Abstract: The degradation mechanism of petroleum hydrocarbon by Brevibacillus brevis and Bacillus cereus was studied on the basis of metabolite analysis.The content of heavy component decreased,while the content of light component increased.The ratio of ∑nC₂₁^- to ∑nC₂₂⁺ increased from 1.35 to 1.73 and 1.87 respectively.After treated by brevibacillus brevis and Bacillus cereus,the ratios of Pr to nC₂₇ and Ph to nC₂₈ increased by 19.0%,17.9% and 9.5%,23.1% respectively.The ratios of Pr to nC₁₇ and Ph to nC₁₈ in oil samples almost have no change before and after treatment by Brevibacillus brevis and Bacillus cereus.It is concluded that nC₁₇ and nC₂₁₈ in oil were not degraded,while no nC₁₇ and nC₁₈ were generated when the heavy hydrocarbon was degraded.The micro-infrared spectrogram of oil treated by microbes showed that some fatty acids were generated.The analysis on fatty acid,alcohol and ketone of oil with GC-MS method indicates that the alkyl acids,especially those with linear and saturated alkyl acids,are dominant in the newly generated acids.A certain amount of naphthenic,alkenyl and aromatic acids are also generated in the degraded samples.The bio-oxidation is the main way in the degradation of oil by Brevibacillus brevis and Bacillus cereus.The unconventional subterminal oxidation also existed,and Brevibacillus brevis and Bacillus cereus converted single long-chain hydrocarbon into short-chain fatty monoacids or alcohols.

Key words: Brevibacillus brevis, Bacillus cereus, petroleum hydrocarbon, degradation mechanism, oxidation

摘要： 研究了短短芽孢杆菌和蜡状芽孢杆菌两株微生物采油菌作用于石油烃的机理,原油经两株菌种作用以后,高碳链饱和烃的相对含量降低,低碳链饱和烃的相对含量则相应增加,∑nC₂₁^-/∑nC₂₂⁺值由原来的1.35分别升高到1.73和1.87;Pr/nC₂₇与Ph/nC₂₈值分别增加19.0%、17.9%和9.5%、23.1%,而Pr/nC₁₇与Ph/nC₁₈值在微生物作用前后几乎没有变化.表明短短芽孢杆菌和蜡状芽孢杆菌作用原油烃时只降解高碳链饱和烷烃,同时无低碳饱和烷烃的生成.微生物作用前后原油中非烃的红外光谱分析也同样表明,有一定量的羧酸生成.采用气相色谱-质谱方法,对油样提取物中微生物产生的酸、醇、酮等物质进行了分析研究,两株菌产酸以饱和烷基酸为主,尤其以直链饱和烷基酸居多,同时也生成一定量的环烷、烯基酸和少量的芳基酸.可以推断,短短芽孢杆菌和蜡状芽孢杆菌对大庆原油的降解以氧化降解为主要途径,存在一种非常规的次末端氧化,同时兼有末端氧化和双末端氧化,生成单脂肪酸、羟基脂肪酸和二羧酸.

关键词: 短短芽孢杆菌, 蜡状芽孢杆菌, 石油烃, 降解机制, 氧化