The isolation of Lactic acid bacteria strains from Black tips shark Carcharhinus limbatus producing bacteriocin with potential to be used as probiotic in aquaculture

Mohammed, Alotaibi and Ahmad Zahli, Khairil Ikhwan and Tengku Abdul Hamid, Tengku Haziyamin (2021) The isolation of Lactic acid bacteria strains from Black tips shark Carcharhinus limbatus producing bacteriocin with potential to be used as probiotic in aquaculture. In: International Conference By Biotechnology Society Of Nepal (ICBSN-2021), 12th-14th February 2021, Bhaktapur, Nepal. (Unpublished)

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Abstract

Nowadays, the use of antibiotic and chemical disinfectant is so widespread in managing disease outbreak in aquaculture. This has encourage in the emergence of antibiotic resistance strain among pathogenic organisms. Thus, an alternative antimicrobial agents such as bacteriocin has been considered as attractive substitute. In this work, several strain of Lactic acid bacteria (LAB) producing bactriocin were isolated from intestinal tissues of Black tip shark (Carcharhinus limbatus) based on spot-on-lawn and agar well diffusion methods. From 80 isolates, only 4 isolates which are FA1, FA2, FA3 and FA4, found to be Gram positive coccus, non-spore former, oxidase and catalase negatives, as well as lactose fermenters based on growth on MRS medium. The isolates have shown broad spectrum inhibition acting both against gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) and the gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Vibrio alginolyticus and Vibrio parahaemolyticus). The highest inhibition zone, of about 20.0±0.1 mm, was recorded against V. parahaemolyticus. The genotype of these isolates were identified by 16S ribosomal DNA gene sequencing. All of these strains were found to be belonging to Lactococcus lactis at 99% similarities. All isolates are found to be bacteriocin producer and the supernatants collected from each isolate showed inhibitory activities which were still retained after either pH or catalase treatment. These has indicated that the inhibitory activities were neither due to organic acid nor from hydrogen peroxide (H2O2). Since the inhibitory activities was lost (~95%) after trypsin treatment, there is high possibility that the supernatants harbour a putative bacteriocin. Further growth and inhibition studies conducted with all of these isolates against V. parahemolyticus, demonstrated that the inhibitory secretions were in general growth associated, with maximum inhibition achieved at ~19.0 ± 0.1 mm (or ~168 ± 2 AU/ml) after 17 hours especially by FA1 strain. Observation on the mode of inhibition demonstrated that the antimicrobial activities against V. parahaemolyticus was bactericidal in nature. We can conclude that from this work, few strains from Lactococcus lactis were isolated from shark species which are bacteriocinogenic, and the bacteriocin they produced have potential to be used as future antimicrobial agent useful in aquaculture or food preservation. Being able to antagonise some pathogens, especially those usually involved in fish or shrimp diseases will make these strains useful as potential probiotics in aquaculture.

Item Type:	Conference or Workshop Item (Poster)
Additional Information:	4261/88377
Uncontrolled Keywords:	lactic acid bacteria, lactococcus lactis, bacteriocin, nisin
Subjects:	Q Science > Q Science (General)
Kulliyyahs/Centres/Divisions/Institutes (Can select more than one option. Press CONTROL button):	Kulliyyah of Science > Department of Biotechnology Kulliyyah of Science
Depositing User:	Dr Tengku Haziyamin Tengku Abd Hamid
Date Deposited:	17 Feb 2021 10:42
Last Modified:	17 Feb 2021 10:42
URI:	http://irep.iium.edu.my/id/eprint/88377

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