Biocontrol of acute hepatopancreatic necrosis disease (AHPND) in shrimp using a microalgal-bacterial consortium

Co-culturing microalgae Picochlorum strain S1b with bacterium isolated from non-axenic S1b cultures (i.e., Labrenzia sp. strain #8, Muricauda sp. strain #50, or Arenibacter sp. strain #61) can provide growth inhibitory effects against Vibrio harveyi and/or Vibrio campbellii. To determine whether this strategy can also provide growth inhibitory effects against Vibrio parahaemolyticus and thus help control acute hepatopancreatic necrosis disease (AHPND) in shrimp, this study compared the ability of various microalgal-bacterial consortia (S1b+#8, S1b+#50, S1b+#61, and S1b+#8, #50, #61) to inhibit the growth of V. parahaemolyticus. The challenge tests were then performed to determine whether the identified microalga-bacterial consortium can increase the survival of shrimp infected with AHPND-causing V. parahaemolyticus. The results revealed that only S1b+#8, #50, #61 (S1b+all) significantly inhibited V. parahaemolyticus growth. For this consortium, both feeding (0.8% of shrimp body weight/day) and immersion (10–100 mL microalgal-bacterial co-culture/30 L tank water/day) methods conferred protective effects, thereby demonstrating that the S1b+all has the potential to improve AHPND control. Of the two methods, feeding was found to be more suitable for the outdoor cultivation of juvenile shrimp, whereas immersion was found to be suitable for the indoor cultivation of shrimp postlarvae.