Comparison of cultivable bacterial communities associated with Pacific white shrimp (Litopenaeus vannamei) larvae at different health statuses and growth stages

The relationships between microbial communities and aquatic animals have drawn attention. In this study, samples collected from different health statuses (diseased and healthy) and growth stages (zoea, mysis and postlarvae period) of Pacific white shrimp (Litopenaeus vannamei) were obtained from a shrimp hatchery. A total of 240 cultivable bacterial strains were isolated and characterized using 16S rRNA gene sequencing, and three isolates were identified as potential novel species. It was found that Proteobacteria and Bacteroidetes were widely distributed in healthy shrimp at all growth stages, but varied in relative abundance among different stages. Many opportunistic pathogens, such as genera Vibrio and Nautella, were isolated from the diseased samples. Five dominant strains isolated from the diseased samples were selected to test their virulence and four of them (Nautella italica, Pseudoalteromonas piscicida, Vibrio sinaloensis and Vibrio campbellii), especially V. campbellii, were shown to be pathogenic to Artemia. Additionally, 18 out of 143 isolates from the healthy samples, displayed N-acyl-homoserine lactone (AHL) degrading activity, and two species (Tenacibaculum mesophilum and Microbacterium aquimaris) possessed strong degrading activity. These isolates could be applied as probiotic candidates to shrimp hatcheries for controlling diseases caused by quorum sensing dependent pathogens. Overall, this study demonstrates that the bacterial community associated with Pacific white shrimp larvae was highly dynamic under different health statuses and growth stages. Statement of relevance: Provide scientific guidance to commercial shrimp producers. (C) 2015 Elsevier B.V. All rights reserved.