Antimicrobial efficacy of Lactobacillus plantarum strain against the B. cereus, B. subtilis, S. aureus and E.coli strains

Abstract

The current study aimed to detect the antimicrobial effect of cell free supernatant (CFS) of Lactobacillus plantarum strain against Gram +ve and Gram –ve bacterial strains. The strain of Lactobacillus plantarum was isolated using selective media MRS agar. The strain was characterized on the basis of the gram staining, colony morphology, the biochemical tests and the DNA sequencing based method of 16S ribotyping. A total of four test strains (The three already isolated and reported strains (E.coli, S. aureus and B. subtilis) and the one recently identified novel strain (B. cereus) were used for the analysis of antagonistic activity of bacteriocin produced by L. plantarum strain. The CFS of L. plantarum showed zone of inhibition against all the test strains (Gram +ve and Gram –ve bacteria). The conditions favoring the growth of bacteria were associated with the antimicrobial efficacy of CFS. Bacteriocin activity of CFS remained effective after exposure to temperature stress. Wide range of antagonistic potential of CFS of L. plantarum provides an alternative for antibiotics in pharmaceutical industry. Heat resistant feature of bacteriocin suggests its application in food industry.

Lactic Acid Bacteria and Bacillus subtilis as Potential Protective Cultures for Biopreservation in the Food Industry

“…In contrast, a significant decrease in antimicrobial activity (from 22.35 mm of original halo size) was observed when acidifying or neutralizing the CFS of L. plantarum CNTA 600. This agrees with the results reported by Akhtar and Syed [54] for a L. plantarum strain isolated from yogurt. The CFS from B. subtilis significantly decreased its native antimicrobial activity (28.52 mm) under acidic conditions, similar to what was previously observed by Epparti et al [75].…”

“…Similarly, the CFS of the selected strain L. plantarum CNTA 600 exhibited a strong antimicrobial effect against L. monocytogenes (15.27 ± 0.47 mm), consistent with the findings of Vataščinová et al [53]. A medium antimicrobial activity against B. cereus (13.36 ± 0.67 mm) was observed, corroborating similar previous results by Akhtar and Syed [54]. L. brevis CNTA 1374 CFS showed no antimicrobial activity against any of the pathogenic strains.…”

Application of Commercial Biopreservation Starter in Combination with MAP for Shelf-Life Extension of Burrata Cheese

“…the left to the right side of the plot); the panelists highlighted the worst quality of samples after 28 days of storage, while after 21 days, some samples still were acceptable, i.e., MAP packaged samples were similar to the same samples at T14, which still had good characteristics, and were very different from Ctr. These outcomes revealed that MAP alone or in combination with protective starter, whose bacteriocins have been demonstrated to have antimicrobial activity against a wide range of bacteria [58][59][60], better preserved the sensory characteristics of burrata in agreement with VOC and the other chemicals results. In sum, the overall characteristics decrease over time for almost all products (from the left to the right side of the plot); the panelists highlighted the worst quality of samples after 28 days of storage, while after 21 days, some samples still were acceptable, i.e., MAP packaged samples were similar to the same samples at T14, which still had good characteristics, and were very different from Ctr.…”

“…In sum, the overall characteristics decrease over time for almost all products (from the left to the right side of the plot); the panelists highlighted the worst quality of samples after 28 days of storage, while after 21 days, some samples still were acceptable, i.e., MAP packaged samples were similar to the same samples at T14, which still had good characteristics, and were very different from Ctr. These outcomes revealed that MAP alone or in combination with protective starter, whose bacteriocins have been demonstrated to have antimicrobial activity against a wide range of bacteria [58][59][60], better preserved the sensory characteristics of burrata in agreement with VOC and the other chemicals results.…”

“…Considering the Enterobacteriaceae 2.7 log CFU g −1 count were found in Ctr at the end of storage, vs. 0.9-1.2 log CFU g −1 in the other samples; a similar trend was observed for Pseudomonas, ranging from 1 to 1.4 log CFU g −1 in the experimental samples vs. 2 log CFU g −1 found in the Ctr. The comparison among experimental samples evidenced that the best outcomes were obtained in the case of a combination of the protective starter with MAP; the use of Lactobacillus plantarum, as a producer of bacteriocins, may have played a major role, as widely demonstrated in the literature [58][59][60]; however, a synergic effect with MAP seems to be evident. The observed chemical changes must be interpreted in the light of the storage conditions applied, since refrigeration is known to favor psychrotrophic bacteria that are highly lipolytic [55,56].…”