverse eukaryotic communities were observed, including free-living protozoa, fungi, and metazoa. Sequences of protozoa clustered with Amoebozoa (10 operational taxonomic units [OTUs]), Cercozoa (39 OTUs), Choanozoa (26 OTUs), Ciliophora (29 OTUs), Euglenozoa (13 OTUs), Myzozoa (5 OTUs), and Stramenopiles (5 OTUs). A large variety of protozoa were present in both supplies, but the estimated values for protozoan richness did not differ significantly. H. vermiformis was observed in both supplies but was not a predominant protozoan. One OTU with the highest similarity to Acanthamoeba polyphaga, an opportunistic human pathogen and a host for undesired bacteria, was observed in supply A. The high level of NOM in supply B corresponded with an elevated level of active biomass and with elevated concentrations of H. vermiformis in distributed water. Hence, the application of qPCR may be promising in elucidating the relationship between drinking water quality and the presence of specific protozoa.

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9

Lipscomb, Diana. "Life, Protozoan Style A Functional Biology of Free-Living Protozoa Johanna Laybourn-Parry." BioScience 36, no. 4 (April 1986): 275–76. http://dx.doi.org/10.2307/1310222.

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10

Baré, Julie, Koen Sabbe, Jeroen Van Wichelen, Ineke van Gremberghe, Sofie D'hondt, and Kurt Houf. "Diversity and Habitat Specificity of Free-Living Protozoa in Commercial Poultry Houses." Applied and Environmental Microbiology 75, no. 5 (January 5, 2009): 1417–26. http://dx.doi.org/10.1128/aem.02346-08.

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ABSTRACT Despite stringent biosecurity measures, infections by bacterial food pathogens such as Campylobacter are a recurrent problem in industrial poultry houses. As the main transmission route remains unclear, persistence of these infections has been linked to bacterial survival and possibly multiplication within protozoan vectors. To date, however, virtually no information is available on the diversity and occurrence of free-living protozoa in these environments. Using a combination of microscopic analyses of enrichment cultures and molecular methods (denaturing gradient gel electrophoresis [DGGE]) on natural samples, we show that, despite strict hygiene management, free-living protozoa are common and widespread throughout a 6-week rearing period in both water and dry samples from commercial poultry houses. Protozoan communities were highly diverse (over 90 morphotaxa and 22 unique phylotypes from sequenced bands) and included several facultative pathogens and known bacterial vectors. Water samples were consistently more diverse than dry ones and harbored different communities, mainly dominated by flagellates. The morphology-based and molecular methods yielded markedly different results: amoebic and, to a lesser degree, ciliate diversity was seriously underestimated in the DGGE analyses, while some flagellate groups were not found in the microscopic analyses. Some recommendations for improving biosecurity measures in commercial poultry houses are suggested.

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11

Chavatte, N., E. Lambrecht, I. Van Damme, K. Sabbe, and K. Houf. "Free-living protozoa in the gastrointestinal tract and feces of pigs: Exploration of an unknown world and towards a protocol for the recovery of free-living protozoa." Veterinary Parasitology 225 (July 2016): 91–98. http://dx.doi.org/10.1016/j.vetpar.2016.06.002.

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12

Vaerewijck, Mario J. M., Koen Sabbe, Julie Baré, and Kurt Houf. "Occurrence and diversity of free-living protozoa on butterhead lettuce." International Journal of Food Microbiology 147, no. 2 (May 2011): 105–11. http://dx.doi.org/10.1016/j.ijfoodmicro.2011.03.015.

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13

Vaerewijck, Mario J. M., Koen Sabbe, Julie Baré, and Kurt Houf. "Microscopic and Molecular Studies of the Diversity of Free-Living Protozoa in Meat-Cutting Plants." Applied and Environmental Microbiology 74, no. 18 (July 18, 2008): 5741–49. http://dx.doi.org/10.1128/aem.00980-08.

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ABSTRACT The diversity of free-living protozoa in five meat-cutting plants was determined. Light microscopy after enrichment culturing was combined with sequencing of PCR-amplified, denaturing gradient gel electrophoresis (DGGE)-separated 18S rRNA gene fragments, which was used as a fast screening method. The general results of the survey showed that a protozoan community of amoebae, ciliates, and flagellates was present in all of the plants. Protozoa were detected mainly in floor drains, in standing water on the floor, on soiled bars of cutting tables, on plastic pallets, and in out-of-use hot water knife sanitizers, but they were also detected on surfaces which come into direct contact with meat, such as conveyer belts, working surfaces of cutting tables, and needles of a meat tenderizer. After 7 days of incubation at refrigerator temperature, protozoa were detected in about one-half of the enrichment cultures. Based on microscopic observations, 61 morphospecies were found, and Bodo saltans, Bodo spp., Epistylis spp., Glaucoma scintillans, Petalomonas spp., Prodiscophrya collini, and Vannella sp. were the most frequently encountered identified organisms. Sequencing of DGGE bands resulted in identification of a total of 49 phylotypes, including representatives of the Amoebozoa, Chromalveolata, Excavata, Opisthokonta, and Rhizaria. Sequences of small heterotrophic flagellates were affiliated mainly with the Alveolata (Apicomplexa), Stramenopiles (Chrysophyceae), and Rhizaria (Cercozoa). This survey showed that there is high protozoan species richness in meat-cutting plants and that the species included species related to known hosts of food-borne pathogens.

