title: Screening for antimicrobial and proteolytic activities of lactic acid bacteria isolated from cow, buffalo and goat milk and cheeses marketed in the southeast region of Brazil.
abstract: Lactic acid bacteria (LAB) can be isolated from different sources such as milk and cheese, and the lipolytic, proteolytic and glycolytic enzymes of LAB are important in cheese preservation and in flavour production. Moreover, LAB produce several antimicrobial compounds which make these bacteria interesting for food biopreservation. These characteristics stimulate the search of new strains with technological potential. From 156 milk and cheese samples from cow, buffalo and goat, 815 isolates were obtained on selective agars for LAB. Pure cultures were evaluated for antimicrobial activities by agar antagonism tests and for proteolytic activity on milk proteins by cultivation on agar plates. The most proteolytic isolates were also tested by cultivation in skim milk followed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis of the fermented milk. Among the 815 tested isolates, three of them identified as Streptococcus uberis (strains FT86, FT126 and FT190) were bacteriocin producers, whereas four other ones identified as Weissella confusa FT424, W. hellenica FT476, Leuconostoc citreum FT671 and Lactobacillus plantarum FT723 showed high antifungal activity in preliminary assays. Complementary analyses showed that the most antifungal strain was L. plantarum FT723 that inhibited Penicillium expansum in modified MRS agar (De Man, Rogosa, Sharpe, without acetate) and fermented milk model, however no inhibition was observed against Yarrowia lipolytica. The proteolytic capacities of three highly proteolytic isolates identified as Enterococcus faecalis (strains FT132 and FT522) and Lactobacillus paracasei FT700 were confirmed by SDS-PAGE, as visualized by the digestion of caseins and whey proteins (β-lactoglobulin and α-lactalbumin). These results suggest potential applications of these isolates or their activities (proteolytic activity or production of antimicrobials) in dairy foods production.
authors.affiliation: Faculdade de Ciências Farmacêuticas de Ribeirão Preto,Universidade de São Paulo - Ribeirão Preto,Brazil.
authors.forename: Fabricio L
authors.initials: FL
authors.lastname: Tulini
authors.affiliation: Université de Brest,EA3882,Laboratoire Universitaire de Biodiversité et d'Ecologie Microbienne,SFR ScInBioS,ESIAB,Technopôle de Brest Iroise,29280 Plouzané,France.
authors.forename: Nolwenn
authors.initials: N
authors.lastname: Hymery
authors.affiliation: Institut National de la Recherche Agronomique (INRA) Angers-Nantes,BIA-FIPL - Nantes,France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Haertlé
authors.affiliation: Université de Brest,UMR UBO,CNRS,IFREMER 6197,Laboratoire de Microbiologie des Environnements Extrêmes,IUEM,Technopôle de Brest Iroise,29280 Plouzané,France.
authors.forename: Gwenaelle
authors.initials: G
authors.lastname: Le Blay
authors.affiliation: Faculdade de Ciências Farmacêuticas de Ribeirão Preto,Universidade de São Paulo - Ribeirão Preto,Brazil.
authors.forename: Elaine C P
authors.initials: EC
authors.lastname: De Martinis
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents; D000898:Antibiosis / Q000502:physiology; D001419:Bacteria / Q000145:classification* / Q000378:metabolism; D001938:Brazil; D002020:Buffaloes; D002417:Cattle; D002611:Cheese / Q000382:microbiology*; D005516:Food Microbiology; D006041:Goats; D008892:Milk / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents
keywords: Lactic acid bacteria; antimicrobials; dairy; identification; proteinase