Inhibition of Staphylococcus aureus in vitro by bacteriocinogenic Lactococcus lactis KTH0-1S isolated from Thai fermented shrimp (Kung-som) and safety evaluation

Abstract

Lactococcus lactis KTH0-1S isolated from Thai traditional fermented shrimp (Kung-som) is able to produce heat-stable bacteriocin and inhibits food spoilage bacteria and food-borne pathogens. The inhibitory effect of bacteriocin remained intact after treatment with different pHs and after heating, but was sensitive to some proteolytic enzymes. Addition of bacteriocin KTH0-1S to Staphylococcus aureus cultures decreased viable cell counts by 2.8 log CFU/ml, demonstrating a bactericidal mode of action. Furthermore, the growth of S. aureus decreased significantly after 12-h co-cultivation with bacteriocinogenic strain. The molecular mass of bacteriocin KTH0-1S was found to be 3.346 kDa after ammonium sulfate precipitation, reversed phase (C Sep-Pak), cation-exchange chromatography, RP-HPLC on C column and mass spectrometry (MS/MS) analysis. Bacteriocin KTH0-1S was identified as nisin Z using PCR amplification and sequencing. The majority of tested virulence factors were absent, confirming the safety. Evidenced inhibitory effect of this strain, the absence of virulence factors creates the possibility for its application as protective culture to inhibit pathogenic bacteria in the several fermented seafood products.

The Health Benefits of Fermented Food: A Narrative Review

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“…Overall, all these findings accentuate the importance of understanding the microbial diversity in fermented shrimp products. Certain microorganisms such as Lactococcus were reported to have antimicrobial properties through the production of antibacterial substances that inhibit the growth of spoilage and pathogenic bacteria, which would extend the shelf life of shrimp paste and boost its functional attributes (Hamid & Fuzi, 2020; Saelao et al., 2017). Lactococcus could also potentially produce enzymes and metabolites that react with alcohols, aldehydes, and ketones to produce a mixture of new taste substances (Dai et al., 2018).…”

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