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14

Hutner, Seymour H. "Ecology of Protozoa. The Biology of Free-Living Phagotrophic Protists.Tom Fenchel." Quarterly Review of Biology 62, no. 3 (September 1987): 321–22. http://dx.doi.org/10.1086/415555.

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15

Kusch, J., and H. J. Schmidt. "Genetically Controlled Expression of Surface Variant Antigens in Free-Living Protozoa." Journal of Membrane Biology 180, no. 2 (March 15, 2001): 101–9. http://dx.doi.org/10.1007/s002320010062.

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16

Valster, Rinske M., Bart A. Wullings, and Dick van der Kooij. "Detection of Protozoan Hosts for Legionella pneumophila in Engineered Water Systems by Using a Biofilm Batch Test." Applied and Environmental Microbiology 76, no. 21 (September 17, 2010): 7144–53. http://dx.doi.org/10.1128/aem.00926-10.

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ABSTRACT Legionella pneumophila proliferates in aquatic habitats within free-living protozoa, 17 species of which have been identified as hosts by using in vitro experiments. The present study aimed at identifying protozoan hosts for L. pneumophila by using a biofilm batch test (BBT). Samples (600 ml) collected from 21 engineered freshwater systems, with added polyethylene cylinders to promote biofilm formation, were inoculated with L. pneumophila and subsequently incubated at 37°C for 20 days. Growth of L. pneumophila was observed in 16 of 18 water types when the host protozoan Hartmannella vermiformis was added. Twelve of the tested water types supported growth of L. pneumophila or indigenous Legionella anisa without added H. vermiformis. In 12 of 19 BBT flasks H. vermiformis was indicated as a host, based on the ratio between maximum concentrations of L. pneumophila and H. vermiformis, determined with quantitative PCR (Q-PCR), and the composition of clone libraries of partial 18S rRNA gene fragments. Analyses of 609 eukaryotic clones from the BBTs revealed that 68 operational taxonomic units (OTUs) showed the highest similarity to free-living protozoa. Forty percent of the sequences clustering with protozoa showed ≥99.5% similarity to H. vermiformis. None of the other protozoa serving as hosts in in vitro studies were detected in the BBTs. In several tests with growth of L. pneumophila, the protozoa Diphylleia rotans, Echinamoeba thermarum, and Neoparamoeba sp. were identified as candidate hosts. In vitro studies are needed to confirm their role as hosts for L. pneumophila. Unidentified protozoa were implicated as hosts for uncultured Legionella spp. grown in BBT flasks at 15°C.

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17

Zhang, Wenjing, Yuhe Yu, Yunfen Shen, Wei Miao, and Weisong Feng. "Preliminary study on applicability of microsatellite DNA primers from parasite protozoa Trypanosoma cruzi in free-living protozoa." Journal of Ocean University of China 3, no. 1 (April 2004): 80–84. http://dx.doi.org/10.1007/s11802-004-0014-y.

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18

Spagnolo, Anna Maria, Marina Sartini, David Di Cave, Beatrice Casini, Benedetta Tuvo, and Maria Luisa Cristina. "Evaluation of Microbiological and Free-Living Protozoa Contamination in Dental Unit Waterlines." International Journal of Environmental Research and Public Health 16, no. 15 (July 24, 2019): 2648. http://dx.doi.org/10.3390/ijerph16152648.

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Studies conducted over the last 40 years have demonstrated that the water output from dental unit waterlines (DUWLs) is often contaminated with high densities of microorganisms. It has been monitored the microbiological quality of the water in 30 public dental facilities in northern Italy in order to assess the health risk for patients and dental staff. In each facility, samples of water both from taps and from DUWLs were analyzed in order to evaluate heterotrophic plate counts (HPCs) at 22 °C and 36 °C, and to detect coliform bacteria, Pseudomonas aeruginosa, Legionella pneumophila and amoebae. In 100% of the samples taken from the DUWLs, the concentration of HPCs was above the threshold as determined by the Ministère de la Santé et des Solidarités (2007). The concentration of P. aeruginosa was greater than the indicated threshold in 16.67% of the hand-pieces analyzed. A total of 78.33% of samples were contaminated by L. pneumophila, while in the samples taken from the DUWLs alone, this percentage rose to 86.67%. Amoebae were detected in 60% of the samples taken from hand-pieces; all belonging to the species V. vermiformis. This study documented the presence of various microorganisms, including Legionella spp., at considerably higher concentrations in water samples from DUWLs than in samples of tap water in the same facilities, confirming the role of the internal DUWLs in increasing microbial contamination, especially in the absence of proper management of waterborne health risks.

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19

Fenchel, Tom, and Bland J. Finaly. "Anaerobic free-living protozoa: growth efficiencies and the structure of anaeorobic communities." FEMS Microbiology Letters 74, no. 4 (December 1990): 269–75. http://dx.doi.org/10.1111/j.1574-6968.1990.tb04073.x.

