Journal articles: 'Nitrogen Nitrogen-fixing microorganisms. Klebsiella pneumoniae'

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Lawal, I., and I. Yusuf. "Physicochemical and Characterization of Nitrogen Fixing Bacteria from Soil Samples Within the Vicinity of Telecommunication Mast (Site No: 000148) Located at Karfi Town Kura Local Government, Kano State." UMYU Journal of Microbiology Research (UJMR) 6, no. 1 (June 30, 2021): 77–85. http://dx.doi.org/10.47430/ujmr.2161.010.

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The telecommunication mast associated-radiation is one of the primary factors influencing the way in which microorganisms interact with ecosystem. This study aims to assess the physicochemical and non-symbiotic nitrogen fixing bacteria (NNFB) from soil samples within the vicinity of telecommunication mast located at Karfi town Kura local government Kano state. Soil samples A, B, and C were collected within the vicinity of the mast at an interval of 10 meters, 20 meters and 30 meters from the mast respectively and control sample (D) was collected from location *(outside the vicinity of the mast)*. Physicochemical parameters of the soil samples were analyzed, isolation and identification of non-symbiotic nitrogen fixing bacteria were carried out using standard procedures. Samples B showed higher values of pH (8.02), phosphorus (23.95mg/kg), organic carbon (1.45%), nitrogen (0.28%) and organic matter content (2.50%) while control sample (D) showed lower values with 6.24, 2.77mg/kg, 0.41%, 0.07% and 0.71% of pH, phosphorus, organic carbon, nitrogen and organic matter content respectively. However, the moisture content(0.21%) of control sample is higher than that of sample A and B with 0.12% and 0.11% respectively The mean count of NNFB of the soil samples were 3.20 ± 0.06, 1.80± 0.12, 1.40±0.23, 1.20±0.20 for sample B, C, A and D respectively. Total of 14 isolates of the species Azomonas agilis 1(7.14%), Azotomonas insolita 1(7.14%), Bacillus megaterium 2(14.28 %), Bacillus azotoformans 1(7.14%), Bacillus mycoides 3(21.42%), Enterobacter cloacae 3(21.42%), and Klebsiella pneumonia 3(21.42%) were obtained. This indicates that the electromagnetic radiation from the mast has no effect on soil physicochemical parameters as well as non symbiotic nitrogen fixing bacteria proliferation. Key words: Non symbiotic Bacteria, telecommunication mast

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Berman, Donald, Robert Sullivan, and Christon J. Hurst. "Effect of the method of preparing monochloramine upon inactivation of MS2 coliphage, Escherichia coli, and Klebsiella pneumoniae." Canadian Journal of Microbiology 38, no. 1 (January 1, 1992): 28–33. http://dx.doi.org/10.1139/m92-004.

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Monochloramine prepared in situ by first adding chlorine to a suspension of microorganisms, followed by subsequent addition of ammonia, inactivated the MS2 coliphage more rapidly than did exposure of phage to monochloramine prepared either by adding chlorine to ammonia or by adding chlorine and ammonia simultaneously. The rapid viral inactivation was apparently due to the exposure of MS2 to free chlorine before the addition of ammonia. The average 99% CT value of MS2 when exposed to free chlorine was 1.3 and 1.1 at 5 and 15 °C, respectively. The average 99% CT values of MS2 briefly exposed to the combined action of free chlorine followed by the addition of ammonia to form monochloramine in situ were 19.3 and 1.5 at 5 and 15 °C, respectively. No 99% CT values were calculated for the inactivation of MS2 with preformed monochloramine because less than 1 log (90%) of inactivation occurred during a 4-h contact time. Inactivation of MS2 by monochloramine was more rapid at 15 than at 5 °C and when the chlorine to nitrogen weight ratio was 5:1 compared with 3:1. Monochloramine was a more efficient inactivating agent for the coliforms Escherichia coli and Klebsiella pneumoniae than it was for the MS2 coliphage. Key words: chlorine, monochloramine, virus, bacteria, disinfection.

