[Isolation, identification of a pyrene-degrading strain Mycobacterium sp. M11 and its degrading characteristics].

A bacterial strain M11 using phenanthrene, anthracene, fluorethene,pyrene as a sole carbon and energy sources was isolated from soils contaminated with polycyclic aromatic hydrocarbons. Strain M11 was identified as Mycobacterium sp. according to the results of morphology, physiology and the phylogenetical analyses of 16S rDNA sequence. The degradation rate of pyrene (at levels of 50 mg/L, 100 mg/L and 200 mg/L) by strain M11 was 76.9%, 91.8% and 79.23% within 16 d in broth assay. Mycobacterium sp. M11 showed a strong ability to grow from pH 5 to pH 9 in liquid minimal medium containing pyrene 100 mg/L. Mycobacterium sp. M11 possessed aromatic-ring dioxygenase genes, which are highly homologous to the known nidAB genes from pyrene-degrading Mycobacteria.

[Screening of two phenanthrene-utilizing and high-effective phosphorus-accumulating bacteria and their effects on phosphorus-accumulating characteristics].

In this study, two phenanthrene-utilizing and high-effective P-accumulating bacteria Y11 and Y4-2 were isolated from sludge samples of Taihu Lake using plate culture and blue-colored colonies methods. Strains Y11 and Y4-2 were identified as Acinetobacter sp. according to the results of morphology, physiology and the phylogenetical analyses of 16S rDNA sequences. The two strains showed high effective P-accumulating ability in plate and broth cultures. Y11 could grow well from 10 degrees C to 35 degrees C and pH from 6 to 9, Y4-2 could grow well from 10 degrees C to 35 degrees C and pH from 6 to 8. Phenanthrene could be used as sole carbon and energy sources. In our experiment, high phosphorus concentration in broth culture had no negative effect on the growth of strain Y11, however the growth of strain Y4-2 was slightly affected. Under cultivation condition of 30 degrees C, 170 r/min, 1% inoculation (D600 = 0.4), the accumulation of phosphorus was various by strains and cultivation concentration of phosphorus as well: In 2 mg/L phosphorus concentration medium, the highest phosphorus-accumulation ratio of strains Y11 and Y4-2 were 96.13% and 94.65%, the phosphorus concentration decreased from 2 mg/L to 0.08 mg/L and 0.11 mg/L, respectively. In 5 mg/L phosphorus concentration medium, the highest phosphorus-accumulation ratio of strains Y11 and Y4-2 were 95.94% and 71.19%, the phosphorus concentration decreased from 5 mg/L to 0.20 mg/L and 1.44 mg/L, respectively. In 8 mg/L phosphorus concentration medium, the highest phosphorus-accumulation ratio of strains Y11 and Y4-2 were 71.24% and 47.81%, the phosphorus concentration decreased from 8 mg/L to 2.30 mg/L and 4.18 mg/L, respectively. For the P removal of Yunnan Dianchi water sample containing 1.01 mg/L phosphorus, Y11 and Y4-2 were successful to decrease the phosphorus concentration from 1.01 mg/L to 0.06 mg/L in 6 h and 48 h, respectively. The results indicated that Acinetobacter sp.Y11 and Y4-2 possess high ability of phosphorus removal and suitability to various water environments. Y11 strain adapt to all kinds of eutrophic waterbody even polluted with phenanthrene, Y4-2 adapt to pH < or = 8.0 eutrophic waterbody with phenanthrene pollution.