Isolation and identification of pathogenic Vibrio spp. retrieved from diseased Litopenaeus vannamei and beneficial role of some functional probiotic bacteria for control.

Autor: Yu, Peng, Wang, Teng, Ye, Haibin, Shan, Hongwei, Ma, Shen
Předmět:
Zdroj: Aquaculture International; Aug2020, Vol. 28 Issue 4, p1403-1420, 18p
Abstrakt: The hepatopancreatic disease in shrimp has caused great economic losses in recent years, and it is necessary to identify the responsible pathogen and establish control methods. The present study aimed to identify the primary pathogenic bacteria in diseased Litopenaeus vannamei hepatopancreas (HP) and to explore the protective effects of functional bacteria on shrimp. Four pathogenic Vibrio spp. were isolated and identified from shrimp with hepatopancreatic disease, of which Vibrio harveyi HAH could be the primary pathogen causing higher rates of mortality (~ 73%) with observed symptoms. In addition, HAH had five virulence-related genes: luxR, flaB, toxR, vhhA, and vhhB. Anti-Vibrio bacterium M146 and quorum quenching (QQ) bacterium W1B were screened and used as a feed supplement. The results showed that M146 and W1B (dosed at 1.0 × 107 CFU/g) decreased the mortality of shrimp after challenge with HAH. Supplementation with M146 significantly increased the activities of alkaline phosphatase (AKP) and lysozyme (LZM), whereas supplementation with W1B had no significant effect. AKP and acid phosphatase (ACP) activities of shrimp supplemented with W1B showed a significant increase after infection with HAH, whereas a decrease in the activities of AKP and superoxide dismutase (SOD) was observed in the negative control (NC). Supplementation with M146 and W1B significantly decreased the relative messenger RNA expression of Relish and TRAF6. However, after infection with HAH, the M146 and W1B groups exhibited a different pattern of gene expression regulation compared with that in the NC group, which might suggest weakening of the virulence of the pathogen. The results suggest that these two bacteria can protect L. vannamei and that M146 not only inhibited the growth of HAH but also had an immunostimulatory effect on shrimp. On contrast, W1B did not improve the immunity of shrimp, so it is speculated that it may protect the host by affecting the quorum sensing (QS) system of pathogenic bacteria. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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