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Mpongwana, Ncumisa, Seteno K. O. Ntwampe, Elizabeth I. Omodanisi, Boredi S. Chidi, and Lovasoa C. Razanamahandry. "Sustainable Approach to Eradicate the Inhibitory Effect of Free-Cyanide on Simultaneous Nitrification and Aerobic Denitrification during Wastewater Treatment." Sustainability 11, no. 21 (November 5, 2019): 6180. http://dx.doi.org/10.3390/su11216180.

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Simultaneous nitrification and aerobic denitrification (SNaD) is a preferred method for single stage total nitrogen (TN) removal, which was recently proposed to improve wastewater treatment plant design. However, SNaD processes are prone to inhibition by toxicant loading with free cyanide (FCN) possessing the highest inhibitory effect on such processes, rendering these processes ineffective. Despite the best efforts of regulators to limit toxicant disposal into municipal wastewater sewage systems (MWSSs), FCN still enters MWSSs through various pathways; hence, it has been suggested that FCN resistant or tolerant microorganisms be utilized for processes such as SNaD. To mitigate toxicant loading, organisms in SNaD have been observed to adopt a diauxic growth strategy to sequentially degrade FCN during primary growth and subsequently degrade TN during the secondary growth phase. However, FCN degrading microorganisms are not widely used for SNaD in MWSSs due to inadequate application of suitable microorganisms (Chromobacterium violaceum, Pseudomonas aeruginosa, Thiobacillus denitrificans, Rhodospirillum palustris, Klebsiella pneumoniae, and Alcaligenes faecalis) commonly used in single-stage SNaD. This review expatiates the biological remedial strategy to limit the inhibition of SNaD by FCN through the use of FCN degrading or resistant microorganisms. The use of FCN degrading or resistant microorganisms for SNaD is a cost-effective method compared to the use of other methods of FCN removal prior to TN removal, as they involve multi-stage systems (as currently observed in MWSSs). The use of FCN degrading microorganisms, particularly when used as a consortium, presents a promising and sustainable resolution to mitigate inhibitory effects of FCN in SNaD.

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Iniguez, A. Leonardo, Yuemei Dong, and Eric W. Triplett. "Nitrogen Fixation in Wheat Provided by Klebsiella pneumoniae 342." Molecular Plant-Microbe Interactions® 17, no. 10 (October 2004): 1078–85. http://dx.doi.org/10.1094/mpmi.2004.17.10.1078.

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In this report, all of the criteria necessary for the demonstration of nitrogen fixation in wheat (Triticum aestivum L.), the world's most important crop, are shown upon inoculation with a nitrogen-fixing bacterium, Klebsiella pneumoniae 342 (Kp342). Kp342 relieved nitrogen (N) deficiency symptoms and increased total N and N concentration in the plant. Nitrogen fixation was confirmed by 15N isotope dilution in the plant tissue and in a plant product, chlorophyll. All of these observations were in contrast to uninoculated plants, plants inoculated with a nitrogen-fixing mutant of Kp342, and plants inoculated with dead Kp342 cells. Nitrogenase reductase was produced by Kp342 in the intercellular space of the root cortex. Wild-type Kp342 and the nifH mutant colonized the interior of wheat roots in equal numbers on a fresh weight basis. The nitrogen fixation phenotype described here was specific to cv. Trenton. Inoculation of cvs. Russ or Stoa with Kp342 resulted in no relief of nitrogen deficiency symptoms.

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Machray, G. C., and W. D. P. Stewart. "Genetics of plant-microbe nitrogen-fixing symbiosis." Proceedings of the Royal Society of Edinburgh. Section B. Biological Sciences 85, no. 3-4 (1985): 239–52. http://dx.doi.org/10.1017/s0269727000004048.

