Safety assessment of lactic acid bacteria isolated from chia sourdoughs

SAVOY DE GIORI, G.; VIGNOLO, G.; DENTICE MAIDANA, STEFANIA

San Miguel de Tucumán

Simposio; V International Symposium of Lactic Acid Bacteria; 2016

Centro de Referencia para Lactobacilos (CERELA)-CONICET

Lactic Acid Bacteria (LAB) have traditionally been used as starter cultures in the production of fermented feeds and foodstuffs. Among the features allowing the selection of LAB intended to be used as funcional starter cultures, the production of antimicrobial compounds and antibiotic resistance are of major concern. Bacteriocins production by LAB has been widely reported and applied to extend the shelf-life of raw materials and fermented foods. LAB are able to produce various compounds (organic acids, diacetyl, hydrogen peroxide and bacteriocins) during growth, which exert strong antagonistic activity against food spoilage organisms and pathogens. On the other hand, foodborne LAB have received increasing attention as potential reservoir of antibiotic resistance determinants, which may be horizontally transferred to opportunistic pathogens. The microbial resistance to antibiotics of clinical importance should be absent as it is required by the European Food Safety Authority (EFSA) as part of its qualified presumption of Safety (QPS) assessment of bacteria deliberately introduced in the food chain. The aim of this study was to evaluate the safety properties of LAB strains (297) isolated during chia sourdough fermentation. Antibiotic resistance was examined by phenotypic assay using the following antimicrobials: Ampicillin (AMP), Tetracycline (TET), Chloramphenicol (CHL), Gentamicin (GEN), Streptomycin (STR), Kanamycin (KAN), Vancomycin (VAN) and Erythromycin (ERY) and Clindamycin (CLI). The minimum inhibitory concentration (MIC) was determined by agar dilution method and (EFSA) proposed cut off values were applied. Results showed different antibiotic susceptibility/resistance patterns displayed by LAB, most of the strains being susceptible to TET and KAN. lsolated LAB cocci were mostly sensitive to VAN, but more resistant to CLlN, whereas tetrads and bacilli (presumptive pediococci and lactobacilli) were all susceptible to GEN and resistant to VAN. Based on these outcomes, 85 antibiotics susceptible strains were preliminarily selected to evaluate their antimicrobial activity by agar diffusion and conidial germination assay using Listeria innocua, Bacillus subtilis as well as Penicillium roquefortis and Aspergillus niger as indicator strains. LAB strains displaying higher antagonistic activity against fungus than bacteria. P. roquefortis and A. niger were inhibited by 41% and 30.5% of the analyzed strains, respectively. ln view to formulate a novel functional culture for chia flour fermentation, LAB from native microbiota should be rationally selected on their antimicrobial activity and antibiotic susceptibility besides their technological and functional properties, in order to ensure shelf-life and safety of gluten-free fermented products