A comparison of factors affecting the production of two bacteriocins from lactic acid bacteria

Abstract

The effect of tryptone, yeast extract, Tween 80 and initial pH on the production of enterocin 1146 and lactocin D, two bacteriocins produced by lactic acid bacteria, was studied in a basal buffered medium (tryptone‐yeast extract‐tween, TYT) using factorial experiments and empirical modelling. Production of enterocin 1146 was affected by pH, yeast extract and Tween 80 and to a lesser degree, by the initial pH of the medium. On the basis of the predictions of the models developed, three TYT media (TYT10, TYT11 and TYT30) were designed to maximize bacteriocin production while minimizing the amount of peptides in the medium. Growth and bacteriocin production by Enterococcus faecium DPC 1146 (enterocin 1146), Lactococcus lactis subsp. lactis biovar diacetylactis DPC 3286 (lactocin D) and Lact. lactis subsp. cremoris LMG2130 (lactococcin A) was compared in TYT media and seven other culture media (Elliker lactic broth, M17, M17 dialysate, MRS, tryptose phosphate, tryptone yeast extract broth, yeast glucose Lemco broth). Bacteriocin production in TYT media was comparable with that in M17 and MRS, which had a higher peptide content. TYT30 allowed good production of enterocin 1146 and lactocin D while TYT11 proved acceptable for all the strains tested.

Exopolysaccharide production by Streptococcus thermophilus SY: production and preliminary characterization of the polymer

“…Statistical methods have frequently been applied in predictive microbiology to evaluate the effect of several factors on pathogenic and spoilage micro-organisms (Whiting 1995) and their use for the optimization of media and fermen- Fig. 3 Kinetics of growth (s, X, g l -1 ), exopolysaccharide (EPS) (n, EPS, mg l -1 ), lactic acid (h, g l -1 ) and galactose production (m, g l -1 ) and lactose consumption (d, g l -1 ) by Streptococcus thermophilus SY grown in batch culture in a whey-based medium with 4 g l -1 yeast extract at pH 6AE4 and 36°C tation conditions for LAB is not new (Parente and Hill 1992;Monteagudo et al 1993;Rincón et al 1993;Oh et al 1995;Wijtzes et al 1995;Dobmann et al 1996). Polynomial quadratic models are often insufficient to provide a satisfactory representation of the relationship between experimental factors and response variables (final population, l max and lag time) and polynomial cubic or quartic models Monteagudo et al 1993;Oh et al 1995;Dobmann et al 1996) or other non-linear models (Wijtzes et al 1995) have sometimes been used.…”

Characterization of the genetic locus responsible for the production of ABP-118, a novel bacteriocin produced by the probiotic bacterium Lactobacillus salivarius subsp. salivarius UCC118 The GenBank accession number for the sequence reported in this paper is AF408405.

“…The bacteriocin activity present in the neutralized (pH 6n5) cell-free supernatant (CFS) of a producing culture and the activity of purified bacteriocin were determined by critical dilution using the direct, spot-on-lawn assay (Mayr-Harting et al, 1972) or the agar well-diffusion assay (Parente & Hill, 1992). Activity units (AUs) per millilitre were determined as the inverse of the last dilution at which growth inhibition was still detectable.…”

Optimization of Bacteriocin Production by Batch Fermentation of Lactobacillus plantarum LPCO10

“…They have generally focused on the effects of pH, temperature, composition of the culture medium, and general microbial growth conditions (in vitro as well as in natural fermentations) on maximal bacteriocin production (2,4,6,8,11,14,24,25,(28)(29)(30)(38)(39)(40). However, although some of these studies claim validation by a statistical test, usually variance analysis, the combination of variables and their values and limits are arbitrarily chosen, based mainly on subjective personal experience.…”