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20

Fenchel, Tom, and Bland J. Finlay. "Anaerobic free-living protozoa: growth efficiencies and the structure of anaerobic communities." FEMS Microbiology Ecology 7, no. 4 (December 1990): 269–75. http://dx.doi.org/10.1111/j.1574-6941.1990.tb01693.x.

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21

Jones, H. I., and G. R. Shellam. "The occurrence of blood-inhabiting protozoa in captive and free-living penguins." Polar Biology 21, no. 1 (January 1, 1999): 5–10. http://dx.doi.org/10.1007/s003000050327.

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22

Chavatte, N., E. Lambrecht, I. Van Damme, K. Sabbe, and K. Houf. "Abundance, diversity and community composition of free-living protozoa on vegetable sprouts." Food Microbiology 55 (May 2016): 55–63. http://dx.doi.org/10.1016/j.fm.2015.11.013.

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23

Barratt, J. L. N., J. Harkness, D. Marriott, J. T. Ellis, and D. Stark. "Importance of Nonenteric Protozoan Infections in Immunocompromised People." Clinical Microbiology Reviews 23, no. 4 (October 2010): 795–836. http://dx.doi.org/10.1128/cmr.00001-10.

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SUMMARY There are many neglected nonenteric protozoa able to cause serious morbidity and mortality in humans, particularly in the developing world. Diseases caused by certain protozoa are often more severe in the presence of HIV. While information regarding neglected tropical diseases caused by trypanosomatids and Plasmodium is abundant, these protozoa are often not a first consideration in Western countries where they are not endemic. As such, diagnostics may not be available in these regions. Due to global travel and immigration, this has become an increasing problem. Inversely, in certain parts of the world (particularly sub-Saharan Africa), the HIV problem is so severe that diseases like microsporidiosis and toxoplasmosis are common. In Western countries, due to the availability of highly active antiretroviral therapy (HAART), these diseases are infrequently encountered. While free-living amoebae are rarely encountered in a clinical setting, when infections do occur, they are often fatal. Rapid diagnosis and treatment are essential to the survival of patients infected with these organisms. This paper reviews information on the diagnosis and treatment of nonenteric protozoal diseases in immunocompromised people, with a focus on patients infected with HIV. The nonenteric microsporidia, some trypanosomatids, Toxoplasma spp., Neospora spp., some free-living amoebae, Plasmodium spp., and Babesia spp. are discussed.

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24

Lambrecht, Ellen, Julie Baré, Natascha Chavatte, Wim Bert, Koen Sabbe, and Kurt Houf. "Protozoan Cysts Act as a Survival Niche and Protective Shelter for Foodborne Pathogenic Bacteria." Applied and Environmental Microbiology 81, no. 16 (June 12, 2015): 5604–12. http://dx.doi.org/10.1128/aem.01031-15.

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ABSTRACTThe production of cysts, an integral part of the life cycle of many free-living protozoa, allows these organisms to survive adverse environmental conditions. Given the prevalence of free-living protozoa in food-related environments, it is hypothesized that these organisms play an important yet currently underinvestigated role in the epidemiology of foodborne pathogenic bacteria. Intracystic bacterial survival is highly relevant, as this would allow bacteria to survive the stringent cleaning and disinfection measures applied in food-related environments. The present study shows that strains of widespread and important foodborne bacteria (Salmonella enterica,Escherichia coli,Yersinia enterocolitica, andListeria monocytogenes) survive inside cysts of the ubiquitous amoebaAcanthamoeba castellanii, even when exposed to either antibiotic treatment (100 μg/ml gentamicin) or highly acidic conditions (pH 0.2) and resume active growth in broth media following excystment. Strain- and species-specific differences in survival periods were observed, withSalmonella entericasurviving up to 3 weeks inside amoebal cysts. Up to 53% of the cysts were infected with pathogenic bacteria, which were located in the cyst cytosol. Our study suggests that the role of free-living protozoa and especially their cysts in the persistence and epidemiology of foodborne bacterial pathogens in food-related environments may be much more important than hitherto assumed.

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25

Vaerewijck, Mario J. M., Julie Baré, Ellen Lambrecht, Koen Sabbe, and Kurt Houf. "Interactions of Foodborne Pathogens with Free-living Protozoa: Potential Consequences for Food Safety." Comprehensive Reviews in Food Science and Food Safety 13, no. 5 (August 19, 2014): 924–44. http://dx.doi.org/10.1111/1541-4337.12100.

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26

Santana Lima, Victor Fernando, Patrício Adriano Rocha, Mylena Adriele Dias Silva, Raone Beltrão-Mendes, Rafael Antonio Nascimento Ramos, Alessio Giannelli, Laura Rinaldi, Giuseppe Cringoli, Pedro Cordeiro Estrela, and Leucio Câmara Alves. "Survey on helminths and protozoa of free-living Neotropical bats from Northeastern Brazil." Acta Tropica 185 (September 2018): 267–72. http://dx.doi.org/10.1016/j.actatropica.2018.06.002.

