ISOLATION AND PARTIAL CHARACTERIZATION OF A NOVEL BACTERIOCIN PRODUCED BY LACTOCOCCUS LACTIS SSP. LACTIS MC38

Abstract

This work presents the isolation and partial characterization of a new lactococcal bacteriocin produced by Lactococcus lactis ssp. lactis MC38. The bacteriocin demonstrated broad spectrum of inhibition activity against both pathogenic and food spoilage organisms, and various lactic acid bacteria. This antimicrobial substance appeared to be proteinaceous because its activity was completely inactivated by proteinase K and α‐chymotrypsin. It was heat and pH stable. The apparent molecular mass of the purified bacteriocin, determined by sodium dodecyl sulfate–polyacrylamide gel electrophoresis, was 8.0 kDa. The amino acid composition of the studied bacteriocin was found to be quite different from known lactococcal bacteriocins. The calculation of the number of amino acid residues in the bacteriocin molecule revealed that it contained 62 amino acids.

Molecular identification of naturally occurring bacteriocinogenic and bacteriocinogenic-like lactic acid bacteria in raw milk and soft cheese

“…The variation in sensitivity of bacteriocins and bacteriocin-like substances to different enzymes is important for the identification of potential uses of these cultures in the control of foodborne pathogens (Table 2). Similar types of enzyme sensitivities of bacteriocinogenic LAB have been observed in other studies (Tükel et al, 2007;Rashid et al, 2009).…”

Antagonistic effect of brevicin on Gram positive and Gram negative food borne bacteria and its biopreservative efficacy in milk

“…Similarly, Juck et al (2010) have also reported that the antimicrobials consisting of nisin and rosemary extract was shown to be more effective in an acidic environment. The above mentioned results were correlated to the study of Tukel et al (2007) who reported that the bacteriocin showed maximum activity at 50°C and at pH 5 but it retained its activity till 100°C for 15 min and at pH 9. The brevicin was inactivated by pepsin, proteinase K and trypsin, thereby no inhibition zone around the colonies.…”

“…lactis MC38 did not show any antimicrobial activity against the Gram negative bacteria tested. However, it is found to be active against the entire Gram positive bacteria tested (Tukel et al, 2007). Mandal et al (2011) also proved that pediocin NV5 had strong antimicrobial efficacy against L. mesenteroides, L. monocytogens and Enterococcus faecalis.…”

“…The supernatant was collected and its pH was adjusted to 6.0 to prevent the effect of organic acids (Todorov and Dicks, 2005) and it was filter sterilized by cellulose nitrate membrane (0.45 µm, Sartorius AG, Germany) to use as a CEP (Simova et al, 2009). The different concentrations of CEP (50 and 100 µl) were analyzed for their antimicrobial activity by well diffusion assay (Tukel et al, 2007) …”

“…Then, the antimicrobial activity was carefully checked (Bhattar-charya and Das, 2010). The effect of different enzymes like pro-tease, lipase diastase, pepsin, trypsin, catalase and amylase and organic solvents like ethanol and chloroform was determined by treating the solution with these enzymes and organic solvents (Tukel et al, 2007) separately. After 2 h, the antimicrobial activity was checked using B. coagulans and S. typhi.…”