Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao, Shandong 266003, China.
Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao, Shandong 266003, China.
Sci Total Environ. 2020 Aug 25;732:139268. doi: 10.1016/j.scitotenv.2020.139268. Epub 2020 May 8.
The rapid expansion of aquaculture industry brings about significant environmental concerns, especially nitrogen pollution. Compared to nitrogen bioconversion implemented by the conventional autotrophic nitrifiers and anaerobic denitrifiers, bacteria capable of heterotrophic nitrification-aerobic denitrification (HNAD) in mariculture environments have yet to be well understood. In this study, twenty-five species of new halophilic HNAD bacteria were isolated and identified from mariculture water. By these strains co-cultured in the synthetic mariculture water (ammonia: 5 mg/L, C/N: 5, salinity: 30‰), microbial dynamic analysis showed that ammonia were mainly removed by dominant genera of Marinomonas, Marinobacterium, Halomonas, and Cobetia which simultaneously had positive correlations to total nitrogen removal. Metagenomic annotations revealed that inorganic-N was converted into gaseous-N and organic-N by these HNAD bacteria through nitrogen metabolism pathways of assimilation, partial nitrification, nitroalkane oxidation, nitrate/nitrite dissimilation reduction, and denitrification. Among them, due to the interspecific coexistence and cooperation, Marinomonas communis &Halomonas titanicae, Marinomonas communis &Cobetia marina, Marinomonas aquimarina &Halomonas titanicae, and Marinomonas aquimarina &Cobetia marina exhibited significantly better inorganic-N removal efficiency and stability. The four novel bacterial consortia could transform approximately 60% of initial ammonia into intracellular organic-N (18-20%) and gaseous-N (36-38%), which were significantly higher than those of their single strains. These findings will contribute to understanding and developing the culturable HNAD bacteria as promising candidates for nitrogen pollution control and water bioremediation in mariculture or other saline environments.
水产养殖的快速扩张带来了重大的环境问题，特别是氮污染。与传统的自养硝化菌和厌氧反硝化菌实施的氮生物转化相比，在海水养殖环境中能够进行异养硝化-好氧反硝化（HNAD）的细菌尚未得到很好的理解。在这项研究中，从海水养殖水中分离和鉴定了 25 种新的嗜盐 HNAD 细菌。通过这些菌株在合成海水养殖水中（氨：5mg/L，C/N：5，盐度：30‰）共培养，微生物动态分析表明，氨主要被优势属 Marinomonas、Marinobacterium、Halomonas 和 Cobetia 去除，这些菌同时与总氮去除呈正相关。宏基因组注释表明，这些 HNAD 细菌通过同化、部分硝化、硝基烷氧化、硝酸盐/亚硝酸盐异化还原和反硝化等氮代谢途径将无机-N转化为气态-N 和有机-N。其中，由于种间共存和合作，Marinomonas communis 和 Halomonas titanicae、Marinomonas communis 和 Cobetia marina、Marinomonas aquimarina 和 Halomonas titanicae 以及 Marinomonas aquimarina 和 Cobetia marina 表现出更好的无机-N去除效率和稳定性。这四个新型细菌共生体可以将大约 60%的初始氨转化为细胞内有机-N（18-20%）和气态-N（36-38%），明显高于其单菌株。这些发现将有助于理解和开发可培养的 HNAD 细菌，作为海水养殖或其他盐环境中氮污染控制和水生物修复的有前途的候选物。
