Biofloc technology has shown positive effects in aquaculture, especially on the growth performance of cultured animals. The aims of this study were to evaluate the effects of adding different probiotic strains in a biofloc system on the growth performance and disease resistance of red hybrid tilapia (Oreochromis spp.). Three different probiotics (Lysinibacillus fusiformis SPS11, Bacillus amyloliquefaciens L9, and Enterococcus hirae LAB3), commercial probiotics (MG1) and a mixed probiotics (MP) combining all three strains were used in this study. The in vitro assay results showed that the mixed probiotic (MP) was able to inhibit the growth of Streptococcus agalactiae and Streptococcus iniae significantly compared to the single and commercial probiotic. The efficacy of MP was further tested in in vivo tilapia culture challenged with S. agalactiae. The best specific growth rate (3.73 ± 0.23% day−1) and feed conversion ratio (0.76 ± 0.04) were recorded in the group of biofloc with addition of MP. After being challenged with S. agalactiae, the group of biofloc with MP had significantly higher survival (83 ± 1.43%) compared to the other groups. Furthermore, the nitrogen concentration (NO2-N and NH4-N) was significantly lower in all the biofloc groups compared to the control. Hence, the addition of probiotics was able to provide beneficial effects to red hybrid tilapia culture in the biofloc system.
Bacteria and microalgae are essential elements in the aquatic ecosystem, co-existing and having constant interactions with each other which help microalgae to exert its beneficial effect as probiotics in aquaculture. This research aims to isolate and identify potential probiotics from different species of microalgae and to evaluate their antimicrobial activity against pathogenic Vibrio spp. via series of in vitro assays; disc diffusion, well diffusion, and co-culture assays. A total of 18 bacterial strains were isolated from five species of microalgae; Chlorella sp., Nannochloropsis sp., Amphora sp., Chaetoceros sp., and Spirulina sp.. The isolated strains were tested in in vitro antagonistic assay against four Vibrio spp. (Vibrio harveyi, Vibrio alginolyticus, Vibrio vulnificus, and Vibrio parahaemolyticus). Seventeen strains demonstrated antimicrobial activity with the highest inhibition was observed by strain SPS11 against V. parahaemolyticus (12.6 ± 0.36 mm) in disc diffusion assay and strain NAS32 showed 13.2 ± 0.45 mm clear zone against V. vulnificus in well diffusion assay. In co-culture assay, both the SPS11 and NAS32 were able to reduce the growth of V. parahaemolyticus and V. harveyi at concentration of 106 and 108 CFU mL-1, respectively. Strains SPS11 and NAS32 were characterized as gram positive bacteria with rod shape and further identified as Lysinibacillus fusiformis (SPS11) and Lysinibacillus sphaericus (NAS32) using 16s rRNA. These two strains should be further studied in in vivo challenged experiments in fish and shellfish to explore their probiotic effects.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.