Scientists use bacterial strains found in sharks to develop a probiotic prototype that can help shrimp fight bacterial infections and so, minimise aquaculture pandemics.
Researchers have announced the release of a new probiotic-based treatment that can boost shrimp immunity and help these crustaceans fight Vibrio infections. With this probiotic, scientists hope to curb infections and prevent shrimp from developing acute hepatopancreatic necrosis syndrome (AHPNS), or previously known as the early mortality syndrome (EMS).
Acute hepatopancreatic necrosis syndrome is one of the most complex and dangerous diseases in shrimp aquaculture, with a mortality rate of 100 per cent. In the past decade, it has caused episodes of aquaculture pandemic and brought about a spiral of shrimp deaths and a reduction in exports. After a series of investigations, it was found that the culprit behind the outbreaks was a bacteria known as Vibrio parahaemolyticus. The bacteria produces a potent toxin that can damage the shrimps’ hepatopancreas, a vital digestive organ, leading to acute hepatopancreatic necrosis syndrome.
Given the destructiveness of this disease, many farmers have turned to antibiotics and a whole range of chemicals to treat and prevent infections. However, such treatments have proven to only bring about the emergence of antibiotic-resistant strains of Vibrio parahaemolyticus and the production of contaminated shrimp. Probiotics have also been used to manage and minimise bacterial outbreaks in shrimp farms. However, the components of many commercial probiotics are often undefined and not standardised. Moreover, some probiotic strains have yet to receive approvals of safety or do not have the GRAS (generally regarded as safe) status, and thus can potentially compromise human health.
To address the limitations of current treatment methods against the early mortality syndrome, a team of scientists, led by Dr. Tengku Haziyamin Tengku Abdul Hamid at Kulliyyah of Science, International Islamic University Malaysia, has developed a new prototype probiotic-based treatment called ProAquaVcare. Formulated with probiotic bacterial strains derived from black tip sharks, ProAquaVcare is to be used in conjunction with garlic powder as the latter is known to stimulate the shrimp immune system.
Dr. Hamid and colleagues first encountered the probiotic strains while they were working with the intestinal tissues of a freshly caught black tip shark (Carchahinus limbatus). The team spotted a variety of bacterial strains and isolated them. Out of the 80 isolated, it was found that only four strains exhibited antagonistic activities and broad range inhibition against relevant pathogens implicated in shrimp or fish diseases. In particular, these strains were able to produce bacteriocin, an antibacterial protein that could induce potent antagonistic effects against the virulent strains of V. parahemolyticus and V. alginolyticus. These four strains were later identified as Lactococcus lactis strain FA1, FA2, FA3, and FA4, all of which are Gram-positive coccus, non-spore formers, and lactose fermenters.
With these findings, the team is excited to run further trials on shrimp models to demonstrate the efficacy of their probiotic and is looking forward to bring their novel product for commercialisation.
Awarded the gold medal for International Innovation Award in the recent Malaysian Technology Expo 2021, ProAquaVcare is believed to be a future game-changer in shrimp probiotics and a powerful tool to bring the shrimp industry back to its full capacity.
Source: Hamid et al. (2021). Lactococcus lactis strains from intestinal organ of Black tips shark Carcharhinus limbatus producing nisin-like bacteriocin active against shrimp and fish pathogens (Vibrio parahaemolyticus and Vibrio alginolyticus). Journal of Microbiology, Biotechnology and Food Sciences. 10(3), 354-360.