Hydrocarbon Degradation Bacteria Screening And The Degradation Specificity In Harbor Area

The harbor area was seriously polluted by the petroleum hydrocarbons, These compositions will be the potential risks of the ecological health, and therefore, it is necessary to take measures for the oil pollution in harbor. The investigations about the petroleum hydrocarbon pollution of the seawater and sediments in Tianjin Harbor were taken. Based on the investigation, hydrocarbon degradation bacteria were screened, the degradation specificity for the petroleum hydrocarbons were studied, in order to find the theoretical support for the bioremediation of harbor area. The main fingdings are as follows:With the survey of seawater and sediments in intertidal zone from Tianjin Harbor, the concentration of alkanes was 24.44 μg/L, the concentration of methyl-substituted aromatics of 1.60 μg/L, the concentrations of PAHs at the sediments from high, middle and low tide were 154.07 ng/gdw,42.21 ng/gdw,33.11 ng/gdw, respectively, were higher than other sea area.With the method of gradual domestication cultivation, five hydrocarbon degradation bacteria CHI, CH2, CH3, CH4 and CH5 were screened from harbor seawaters of Tianjin. With 16S rRNA gene sequence similarity search, Strain CHI was identified as Bacillus sp. F67. Strain CH2 identified as Vibrio sp. BJGMM-B31. Strain CH3 was identified as Bacillus amyloliquefaciens. Strain CH4 was identified as Vibrio rumoiensis. Strain CH5 was identified Cobetia marina strain NIOT-Cu-22.The isolated strains were cultured in the medium with different hydrocarbons, the growth conditions were characterized by OD600, the results showed that:Strains CHI, CH4 and CH5 were well growth, whereas strains CH2 and CH3 was inhibited. All strains were well growth with the concentration of phenanthrene at 1 mg/L, but inhibited at the concentration of 5 mg/L. After 30 days the growth of single strain and mixed bacteria (1:1:1:1:1) was better in the culture medium with pristane, phenanthrene, fluoranthene, benzo(a)pyrene mixed than the one in control group. The growth of mixed bacteria with hydrocarbons of pristane, phenanthrene, fluoranthene and benzo(a)pyrene was significantly higher to the control group.The community of mixed bacteria in the culture medium with different hydrocarbons was examined after 30 days growth, strain CHI was well growth and strains CH2 and CH4 disappear in the control group. All bacteria could exist with hydrocarbons in. The amount of strains CHI and CH4 were less with pristane as specific hydrocarbon. The amount of strains CH2 and CH3 were less with phenanthrene in. The amount of strain CH5 were more with fluoranthene in. The amount of strains CH3, CH4 and CH5 were more with benzo(a)pyrene in.Using the streaked plate to judge whether the n-Nonadecane, pristane, phenanthrene, fluoranthene, pyrene and benzo(α)pyrene could be specific degradated by screened strains. The result is that n-Nonadecane, pristane, phenanthrene, pyrene and benzo(a)pyrene can be degradated by strain CHI. N-Nonadecane, fluoranthene, and pyrene can be degradated by strains CH2 and CH3. Pristane and benzo(a)pyrene can be degradated by strain CH4. N-Nonadecane, phenanthrene, pyrene and benzo(a)pyrene can be degradated by strain CH5.The proportion of volatile n-Nonadecane was 97%-99% after 20 days except the concentration of 20 μg/L. The effect with the bacteria to the degradation rate were CH2> CH1> CH3> CH5> CH4. The degradation products of n-Nonadecane were aldehydes, ketones and esters.Single strain CHI, CH2, CH3, CH4 and CH5 and mixed bacteria was cultured 30 days in the culture medium with mixed hydrocarbon. The degradation rates of phenanthrene were bigger than 60%, the degradation rate of mixed bacteria was lower. The degradation rates of fluoranthene were nearly 100% except CH3. The degradation rates of benzo(a)pyrene were between 20% and 70%, the degradation rates of CHI and CH3 were lower. The degradation rates of pristane were between 60% and 95%, the degradation rate of CH4 was the lowest. The specific degradation rates of phenanthrene, benzo (a) pyrene and pristane by mixed bacteria were 56.47%,8.95% and 30.37% respectively. The results mabe caused by the effects between strains.