Effect of depuration on microbial content of mangrove oyster (crassostr ea tulipa) from Benya Lagoon, Ghana

Abstract

Mangrove oysters and water samples collected from Benya lagoon, located at Elmina in the Central Region of Ghana were investigated for microbial contamination. A total of nine fungal isolates were identified. These were Aspergilus niger, A. sulphurus, species of Penicillium, Rhizopus, Trichoderma, Fusarium, Saccharomycetes and Sterilia mycelia. Accumulations of fungal and bacterial populations in the non-depurated oysters were greater than the surrounding water. However, when mangrove oysters were depurated, populations of fungi and bacteria showed marked reduction, with some of the species disappearing completely. Saccharomycetes had a mean population of 6.3 x 10 2 CFUs/g before depuration of oysters. This reduced to 0.0 CFU/g after depuration for 12 hours; and 7.0 x10 2 CFUs/g before depuration and 4.0 x 10 2 CFUs/g after depuration during the first and second investigations, respectively. Bacterial populations present on selective media (Levine Eosin Methylene Blue agar and MacConkey agar) suggested possible presence of sewage indicators, which are surrogates for water quality assay