Abstract：
Petroleum hydrocarbons are being released into the marine environment continuously. They will undergo weathering and may eventually be biodegraded by bacteria and other microbes. While nanoplankton (2-20 μm) are the major consumers of marine bacteria, their effect on the process of biodegradation of oil hydrocarbons is still debated. A 14-day microcosm experiment was conducted to investigate the effects of crude oil hydrocarbons on nanoplankton bacterivory and bacterial community in coastal waters. The coefficients of population growth (0.56-1.80 d-1 for all treatments considered) and grazing mortality (0.38-1.65 d-1 for all treatment considered) of bacteria estimated with the dilution method did not differ among the treatments of control (Ctrl), low dose chemically dispersed oil (LDOil, 2 μL L-1 of crude oil), and high dose chemically dispersed oil (HDOil, 8 μL L-1 of crude oil). Bacterial abundance ranged between 0.21-0.86 × 106 cells mL-1 on average for all treatments. The lack of drastic increases in the cell density of bacterial cells in the oil-loaded treatments was observed throughout the experiment period. Sequencing analysis of the 16S rRNA gene revealed the progressive changes in the community compositions of bacteria in all treatments. The relatively high abundance of oil-degrading bacteria, including Cycloclasticus and Alcanivorax on Days 3-14 of the experiment reflected the presence of biodegradation of oil in the LDOil and HDOil treatments. Throughout the 14 days, the community composition of bacteria in the LDOil and HDOil treatments became more similar and they both differed from that in the Ctrl treatment. This study concluded that, in oil-polluted seawater, the changes in the bacterial community composition were mainly resulting from the addition of chemically dispersed crude oil.
摘要：
石油碳氢化合物不断释放到海洋环境中。它们将经历风化，最终可能被细菌和其他微生物生物降解。虽然纳米浮游生物（2-20μm）是海洋细菌的主要消费者，它们对石油烃生物降解过程的影响仍存在争议。进行了14天的微观实验，以研究原油烃对沿海水域纳米浮游生物细菌和细菌群落的影响。用稀释方法估计的细菌的种群增长系数（所有考虑的处理为0.56-1.80d-1）和放牧死亡率（所有考虑的处理为0.38-1.65d-1）在对照处理（Ctrl）之间没有差异，低剂量化学分散油(LDOil，2μL-1的原油)，和高剂量化学分散油(HDOil，8μL-1的原油)。所有处理的细菌丰度平均在0.21-0.86×106个细胞mL-1之间。在整个实验期间,观察到在装载油的处理中细菌细胞的细胞密度没有急剧增加。16SrRNA基因的测序分析揭示了在所有处理中细菌群落组成的进行性变化。油脂降解菌的丰度相对较高,在实验的第3-14天，包括Cycloclasticus和Alcanivorax反映了LDOil和HDOil处理中油的生物降解的存在。在这14天里,LDOil和HDOil处理中的细菌群落组成变得更加相似，并且它们都与Ctrl处理中的细菌群落组成不同。这项研究的结论是,在石油污染的海水中，细菌群落组成的变化主要是由于添加了化学分散的原油。
