Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n, 47011, Valladolid, Spain; Institute of Sustainable Processes (ISP), Dr. Mergelina s/n, 47011, Valladolid, Spain.
Department of Chemical Engineering, University of Almería, Ctra. Sacramento s/n, 04120, Almería, Spain.
Chemosphere. 2021 Dec;284:131271. doi: 10.1016/j.chemosphere.2021.131271. Epub 2021 Jun 23.
The effects of water depth, operational and environmental conditions on bacterial communities were analyzed in microalgal-bacterial outdoor photobioreactors treating urban wastewaters from March to August 2014. Three raceway photobioreactors inoculated with Scenedesmus sp. and with different water depths (20, 12, and 5 cm) were used at different dilution rates (0.15, 0.3, 0.4, and 0.5 d). A thin-layer reactor with 2 cm water depth and operated at 0.3 d was used as a control. The results showed that biomass productivity increased as water depth decreased. The highest biomass productivity was 0.196 gLd, 0.245 gLd, and 0.457 gLd for 20, 12, and 5 cm depth raceway photobioreactors, respectively. These values were lower than the maximum productivity registered in the control reactor (1.59 gLd). Bacterial communities, analyzed by high-throughput 16S rRNA sequencing, were not affected by water depth. A decrease in community evenness was related to a decrease in nutrient removal. Hetetrotrophs and phototrophs, mainly from the family Rhodobacteraceae, dominated bacterial diversity. The community changed due to increasing temperatures, irradiance, and organic carbon, ammonia, and phosphate contents in the photobioreactor-influent as well as, microalgae inhibition and higher organic carbon in the effluent. The photobioreactors shared a core-biome that contained five clusters of co-occurring microorganisms. The bacteria from the different clusters were taxonomically and ecologically different but functionally redundant. Overall, the drivers of the community changes could be related to abiotic variables and complex biological interactions, likely mediated by microalgae excretion of organic substances and the microorganisms' competence for substrates.
2014 年 3 月至 8 月期间，在处理城市废水的户外微藻-细菌光生物反应器中，分析了水深、操作和环境条件对细菌群落的影响。使用了三种不同水深（20、12 和 5cm）的跑道式光生物反应器，接种了 Scenedesmus sp.，并在不同稀释率（0.15、0.3、0.4 和 0.5d）下运行。一个水深为 2cm 的薄层反应器，以 0.3d 的稀释率运行，作为对照。结果表明，生物量生产力随着水深的降低而增加。20、12 和 5cm 水深跑道式光生物反应器的最高生物量生产力分别为 0.196gLd、0.245gLd 和 0.457gLd。这些值低于对照反应器中记录的最大生产力（1.59gLd）。通过高通量 16S rRNA 测序分析的细菌群落不受水深影响。群落均匀度的降低与养分去除的减少有关。异养菌和光合菌主要来自 Rhodobacteraceae 科，主导了细菌多样性。由于光生物反应器进水的温度、光照、有机碳、氨和磷酸盐含量的增加，以及微藻的抑制作用和出水中较高的有机碳含量，群落发生了变化。光生物反应器共享一个核心生物群，其中包含五个共同存在的微生物簇。不同簇中的细菌在分类学和生态学上不同，但功能上是冗余的。总的来说，群落变化的驱动因素可能与非生物变量和复杂的生物相互作用有关，这可能是由微藻分泌有机物质和微生物对底物的竞争力介导的。