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SynopsisA wide variety of plant-microbe nitrogen-fixing symbioses which include cyanobacteria as the nitrogenfixing partner exist. While some information has been gathered on the biochemical changes in the cyanobacterium upon entering into symbiosis, very little is known about the accompanying changes at the genetic level. Much of our present knowledge of the organisation and control of expression of nitrogenfixation (nif) genes is derived from studies of the free-living diazotroph Klebsiella pneumoniae. This organism thus provides a model system and source of experimental material for the genetic analysis of symbiotic nitrogen fixation. We describe the use of cloned K. pneumoniae genes for nitrogen fixation and its regulation in the genetic analysis' of nitrogen fixation in cyanobacteria which can enter into symbiosis with plants. These studies reveal some dissimilarities in the organisation of nif genes and raise questions as to the genetic control of nitrogen fixation in symbiosis.

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Jacob, G. S., J. Schaefer, J. R. Garbow, and E. O. Stejskal. "Solid-state NMR studies of Klebsiella pneumoniae grown under nitrogen-fixing conditions." Journal of Biological Chemistry 262, no. 1 (January 1987): 254–59. http://dx.doi.org/10.1016/s0021-9258(19)75919-5.

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Milenkov, M., R. Thummer, J. Gloer, J. Grotzinger, S. Jung, and R. A. Schmitz. "Insights into Membrane Association of Klebsiella pneumoniae NifL under Nitrogen-Fixing Conditions from Mutational Analysis." Journal of Bacteriology 193, no. 3 (November 5, 2010): 695–705. http://dx.doi.org/10.1128/jb.00775-10.

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Doolittle, Mark, Ashok Raina, Alan Lax, and Raj Boopathy. "Presence of nitrogen fixing Klebsiella pneumoniae in the gut of the Formosan subterranean termite (Coptotermes formosanus)." Bioresource Technology 99, no. 8 (May 2008): 3297–300. http://dx.doi.org/10.1016/j.biortech.2007.07.013.

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Brostedt, E., and S. Nordlund. "Purification and partial characterization of a pyruvate oxidoreductase from the photosynthetic bacterium Rhodospirillum rubrum grown under nitrogen-fixing conditions." Biochemical Journal 279, no. 1 (October 1, 1991): 155–58. http://dx.doi.org/10.1042/bj2790155.

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A pyruvate oxidoreductase with the capacity to support pyruvate-dependent nitrogenase activity in vitro has been purified from the photosynthetic bacterium Rhodospirillum rubrum. The enzyme requires CoA for activity and is irreversibly inactivated by oxygen. The molecular properties and Km values for the substrates have been studied. In supporting nitrogenase activity addition of ferredoxin is required. Overall the enzyme is similar to the nif-specific pyruvate: flavodoxin oxidoreductase purified from Klebsiella pneumoniae.

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Jones, K., and S. B. Bradshaw. "Biofilm formation by the Enterobacteriaceae: a comparison between Salmonella enteritidis, Escherichia coli and a nitrogen-fixing strain of Klebsiella pneumoniae." Journal of Applied Bacteriology 80, no. 4 (April 1996): 458–64. http://dx.doi.org/10.1111/j.1365-2672.1996.tb03243.x.

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Reiter, Birgit, Helmut Bürgmann, Kornel Burg, and Angela Sessitsch. "EndophyticnifHgene diversity in African sweet potato." Canadian Journal of Microbiology 49, no. 9 (September 1, 2003): 549–55. http://dx.doi.org/10.1139/w03-070.

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A cultivation-independent approach was used to identify potentially nitrogen-fixing endophytes in seven sweet potato varieties collected in Uganda and Kenya. Nitrogenase reductase genes (nifH) were amplified by PCR, and amplicons were cloned in Escherichia coli. Clones were grouped by restriction fragment length polymorphism analysis, and representative nifH genes were sequenced. The resulting sequences had high homologies to nitrogenase reductases from α-, β-, and γ-Proteobacteria and low G+C Gram positives, however, about 50% of the sequences derived from rhizobia. Several highly similar or even identical nitrogenase reductase sequences clustering with different bacterial genera and species, including Sinorhizobium meliloti, Rhizobium sp. NGR234, Rhizobium etli, Klebsiella pneumoniae, and Paenibacillus odorifer, could be detected in different plants grown in distinct geographic locations. This suggests that these bacterial species preferentially colonize African sweet potato as endophytes and that the diazotrophic, endophytic microflora is determined only to a low degree by the plant genotype or the soil microflora.Key words: endophytes, nitrogenase reductase, nifH, nitrogen fixation, sweet potato.

