Inhibition of Fungi and Gram-Negative Bacteria by Bacteriocin BacTN635 Produced by Lactobacillus plantarum sp. TN635

Abstract

The aim of this study was to evaluate 54 lactic acid bacteria (LAB) strains isolated from meat, fermented vegetables and dairy products for their capacity to produce antimicrobial activities against several bacteria and fungi. The strain designed TN635 has been selected for advanced studies. The supernatant culture of this strain inhibits the growth of all tested pathogenic including the four Gram-negative bacteria (Salmonella enterica ATCC43972, Pseudomonas aeruginosa ATCC 49189, Hafnia sp. and Serratia sp.) and the pathogenic fungus Candida tropicalis R2 CIP203. Based on the nucleotide sequence of the 16S rRNA gene of the strain TN635 (1,540 pb accession no FN252881) and the phylogenetic analysis, we propose the assignment of our new isolate bacterium as Lactobacillus plantarum sp. TN635 strain. Its antimicrobial compound was determined as a proteinaceous substance, stable to heat and to treatment with surfactants and organic solvents. Highest antimicrobial activity was found between pH 3 and 11 with an optimum at pH = 7. The BacTN635 was purified to homogeneity by a four-step protocol involving ammonium sulfate precipitation, centrifugal microconcentrators with a 10-kDa membrane cutoff, gel filtration Sephadex G-25, and C18 reverse-phase HPLC. SDS-PAGE analysis of the purified BacTN635, revealed a single band with an estimated molecular mass of approximately 4 kDa. The maximum bacteriocin production (5,000 AU/ml) was recorded after a 16-h incubation in Man, Rogosa, and Sharpe (MRS) medium at 30 degrees C. The mode of action of the partial purified BacTN635 was identified as bactericidal against Listeria ivanovii BUG 496 and as fungistatic against C. tropicalis R2 CIP203.

Identification of potential probiotic Lactobacillus plantarum isolates with broad-spectrum antibacterialactivity

“…The highest antibacterial activity (inhibition zones of >12.00 mm) was achieved by 6.6, 3.5, 4.3, 3.2, and 2.6% of L. plantarum isolates against E. coli, Salmonella typhimurium, Shigella flexneri, Staphylococcus aureus, and L. monocytogenes, respectively. This is in line with the study of Smaoui et al (2010) who found that only one isolate of L. plantarum (TN635) out of 54 isolates evaluated showed significant levels of inhibitory activities against four Gram-negative pathogenic bacteria (Salmonella enterica, Pseudomonas aeruginosa, Hafnia sp., and Serratia sp.). Based on these results, nine isolates could be identified as having broad and effective antibacterial activity against four (IMAU70095 and IMAU50045) or all five of the indicator bacteria (IMAU80106, IMAU10996, IMAU10216, IMAU70023, IMAU30043, IMAU30162, and IMAU10256) (Supplementary Table 1).…”

“…In addition, the use of chemical preservatives in food production has been significantly reduced recently, due to increased public awareness of the health concerns associated with them. The addition of natural biopreservatives, such as isolates of lactic acid bacteria (LAB) with antibacterial activity, is one potential strategy to both improve food quality and extend shelf life (Smaoui et al 2010). However, the practical application of such an approach does suffer from technical problems such as incompatibility with the taste of food and loss of antimicrobial activity during food digestion (Gálvez et al 2007).…”

“…Some L. plantarum isolates have been reported to exert beneficial health effects following consumption, including maintenance of the colonic microbial balance, elimination of potential food toxicants, protection from intestinal infections, reduction of inflammation, and lowering of blood cholesterol (Nguyen et al 2007). Furthermore, some L. plantarum isolates have good antimicrobial characteristics; both Hernández et al (2005) and Smaoui et al (2010) successfully isolated antimicrobial L. plantarum from food sources through large-scale screening experiments. These two reports suggest that large-scale screening is a feasible approach to identify and isolate LAB with antibacterial activity.…”

<b>Antagonistic activity of dairy lactobacilli against gram-foodborne pathogens</b> - doi: 10.4025/actascitechnol.v36i1.18776

“…Supernatant of L. plantarum TN635 strain inhibited the growth of all used indicator microorganisms, among which E. coli ATCC8739 (SMAOUI et al, 2010).…”

Safety and quality parameters of ready-to-cook minced pork meat products supplemented with Helianthus tuberosus L. tubers fermented by BLIS producing lactic acid bacteria

“…Lactic acid bacteria (LAB) as bio-preservation organisms play a key role in food fermentations where they not only contribute to the development of desired sensory properties in the final product but also to their microbiological safety (Smaoui et al 2010;Cizeikiene et al 2013). The antimicrobial effect of LAB is related to the production of organic acids, short chain fatty acids, hydrogen peroxide and proteinaceous compounds -bacteriocins and bacteriocin-like inhibitory substances (BLIS) (Dalié et al 2010).…”