牵牛花对石油污染盐碱土壤微生物群落与石油烃降解的影响

利用磷脂脂肪酸（PLFAs）生物标记法分析野生型牵牛花（Pharbitis nil （Linn.） Choisy）根际土壤微生物群落结构，探讨牵牛花生长对石油烃污染土壤微生物群落与石油烃降解的影响.结果表明，供试土壤微生物群落中，先后出现了24种PLFAs，包括标记细菌的饱和脂肪酸（SAT）、革兰氏阳性菌（G⁺）的末端支链饱和脂肪酸（TBSAT）、革兰氏阴性菌（G^-）的单不饱和脂肪酸（MONO）和环丙脂肪酸（CYCLO）、真菌的多不饱和脂肪酸（PUFA）和放线菌的中间型支链饱和脂肪酸（MBSAT）等六大类型.PLFAs的主成分分析（PCA）表明，牵牛花根际与对照组（未种牵牛花，CK）土壤微生物群落具有明显的差异，微生物多样性在春季增加83%、夏季增加140%、秋季增加50%；微生物的生物量在春季增加97.6%，夏季增加116.3%，秋季增加60.3%.牵牛花根际与对照组相比土壤中石油烃降解率明显提高，在春、夏、秋季分别提高了7.5%、34.2%和19.7%；并且，在牵牛花生长的不同季节石油烃的降解率有明显的差异，春季为22.3%，夏季为51.8%，秋季为38.0%.相关性分析表明，石油烃降解与土壤微生物总生物量具有中等程度的相关性（|r|=0.75）；与G⁺细菌、甲烷氧化菌的生物量具有高度相关性，相关系数|r|>0.8；与G^-的生物量具有中度相关性，相关系数为|r|=0.74；与真菌的生物量具有低度相关性，相关系数为|r|=0.36，与放线菌没有相关性，相关系数为|r|<0.30.

Effect of Pharbitis nil (Linn.) Choisy growth on the microbial community and petroleum hydrocarbon degradation in petroleum-contaminated saline-alkali soil

The diversity in the soil microbial community of petroleum-contaminated soil that was planted with Pharbitis nil (Linn.) Choisy was evaluated in different seasons (spring, summer, and autumn) by phospholipid fatty acid (PLFA) analysis method. We identified 24 types of PLFAs, including bacteria biomarkers of saturated fatty acids (SAT), gram-negative (G^-) bacteria biomarkers of monounsaturated fatty acids (MUFA) and cycle fatty acids (CYCLO), gram-positive (G⁺) bacteria biomarkers of terminal branched saturated fatty acids (TBSAT), actinomycetes biomarkers of middle branched saturated fatty acids (MBSAT), and fungi biomarkers of polyunsaturated fatty acid (PUFA) species. The principal component analysis (PCA) of the PLFAs signatures revealed marked differences between soil with and without Pharbitis. Differences were also observed in different seasons. The microbial diversity increased by 83%, 140%, and 50% and biomass of soil microbes increased by 97.5%, 116.3%, and 60.3% for spring, summer, and autumn, respectively. In addition, the degradation rates of total petroleum hydrocarbon (TPH) was 22.3%, 51.8%, and 38.0% and increased by 7.5%, 34.2%, and 19.7% in spring, summer, and autumn respectively, when Pharbitis nil (Linn.) Choisy was grown on saline alkali soils. Correlation analysis was used to determine the correlation between TPH degradation and the soil microbial community. The total soil microbial biomass showed medium to high correlation with TPH degradation. The correlation coefficient was |r|=0.75 for bacteria; G⁺ and methane-oxidizing bacterial biomass had a correlation coefficient |r|>0.80 and G^- bacterial biomass had a correlation coefficient |r|=0.74. The biomass of fungi had low correlation with TPH degradation, with a correlation coefficient |r|=0.36. The biomass of actinomycetes showed no correlation with TPH degradation (|r|<0.30).