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Martínez, Marta, José M. Palacios, Juan Imperial, and Tomás Ruiz-Argüeso. "Symbiotic Autoregulation of nifA Expression in Rhizobium leguminosarum bv. viciae." Journal of Bacteriology 186, no. 19 (October 1, 2004): 6586–94. http://dx.doi.org/10.1128/jb.186.19.6586-6594.2004.

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ABSTRACT NifA is the general transcriptional activator of nitrogen fixation genes in diazotrophic bacteria. In Rhizobium leguminosarum bv. viciae UPM791, the nifA gene is part of a gene cluster (orf71 orf79 fixW orf5 fixABCX nifAB) separated by 896 bp from an upstream and divergent truncated duplication of nifH (ΔnifH). Symbiotic expression analysis of genomic nifA::lacZ fusions revealed that in strain UPM791 nifA is expressed mainly from a σ54-dependent promoter (P nifA1 ) located upstream of orf71. This promoter contains canonical NifA upstream activating sequences located 91 bp from the transcription initiation site. The transcript initiated in P nifA1 spans 5.1 kb and includes nifA and nifB genes. NifA from Klebsiella pneumoniae was able to activate transcription from P nifA1 in a heterologous Escherichia coli system. In R. leguminosarum, the P nifA1 promoter is essential for effective nitrogen fixation in symbiosis with peas. In its absence, partially efficient nitrogen-fixing nodules were produced, and the corresponding bacteroids exhibited only low levels of nifA gene expression. The basal level of nifA expression resulted from a promoter activity originating upstream of the fixX-nifA intergenic region and probably from an incomplete duplication of P nifA1 located immediately upstream of fixA.

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Gauthier, Francis, Josh D. Neufeld, Brian T. Driscoll, and Frederick S. Archibald. "Coliform Bacteria and Nitrogen Fixation in Pulp and Paper Mill Effluent Treatment Systems." Applied and Environmental Microbiology 66, no. 12 (December 1, 2000): 5155–60. http://dx.doi.org/10.1128/aem.66.12.5155-5160.2000.

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ABSTRACT The majority of pulp and paper mills now biotreat their combined effluents using activated sludge. On the assumption that their wood-based effluents have negligible fixed N, and that activated-sludge microorganisms will not fix significant N, these mills routinely spend large amounts adding ammonia or urea to their aeration tanks (bioreactors) to permit normal biomass growth. N2 fixation in seven Eastern Canadian pulp and paper mill effluent treatment systems was analyzed using acetylene reduction assays, quantitative nitrogenase (nifH) gene probing, and bacterial isolations. In situ N2 fixation was undetectable in all seven bioreactors but was present in six associated primary clarifiers. One primary clarifier was studied in greater detail. Approximately 50% of all culturable cells in the clarifier contained nifH, of which >90% were Klebsiella strains. All primary-clarifier coliform bacteria growing on MacConkey agar were identified as klebsiellas, and all those probed contained nifH. In contrast, analysis of 48 random coliform isolates from other mill water system locations showed that only 24 (50%) possessed thenifH gene, and only 13 (27%) showed inducible N2-fixing activity. Thus, all the pulp and paper mill primary clarifiers tested appeared to be sites of active N2fixation (0.87 to 4.90 mg of N liter−1 day−1) and a microbial community strongly biased toward this activity. This may also explain why coliform bacteria, especially klebsiellas, are indigenous in pulp and paper mill water systems.

