细菌对城市污水中小球藻生长和油脂积累的影响

利用城市污水培养微藻,可在实现污水无害化处理的同时,培养微藻回收生物质能源.污水为微藻的培养提供氮、磷等营养组分和所需水源,同时污水中的细菌可分解污水中的有机物产生CO_2,为微藻提供生长所需碳源.菌藻混合培养既可以收获藻类,又可以净化污水,由于城市污水含有大量的原生菌类,且微藻与细菌之间存在着互生、拮抗等复杂的相互关系,因此,需要筛选出既能够适应于城市污水又能促进微藻生长和油脂积累的优势菌种.本文从不同来源的13种细菌中筛选出2种能够显著促进蛋白核小球藻(Chlorella pyrenoidosa)生长和油脂积累细菌,并分析了微藻培养结束后城市污水的菌群结构.结果表明:污水中光合细菌初始吸光度D600为0.01,W4菌初始吸光度D_(600)为0.02时,对小球藻的干重和油脂产量促进作用最显著,油脂产量分别可达0.114 g·L~(-1)、0.113 g·L~(-1),油脂产量比空白对照组分别提高了22.58%、21.50%.通过对生成的脂肪酸甲酯进行气相色谱分析,结果显示光合细菌和W4菌的添加并未改变小球藻脂肪酸成分,但提升了单不饱和脂肪酸的含量,有利于提升所得生物柴油的品位.培养结束后污水的菌群结构分析显示投加细菌会降低污水中菌群的丰富度和多样性,初步判断是投加的菌在藻液中能够成为优势菌群,且实验组中丛毛单胞菌属(Comamonas)和假单胞菌属(Pseudomonas)的丰度大于对照组.

Effects of Bacteria on the Growth of and Lipid Accumulation in Chlorella pyrenoidosa Cultivated in Municipal Wastewater

Cultivating microalgae using municipal wastewater can treat wastewater and recover algal biofuel as an energy source. Wastewater provides necessary nutrients such as nitrogen, phosphorus, and water for microalgal growth. Due to the complexity of the components of municipal wastewater and the complex symbiotic and antagonistic relationship between microalgae and bacteria, it is necessary to select the suitable dominant bacterial species that can promote the microalgae to achieve high lipid production and algal biofuel production using municipal wastewater. Based on the microalgal growth and lipid production, we selected Photosynthetic bacteria and W4 bacteria from 13 different types of bacteria and analyzed the microbial community structure of the municipal wastewater at the end of the microalgal culture cycle. Laboratory test results showed that the amount of lipid production by Photosynthetic bacteria and W4 was 0.114 g·L^-1 and 0.113 g·L^-1, which is 22.58% and 21.50% higher than the production by the control group, respectively. According to the gas chromatography (GC) analysis of the lipids, Photosynthetic bacteria and W4 bacteria exerted a relatively low influence on the composition of fatty acids of Chlorella pyrenoidosa but increased the content of monounsaturated fatty acids that improve the grade of biodiesel. The results of the analysis of microbial community structure of the municipal wastewater showed that Photosynthetic and W4 bacteria reduced the richness and diversity of bacterial communities and have the potential to become the dominant bacterial community.