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27

Sousa-Ramos, Djeniffer, María Reyes-Batlle, Natália K. Bellini, Rubén L. Rodríguez-Expósito, José E. Piñero, and Jacob Lorenzo-Morales. "Free-Living Amoebae in Soil Samples from Santiago Island, Cape Verde." Microorganisms 9, no. 7 (July 7, 2021): 1460. http://dx.doi.org/10.3390/microorganisms9071460.

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Free-Living Amoebae (FLA) are widely distributed protozoa, which contain some groups considered as pathogenic microorganisms. These members are able to produce several opportunistic diseases including epithelial disorders, such as keratitis and fatal encephalitis. Even though they have been reported in numerous sources, such as soils, dust and water, there is no legislation related to the presence of these protozoa in soil-related environments worldwide. Therefore, there are no established prevention or disinfection protocols to advise the population regarding FLA infections or eliminate these microorganisms from human-related environments to date. Acanthamoeba spp. are the most common FLA isolated in soil samples, which is also the most common genera found in clinical cases. Thus, the aim of the present study was to evaluate the presence of potentially pathogenic FLA in human-related soil samples of Santiago Island, Cabo Verde. A total of 26 soil samples were seeded in non-nutrient agar plates (2%), incubated at 26 °C, and monitored daily to evaluate the presence of FLA. DNA was extracted from those plates on which there was suspected FLA growth, and PCR amplification of the 18S rRNA gene was carried out. A total of 17 from the 26 analysed samples were positive for FLA, where Acanthamoeba is the most abundant isolated genus (14/17; 82.4%), with the T4 genotype being the most common (13/14; 92.9%), followed by the T5 genotype, A. lenticulata (1/14; 7.1%). Moreover, Vermamoeba vermiformis, Stenamoeba dejonckheerei and Vannella pentlandi were isolated in three other samples. To the best of our knowledge, this is the first report of FLA presence in Cape Verde and the first report of V. vermiformis in beach sand worldwide.

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28

Fouque, Emilie, Marie-Cécile Trouilhé, Vincent Thomas, Philippe Hartemann, Marie-Hélène Rodier, and Yann Héchard. "Cellular, Biochemical, and Molecular Changes during Encystment of Free-Living Amoebae." Eukaryotic Cell 11, no. 4 (February 24, 2012): 382–87. http://dx.doi.org/10.1128/ec.05301-11.

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ABSTRACTFree-living amoebae are protozoa found in soil and water. Among them, some are pathogenic and many have been described as potential reservoirs of pathogenic bacteria. Their cell cycle is divided into at least two forms, the trophozoite and the cyst, and the differentiation process is named encystment. As cysts are more resistant to disinfection treatments than trophozoites, many studies focused on encystment, but until recently, little was known about cellular, biochemical, and molecular modifications operating during this process. Important signals and signaling pathways at play during encystment, as well as cell responses at the molecular level, have been described. This review summarizes our knowledge and focuses on new findings.

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29

Guzmán-Téllez, Paula, Moisés Martínez-Castillo, Nadia Flores-Huerta, Gabriela Rosales-Morgan, Judith Pacheco-Yépez, Mireya de la Garza, Jesús Serrano-Luna, and Mineko Shibayama. "Lectins as virulence factors in Entamoeba histolytica and free-living amoebae." Future Microbiology 15, no. 10 (July 2020): 919–36. http://dx.doi.org/10.2217/fmb-2019-0275.

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Currently, there is growing interest in the identification and purification of microbial lectins due to their involvement in the pathogenicity mechanisms of pathogens, such as Entamoeba histolytica and free-living amoebae. The Gal/GalNAc lectin from E. histolytica participates in adhesion, cytotoxicity and regulation of immune responses. Furthermore, mannose- and galactose-binding protein have been described in Acanthamoeba castellanii and Balamuthia mandrillaris, respectively and they also contribute to host damage. Finally, in Naegleria fowleri, molecules containing mannose and fucose are implicated in adhesion and cytotoxicity. Considering their relevance in the pathogenesis of the diseases caused by these protozoa, lectins appear to be promising targets in the diagnosis, vaccination and treatment of these infections.

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30

Christophersen, C., A. D. Wright, and P. Vercoe. "Examining diversity of free-living methanogens and those associated with protozoa in the rumen." Journal of Animal and Feed Sciences 13, Suppl. 1 (August 30, 2004): 51–54. http://dx.doi.org/10.22358/jafs/73736/2004.

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31

Ellis, Jayne E., Kenneth D. R. Setchell, and Edna S. Kaneshiro. "Detection of ubiquinone in parasitic and free-living protozoa, including species devoid of mitochondria." Molecular and Biochemical Parasitology 65, no. 2 (June 1994): 213–24. http://dx.doi.org/10.1016/0166-6851(94)90073-6.

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32

Lambrecht, E., J. Baré, I. Van Damme, W. Bert, K. Sabbe, and K. Houf. "Behavior of Yersinia enterocolitica in the Presence of the Bacterivorous Acanthamoeba castellanii." Applied and Environmental Microbiology 79, no. 20 (August 9, 2013): 6407–13. http://dx.doi.org/10.1128/aem.01915-13.