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Liu, Yang, Hui Wang, Xiaolu Sun, Hailian Yang, Yunshan Wang, and Wei Song. "Study on Mechanisms of Colonization of Nitrogen-Fixing PGPB, Klebsiella pneumoniae NG14 on the Root Surface of Rice and the Formation of Biofilm." Current Microbiology 62, no. 4 (December 7, 2010): 1113–22. http://dx.doi.org/10.1007/s00284-010-9835-7.

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Achouak, Wafa, Jean-Marie Pages, Rene De Mot, Gerard Molle, and Thierry Heulin. "A Major Outer Membrane Protein of Rahnella aquatilisFunctions as a Porin and Root Adhesin." Journal of Bacteriology 180, no. 4 (February 15, 1998): 909–13. http://dx.doi.org/10.1128/jb.180.4.909-913.1998.

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ABSTRACT A 38-kDa major outer membrane protein (OMP) was isolated from the nitrogen-fixing enterobacterium Rahnella aquatilis CF3. This protein exists as a stable trimer in the presence of 2% sodium dodecyl sulfate at temperatures below 60°C. Single channel experiments showed that this major OMP of R. aquatilis CF3 is able to form pores in the planar lipid membrane. Two oligonucleotides encoding the N-terminal portion of the 38-kDa OMP and C-terminal portion of OmpC were used to amplify the 38-kDa gene by PCR. The deduced amino acid sequence showed a strong homology withEscherichia coli, Klebsiella pneumoniae,Salmonella typhi, and Serratia marcescens OmpC sequences, except loops L6 and L7, which are postulated to be cell surface exposed. On the basis of the OmpF-PhoE three-dimensional structure, it seems likely that this 38-kDa organizes three 16-strand β-barrel subunits. The relationship between the structure and the double functionality of this protein as porin and as a root adhesin is discussed.

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Zhang, Yaoping, Edward L. Pohlmann, Cale M. Halbleib, Paul W. Ludden, and Gary P. Roberts. "Effect of PII and Its Homolog GlnK on Reversible ADP-Ribosylation of Dinitrogenase Reductase by Heterologous Expression of the Rhodospirillum rubrum Dinitrogenase Reductase ADP-Ribosyl Transferase–Dinitrogenase Reductase-Activating Glycohydrolase Regulatory System inKlebsiella pneumoniae." Journal of Bacteriology 183, no. 5 (March 1, 2001): 1610–20. http://dx.doi.org/10.1128/jb.183.5.1610-1620.2001.

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ABSTRACT Reversible ADP-ribosylation of dinitrogenase reductase, catalyzed by the dinitrogenase reductase ADP-ribosyl transferase–dinitrogenase reductase-activating glycohydrolase (DRAT-DRAG) regulatory system, has been characterized in Rhodospirillum rubrum and other nitrogen-fixing bacteria. To investigate the mechanisms for the regulation of DRAT and DRAG activities, we studied the heterologous expression of R. rubrum draTG in Klebsiella pneumoniae glnB and glnK mutants. In K. pneumoniae wild type, the regulation of both DRAT and DRAG activity appears to be comparable to that seen in R. rubrum. However, the regulation of both DRAT and DRAG activities is altered in a glnB background. Some DRAT escapes regulation and becomes active under N-limiting conditions. The regulation of DRAG activity is also altered in a glnBmutant, with DRAG being inactivated more slowly in response to NH4 + treatment than is seen in wild type, resulting in a high residual nitrogenase activity. In aglnK background, the regulation of DRAT activity is similar to that seen in wild type. However, the regulation of DRAG activity is completely abolished in the glnK mutant; DRAG remains active even after NH4 + addition, so there is no loss of nitrogenase activity. The results with this heterologous expression system have implications for DRAT-DRAG regulation inR. rubrum.

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Rueda-Puente, E., T. Castellanos, E. Troyo-Dieguez, J. L. Diaz de Leon-Alvarez, and B. Murillo-Amador. "Effects of a Nitrogen-Fixing Indigenous Bacterium (Klebsiella pneumoniae) on the Growth and Development of the Halophyte Salicornia bigelovii as a New Crop for Saline Environments." Journal of Agronomy and Crop Science 189, no. 5 (October 2003): 323–32. http://dx.doi.org/10.1046/j.1439-037x.2003.00051.x.

