Academic literature on the topic 'AGR/16: MICROBIOLOGIA AGRARIA'

Several studies support the use of probiotics for the treatment of minor gastrointestinal problems in infants. Positive effects on newborn colics have been evidenced after administration of Lactobacillus strains, whereas no studies have been reported regarding the use of bifidobacteria for this purpose. This work was therefore aimed at the characterization of Bifidobacterium strains capable of inhibiting the growth of pathogens typical of the infant gastro-intestinal tract and of coliforms isolated from colic newborns. Among the 46 Bifidobacterium strains considered, 16 showed high antimicrobial activity against potential pathogens; these strains were further characterized from a taxonomic point of view, for the presence and transferability of antibiotic resistances, for citotoxic effects and adhesion to non tumorigenic gut epithelium cell lines. Moreover, their ability to stimulate gut health by increasing the metabolic activity and the immune response of epithelial cells was also studied. The examination of all these features allowed to identify 3 B. breve strains and a B. longum subsp. longum strain as potential probiotics for the treatments of enteric disorders in newborns such as infantile colics. The formulation of a synbiotic product with an appropriate prebiotic fiber capable of supporting the growth of the selected Bifidobacterium strains was also considered in this study. In this respect the ability of the 4 selected Bifidobacterium strains to use as the sole carbon source and energy source different polisaccharide fibers was investigated The last phase of the work has been dedicated to the evaluation of the gut microbial diversity in newborns whose mothers has been subjected to antibiotic therapy a few hours before the delivery because of a Streptococcus type B infection. These newborns can represent a possible target for the probiotic strains selected in this work.

Several studies support the use of probiotics for the treatment of minor gastrointestinal problems in infants. Positive effects on newborn colics have been evidenced after administration of Lactobacillus strains, whereas no studies have been reported regarding the use of bifidobacteria for this purpose. This work was therefore aimed at the characterization of Bifidobacterium strains capable of inhibiting the growth of pathogens typical of the infant gastro-intestinal tract and of coliforms isolated from colic newborns. Among the 46 Bifidobacterium strains considered, 16 showed high antimicrobial activity against potential pathogens; these strains were further characterized from a taxonomic point of view, for the presence and transferability of antibiotic resistances, for citotoxic effects and adhesion to non tumorigenic gut epithelium cell lines. Moreover, their ability to stimulate gut health by increasing the metabolic activity and the immune response of epithelial cells was also studied. The examination of all these features allowed to identify 3 B. breve strains and a B. longum subsp. longum strain as potential probiotics for the treatments of enteric disorders in newborns such as infantile colics. The formulation of a synbiotic product with an appropriate prebiotic fiber capable of supporting the growth of the selected Bifidobacterium strains was also considered in this study. In this respect the ability of the 4 selected Bifidobacterium strains to use as the sole carbon source and energy source different polisaccharide fibers was investigated The last phase of the work has been dedicated to the evaluation of the gut microbial diversity in newborns whose mothers has been subjected to antibiotic therapy a few hours before the delivery because of a Streptococcus type B infection. These newborns can represent a possible target for the probiotic strains selected in this work.

