ABSTRACT
AIMS: The aim of the study was to characterize isolates of lactic acid bacteria from Beyaz cheese and to study some of their technologically important properties. METHODS AND RESULTS: Seventy-seven lactic acid bacteria isolated from Beyaz, a Turkish white-brined cheese made from raw ewes' milk without any starter, were classified by phenotypic criteria and sodium dodecyl sulphate-polyacrylamide gel electrophoresis of whole-cell proteins. Whole cells of Lactococcus lactis subsp. lactis and enterococci showed lipolytic and proteolytic activities. Strains were found that differed in terms of their acidifying and caseinolytic activity. Most of the enterococci isolates showed tyrosine decarboxylase activity; moreover, lactobacilli exhibited weak antibacterial activities against foodborne pathogens. CONCLUSIONS: Strains of lactic acid bacteria with interesting biotechnologically important properties may be found in Beyaz cheese. SIGNIFICANCE AND IMPACT OF THE STUDY: Lactic acid bacteria isolates with interesting biotechnological profiles may influence the quality and variety of dairy products, if they are used as starters, and their cheese-making characteristics seem promising.
Subject(s)
Cheese/microbiology , Enterococcus/classification , Lactobacillus/classification , Lactococcus lactis/classification , Milk/microbiology , Sheep , Animals , Bacterial Proteins/chemistry , Bacterial Typing Techniques , Biotechnology/methods , Electrophoresis, Polyacrylamide Gel , Enterococcus/enzymology , Lactobacillus/enzymology , Lactococcus lactis/enzymology , PhenotypeABSTRACT
Thirty-two Lactobacillus plantarum strains isolated from Feta cheese throughout ripening were studied for their phenotypic characteristics, protein profile of cell-free extracts, enzyme profiles, plasmid profiles, proteolytic and acidifying abilities and ability to grow at low pH and in the presence of bile. Results showed that some biotechnologically important characteristics, such as acidifying and proteolytic activities, can differ between strains. In addition, different plasmid profiles suggest the presence of different Lact. plantarum strains in Feta cheese throughout ripening. The results suggest the possibility of choosing strains with specific biotechnologically interesting properties.
Subject(s)
Cheese/microbiology , Food Microbiology , Lactobacillus/physiology , Acids/analysis , Bacterial Proteins/analysis , Culture Media/chemistry , Electrophoresis, Polyacrylamide Gel , Food Industry , Hydrogen-Ion Concentration , Lactobacillus/enzymology , Lactobacillus/genetics , Peptide Hydrolases/analysis , Phenotype , Plasmids/chemistry , Time FactorsABSTRACT
Isolates of lactobacilli from infant faeces phenotypically characterized as Lactobacillus paracasei subsp. paracasei (six strains), Lact. rhamnosus (six strains), Lact. gasseri (three strains), Lact. acidophilus (one strain) and Lact. fermentum/reuteri (three strains) according to recent classification systems were subjected to SDS-PAGE of whole cell proteins and rRNA-targeted oligonucleotide probe hybridization, in order to confirm the phenotypic characterization and elucidate the exact taxonomic position of the three strains that had properties between fermentum and reuteri. Results suggested a good agreement between the phenotypic characterization, SDS-PAGE and rRNA-targeted oligonucleotide probe hybridization for strains of all species except for the Lact. fermentum/reuteri strains. Results obtained by rRNA probes suggested a possible phylogenetic relatedness of the strains to Lact. reuteri. Isolates from infant faeces with interesting probiotic properties could be used as components of fermented milk products.
