Composition diversity and nutrition conditions for accumulation of polyhydroxyalkanoate (PHA) in a bacterial community from activated sludge.

ABSTRACT

We investigated the effect of chemical oxygen demand (COD)/N ratio on polyhydroxybutyrate (PHB) accumulating ability in an anaerobic/aerobic cycle sequential batch reactor (SBR). Compared the COD/N ratio of 10, 20, 50, and 125, the COD/N of 125 was the most suitable nutritional proportion. When COD was 1,200 mg/L and COD/N/P was 1,200/9.6/30, activated sludge PHB synthesis reached a maximum of 64.2 % of the dry weight of the cells. The population of the activated sludge was detected periodically by denaturing gradient gel electrophoresis (DGGE). The predominant strains belonged to five genera Bacteroidetes sp., Acinetobacter sp., Betaproteobacteria sp., Gammaproteobacteria sp., Arcobacter sp., and Bacillus sp. Pyrosequencing analysis of the 16S rRNA gene indicated that the PHB synthesis community was more diverse than that was detected by DGGE, specifically Acidobacteria (12.25 %), Alphaproteobacteria (10.78 %), Actinomycetales (9.68 %), Actinobacteria (5.15 %), Proteobacteria (4.04 %), and unclassified bacteria (24.14 %).