不同营养环境下棕鞭藻共栖细菌的群落结构比较

微藻富含油脂，可以用作合成生物柴油的原料，被认为是最具发展前景的生物质能源.微藻的光合培养体系往往是非纯培养体系，现有研究更多地关注微藻生物量的积累及其对废水环境的净化效果，而对体系中广泛存在的共栖细菌缺乏全面深入的认知.本文通过对棕鞭藻共栖细菌的16S rDNA基因进行高通量测序分析，研究棕鞭藻（Ochromonas）在生活废水、BG11及Glu+BG11（BG11中添加10 g·L^-1葡萄糖）3种不同营养环境中共栖细菌的群落结构差异，进而阐明有机物及复杂废水环境对微藻共栖细菌群落结构的影响效果.结果表明，生活废水、BG11及Glu+BG11 3种营养环境中共栖细菌群落结构存在显著差异，生活废水体系中生物多样性显著高于BG11及Glu+BG11体系，生活废水中共栖细菌香浓（Shannon）多样性指数高达4.32，其次是BG11及Glu+BG11，Shannon指数分别为2.13、1.54.从共栖细菌群落的组成上看，3种营养环境中优势菌属差异显著，生活废水中优势菌属有芽殖杆菌属（Gemmobacter）、鞘脂单胞菌属（Sphingomonas）及玫瑰球菌属（Roseococcus），相对丰度分别为14.46%、14.9%、14.54%，其中，芽殖杆菌属只在生活废水中有较高丰度.BG11中寡养单胞菌属（Stenotrophomonas）与玫瑰球菌属的丰度分别高达26.86%、51.03%.Glu+BG11中寡养单胞菌属较BG11中显著增加，达到82.41%，而玫瑰球菌属较生活废水及BG11中则明显降低，菌群丰度仅为6.2%.对比3种营养环境，玫瑰球菌属均具有较高丰度，是棕鞭藻良好的共生菌.

Comparison of community structure of symbiotic bacteria of Ochromonas in different nutritional environments

Microalgae is usually considered to be the most promising biomass energy due to high oil content, which can be used as feedstock for the production of biodiesel. Lots of attention has been paid to the accumulation of microalgae biomass and its purification performance for wastewater. However, for such non-axenic cultivation system of microalgae, limited studies have been conducted on the effect of indigenous bacteria. In this study, the community structure of symbiotic bacteria in domestic wastewater, BG11 and Glu+BG11 (10 g·L^-1 glucose added to BG11) were analyzed with high throughput sequencing, and the effect of organic matter and complex wastewater environment on the community structure of microalgae symbiotic bacteria was clarified. The results showed that there were significant differences in the community structure of symbiotic bacteria in the three systems. The biodiversity of domestic wastewater system was significantly higher than that of BG11 and Glu+BG11. In terms of the composition of symbiotic bacterial community, the dominant bacteria were significantly different. The dominant bacteria in domestic wastewater were Gemmobacter, Sphingomonas and Roseococcus, accounting for 14.46%, 14.9% and 14.54% of the total bacterial community respectively, and only in domestic wastewater Gemmobacter occupied high abundance. In the BG11 culture system, the dominant symbiotic bacteria of Ochromonas mainly included Stenotrophomonas and Roseococcus, and the population abundance accounted for 26.86% and 51.03%, respectively. Compared with BG11, the abundance of Stenotrophomonas in Glu+BG11 increased significantly, reaching 82.41%, while Roseococcus was dramatically lower than domestic wastewater and BG11, accounting for 6.2% of the total bacterial community. It is worth noting that Roseococcus has a high abundance in the three different nutrient environments, which is generally considered to be a favorable symbiotic bacteria of Ochromonas.