Isolation and Characterization of Antimicrobial-Producing Bacteria from the Donkey's Ear Abalone Haliotis asinina

This study was conducted to isolate, test the antimicrobial potential, and characterize bacterial isolates from the gut of Haliotis asinina collected from cage culture and wild population. Isolation was performed using dilution spread plate method and antimicrobial property was determined using streak plate method against nine test microorganisms. Results showed that of the 29 isolates from the cage-cultured samples, five isolates showed the presence of antimicrobial property against Escherichia coli, Staphylococcus aureus, Bacillus cereus, Bacillus subtilis, Bacillus megaterium, Pseudomonas aeruginosa, and Candida albicans. Among the 30 isolates from the wild-caught samples, six isolates showed the presence of antimicrobial potential when tested against E. coli, S. aureus, B. cereus, B. subtilis, B. megaterium, and C. albicans. None of the isolates inhibited Aspergillus niger or Aspergillus flavus. The bacterial strain coded C28, isolated from cage-cultured abalone, and that inhibited the most test microorganisms was subjected to cultural, morphological, and physiological characterization. It was characterized as a bacterial strain closely related to the genus Pseudomonas. The results suggest that bacteria in the gut of H. asinina have potential antimicrobial properties where bacteria related to Pseudomonas spp. are present.