Partial characterisation of bacteriocins produced by lactic acid bacteria isolated from Thai fermented meat and fish products

Abstract

Lactic acid bacteria (LAB) from Thai fermented meat and fish products were isolated. From a total of 93 samples, 152 isolates of lactic acid bacteria were obtained. Antimicrobial activity screening was performed using the agar spot test and the agar well diffusion method. Of the six isolates which produced antimicrobial activities against Weissella confusa N31, only isolate N23 was identified as Weissella cibaria (GenBank accession number AB494716.1) with 99% similarity by 16S rDNA sequence analyses. Complete inactivation of antimicrobial activity produced by W. cibaria N23 was observed after treatment of the bacteriocins with trypsin, actinase, protease XIII, ficin, trypsin from porcine pancreas, α-chymotrypsin and pepsin. In addition, the inhibitory activities were not affected by the addition of catalase. Taken together, these results confirmed that the inhibitory compounds produced by this strain were proteinaceous in nature and possessed typical characteristics of bacteriocins. The highest yield of bacteriocin produced by W. cibaria N23 was recorded at 20 h. The bacteriocin N23 remained stable after 2 h of incubation at pH values between 2.0 and 8.0, and also for 15 min at 121 °C. The bacteriocin produced by W. cibaria N23 was found to have a narrow antibacterial spectrum, being able to inhibit only W. confusa N31. In addition, bacteriocin N23 did not adhere to the surface of the producer cells. The results produced from this study will contribute to the existing body of knowledge and enhance the databases of bacteriocin-producing Weissella.