Department of Molecular Biosciences and Bioengineering , University of Hawai'i at Ma̅noa , 1955 East-West Road , Honolulu , Hawai'i 96822 , United States.
Department of Earth and Environmental Engineering , Columbia University , 500 West 120th Street , New York , New York 10027 , United States.
Environ Sci Technol. 2018 Nov 6;52(21):12728-12739. doi: 10.1021/acs.est.8b04177. Epub 2018 Oct 15.
Aquaponics is a technology for food production (fish and vegetables/fruits) with concomitant remediation of nitrogen-rich aquaculture effluent. There is, however, a critical need to improve the nitrogen use efficiency (NUE) in aquaponics. Here, we employed quantitative polymerase chain reactions and next-generation sequencing to evaluate the bacterial communities and their links to nitrogen transformations for improving NUEs in four bench-scale plant-based floating-raft aquaponics (pak choi, lettuce, chive, and tomato) and three pH levels (7.0, 6.0, and 5.2). Low relative abundance of nitrifiers in plant roots and biofilters suggested nitrogen loss, which decreased NUE in aquaponics. Low pH level was a major factor that shifted the microbial communities and reduced the relative abundance of nitrifiers in aquaponic systems, leading to total ammonia nitrogen accumulation in recirculating water. In plant roots, the abundance of nitrite-oxidizing bacteria (e.g., Nitrospira spp.) did not decrease at low pH levels, suggesting the benefit of growing plants in aquaponics for efficient nitrification and improving NUE. These findings on microbial communities and nitrogen transformations provided complementary strategies to improve the performance of the aquaponics regarding water quality and extent of nutrient recovery from aquaculture effluent.
水培是一种用于生产食物（鱼类和蔬菜/水果）的技术，同时可以修复富含氮的水产养殖废水。然而，水培技术迫切需要提高氮利用效率（NUE）。在这里，我们采用定量聚合酶链式反应和下一代测序技术，评估了细菌群落及其与氮转化的关系，以提高四种基于植物的浮筏水培系统（白菜、生菜、韭菜和番茄）和三种 pH 值（7.0、6.0 和 5.2）的 NUE。植物根系和生物过滤器中硝化菌的相对丰度较低表明存在氮损失，这降低了水培系统的 NUE。低 pH 值是一个主要因素，它改变了微生物群落，降低了水培系统中硝化菌的相对丰度，导致循环水中总氨氮的积累。在植物根系中，亚硝酸盐氧化菌（如 Nitrospira 属）的丰度在低 pH 值下并没有下降，这表明在水培系统中种植植物有利于高效硝化作用和提高 NUE。这些关于微生物群落和氮转化的发现为提高水培系统的性能提供了补充策略，涉及到水质和从水产养殖废水中回收营养物质的程度。
