Combating vibriosis in Penaeus monodon culture system by administration of endophytic Penicillium citrinum SW171 extract that confers better growth and protection

The black tiger shrimp, Penaeus monodon, has been a key species in the development and expansion of intensive shrimp aquaculture worldwide. The problem of disease susceptibility in P. monodon, particularly vibriosis caused by Vibrio harveyi, poses a significant threat and leads to substantial economic losses. To combat bacterial infections, researchers are exploring the antimicrobial potential of microbes from unique environments, like algicolous endophytes. In this study, we investigated the in vivo exclusion of Vibrio in P. monodon post-larvae using an extract from the endophytic fungus Penicillium citrinum SW171 (PCE), evaluating its impact on disease resistance, growth, and survival. Crude endophytic extract was administered both via feed and rearing water for 28 days before the challenge with V. harveyi. Treatment with PCE improved the water quality of rearing water by significantly reducing ammonia and nitrate levels compared to the control. This treatment notably decreased Vibrio colonies without substantial alteration in the overall microbial load of the rearing water. Moreover, the endophytic extract not only inhibited pathogens but also enhanced productivity, as evidenced by improved growth rates (1272 ± 20.8 and 1109.02 ± 28.4 mg) compared to the control (1026.02 ± 33.8 mg). Transcript levels of the immune-related genes i.e., anti-lipopolysaccharide factor (ALF), crustin, penaeidin, prophenoloxidase-activating enzyme (PPA), phagocytosis-activating protein (PAP), lysozyme-like, ferritin, haemocyanin, lectin, and survivin, were assessed in post-larvae using qRT-PCR. Extract treatment led to significant up-regulation of all genes except PPA, survivin and ALF. The cumulative survival rate of the group orally treated with PCE was 66.9 %, while that of water treatment was 64.5 %, significantly higher than that of the control group. The higher growth rate and post-challenge survival of P. monodon larvae point towards the immunostimulatory and antibacterial properties of endophytic P. citrinum extract which can be exploited in aquaculture for better production.