Abstract Biofloc-based recirculating aquaculture system (BRAS) is beneficial for nitrogen recovery and culturing turbidity-intolerant fish. BRAS and traditional flow-through system were established to evaluate nitrogen mass balance for 90 days. In comparison with the flow-through system, BRAS increased the nitrogen recovery in the forms of fish and biofloc biomass by 3.2% and 11.9%, respectively. However, BRAS showed a significantly high level of gaseous nitrogen loss (64.4%). Aerobic denitrifiers such as bacteria belonging to the genera Hydrogenophaga, Flavobacterium, Rhodobacter, Pseudomonas, Zoogloea, and Dechloromonas were observed in both systems through Illumina Miseq sequencing. Hydrogenophaga, an autotrophic denitrifier, was predominant in the flow-through system (17% ± 7%). In BRAS, the relative abundance of napA, which is a functional marker for aerobic denitrification, together with nirK and nosZ, significantly increased. These findings indicate that increased aerobic denitrification may be a key factor for the increased gaseous nitrogen loss in BRAS.

中文翻译：

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好氧反硝化影响基于生物絮团的循环水养殖系统中的气态氮损失

摘要 基于生物絮团的循环水养殖系统（BRAS）有利于氮的回收和养殖不耐浊鱼。建立了 BRAS 和传统的流通系统来评估 90 天的氮质量平衡。与流通系统相比，BRAS 将鱼和生物絮团生物量形式的氮回收率分别提高了 3.2% 和 11.9%。然而，BRAS 显示出显着高水平的气态氮损失（64.4%）。通过 Illumina Miseq 测序，在两个系统中均观察到需氧反硝化菌，例如属于 Hydrogenophaga、黄杆菌、红杆菌、假单胞菌、动物胶菌和脱氯单胞菌属的细菌。Hydrogenophaga 是一种自养反硝化菌，在流通系统中占主导地位 (17% ± 7%)。在 BRAS 中，napA 的相对丰度，它是好氧反硝化的功能标记，与 nirK 和 nosZ 一起显着增加。这些发现表明，增加好氧反硝化作用可能是 BRAS 中气态氮损失增加的关键因素。