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Deistung, J., and R. N. F. Thorneley. "Electron transfer to nitrogenase. Characterization of flavodoxin from Azotobacter chroococcum and comparison of its redox potentials with those of flavodoxins from Azotobacter vinelandii and Klebsiella pneumoniae (nifF-gene product)." Biochemical Journal 239, no. 1 (October 1, 1986): 69–75. http://dx.doi.org/10.1042/bj2390069.

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Flavodoxin in the hydroquinone state acts as an electron donor to nitrogenase in several nitrogen-fixing organisms. The mid-point potentials for the oxidized-semiquinone and semiquinone-hydroquinone couples of flavodoxins isolated from facultative anaerobe Klebsiella pneumoniae (nifF-gene product, KpFld) and the obligate aerobe Azotobacter chroococcum (AcFld) were determined as a function of pH. The mid-point potentials of the semiquinone-hydroquinone couples of KpFld and AcFld are essentially independent of pH over the range pH 7-9, being -422 mV and -522 mV (normal hydrogen electrode) at pH 7.5 respectively. The mid-point potentials of the quinone-semiquinone couples at pH 7.5 are -200 mV (KpFld) and -133 mV (AcFld) with delta Em/pH of -65 +/- 4 mV (KpFld) and -55 +/- 2 mV (AcFld) over the range pH 7.0-9.5. This indicates that reduction of the quinone is coupled to protonation to yield a neutral semiquinone. The significance of these values with respect to electron transport to nitrogenase is discussed. The amino acid compositions, the N- and C-terminal amino acid sequences and the u.v.-visible spectra of KpFld and AcFld were determined and are compared with published data for flavodoxins isolated from Azotobacter vinelandii.

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Thorneley, R. N. F., and G. A. Ashby. "Oxidation of nitrogenase iron protein by dioxygen without inactivation could contribute to high respiration rates of Azotobacter species and facilitate nitrogen fixation in other aerobic environments." Biochemical Journal 261, no. 1 (July 1, 1989): 181–87. http://dx.doi.org/10.1042/bj2610181.

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The kinetics of oxidation of the Fe proteins of nitrogenases from Klebsiella pneumoniae (Kp2) and Azotobacter chroococcum (Ac2) by O2 and H2O2 have been studied by stopped-flow spectrophotometry at 23 degrees C, pH 7.4. With excess O2, one-electron oxidation of Kp2 and Ac2 and their 2 MgATP or 2 MgADP bound forms occurs with rate constants (k) in the range 5.3 x 10(3) M-1.S-1 to 1.6 x 10(5) M-1.S-1. A linear correlation between log k and the mid-point potentials (Em) of these protein species indicates that the higher rates of electron transfer from the Ac2 species are due to the differences in Em of the 4Fe-4S cluster. The reaction of Ac2(MgADP)2 with O2 is sufficiently rapid for it to contribute significantly to the high respiration rate of Azotobacter under N2-fixing conditions and may represent a new respiratory pathway. Excess O2 rapidly inactivates Ac2(MgADP)2 and Kp2(MgADP)2; however, when these protein species are in greater than 4-fold molar excess over the concentration of O2, 4 equivalents of protein are oxidized with no loss of activity. The kinetics of this reaction suggest that H2O2 is an intermediate in the reduction of O2 to 2 H2O by nitrogenase Fe proteins and imply a role for catalase or peroxidase in the mechanism of protection of nitrogenase from O2-induced inactivation.

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Li, Yongbin, Qin Li, and Sanfeng Chen. "Diazotroph Paenibacillus triticisoli BJ-18 Drives the Variation in Bacterial, Diazotrophic and Fungal Communities in the Rhizosphere and Root/Shoot Endosphere of Maize." International Journal of Molecular Sciences 22, no. 3 (February 2, 2021): 1460. http://dx.doi.org/10.3390/ijms22031460.