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ABSTRACTFree-living protozoa play an important role in the ecology and epidemiology of human-pathogenic bacteria. In the present study, the interaction betweenYersinia enterocolitica, an important food-borne pathogen, and the free-living amoebaAcanthamoeba castellaniiwas studied. Several cocultivation assays were set up to assess the resistance ofY. enterocoliticatoA. castellaniipredation and the impact of environmental factors and bacterial strain-specific characteristics. Results showed that allY. enterocoliticastrains persist in association withA. castellaniifor at least 14 days, and associations withA. castellaniienhanced survival ofYersiniaunder nutrient-rich conditions at 25°C and under nutrient-poor conditions at 37°C. Amoebae cultivated in the supernatant of oneYersiniastrain showed temperature- and time-dependent permeabilization. Intraprotozoan survival ofY. enterocoliticadepended on nutrient availability and temperature, with up to 2.8 log CFU/ml bacteria displaying intracellular survival at 7°C for at least 4 days in nutrient-rich medium. Transmission electron microscopy was performed to locate theYersiniacells inside the amoebae. AsYersiniaandAcanthamoebashare similar ecological niches, this interaction identifies a role of free-living protozoa in the ecology and epidemiology ofY. enterocolitica.

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33

Strahl, Eileen D., Glenda E. Gillaspy, and Joseph O. Falkinham. "Fluorescent Acid-Fast Microscopy for Measuring Phagocytosis of Mycobacterium avium,Mycobacterium intracellulare, and Mycobacterium scrofulaceum by Tetrahymena pyriformis and Their Intracellular Growth." Applied and Environmental Microbiology 67, no. 10 (October 1, 2001): 4432–39. http://dx.doi.org/10.1128/aem.67.10.4432-4439.2001.

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ABSTRACT Fluorescent acid-fast microscopy (FAM) was used to enumerate intracellular Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium scrofulaceumin the ciliated phagocytic protozoan Tetrahymena pyriformis. There was a linear relationship between FAM and colony counts of M. avium cells both from cultures and within protozoa. The Ziehl-Neelsen acid-fast stain could not be used to enumerate intracellular mycobacteria because uninfected protozoa contained acid-fast, bacterium-like particles. Starved, 7-day-old cultures of T. pyriformis transferred into fresh medium readily phagocytized M. avium, M. intracellulare, and M. scrofulaceum. Phagocytosis was rapid and reached a maximum in 30 min. M. avium, M. intracellulare, and M. scrofulaceum grew within T. pyriformis, increasing by factors of 4- to 40-fold after 5 days at 30°C. Intracellular M. avium numbers remained constant over a 25-day period of growth (by transfer) of T. pyriformis. Intracellular M. avium cells also survived protozoan encystment and germination. The growth and viability of T. pyriformis were not affected by mycobacterial infection. The results suggest that free-living phagocytic protozoa may be natural hosts and reservoirs for M. avium, M. intracellulare, and M. scrofulaceum.

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Valster, Rinske M., Bart A. Wullings, Riemsdijk van den Berg, and Dick van der Kooij. "Relationships between Free-Living Protozoa, Cultivable Legionella spp., and Water Quality Characteristics in Three Drinking Water Supplies in the Caribbean." Applied and Environmental Microbiology 77, no. 20 (August 26, 2011): 7321–28. http://dx.doi.org/10.1128/aem.05575-11.

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ABSTRACTThe study whose results are presented here aimed at identifying free-living protozoa (FLP) and conditions favoring the growth of these organisms and cultivableLegionellaspp. in drinking water supplies in a tropical region. Treated and distributed water (±30°C) of the water supplies of three Caribbean islands were sampled and investigated with molecular techniques, based on the 18S rRNA gene. The protozoan hostHartmannella vermiformisand cultivableLegionella pneumophilawere observed in all three supplies. Operational taxonomic units (OTUs) with the highest similarity to the potential or candidate hostsAcanthamoebaspp.,Echinamoeba exundans,E. thermarum, and anNeoparamoebasp. were detected as well. In total, 59 OTUs of FLP were identified. The estimated protozoan richness did not differ significantly between the three supplies. In supply CA-1, the concentration ofH. vermiformiscorrelated with the concentration ofLegionellaspp. and clones related to Amoebozoa predominated (82%) in the protozoan community. These observations, the low turbidity (<0.2 nephelometric turbidity units [NTU]), and the varying ATP concentrations (1 to 12 ng liter−1) suggest that biofilms promoted protozoan growth in this supply. Ciliophora represented 25% of the protozoan OTUs in supply CA-2 with elevated ATP concentrations (maximum, 55 ng liter−1) correlating with turbidity (maximum, 62 NTU) caused by corroding iron pipes. Cercozoan types represented 70% of the protozoan clones in supply CA-3 with ATP concentrations of <1 ng liter−1and turbidity of <0.5 NTU in most samples of distributed water. The absence ofH. vermiformisin most samples from supply CA-3 suggests that growth of this protozoan is limited at ATP concentrations of <1 ng liter−1.