La tradizione casearia dell’Italia centrale comprende una grande varietà di formaggi prodotti con latte locale ed antiche tecniche di caseificazione. Tali formaggi sono parte integrante del patrimonio storico e culturale delle comunità locali, nonché risorse da conservare e valorizzare, anche a fronte del sempre più incalzante processo di globalizzazione. La regione Marche, in particolare, vanta un cospicuo numero di produzioni casearie tipiche, come riportato nell’”Elenco nazionale dei prodotti agro-alimentari tradizionali” (DM 18/07/2000). La valorizzazione di tali produzioni rappresenta un obiettivo primario delle politiche volte a promuovere la salvaguardia delle risorse e dello sviluppo socio-economico dei territori locali. Obiettivo della presente ricerca è stato la caratterizzazione compositiva, microbiologica e sensoriale di produzioni tradizionali di caciotta, pecorino e caprino della regione Marche, anche caratterizzate da tratti peculiari quali l’impiego di caglio d’origine vegetale (estratto acquoso di Cynara cardunculus), l’aggiunta di ingredienti caratteristici (erbe locali, olio d’oliva, buccia di limone grattugiata), la stagionatura in botte o all’interno di fosse tufacee. I dati ottenuti dalle analisi fisico-chimiche, microbiologiche e gas-cromatografiche sono stati elaborati statisticamente al fine di individuare correlazioni con le specifiche tecniche di caseificazione ed identificare marcatori oggettivi di qualità. A tale scopo, sono stati campionati complessivamente 29 formaggi, di cui 8 caprini, 12 pecorini e 9 caciotte, di cui 2 a latte vaccino e 7 a latte misto (bovino ed ovino); di questi, le produzioni a latte crudo (19 campioni) sono state prelevate presso caseifici artigianali della regione Marche, mentre i formaggi a latte pastorizzato (10 campioni) sono stati acquistati presso supermercati della provincia di Ancona. Tutti i campioni sono stati sottoposti a: (i) determinazione del contenuto di NaCl, proteina grezza e grassi totali; (ii) misurazione di pH, attività dell’acqua (aw), numero di perossidi della sostanza grassa; (iii) ricerca di Listeria monocytogenes, Salmonella spp. ed enterotossine stafilococciche; (iv) enumerazione di batteri lattici mesofili e termofili; (v) analisi PCR-DGGE della popolazione batterica; (vi) analisi della componente volatile mediante SPME-GC. L’insieme dei dati composizionali, microbiologici e del profilo aromatico è stato sottoposto ad analisi PCA (Principal Component Analysis) e PLS-DA (Partial Least Square Discriminant Analysis) utilizzando il software SIMCA-Pv 11.5 (UMETRICS). Tutte le produzioni in studio sono risultate conformi ai limiti legislativi per i parametri igienico-sanitari considerati. L’analisi multivariata mediante PCA dell’insieme dei dati ottenuti ha prodotto un modello a 2 componenti che spiega il 31.5% della varianza. Nello score plot t1/t2, le 3 tipologie di formaggio sono risultate ben separate; al contrario, non è stato possibile separare i formaggi sulla base del processo produttivo (da latte crudo o pastorizzato), indipendentemente dalla tipologia considerata (caciotta, pecorino o caprino). Il corrispondente loading plot ha permesso di evidenziare 3 gruppi di variabili; nello specifico, le variabili relative al profilo aromatico sono risultate responsabili della distinzione dei formaggi appartenenti alla tipologia caprino; quelle relative a conte microbiche, proprietà fisico-chimiche e composizionali hanno permesso di separare i formaggi appartenenti alla tipologia caciotta; infine, le variabili relative all’ecologia microbica sono risultate utili per discriminare i formaggi appartenenti alla tipologia pecorino. In particolare, conte più elevate di batteri lattici e valori più alti di aw hanno permesso di differenziare le caciotte dai pecorini e caprini, questi ultimi caratterizzati da concentrazioni più elevate di composti aromatici, mentre i pecorini si sono distinti per la presenza delle specie Lactobacillus coryniformis, Lb. rhamnosus e Lb. plantarum. L’analisi PLS-DA ha prodotto un modello a 2 componenti; più in dettaglio, lo score plot t1/t2 ha confermato la separazione delle 3 tipologie di formaggio. Dall’analisi del corrispondente loading plot, è emerso che tale separazione è principalmente dovuta a 10 descrittori legati alla definizione del profilo aromatico: acetone, etanolo, acido acetico, butirrico, caproico, enantico, caprilico, caprico, undecanoico ed undecenoico. L’approccio polifasico applicato nel presente studio ha permesso, nel complesso, di caratterizzare le produzioni casearie considerate, nonché di identificare marcatori utili per una discriminazione oggettiva delle stesse.