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Application of diazotrophs (N2-fixing microorganisms) can decrease the overuse of nitrogen (N) fertilizer. Until now, there are few studies on the effects of diazotroph application on microbial communities of major crops. In this study, the diazotrophic and endospore-forming Paenibacillus triticisoli BJ-18 was inoculated into maize soils containing different N levels. The effects of inoculation on the composition and abundance of the bacterial, diazotrophic and fungal communities in the rhizosphere and root/shoot endosphere of maize were evaluated by sequencing the 16S rRNA, nifH gene and ITS (Inter Transcribed Spacer) region. P. triticisoli BJ-18 survived and propagated in all the compartments of the maize rhizosphere, root and shoot. The abundances and diversities of the bacterial and diazotrophic communities in the rhizosphere were significantly higher than in both root and shoot endospheres. Each compartment of the rhizosphere, root and shoot had its specific bacterial and diazotrophic communities. Our results showed that inoculation reshaped the structures of the bacterial, diazotrophic and fungal communities in the maize rhizosphere and endosphere. Inoculation reduced the interactions of the bacteria and diazotrophs in the rhizosphere and endosphere, while it increased the fungal interactions. After inoculation, the abundances of Pseudomonas, Bacillus and Paenibacillus in all three compartments, Klebsiella in the rhizosphere and Paenibacillus in the root and shoot were significantly increased, while the abundances of Fusarium and Giberella were greatly reduced. Paenibacillus was significantly correlated with plant dry weight, nitrogenase, N2-fixing rate, P solubilization and other properties of the soil and plant.

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Prashanthi, R., Shreevatsa G.K., Krupalini S., and Manoj L. "Isolation, characterization, and molecular identification of soil bacteria showing antibacterial activity against human pathogenic bacteria." Journal of Genetic Engineering and Biotechnology 19, no. 1 (August 18, 2021). http://dx.doi.org/10.1186/s43141-021-00219-x.

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Abstract Background The present study dealt with the screening of soil bacteria with antibacterial activity from different locations in Bangalore, India. Antibiotics play the role of self-defense mechanism for the bacteria and are produced as secondary metabolites to protect themselves from other competitive microorganisms. The need for new antibiotics arose as the pathogenic bacteria acquire resistance to various antibiotics meant for treating human diseases. Given the importance of antibiotics of bacterial origin, standard techniques have been used to isolate and characterize the soil bacteria which showed antibacterial activity. Results The isolated bacteria were tested against human pathogenic bacteria like Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae by primary and secondary screening methods. The isolates PR1, PR2, and PR3 were confirmed to have antibacterial activity against S. aureus, E. coli, P. aeruginosa, and K. pneumoniae by both methods. Studies on the effect of filter sterilization, autoclaving, and proteinase K treatment on culture filtrates showed filter sterilization as the best method. The effect of different carbon and nitrogen sources on the antibacterial activity showed that preference by each isolate differed for carbon and nitrogen requirements. The isolates PR1, PR2, and PR3 were identified as Bacillus aryabhattai strain PR-D07, Arthrobacter humicola strain PR-F07, and Neomicrococcus lactis strain PR-F11 through 16S rRNA sequencing. Conclusion Findings from this research work are encouraging and could proceed further to applied aspects. Only 3 bacterial isolates out of 263 isolates from soil samples displayed antibacterial activity against human pathogens S. aureus, E. coli, P. aeruginosa, and K. pneumoniae. They were identified as B. aryabhattai, A. humicola, and N. lactis by 16S rRNA studies and all of them are Gram-positive. Each isolate preferred different carbon and nitrogen sources for their enhanced antibacterial activity. Efficacy of the culture filtrates of these isolates was tested by filter sterilization, autoclaving, and proteinase K treatment. Filter-sterilized culture filtrates showed higher antibacterial activity than other treatments. A comparison of the antibacterial activity of culture filtrates and antibiotic streptomycin produced an inhibition zone of 18.5 mm and 15.5 mm respectively. This is the first report on the antibacterial activity of all the 3 bacterial strains (B. aryabhattai strain PR-D07, A. humicola strain PR-F07, and N. lactis strain PR-F11), against all the human pathogens, mentioned earlier. It is also found that the antibiotic factor is proteinaceous as proteinase K considerably reduced the antibacterial activity of the culture filtrates. With the above significant results, these 3 bacteria are considered to be promising candidates for the isolation of new antibacterial agents.