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35

Coppellotti, O., C. Fabris, M. Camerin, M. Magaraggia, M. Soncin, G. Jori, and L. Guidolin. "Potential of PDT for the treatment of diseases caused by parasitic and free-living protozoa." Photodiagnosis and Photodynamic Therapy 8, no. 2 (June 2011): 178. http://dx.doi.org/10.1016/j.pdpdt.2011.03.178.

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36

Quisehuatl-Tepexicuapan, E., R. Ferrera-Cerrato, H. V. Silva-Rojas, S. Rodriguez-Zaragoza, A. Alarcón, and J. J. Almaraz-Suárez. "Free-living culturable bacteria and protozoa from the rhizoplanes of three floating aquatic plant species." Plant Biosystems - An International Journal Dealing with all Aspects of Plant Biology 150, no. 5 (December 13, 2014): 855–65. http://dx.doi.org/10.1080/11263504.2014.989282.

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37

Lamrabet, Otmane, Vicky Merhej, Pierre Pontarotti, Didier Raoult, and Michel Drancourt. "The Genealogic Tree of Mycobacteria Reveals a Long-Standing Sympatric Life into Free-Living Protozoa." PLoS ONE 7, no. 4 (April 12, 2012): e34754. http://dx.doi.org/10.1371/journal.pone.0034754.

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38

Chavatte, N., J. Baré, E. Lambrecht, I. Van Damme, M. Vaerewijck, K. Sabbe, and K. Houf. "Co-occurrence of free-living protozoa and foodborne pathogens on dishcloths: Implications for food safety." International Journal of Food Microbiology 191 (November 2014): 89–96. http://dx.doi.org/10.1016/j.ijfoodmicro.2014.08.030.

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39

Fuller, Claire A. "Variable levels of immunity to experimental Eimetia arizonensis infections in natural, seminatural, and laboratory populations of deer mice (Peromyscus maniculatus)." Canadian Journal of Zoology 74, no. 4 (April 1, 1996): 750–57. http://dx.doi.org/10.1139/z96-085.

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Acquired immunity to parasites may affect both host and parasite population dynamics. Although immunity has been studied experimentally in laboratory-reared hosts, less attention has focused on free-living animals. I examined acquired immunity of free-living deer mice (Peromyscus maniculatus) to naturally occurring and experimental infections of Eimeria arizonensis (Protozoa: Coccidia). In a mark – recapture study, I found evidence of complete immunity to natural infections in only 1 of 3 years and evidence of partial immunity in all years. I subsequently examined partial immunity to experimental infections by giving laboratory-reared, free-living, and enclosure populations of deer mice two or three consecutive E. arizonensis infections. Greater than 90% (13 of 14) of laboratory-reared animals developed immunity after only one exposure, suggesting that E. arizonensis is immunogenic. However, significantly fewer animals living under natural and seminatural conditions developed immunity after one exposure in two of three experiments. These observational and experimental results suggest that immunocompetence of free-living deer mice to E. arizonensis may be variable and may differ with respect to that of laboratory-reared animals.

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40

Hegarty, R. S. "Reducing rumen methane emissions through elimination of rumen protozoa." Australian Journal of Agricultural Research 50, no. 8 (1999): 1321. http://dx.doi.org/10.1071/ar99008.

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Methanogens living on and within rumen ciliate protozoa may be responsible for up to 37% of the rumen methane emissions. In the absence of protozoa, rumen methane emissions are reduced by an average of 13% but this varies with diet. Decreased methane emissions from the protozoa-free rumen may be a consequence of: (1) reduced ruminal dry matter digestion; (2) a decreased methanogen population; (3) an altered pattern of volatile fatty acid production and hydrogen availability; or (4) increased partial pressure of oxygen in the rumen. The decline in methanogenesis associated with removal of protozoa is greatest on high concentrate diets and this is in keeping with protozoa being relatively more important sources of hydrogen on starch diets, because many starch-fermenting bacteria do not produce H2. Because protozoa also decrease the supply of protein available to the host animal, their elimination offers benefits in both decreasing greenhouse gas emissions and potentially increasing livestock production. Strategies for eliminating protozoa are reviewed. None of the available techniques is considered practical for commercial application and this should be addressed.

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Newsome, Anthony L., Tammy M. Scott, Robert F. Benson, and Barry S. Fields. "Isolation of an Amoeba Naturally Harboring a Distinctive Legionella Species." Applied and Environmental Microbiology 64, no. 5 (May 1, 1998): 1688–93. http://dx.doi.org/10.1128/aem.64.5.1688-1693.1998.

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ABSTRACT There are numerous in vitro studies documenting the multiplication of Legionella species in free-living amoebae and other protozoa. It is believed that protozoa serve as host cells for the intracellular replication of certain Legionella species in a variety of environmental settings. This study describes the isolation and characterization of a bacterium initially observed within an amoeba taken from a soil sample. In the laboratory, the bacterium multiplied within and was highly pathogenic for Acanthamoeba polyphaga. Extracellular multiplication was observed on buffered charcoal yeast extract agar but not on a variety of conventional laboratory media. A 16S rRNA gene analysis placed the bacterium within the genus Legionella. Serological studies indicate that it is distinct from previously described species of the genus. This report also describes methods that should prove useful for the isolation and characterization of additional Legionella-like bacteria from free-living amoebae. In addition, the characterization of bacterial pathogens of amoebae has significant implications for understanding the ecology and identification of other unrecognized bacterial pathogens.

