A heterotrophic nitrification-aerobic denitrification bacterium Acinetobacter sp. WZ-1: the superior stress resistance and the unconventional nitrogen metabolic pathways

IF 8.2 2区环境科学与生态学 Q1 ENGINEERING, ENVIRONMENTAL

Water Research X Pub Date : 2025-09-30 DOI:10.1016/j.wroa.2025.100422

Hong Wang , Peike Wu , Li Chen , Lan Wang , Dan Zheng , Wenguo Wang , Liangwei Deng

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Abstract

Heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria are outstanding in nitrogen removal for wastewater treatment. In this study, Acinetobacter sp. WZ-1 and Rhodococcus sp. JY-5 were isolated and identified as HN-AD strains. The ¹⁵N isotope experiments demonstrated that WZ-1 and JY-5 both converted inorganic nitrogen to N₂. Compared with JY-5, WZ-1 showed the superior ability on NH₄⁺-N removal under environmental stress. WZ-1 removed 85.15% and 97.06% of NH₄⁺-N at the initial pH values of 5 and 9, respectively. At the high temperature of 40 °C, NH₄⁺-N removal efficiency by WZ-1 still reached to 80.66%. Moreover, high C/N ratios showed the significant inhibition on growth of WZ-1 and JY-5 under alkaline environment. WZ-1 still removed NH₄⁺-N of 47.15–87.68% with the low C/N ratios of 4–8 at pH 9. It indicated the potential of WZ-1 to treat high-ammonia wastewater featured by the high pH values and low C/N ratios. The genome and intermediate products inferred the unconventional nitrification-denitrification pathway of WZ-1 strain (NH₄⁺→NH₂OH→NO→NO₃⁻→NO₂⁻→NO→N₂→N₂). Particularly, nitrate production is attributed to NO oxidation according the hmp gene. Traditional genes for denitrification (narGH, nirKS, norBD and nosZ) were not found in genome, while flavorubredoxins and NosD protein might involve in nitrite/NO reduction and N₂O reduction, respectively. This study proved that certain unreported enzymes and proteins play important roles in nitrogen removal of the unconventional HN-AD bacteria.

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异养硝化-好氧反硝化细菌不动杆菌sp. WZ-1：优越的抗逆性和非常规的氮代谢途径

异养硝化-好氧反硝化（HN-AD）细菌在污水处理中的脱氮能力突出。本研究分离到不动杆菌sp. WZ-1和红球菌sp. JY-5，鉴定为HN-AD菌株。15N同位素实验表明，WZ-1和JY-5均将无机氮转化为N2。与JY-5相比，WZ-1在环境胁迫下对NH4+-N的去除能力更强。在初始pH值为5和9时，WZ-1对NH4+-N的去除率分别为85.15%和97.06%。在40℃高温下，WZ-1对NH4+-N的去除率仍然达到80.66%。高碳氮比对WZ-1和JY-5在碱性环境下的生长有显著的抑制作用。WZ-1在pH为9时，当C/N为4 ~ 8时，NH4+-N去除率仍为47.15 ~ 87.68%。说明了WZ-1处理高pH值、低碳氮比的高氨废水的潜力。基因组和中间产物推测了WZ-1菌株的非常规硝化-反硝化途径（NH4+→NH2OH→NO→NO3−→NO2−→NO→N2→N2）。特别是，根据hmp基因，硝酸盐的产生归因于NO氧化。基因组中未发现传统的反硝化基因narGH、nirKS、norBD和nosZ，而flavorubredoxins和NosD蛋白可能分别参与亚硝酸盐/NO还原和N2O还原。本研究证实了一些未报道的酶和蛋白在非常规HN-AD菌脱氮过程中发挥重要作用。

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来源期刊

Water Research X Environmental Science-Water Science and Technology

CiteScore

12.30

自引率

1.30%

发文量

期刊介绍： Water Research X is a sister journal of Water Research, which follows a Gold Open Access model. It focuses on publishing concise, letter-style research papers, visionary perspectives and editorials, as well as mini-reviews on emerging topics. The Journal invites contributions from researchers worldwide on various aspects of the science and technology related to the human impact on the water cycle, water quality, and its global management.