Search results for "ACID BACTERIA"
showing 10 items of 165 documents
BATTERI LATTICI CON ATTIVITA’ ANTIBATTERICA ISOLATI DA FORMAGGI TRADIZIONALI SICILIANI
2013
The study was conducted on typical Sicilian cheeses made from raw cow milk (Caciocavallo Palermitano) and sheep milk (Vastedda della valle del Belice PDO e Pecorino PDO). Genotypic identification of the LAB isolates was carried out by 16S/23S rRNA sequencing. a total of 400 bacteria strains were isolated and genotypically identified as Lactobacillus spp., Lactoccoccus spp., Pediococcus spp., Leuconostoc spp., Enterococcus spp. and Streptococcus spp. Evaluation of bacteriocin-producing LAB was investigated in vitro using the “spot on the lawn” method (2) aganist Listeria monocytogenes, Staphylococcus aureus, Salmonella enteritidis and Escherichia coli. Results showed a predominance of LAB sh…
Combined approach for the investigation of dominant fermenting microbiota in two traditional sourdoughs produced in sicily
2017
In order to explore the community of lactic acid bacteria (LAB) and yeasts present in two major typical Sicilian sourdoughs, seven mature sourdoughs for "Pane Nero di Castelvetrano" (CV1 - CV3 samples) and "Pane di Monreale" (MR1 - MR4 samples) were analysed through a culturedependent and culture-independent approach. The highest values of microbial counts were revealed in MR1 sourdough. In particular, LAB counts were at about 109 CFU/g in media specific for typical sourdough LAB, such as SDB and SFM, while levels of 106 CFU/g were registered for yeasts. The total DNA form each sourdough sample was extracted and subjected to a multiplex-PCR in order to recognize the major groups of LAB. Sev…
Addition of selected starter/non-starter lactic acid bacterial inoculums to stabilise PDO Pecorino Siciliano cheese production
2020
Abstract The present study was carried out to produce Protected Denomination of Origin (PDO) Pecorino Siciliano cheese with a multi-species lactic acid bacteria (LAB) culture, composed of starter and non-starter strains in order to reduce the microbiological variability of the products derived without LAB inoculums. To this end, cheese samples produced in six factories located in five provinces (Agrigento, Catania, Enna, Palermo and Trapani) of Sicily, and previously characterised for physicochemical, microbiological and sensory aspects, have been investigated in this work for bacterial microbiome, fatty acid (FA) composition as well as volatile organic compound (VOC) profiles. Analysis of …
A stochastic interspecific competition model to predict the behaviour of Listeria monocytogenes in the fermentation process of a traditional Sicilian…
2008
The present paper discusses the use of modified Lotka-Volterra equations in order to stochastically simulate the behaviour of Listeria monocytogenes and Lactic Acid Bacteria (LAB) during the fermentation period (168 h) of a typical Sicilian salami. For this purpose, the differential equation system is set considering T, pH and aw as stochastic variables. Each of them is governed by dynamics that involve a deterministic linear decrease as a function of the time t and an "additive noise" term which instantaneously mimics the fluctuations of T, pH and aw. The choice of a suitable parameter accounting for the interaction of LAB on L. monocytogenes as well as the introduction of appropriate nois…
Animal rennets as sources of dairy lactic acid bacteria
2014
ABSTRACT The microbial composition of artisan and industrial animal rennet pastes was studied by using both culture-dependent and -independent approaches. Pyrosequencing targeting the 16S rRNA gene allowed to identify 361 operational taxonomic units (OTUs) to the genus/species level. Among lactic acid bacteria (LAB), Streptococcus thermophilus and some lactobacilli, mainly Lactobacillus crispatus and Lactobacillus reuteri , were the most abundant species, with differences among the samples. Twelve groups of microorganisms were targeted by viable plate counts revealing a dominance of mesophilic cocci. All rennets were able to acidify ultrahigh-temperature-processed (UHT) milk as shown by pH …
Transformation of raw ewes' milk applying “Grana” type pressed cheese technology: development of extra-hard “Gran Ovino” cheese
2019
Abstract This work was carried out to pursue a double objective: to improve the hygienic safety of cheeses produced from raw ewes' milk; and to produce a new typology of raw ewes' milk through the application of “Grana” technology for which the name “Gran Ovino” was chosen. With this in mind, raw milk from an individual farm was transformed under controlled conditions at a dairy pilot plant. The production technology included the partial skimming of the evening and morning milk mixture by cream surfacing and the addition of a natural whey starter cultures (NWSC) prepared with four selected Streptococcus thermophilus strains (PON6, PON244, PON261 e PON413). Ten microbial groups were investig…
In vivo application and dynamics of lactic acid bacteria for the four-season production of Vastedda-like cheese.
2014
article Twelve lactic acid bacteria (LAB), previously selected in vitro (Gaglio et al., 2014), were evaluated in situ for their potential to act as starter cultures for the continuous four-season production of Vastedda-like cheese, made with raw ewes' milk. The strains belonged to Lactobacillus delbrueckii, Lactococcus lactis subsp. cremoris, Leuconostoc mesenteroides subsp. mesenteroides and Streptococcus thermophilus .L AB werefirst inoculated in multiple-strain combinations on the basis of their optimal growth temperatures in three process conditions which differed for milk treatment and medium for strain development: process 1, growth of strains in the optimal synthetic media and pasteu…
Identification, typing, and investigation of the dairy characteristics of lactic acid bacteria isolated from 'Vastedda della valle del Belìce' cheese
2013
Traditional cheeses made without starter cultures can be characterised by the attribute of instability. The addition of autochthonous starter cultures can ensure stability without compromising the characteristics of the final product. This study aimed to characterise the autochthonous lactic acid bacteria (LAB) population in “Vastedda della valle del Belice” cheeses, which have a protected designation of origin (PDO) status, in order to develop an ad hoc starter culture to be used in its future production. Winter and spring productions were analysed to ensure isolation of specific LAB that had adapted to perform fermentation at low temperatures. Plate counts revealed total microbial numbers…
Microbial strategies to improve the final quality of traditional Sicilian cheeses
Polyphasic Characterization of Microbiota of “Mastredda”, a Traditional Wooden Tool Used during the Production of PDO Provola dei Nebrodi Cheese
2021
The biofilms of the wooden tables used for the acidification of the curd were investigated for PDO Provola dei Nebrodi cheese, a traditional stretched cheese made in eastern Sicily (southern Italy) from raw cows’ milk. To this purpose the wooden tables of four dairy facilities were analysed for their microbiota by scanning electron microscopy (SEM) analysis and a combined culture-independent and -dependent microbiological approach. SEM inspection showed an almost continuous biofilm formation. MiSeq Illumina analysis identified 8 phyla, 16 classes, 25 orders, 47 families and 50 genera. Corynebacterium, Bifidobacterium and lactic acid bacteria (LAB) were detected in all samples. In particular…