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Pérez-Castiñeira, José R., Jorge Alvar, Luis M. Ruiz-Pérez, and Aurelio Serrano. "Evidence for a wide occurrence of proton-translocating pyrophosphatase genes in parasitic and free-living protozoa." Biochemical and Biophysical Research Communications 294, no. 3 (June 2002): 567–73. http://dx.doi.org/10.1016/s0006-291x(02)00517-x.

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43

Rivera, Fermín, Irma Rosas, Máximo Castillo, Mario Chávez, Rodolfo Gómez, Rosa E. Chío, and Jesús Islas. "Pathogenic and free-living protozoa cultured from the nasopharyngeal and oral regions of dental patients: II." Environmental Research 39, no. 2 (April 1986): 364–71. http://dx.doi.org/10.1016/s0013-9351(86)80062-7.

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Rønn, Regin, Mayra Gavito, John Larsen, Iver Jakobsen, Helle Frederiksen, and Søren Christensen. "Response of free-living soil protozoa and microorganisms to elevated atmospheric CO2 and presence of mycorrhiza." Soil Biology and Biochemistry 34, no. 7 (July 2002): 923–32. http://dx.doi.org/10.1016/s0038-0717(02)00024-x.

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Shanan, Salah, Hadi Abd, Magdi Bayoumi, Amir Saeed, and Gunnar Sandström. "Prevalence of Protozoa Species in Drinking and Environmental Water Sources in Sudan." BioMed Research International 2015 (2015): 1–5. http://dx.doi.org/10.1155/2015/345619.

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Protozoa are eukaryotic cells distributed worldwide in nature and are receiving increasing attention as reservoirs and potential vectors for the transmission of pathogenic bacteria. In the environment, on the other hand, many genera of the protozoa are human and animal pathogens. Only limited information is available on these organisms in developing countries and so far no information on their presence is available from Sudan. It is necessary to establish a molecular identification of species of the protozoa from drinking and environmental water. 600 water samples were collected from five states (Gadarif, Khartoum, Kordofan, Juba, and Wad Madani) in Sudan and analysed by polymerase chain reaction (PCR) and sequencing. 57 out of 600 water samples were PCR positive for protozoa. 38 out of the 57 positive samples were identified by sequencing to contain 66 protozoa species including 19 (28.8%) amoebae, 17 (25.7%) Apicomplexa, 25 (37.9%) ciliates, and 5 (7.6%) flagellates. This study utilized molecular methods identified species belonging to all phyla of protozoa and presented a fast and accurate molecular detection and identification of pathogenic as well as free-living protozoa in water uncovering hazards facing public health.

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Rodriguez-Zaragoza, Salvador, Einav Mayzlish, and Yosef Steinberger. "Vertical Distribution of the Free-Living Amoeba Population in Soil under Desert Shrubs in the Negev Desert, Israel." Applied and Environmental Microbiology 71, no. 4 (April 2005): 2053–60. http://dx.doi.org/10.1128/aem.71.4.2053-2060.2005.

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ABSTRACT A field study was designed to examine the effect of desert shrubs on the dynamics of free-living amoebae in arid soil. Soil samples from 0- to 50-cm depths were collected at 10-cm intervals in each of the four seasons. The vertical distributions of the four main morphological types of amoebae, grouped according to their mobility, and of small flagellate populations were measured under the canopies of Hammada scoparia and Atriplex halimus, shrubs belonging to the chloride-absorbing xerohalophytes. The result obtained from the field study demonstrated that the total number of protozoa was significantly higher during the wet seasons (winter and spring) than during the dry seasons. The protozoan population was more diverse under the canopy of H. scoparia during the wet seasons, reaching 8,000 individuals per 1 g of dry soil, whereas during the dry seasons, the populations were higher under the canopy of A. halimus, with a mean of 250 individuals. The protozoan population in the deeper layers (40 to 50 cm) was found to be as active as that in the upper layers, demonstrating that, in the desert, soil columns below 20 cm are fertile and worth studying. The type 1 amoebae (e.g., Acanthamoeba and Filamoeba spp.) were the most abundant throughout the study period, and their numbers were significantly higher than those of the other amoeba types.

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Üstüntürk-Onan, Miray. "Isolation and identification of free-living amoebae isolated from well water in Istanbul." Journal of Water and Health 18, no. 6 (November 17, 2020): 1139–45. http://dx.doi.org/10.2166/wh.2020.255.

