Antibacterial activity of lactic acid bacteria from black soldier fly (Hermetia illucens) larvae fed with empty fruit bunch and tofu waste

Abstract

Antibiotic Growth Promoters (AGP) are prohibited for use in livestock due to their detrimental effects on consumer safety and livestock productivity. Probiotics are an alternative to AGP because they offer microorganisms that are beneficial to the livestock health. In this investigation, Lactic acid bacteria (LAB) from the Black Soldier Fly (BSF) larvae’s will be isolated, tested for their antimicrobial activities and molecularly identified using 16S rRNA gene with Polymerase Chain Reaction (PCR) technique. The larvae are fed with empty fruit bunch and tofu wastes as a source of prebiotics to the indigenous LAB. The LAB isolates were enumerated and morpho-biochemically characterized. Disk diffusion method was used to determine the antibacterial efficacy of LAB isolates against pathogenic bacteria, such as Salmonella enterica serotype Pullorum, Salmonella enterica serotype Typhimurium ATCC® 14028, and Escherichia coli ATCC® 8739. Nine bacterial isolates were purified from a population density of log 6 Colony-forming unit (CFU)/mL on de Man Rogosa Sharp (MRS) agar. Four LAB isolates were confirmed through (-) catalase activity and acids production (homofermentative). Two LAB isolates namely 5P3i3 and 5P3i5 were designated as the most potential strains against three pathogenic bacteria with the strongest inhibitory activities against E. coli, followed by S. enterica ser. Typhimurium and S. enterica ser. Pullorum. By using 16S rRNA gene sequencing, the two LAB isolates were assigned to Lactiplantibacillus pentosus and submitted to GenBank as L. pentosus strain 5P3i3 (OP445834.1) and L. pentosus strain 5P3i5 (OP445835.1). The results of this study will be further investigated with the characterization of potential isolates as probiotic candidates to be supplemented in poultry.