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Rizo, Jocelin, Marco A. Rogel, Daniel Guillén, Carmen Wacher, Esperanza Martinez-Romero, Sergio Encarnación, Sergio Sánchez, and Romina Rodríguez-Sanoja. "Nitrogen Fixation in Pozol, a Traditional Fermented Beverage." Applied and Environmental Microbiology 86, no. 16 (June 5, 2020). http://dx.doi.org/10.1128/aem.00588-20.

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ABSTRACT Traditional fermentations have been widely studied from the microbiological point of view, but little is known from the functional perspective. In this work, nitrogen fixation by free-living nitrogen-fixing bacteria was conclusively demonstrated in pozol, a traditional Mayan beverage prepared with nixtamalized and fermented maize dough. Three aspects of nitrogen fixation were investigated to ensure that fixation actually happens in the dough: (i) the detection of acetylene reduction activity directly in the substrate, (ii) the presence of potential diazotrophs, and (iii) an in situ increase in acetylene reduction by inoculation with one of the microorganisms isolated from the dough. Three genera were identified by sequencing the 16S rRNA and nifH genes as Kosakonia, Klebsiella, and Enterobacter, and their ability to fix nitrogen was confirmed. IMPORTANCE Nitrogen-fixing bacteria are found in different niches, as symbionts in plants, in the intestinal microbiome of several insects, and as free-living microorganisms. Their use in agriculture for plant growth promotion via biological nitrogen fixation has been extensively reported. This work demonstrates the ecological and functional importance that these bacteria can have in food fermentations, reevaluating the presence of these genera as an element that enriches the nutritional value of the dough.

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Kapila, Rachna, Geeta Verma, Aparajita Sen, and Arti Nigam. "Evaluation of Microbiological Quality of Vermicompost Prepared from Different Types of Organic Wastes using Eisenia fetida." Agricultural Science Digest - A Research Journal, Of (March 4, 2021). http://dx.doi.org/10.18805/ag.d-5275.

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Background: Vermicomposting is the agricultural technique of conversion of organic wastes to a fertile product, which can result in better crop growth and production. However, even though earthworms are the main organisms participating in the process, the microbes associated with it also have an important role to play. These microbes degrade the waste products biochemically and are responsible of the conversion processes. Few studies are carried out on microbial diversity and related enzymes activities in the vermicompost prepared from different organic waste materials. Methods: In this paper, we isolated both bacteria and fungi from seven different types of vermicompost, using different selective media. We also studied the activity of hydrolytic enzymes that are associated with the isolated microbes.Result: It was observed that bacteria like Bacillus sp., Pseudomonas sp., Klebsiella sp., Staphylococcus aureus, Streptococcus, Micrococcus, Actinomycetes, Pigment producing Actinomycetes, Streptomyces, Azotobactor and fungi like Penicillium purpurogenum, Aspergillus sp., Alternaria alternata, Fusarium solani, Rhizopus sp., Mucor hiemalis, Myrothecium verrucaria etc. were present in our vermicompost preparations. The presence of nitrogen fixing bacteria, phosphate solubilizing microorganisms and PGPR indicated the good fertilizer value of the vermicompost samples. It was also observed that the diversity of microbes present supported significant levels of CMCase Exoglucanase, Xylanase, β-Glucosidase, Phosphatase and Urease activities.

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Journal articles on the topic 'Nitrogen Nitrogen-fixing microorganisms. Klebsiella pneumoniae'

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