The dairy tradition of central Italy territories is characterized by a large variety of cheeses, manufactured with local milk according to ancient cheese-making techniques. These cheeses are an integral part of the historical and cultural heritage of local communities and resources to preserve and enhance, even in the face of increasingly insistent globalization process. The Marche region, in particular, boasts a large number of typical dairy products, as reported in the “Italian list of traditional agro-alimentary products” (DM 18/07/2000). The exploitation of these dairy products is a primary objective of politics to promote the conservation of resources and socio-economic development of local territories. The aim of this study was the compositional, microbiological and sensory characterization of traditional caciotta, caprino and pecorino cheeses produced in the Marche region, also characterized by peculiar traits such as the use of vegetable rennet (aqueous extract of Cynara cardunculus flowers), the addition of particular ingredients (herbs, olive oil, grated lemon peel) and ripening under unconventional conditions (in wooden barrels or pit ageing). All the data collected from physico-chemical, microbiological and chromatographic assays were statistically processed in order to assess the relationships between cheese-making techniques and compositional, microbiological and aromatic traits and identify objective markers of quality. To this aim, 29 cheeses manufactured in the Marche region, according to traditional techniques, were sampled; these included 8 goats’ (caprino), 12 ewes’ (pecorino) 2 cows’ and 9 mixed (ewes’ and cows’) milk (caciotta) cheeses. Raw milk cheeses (19 samples) were supplied by local artisan dairies, while pasteurized milk cheeses (10 samples) were bought from supermarkets. All the cheese samples were subjected to physico-chemical analyses for the determination of pH and aw values, NaCl, lipid and protein contents and peroxide index. Conventional microbiological analyses were carried out for the detection of pathogenic micro-organisms (Listeria monocytogenes and Salmonella spp.) and their metabolites (staphylococcal enterotoxins) as well as for viable counting of mesophilic and thermophilic lactic acid bacteria. The composition of the bacterial community was also evaluated by PCR-DGGE analysis of the bacterial DNA extracted directly from either the cheese samples or the bulk cells harvested from the MRS and M17 dilution plates. The cheese volatile profiles were determined by solid phase micro-extraction coupled with gas-chromatography (SPME-GC). All the data collected were subjected to Principal Component Analysis (PCA) and Partial Least Square (PLS) analysis by using SIMCA-P v 11.5 software (UMETRICS). The absence of bacterial hazard was demonstrated in both pasteurized and raw milk cheeses. Principal Component Analysis of the outcomes from physico-chemical, microbiological and chromatographic assays yielded a two components model, explaining the 31.5% of the variance. In the t1/t2 score plot, the three cheese types (pecorino, caciotta and caprino) were well separated; by contrast, no separation was seen between raw and pasteurized milk cheeses, irrespective of the cheese type considered. The corresponding loading plot revealed that variables clustered in three separated groups. In more detail, variables referring to aromatic profile are responsible for the grouping of caprino cheeses; variables referring to microbial loads, physico-chemical and compositional traits are responsible for the grouping of caciotta cheeses, while those referring to the PCR-DGGE results are responsible for the grouping of pecorino cheeses. Indeed, higher loads of mesophilic and thermophilic lactic acid bacteria and higher aw values differentiated caciotta from pecorino and caprino cheeses. This latter cheese type was characterized by higher amounts of volatile compounds, while pecorino cheeses were distinguished for the presence of distinctive bacterial species, namely Lactobacillus coryniformis, Lb. rhamnosus and Lb. plantarum. Partial Least Square Discriminant Analysis resulted in a 2 components model. The score plot of the first principal component vs the second principal component confirmed that the three cheese types were clearly separated. The analysis of the corresponding loading plot showed that such separation is mainly due to 10 descriptors related to the definition of the flavour profile: acetone, ethanol, acetic, butyric, caproic, enanthic, caprylic, capric, undecanoic, and undecenoic acids. The polyphasic approach used in this study allowed, in general, to characterize the dairy products concerned, and to identify useful markers for their discrimination.