Culture medium from a marine endophytic fungus protects shrimp against acute hepatopancreatic necrosis disease (AHPND)

Abstract

Because endophytic fungi are widely known for producing secondary metabolites and bioactive compounds, they are of interest to pharmaceutical and biotechnology industries. Many species are found in mangrove forests that are habitats for marine animals, especially in their early life stages. In this research, we screened 42 endophytic fungi originating from Thai mangrove forests for inhibitors of biofilm and planktonic cell growth of 7 Vibrio isolates. Some of these isolates were collected from shrimp ponds exhibiting early mortality syndrome (EMS) and diagnosed as outbreaks of acute hepatopancreatic necrosis disease (AHPND) that is caused by specific isolates of Vibrio parahaemolyticus (VPAHPND). Cell-free supernatants (CFS) of two fungal isolates (MCR433 and MCR 440) that inhibited biofilm growth for at least 5 out of the 7 Vibrio isolates were chosen for further study in shrimp feeding trials. One (MCR433) had strong biofilm inhibition and the other (MCR 440) weak biofilm inhibition for VPAHPND. Feed supplementation with CFS of MCR 433 protected shrimp against AHPND (72% mean survival) when compared to control shrimp given un-supplemented feed (20% mean survival) or given feed supplemented with CFS of MCR 440 (0% survival). Histological analysis of the hepatopancreas confirmed that shrimp given feed supplemented with MCR 433 showed little or no signs of AHPND pathology while shrimp in the other two groups showed histopathology typical AHPND. Using a multigene molecular typing approach, both MCR 433 and MCR 440 were identified as distinct members of the order Muyocopronales, class Dothideomycetes and phylum Ascomycota with differing biological activities. Further research is needed on the lead compounds generated by these strains. Those from MCR 433 have potential for use as feed additives against VPAHPND as an alternative to antibiotics.