产卟啉杆菌对棕鞭藻絮凝收获的影响机制Influence mechanism of Porphyrobacter on flocculation harvest of Ochromonas sp.

生物絮凝法收获微藻细胞具有毒性小、成本低、效率高等优点。为揭示产卟啉杆菌（Porphyrobacter）对棕鞭藻絮凝收获的影响机制，比较在BG11培养基、含5 g/L葡萄糖的BG11（glu+BG11）培养基中纯藻体系以及其与Porphyrobacter共培养体系中的棕鞭藻絮凝效率，并对不同体系中的胞外有机物（AOM）产量与组成及藻际细菌群落结构进行分析。结果表明：在BG11、glu+BG11纯藻培养体系中微藻絮凝效率分别为62.40%和19.02%，而当棕鞭藻与Porphyrobacter在glu+BG11体系中共培养时絮凝效率则高达93.42%，且此时AOM产量及AOM中多糖产量显著降低；对于glu+BG11体系，AOM中的阿拉伯糖、鼠李糖产量均在藻菌共培养时较高，且AOM所含的单糖种类与BG11体系相同；Porphyrobacter可使AOM中的蛋白质酰胺基团发生峰偏移，引起色氨酸、酪氨酸等蛋白质类物质的改变；相比纯藻培养体系，Porphyrobacter能适应棕鞭藻glu+BG11培养体系并成为优势菌属，同时存在芽孢杆菌属（Bacillus）、黄杆菌属（Flavobacterium）、短波单胞菌属（Brevundimonas）等细菌。产卟啉杆菌可显著降低棕鞭藻AOM产量并影响其组成，促进棕鞭藻絮凝。 Harvesting microalgae cells by bioflocculation has the advantages of low toxicity, low cost and high efficiency. In order to reveal the influence mechanism of Porphyrobacter on the flocculation harvest of Ochromonas sp., the flocculation efficiency of Ochromonas sp. in BG11 medium，BG11 medium containing 5 g/L glucose (glu+BG11) pure algal system and coculture system with Porphyrobacter were compared, and the algal organic matter (AOM) yield and composition and the community structure of bacteria in the phycosphere in different systems were analyzed. The results showed that the flocculation efficiency of microalgae in BG11 and glu+BG11 pure algal culture systems were 62.40% and 19.02% respectively. The flocculation efficiency in the coculture system of Ochromonas sp. and Porphyrobacter in glu+BG11 reached 93.42%, and the AOM yield and polysaccharide yield in AOM decreased significantly. For coculture system in glu+BG11, the yield of arabinose and rhamnose in AOM increased significantly, and the type of monosaccharide in AOM was the same as BG11 system. Porphyrobacter shifted the peak of protein amide group in AOM and caused the changes of protein substances such as tryptophan and tyrosine. Compared with the pure algal culture system, Porphyrobacter could adapt to the culture system of Ochromonas sp. as the dominant bacteria, while species of Bacillus, Flavobacterium and Brevundimonas appeared. Porphyrobacter can promote the flocculation of Ochromonas sp. through reducing the AOM yield of Ochromonas sp. and affecting its composition.