Diversity and Vibriostatic Activity of Biofilm-forming Bacteria in Penaeus monodon Pond
Buenaflor D. Jimenez, Francis Zarsuelo and Deverly D. Tumapon
Department of Biological Sciences
MSU-Iligan Institute of Technology
ABSTRACT
Biofilm forming communities deployed in prawn pond aging one to eleven weeks were examined for diversity. Direct microscopic counts were done using fluorescence microscopy and indirect counts using viable counts. Colonization of rounded bacteria was noted for most of the sampling period. The eight-week old biofilm showed the most highly diverse (0.90) and richest microbial community with viable count of 1.25 x 108 cfu ml-L. Vibrio population started to stabilize on the four-week old biofilm and attained its maximum on the eight week at 6.5 x 10-3 cfu ml-L.
A total of 46 isolates were successfully cultured in conventional and selected media and screened for vibriostat activity by parallel streak method, cylinder cup assay and co-cultivation in broth with Vibrio harveyi. Of these isolates, eighteen has showed potential inhibitory activity in parallel steak. Four isolates (V35, V36, N61 and N63) showed reduction on the growth of Vibrio harveyi smear better than the controls, chloramphenicol and furazolidone.
Isolates V17, V35 and V1 showed greater inhibition of Vibrio (>12mm) in the cylinder cup assay than the positive controls. Most of the isolates were within the range of the positive controls (10-12mm inhibition).
Bacteria showing positive activity in parallel streak and cylinder cup were co-cultivated in broth with the pathogen and showed a reduction of 88.24%, 72% and 69.86 by Klebsiella (N39), Vibrio sp.1 (V1) and Vibrio sp.2 (V2), respectively.
The other isolates showing anti-Vibrio activity belong to six major genera: Aeromonas, Bacillus, Flavobacterium, Klebsiella, Pseudomonas and Vibrio.
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