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Commercial ponds receiving two microbial products were monitored for changes in bacterial populations and shrimp production. Nine ponds of 0.5 ha each were treated; three with microbial Product 1, three with Product 2 and three left untreated to serve as control ponds. The products were screened for species composition and administered following manufacturer's instructions throughout the culture period of 110 days. Product 1 contained Bacillus sp. and Saccharomyces sp. and Product 2 contained Bacillus sp., Nitrosomonas sp. and Nitrobacter sp. Water and sediment samples were collected once every 14 days for bacteriological analyses. Various heterotrophic (total plate count, presumptive vibrios, protein mineralising, ammonifying and sulphur reducing) and autotrophic (ammonia oxidising, nitrite oxidising, presumptive sulphur oxidising) bacterial groups were estimated for their population densities in water and sediment. Results showed that the Bacillus spp. were dominant in all ponds. Sediment of ponds treated with Product 1 had significantly higher (P |
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