Journal of Environmental Biology

Evaluation of Enterococcus hirae LAB3 as potential probiont against Vibrio harveyi in Artemia nauplii and Asian seabass larvae (Lates calcarifer) cultures

F. Masduki^1,2, T. Zakaria¹, C.C. Min^1,2 and M. Karim^{1, 3}* 

¹Department of Aquaculture, Faculty of Agriculture, Universiti Putra Malaysia, Serdang, 43400, Malaysia

²Laboratory of Marine Biotechnology, Institute of Bioscience, Universiti Putra Malaysia, 43400, Serdang, Malaysia

³Laboratory of Sustainable Aquaculture, International Institute of Aquaculture and Aquatic Sciences (UPM), Port Dickson, 70150, Malaysia

*Corresponding Author Email : murnimarlina@upm.edu.my

Paper received: 18.09.2019 ?????? ???????????????????????????????????????Revised received: 10.11.2019 ???????????? ?????????????????????????????Accepted: 14.08.2020

Abstract

Aim: To evaluate the ability of Enterococcus hirae strain LAB3 to inhibit the growth of V. harveyi in in-vitro co-culture assay and confer protection towards Artemia nauplii and seabass larvae against V. harveyi in in-vivo assay.?

Methodology: Enterococcus hirae was co-cultured with V. harveyi for 96 hrs and the samples were taken every 6 hr interval to determine the growth of the pathogen in in-vitro assay. In the in-vivo assay, E. hirae at different concentrations were introduced to the Artemia nauplii and seabass larvae cultures. After 24-hr incubation period, V. harveyi at concentration 106 CFU ml^-1 were added into the respective experimental tanks. Mortality was observed and recorded daily, until 50% mortality was observed in negative control group which challenged with V. harveyi only.

Results:? E. hirae was able to reduce the numbers of V. harveyi after 12 hr of co-culture incubation. In addition, E. hirae was administered into the Artemia nauplii and conferred protection against V. harveyi with the best survival rate at concentration of 106 CFUmL^-1 (70?3.1%). The untreated group seabass larvae challenged with V. harveyi presented low survival of (16.7?3.3%), while fish treated with probiotic E. hirae at 106 CFUml^-1 showed significantly increased survival rates (68.3?0.9%) after challenged. The survival of healthy unchallenged fish treated with probiotic was not significantly different with the control group. The pathogen loaded also reduced in groups treated with E. hirae respectively.

Interpretation: E. hirae strain LAB3, a potential probiont was able to reduce the number of Vibrios and conferred protection to Artemia and seabass larvae.

Key words: Artemia nauplii, Enterococcus hirae, Probiotic,? Seabass larvae, V. harveyi 

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