ABSTRACT
AIMS: To screen and identify wine-isolated LAB strains for bacteriocin production, and to identify and characterize bacteriocins. METHODS AND RESULTS: One hundred and fifty-five LAB strains isolated from South African red wines undergoing spontaneous malolactic fermentation were screened for bacteriocin production. Eight isolates were identified to be bacteriocin producers and were identified as Enterococcus faecium. All eight isolates had the same phenotypic and genotypic profiles. The peptides were preliminarily identified as enterocin P using mass spectrometry and further confirmed by PCR-amplifying enterocin P gene. The enterocin activity was inhibited by α-Chymotrypsin, papain and proteinase K treatments. It was heat stable at 37, 60, 80 and 100°C and showed activity over a broad pH range of 2-10. The production of the enterocin followed that of primary metabolite kinetics and, it showed bactericidal effect to some wine spoilage LAB strains. CONCLUSIONS: Our study identified the presence of the enterocin-producing Enterococcus in wine. The enterocin was heat stable; with broad pH range and bactericidal effects to sensitive strains. SIGNIFICANCE AND IMPACT OF THE STUDY: This is one of very few studies that isolated Enterococcus species from wine. It is, however, the first to report presence of bacteriocin-producing Enterococcus in wine fermentation.
Subject(s)
Anti-Bacterial Agents/biosynthesis , Bacteriocins/biosynthesis , Enterococcus faecium/metabolism , Wine/microbiology , Anti-Bacterial Agents/isolation & purification , Anti-Bacterial Agents/metabolism , Anti-Bacterial Agents/pharmacology , Bacteriocins/genetics , Bacteriocins/isolation & purification , Bacteriocins/pharmacology , Enterococcus/classification , Enterococcus faecium/genetics , Enterococcus faecium/isolation & purification , FermentationABSTRACT
Optimal methods for using dried blood spots (DBSs) for population genetics-based studies have not been well established. Using DBS stored for 8 years from 21 pregnant South African women, we evaluated three methods of gDNA extraction with and without whole-genome amplification (WGA) to characterize immune-related genes: interleukin-10 (IL-10), killer immunoglobulin-like receptors (KIRs) and human leukocyte antigen (HLA) class I. We found that the QIAamp DNA mini kit yielded the highest gDNA quality (P< 0.05; Wilcoxon signed rank test) with sufficient yield for subsequent analyses. In contrast, we found that WGA was not reliable for sequence-specific primer polymerase chain reaction (SSP-PCR) analysis of KIR2DL1, KIR2DS1, KIR2DL5 and KIR2DL3 or high-resolution HLA genotyping using a sequence-based approach. We speculate that unequal template amplification by WGA underrepresents gene repertoires determined by sequence-based approaches.
