Isolation and characterization of bacteriocin-producing bacteria from the intestinal microbiota of elderly Irish subjects

Abstract

Aims: To isolate and characterize bacteriocins produced by predominant species of lactic acid bacteria from faeces of elderly subjects. Methods and Results: Screening over 70 000 colonies, from faecal samples collected from 266 subjects, using the indicator organisms Lactobacillus bulgaricus LMG 6901 and Listeria innocua DPC 3572, identified 55 antimicrobial-producing bacteria. Genomic fingerprinting following ApaI digestion revealed 15 distinct strains. The antimicrobial activities associated with 13 of the 15 strains were sensitive to protease treatment. The predominant antimicrobial-producing species were identified as Lactobacillus salivarius, Lactobacillus gasseri, Lactobacillus acidophilus, Lactobacillus crispatus and Enterococcus spp. A number of previously characterized bacteriocins, including ABP-118 and salivaricin B (from Lact. salivarius), enterocin B (Enterococcus faecium), lactacin B (Lact. acidophilus), gassericin T and a variant of gassericin A (Lact. gasseri), were identified. Interestingly, two antimicrobialproducing species, not generally associated with intestinally derived microorganisms were also isolated: Lactococcus lactis producing nisin Z and Streptococcus mutans producing mutacin II.

The Yin and Yang of Bacterial Resilience in the Human Gut Microbiota

“…One is physical exclusion: B. thetaiotaomicron has been found to attach to food sources in the intestinal environment of a gnotobiotic mouse 31 , which would give B. thetaiotaomicron an advantage in accessing essential nutrients over free floating bacteria. Other work has shown that members of the microbiota can deploy their own antimicrobials to gain a competitive advantage 32 . Some pathogens have evolved strategies to circumvent direct competition, such as Salmonella typhimurium , using hydrogen generated by the microbiota as an electron source in early stages of infection 33 .…”

Contribution of plasmid-encoded peptidase S8 (PrtP) to adhesion and transit in the gut of Lactococcus lactis IBB477 strain

“…Moreover, some particular strains, such as L. lactis IBB477 and L. lactis CNCM I-1631, are able to persist in the GIT of gnotobiotic animals for the entire monitoring period (at least 2 weeks) (Boguslawska et al 2009; McNulty et al 2011). In humans, although lactococci are not a frequent element of intestinal microbiota, their presence in faeces was detected in several studies (Finegold et al 1983; Millette et al 2007; Lakshminarayanan et al 2013; David et al 2014). …”

Antimicrobial antagonists against food pathogens: a bacteriocin perspective

“…A recent study of the gut microbiota of elderly Irish subjects revealed Enterococcus strains with anti-listerial activity, which merit closer attention with a view to investigating their use as probiotic strains. In addition, a Lactobacillus gasseri strain producing gassericin T was isolated during the same screening programme [53]. Notably, Lb.…”