outbreaks caused by Vibrio parahaemolyticus (VPAHPND) emerged in Mexico in 2013, causing a 65% drop in shrimp tonnage produced and reaching 95% mortality. This work aimed to isolate the best bacterial strains from Mexican marine ecosystems to assess the microbiota antagonism against VPAHPND and to choose strains with protective roles against this pathogen for an environmentally friendly aquaculture treatment.
Bacterial marine agar and trypticase soy agar isolates were obtained from invertebrates and different Sonora coast ecosystems. Sampled and reisolated pathogens were analysed by qPCR. Among 258 bacterial isolates, only 17 showed antagonist activity in vitro, but only five, 32a, 43, H-A, Y119, and Y100, were chosen based on cell-free supernatant assays (Fig. 1). Bioassay results with white shrimp highlighted Vibrio alginolyticus-32a with a 4.76% cumulative mortality, followed by Bacillus pumilus-Y100 (12.54%) and Vibrio campbellii-H-A (16%); Bacillus pumilus-Y119 and Bacillus pumilus-43 did not show any protection or beneficial effect against VPAHPND (Fig. 2). Pathogen reisolation on CHROMagar Vibrio and qPCR were performed only in the positive control and H-A; however, 32a, Y100, Y119, 43, and a negative control yielded creamy pink and green-blue colonies based on the absence of VPAHPND, which was confirmed with a negative qPCR (Fig. 3). This result suggested that they were able to inhibit the pathogen with a microbicidal effect.