摘要
目前有机废弃物在厌氧发酵方面引起了极大的关注,然而在发酵过程中不可避免地会积累硝态氮(NO_(3)^(-)-N)和亚硝态氮(NO_(2)^(-)-N),它们对链延长微生物在脂肪酸合成过程中的影响尚鲜见报道.为了揭示无机氮污染对厌氧发酵过程可能产生的影响及其机理,探究了1、3、5 g/L的NO_(3)^(-)-N和NO_(2)^(-)-N对Megasphaera hexanoica(己酸巨球菌)厌氧发酵过程中己酸生产性能的影响.结果表明:①1、3、5 g/L的NO_(3)^(-)-N对菌株的生长代谢特性无明显促进或抑制作用,而同浓度的NO_(2)^(-)-N则严重抑制了菌株的生长代谢和己酸产生,其中5 g/L的NO_(2)^(-)-N导致菌株最大生长量仅为2.21 g/L,显著低于对照组的5.83 g/L,同时菌株的乳酸消耗量和己酸产量也分别从5.9和3.8 g/L降至2.2和1.1 g/L.②进一步的代谢活性实验表明,5 g/L的NO_(2)^(-)-N抑制了碳源氧化〔还原型辅酶Ⅰ产量为6.2 nmol/(mg·protein)〕和能量运输〔电子传递系统活性为0.04 mg/(g·protein·min)〕,且导致了菌株膜完整性受到破坏(乳酸脱氢酶释放量为92 mU/mL)以及胞外聚合物分泌增加(多糖含量为94 mg/L).③己酸巨球菌的基因表达结果显示,NO_(2)^(-)-N显著降低了链延长相关功能基因的表达丰度.研究显示,NO_(2)^(-)-N作为厌氧发酵液中的常见污染物,通过抑制己酸巨球菌中链延长相关基因和酶的代谢活性,从而显示出对己酸合成的明显抑制作用.
Nowadays,organic waste has attracted great attention in anaerobic fermentation,but nitrate nitrogen(NO_(3)^(-)-N)and nitrite nitrogen(NO_(2)^(-)-N)inevitably accumulate during the fermentation process,and their effects on chain elongation microorganisms during fatty acid synthesis have not been reported.In order to reveal the possible effects of inorganic nitrogen pollution on the anaerobic fermentation process and its mechanisms,we investigated the effects of 1,3,5 g/L NO_(3)^(-)-N and NO_(2)^(-)-N on the performance of caproic acid production during anaerobic fermentation of Megasphaera hexanoica.The results showed that:(1)1,3,5 g/L NO_(3)^(-)-N had no significant promotion or inhibition effect on the growth and metabolic properties of the strain,while the same concentration of NO_(2)^(-)-N severely inhibited the growth and metabolism of the strain and the production of caproic acid.The maximum growth of the strain was only 2.21 g/L at 5 g/L NO_(2)^(-)-N,which was significantly lower than that of the control group(5.83 g/L),and the lactic acid consumption and caproic acid production of the strain also decreased from 5.9 and 3.8 g/L to 2.2 and 1.1 g/L,respectively.(2)Further metabolic activity experiments showed that NO_(2)^(-)-N at 5 g/L inhibited carbon source oxidation(reduced coenzymeⅠproduction of 6.2 nmol/(mg·protein))and energy transport(electron transport system activity of 0.04 mg/(g·protein·min)).This ultimately led to a disruption of the membrane integrity of the strain(lactate dehydrogenase release of 92 mU/mL)and an increase in extracellular polymer secretion(polysaccharide content of 94 mg/L).(3)The gene expression results of Megasphaera hexanoica suggested that NO_(2)^(-)-N significantly reduced the expression abundance of functional genes related to chain elongation.It was revealed that NO_(2)^(-)-N,as a common pollutant in anaerobic fermentation broth,had a significant inhibitory effect on caproic acid synthesis by suppressing chain elongation-related metabolic activities of genes and enzym
作者
王泽宇
范红叶
刘灵秀
柏萌薇
陈浚
WANG Zeyu;FAN Hongye;LIU Lingxiu;BAI Mengwei;CHEN Jun(Zhejiang Provincial Key Laboratory of Pollution Exposure and Health Intervention,Interdisciplinary Research Academy,Zhejiang Shuren University,Hangzhou 310015,China;Academy of Biology and Environmental Engineering,Zhejiang Shuren University,Hangzhou 310015,China;Academy of Geography and Environmental Science,Zhejiang Normal University,Jinhua 321004,China;College of Environment,Zhejiang University of Technology,Hangzhou 310014,China;Faculty of Sciences Interdisciplinary Centre of Chemistry and Biology,University of La Coruña,La Coruña 15001,Spain)
出处
《环境科学研究》
CAS
CSCD
北大核心
2024年第5期1046-1054,共9页
Research of Environmental Sciences
基金
国家自然科学基金项目(No.42207161,42177115)
浙江省自然科学基金项目(No.LTGS23D030001)。
