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The role of environmental factors and medium composition on bacteriocin-like inhibitory substances (BLIS) production by Enterococcus mundtii strains

Settanni, Luca, Valmorri, Sara, Suzzi, Giovanna, Corsetti, Aldo
Food microbiology 2008 v.25 no.5 pp. 722-728
Enterococcus mundtii, strains, strain differences, wheat, bacteriocins, environmental factors, biosynthesis, culture media, antimicrobial properties, temperature, pH, nitrogen compounds, carbohydrates, ethanol, sodium chloride, plasmids, DNA
Bacteriocin-like inhibitory substances (BLIS)-producers Enterococcus mundtii WGWT1-1A, WGW11.2, WGJ20.1, WGJ40.2 and WGK53 from raw material origin were subjected to a study for the characterization of antimicrobial compound production under several growth conditions, including different cultivation media, growth temperatures, pHs, different concentrations and sources of nitrogen compounds, carbohydrates and other nutritional factors, and in the presence of different percentages of ethanol and NaCl. The five E. mundtii strains showed different behaviors. However, in all cases, MRS and sour dough bacteria (SDB) were found as the optimal media for BLIS production. In general, the higher BLIS production was observed with pH in the range 6.0-8.0 and, except 45 °C, the temperature did not show a defining effect. Low or no BLIS activity was detected after growth without nitrogen sources and carbohydrates. Absence of Tween 80, triammoniun citrate, K2HPO4, MgSO4 and MnSO4 did not affect BLIS activity levels. Except for a strain (WGWT1-1A), ethanol did not play a negative role in BLIS expression, while NaCl determined decrease of BLIS activity, proportional with concentration. The above strains did not contain plasmids, hence, BLIS expression is encoded by chromosomal DNA.