University of Hamburg, Biocenter Klein Flottbek, Microbiology and Biotechnology, Hamburg, Germany.
Appl Environ Microbiol. 2013 Oct;79(20):6196-206. doi: 10.1128/AEM.01641-13. Epub 2013 Aug 2.
Photobioreactors (PBRs) are very attractive for sunlight-driven production of biofuels and capturing of anthropogenic CO2. One major problem associated with PBRs however, is that the bacteria usually associated with microalgae in nonaxenic cultures can lead to biofouling and thereby affect algal productivity. Here, we report on a phylogenetic, metagenome, and functional analysis of a mixed-species bacterial biofilm associated with the microalgae Chlorella vulgaris and Scenedesmus obliquus in a PBR. The biofilm diversity and population dynamics were examined through 16S rRNA phylogeny. Overall, the diversity was rather limited, with approximately 30 bacterial species associated with the algae. The majority of the observed microorganisms were affiliated with Alphaproteobacteria, Betaproteobacteria, and Bacteroidetes. A combined approach of sequencing via GS FLX Titanium from Roche and HiSeq 2000 from Illumina resulted in the overall production of 350 Mbp of sequenced DNA, 165 Mbp of which was assembled in larger contigs with a maximum size of 0.2 Mbp. A KEGG pathway analysis suggested high metabolic diversity with respect to the use of polymers and aromatic and nonaromatic compounds. Genes associated with the biosynthesis of essential B vitamins were highly redundant and functional. Moreover, a relatively high number of predicted and functional lipase and esterase genes indicated that the alga-associated bacteria are possibly a major sink for lipids and fatty acids produced by the microalgae. This is the first metagenome study of microalga- and PBR-associated biofilm bacteria, and it gives new clues for improved biofuel production in PBRs.
光生物反应器（PBR）非常适合利用阳光生产生物燃料和捕获人为产生的二氧化碳。然而，PBR 存在一个主要问题，即与非纯培养微藻相关的细菌通常会导致生物污垢，从而影响藻类的生产力。在这里，我们报告了与 PBR 中微藻小球藻和斜生栅藻相关的混合物种细菌生物膜的系统发育、宏基因组和功能分析。通过 16S rRNA 系统发育分析了生物膜的多样性和种群动态。总体而言，多样性相当有限，与藻类相关的细菌约有 30 种。观察到的大多数微生物与α变形菌、β变形菌和拟杆菌门有关。罗氏 GS FLX Titanium 和 Illumina HiSeq 2000 的测序组合方法总共产生了 3.5 亿 bp 的测序 DNA，其中 1.65 亿 bp 组装成更大的 contigs，最大大小为 0.2 Mbp。KEGG 途径分析表明，在使用聚合物以及芳香族和非芳香族化合物方面具有很高的代谢多样性。与必需 B 族维生素生物合成相关的基因高度冗余和功能齐全。此外，预测和功能脂酶和酯酶基因的相对数量较多，表明与藻类相关的细菌可能是微藻产生的脂质和脂肪酸的主要消耗者。这是首次对微藻和 PBR 相关生物膜细菌进行宏基因组研究，为提高 PBR 中的生物燃料生产提供了新线索。
