Bacteriocin production by Lactococcus lactis LL-HSTU-FPP strain isolated from fermented rice and evaluation of the biopreservation potentiality of bacteriocin on shrimp

Lactococcus lactis LL-HSTU-FPP was isolated from fermented rice and bacteriocin produced by this strain was used to investigate the antagonistic properties against foodborne pathogens. Subsequently, different concentrations (7.5 and 10%, v/v) of bacteriocin were applied to shrimp to analyze the spoilage rates during refrigerated storage. The isolate LL-HSTU-FPP was characterized using different biochemical tests (Catalase, bile esculin) and identified by 16S rRNA gene sequencing. Fourier transform infrared spectroscopy (FTIR) was conducted to assess the amide group in the bacteriocin produced by the strain LL-HSTU-FPP. The bacteriocin exhibited better inhibitory effect than the antibiotic ciprofloxacin against Escherichia coli, Vibrio cholera, and Staphylococcus aureus strains. Furthermore, the bacteriocin retained its activity after treatment with high temperatures ranging from 40 to 121 degrees C, in a wide pH range (2-9), and after treatment with different enzymes. However, the tendency to reduce spoilage microorganisms in shrimp as a consequence of the bacteriocin effect was significant compared to the control and the sample treated with 1% acetic acid after storage. As a result, the 10% concentration of bacteriocin used for the treatment of shrimps was shown to be more effective and suitable for use as a bio-preservative in seafood.