Brakstad Odd G, Bonaunet Kristin, Nordtug Trond, Johansen Oistein
SINTEF Applied Chemistry, Div Marine Environmental Technology, N-7010 Trondheim, Norway.
Biodegradation. 2004 Oct;15(5):337-46. doi: 10.1023/b:biod.0000042189.69946.07.
The objective of this study was to establish methods for controlled studies of hydrocarbon depletion from thin oil films in cold natural seawater, and to determine biotransformation in relation to other essential depletion processes. Mineral oil was immobilized on the surface of hydrophobic Fluortex fabrics and used for studies of microbial biodegradation in an experimental seawater flow-through system at low temperatures (5.9-7.4 degrees C) during a test period of 42 days. The seawater was collected from a depth of 90 m, and microbial characterization by epifluorescence microscopy, fluorescence in situ hybridization, and most-probable number analysis showed relatively larger fractions of archaea and oil-degrading microbes than in the corresponding surface water. Chemical analysis of hydrocarbons attached to the fabrics during the test period showed that n-alkanes (C10-C36) were decreased by 98% after 21 days, while naphthalenes were depleted by 99-100% during the same period. At the end of the period 4-5 ring polyaromatic hydrocarbon (PAH) compounds were removed by 82% from the fabrics. Analysis of the recalcitrant pentacyclic triterpane C30 17alpha(H),21beta(H)-hopane showed that the oil remained adsorbed to the fabrics during the test period. Comparison of depletion analysis with calculation of hydrocarbon dissolution in a flow-through system indicated that naphthalenes and smaller PAH compounds (alkylated 2-ring and 3-ring compounds) were removed from the fabrics by dissolution. The data further implied that depletion of n-alkanes and 4-5 ring PAH hydrocarbons were the result of biotransformation processes. PCR amplification of bacterial 16S rRNA genes from microbes adhering on the immobilized oil surfaces showed the dominance of a few bands when analysed in denaturing gradient gel electrophoresis (DGGE). Sequence analysis of DGGE bands revealed phylogenetic affiliation to the alpha- and gamma-subdivisions of proteobacteria and to the Chloroflexus-Flavobacterium-Bacteroides group.
本研究的目的是建立在寒冷天然海水中对薄油膜碳氢化合物损耗进行对照研究的方法，并确定与其他重要损耗过程相关的生物转化。将矿物油固定在疏水性氟纶织物表面，用于在低温（5.9 - 7.4摄氏度）的实验性海水流通系统中进行42天测试期的微生物生物降解研究。海水取自90米深处，通过落射荧光显微镜、荧光原位杂交和最大可能数分析进行的微生物表征显示，与相应地表水相比，古菌和石油降解微生物的比例相对更大。对测试期间附着在织物上的碳氢化合物进行化学分析表明，正构烷烃（C10 - C36）在21天后减少了98%，而萘在同一时期减少了99 - 100%。在测试期结束时，4 - 5环多环芳烃（PAH）化合物从织物上的去除率为82%。对难降解的五环三萜烷C30 17α(H),21β(H)-藿烷的分析表明，在测试期间油仍吸附在织物上。将损耗分析与流通系统中碳氢化合物溶解计算进行比较表明，萘和较小的PAH化合物（烷基化的2环和3环化合物）通过溶解从织物上被去除。数据进一步表明正构烷烃和4 - 5环PAH碳氢化合物的损耗是生物转化过程的结果。对附着在固定化油表面的微生物的细菌16S rRNA基因进行PCR扩增，在变性梯度凝胶电泳（DGGE）分析时显示出少数条带占主导地位。DGGE条带的序列分析揭示了与变形菌门的α和γ亚群以及绿弯菌-黄杆菌-拟杆菌群的系统发育关系。