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Abstract Free-living amoebae (FLA) are ubiquitous protozoa commonly found in water and soil environments. FLA belonging to various genera, including Acanthamoeba, Balamuthia, Naegleria, and Vermamoeba, can cause opportunistic and non-opportunistic infections in humans and animals such as keratitis or meningoencephalitis. In addition, some of them serve as hosts for a large number of pathogenic bacteria, yeasts, and viruses. The purpose of the present study was to assess the prevalence and molecular characterization of FLA in well water samples in İstanbul. Ten well water samples were collected from the taps and the presence of FLA was monitored both by the culture and polymerase chain reaction methods. FLA were isolated in 8 out of the 10 samples (80%) included in this study. Morphological analysis and partial sequencing of the 18S rDNA revealed the presence of Acanthamoeba genotypes T3 and T4, and Vermamoeba vermiformis in the investigated well water samples. This study reports for the first time the detection of Acanthamoeba genotype T3 in well water samples in İstanbul. The presence of potentially pathogenic amoebae in habitats related to human activities supports the relevance of FLA as a potential public health concern.

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Boratto, Paulo, Jonas Dutra Albarnaz, Gabriel Magno de Freitas Almeida, Lucas Botelho, Alide Caroline Lima Fontes, Adriana Oliveira Costa, Daniel de Assis Santos, et al. "Acanthamoeba polyphaga Mimivirus Prevents Amoebal Encystment-Mediating Serine Proteinase Expression and Circumvents Cell Encystment." Journal of Virology 89, no. 5 (December 17, 2014): 2962–65. http://dx.doi.org/10.1128/jvi.03177-14.

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Acanthamoebais a genus of free-living amoebas distributed worldwide. Few studies have explored the interactions between these protozoa and their infecting giant virus,Acanthamoeba polyphagamimivirus (APMV). Here we show that, once the amoebal encystment is triggered, trophozoites become significantly resistant to APMV. Otherwise, upon infection, APMV is able to interfere with the expression of a serine proteinase related to amoebal encystment and the encystment can no longer be triggered.

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Stott, R., E. May, E. Ramirez, and A. Warren. "Predation of Cryptosporidium oocysts by protozoa and rotifers: implications for water quality and public health." Water Science and Technology 47, no. 3 (February 1, 2003): 77–83. http://dx.doi.org/10.2166/wst.2003.0166.

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Predation by free-living protozoa and rotifers was investigated as a possible mechanism for the removal of Cryptosporidium parvum oocysts in aquatic ecosystems including wastewater treatment plants. Free-living ciliated protozoa (Stylonychia mytilus, Paramecium caudatum and an unidentified wastewater wetland ciliate), an amoeba (Acanthamoeba culbertsoni) and rotifers, all commonly found in aquatic ecosystems, were exposed to varying doses of C. parvum oocysts. All organisms investigated ingested oocysts. Predation activity and rates of ingestion varied with predator species and prey density. Ciliated protozoa demonstrated greater predation activity than A. culbertsoni or rotifers when exposed to 2 × 105 oocyst/mL for up to 3 h. Greatest predation after 1 h exposure was observed in P. caudatum, the largest ciliate, with on average 1.9 oocysts/cell (range 0-9 oocysts/cell). Stylonychia mytilus and the wetland ciliate had a similar mean ingestion of around 0.3 oocysts/cell, with numbers internalised ranging from 0-3 oocysts/cell. Rotifers ingested on average 1.6 oocysts/individual (range 0-7 oocysts/individual) whilst amoebae ingested on average 1.8 oocysts/cell after 2 h exposure (up to 3 oocysts/cell). Grazing activity by P. caudatum was demonstrated at a variety of prey levels ranging from 9 to 9,000 oocysts. Numbers of oocysts internalised by Paramecium frequently exceeded the reported human infective dose of 30 oocysts. In general, numbers of internalised oocysts increased with incubation time of up to 20-30 min although the rate of accumulation was slower at lower dose levels. The significance of predation on the fate of Cryptosporidium oocysts in the environment is discussed.

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Dellow, DW, ID Hume, RTJ Clarke, and T. Bauchop. "Microbial Activity in the Forestomach of Free-Living Macropodid Marsupials - Comparisons With Laboratory Studies." Australian Journal of Zoology 36, no. 4 (1988): 383. http://dx.doi.org/10.1071/zo9880383.

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Parameters of fermentative digestion were measured in five species of macropodid marsupials shot while feeding in the wild. These included details of microbiota, fermentation products (volatile fatty acids, gas, ammonia) and forestomach digesta pH. Ciliate protozoa and fungi, similar to anaerobic rumen fungi, were present in the forestomach of all species except Thylogale thetis. The bacterial flora was complex and numbers were similar to those in the ruminant forestomach. The forestomach gas contained more methane than found previously in captive macropodids, and in Wallabia bicolor hydrogen was present at 10- 11% of total gas. The pH of forestomach digesta was 5.7-6.7, indicative of animals actively feeding. Comparisons of stomach fill, ammonia and volatile fatty acid (VFA) concentrations and molar proportions, and rates of VFA production in the forestomach and hindgut, indicated that conclusions on digestive function in macropodids derived from studies on captive animals are generally applicable to free-living macropodids. The main differences probably lie in greater levels of feed intake in the field, and in greater opportunity for free-living macropodids to select from a more heterogeneous diet.

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