19 strains of filamentous bacteria that accumulated poly-β-hydroxybutyrate(PHB) were isolated from activated sludge by enrichment cultivation.Staining with Sudan Black B was applied to detect PHAs.Quantitative estimation of PHB extracted from the isolates was done by Ultraviolet spectrophotometer method.PHB was extracted from these strains through the CHCl3-CH3CH2OH method.The PHA productivities of strain HY10 was the highest in 19 isolates mentioned above,in which PHB yield and productivities were(37.24 ± 0.74) % dry cell weight(DCW) and 1.15 ± 0.06 g/L,respectively when grown in a medium containing 20 g/L sucrose.According to its clone morphological and the 16S rDNA sequence(GenBank No.JQ353768),it suggested that strain HY10 was Bacillus pseudomycoides.