The efficiency of anaerobic digestion is closely tied to the structure of its microbial community.Determination of microbial dynamics at different depths in biogas plants from sago industries showedthe population of total heterotrophic bacteria (58.4 x 106 cfu/ml), fungi (10.1 x 103cfu/ml), fermenting bacteria (1.4 x 1010 MPN/ml), starch hydrolyzing- (19.5 x 105cfu/ml) and cyanide degrading (11.6 x 103cfu/ml) bacteria were dominant in the bottom zone, denitrifiers (9.4 x 106 MPN/ml) in the middle and methanogens were recorded higher (4.8 x 106 MPN/ml) at the top of biogas plants. This implied that the composition of wastewater could affect the evolution ofquantitative community structure in an anaerobic process. With the study of native cyanide degrading bacteria, sixfacultative anaerobic bacteriaviz., P. putida, B. anthracis, B. cereus C1, B. cereus C2, S. maltophila and B. weihenste phenensis were found to metabolize cyanideinto ammonia and formatevia a hydrolytic pathway. Higher growth interms of optical density and a maximum cyanide removal was obtained with S. maltophila. Ammonia production and glucose consumption were well correlated with disappearance of cyanide.
Sago wastewater, Biogas plants, Anaerobic conditions, cyanide
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