Supernatants of the Probiotic Bacterial Cultures at sub-MIC Levels Attenuate Virulence of Pathogenic Bacteria Towards the Model Host Caenorhabditis elegans

Author(s): Pooja Patel, Chinmayi Joshi, Vijay Kothari*

Journal Name: Infectious Disorders - Drug Targets
Formerly Current Drug Targets - Infectious Disorders

Volume 20 , Issue 6 , 2020

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Objective: This study assessed the anti-pathogenic potential of culture supernatants from three probiotic strains viz. Lactobacillus plantarum, Bifidobacterium bifidum, and Enterococcus faecium against five different gram-positive and gram-negative pathogenic bacteria.

Methods: The effect of probiotic culture supernatants on growth and production of quorum sensing (QS)-regulated pigments was assessed through broth dilution assay. In vivo anti-infective efficacy of these supernatants was evaluated by challenging the model nematode host Caenorhabditis elegans with pathogenic bacteria pre-treated with probiotic culture supernatants, and worm survival was monitored over a period of 8 days.

Results: All the probiotic culture supernatants (at 5-10 %v/v) exhibited bactericidal activity against four of the test pathogens (including three multi-drug resistant gram-negative bacteria) and they (at ≥ 1%v/v) could also modulate QS in pathogenic bacteria. Pre-treatment with culture supernatants from all the three probiotic strains were able to attenuate virulence of four of the test pathogens towards C. elegans. Worms challenged with supernatant-pre-treated pathogens recorded 75-100% better survival than those challenged with pathogens receiving no such pretreatment. Virulence-attenuating effect of the culture supernatants was also carried forward to daughter populations of the supernatant-treated parent pathogens. Lactic acid seemed to contribute notably towards anti-virulence activity of the culture supernatants, but acidic pH did not seem to be important for such activity.

Conclusion: Culture supernatants of probiotic strains used in this study can be said to possess appreciable virulence-attenuating potential. Further investigation for characterization of these supernatants and identification of the bioactive constituents is warranted. Elucidation of the molecular basis associated with the anti-pathogenic potential of these supernatants may lead to the identification of novel targets in pathogenic bacterial populations.

Keywords: Quorum sensing (QS), anti-infective, Caenorhabditis elegans, probiotic culture supernatants, antimicrobial resistance (AMR), post-supernatant effect.

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Article Details

Year: 2020
Published on: 20 January, 2021
Page: [867 - 877]
Pages: 11
DOI: 10.2174/1871526519666191211141827
Price: $65

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