多孔炭对己酸巨球菌的产酸特性及碳通量的影响机制  

Mechanism of the effect of porous charcoal on the acid-producing characteristics and carbon flux of Megasphaera hexanoica

作　　者：王泽宇 范红叶 刘灵秀 陈浚 WANG Zeyu;FAN Hongye;LIU Lingxiu;CHEN Jun(Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province,Interdisciplinary Research Academy,Zhejiang Shuren University,Hangzhou 310015,China;Faculty of Sciences Interdisciplinary Centre of Chemistry and Biology,University of La Coruña,La Coruña 15001,Spain;College of Environment,Zhejiang University of Technology,Hangzhou 310014,China;College of Geography and Environmental Science,Zhejiang Normal University,Jinhua 321004,China)

机构地区：[1]浙江树人学院交叉科学研究院浙江省污染暴露与健康干预重点实验室,杭州310015 [2]拉科鲁尼亚大学理学院化学与生物学跨学科中心,拉科鲁尼亚150013 [3]浙江工业大学环境学院,杭州310014 [4]浙江师范大学地理与环境科学学院,金华321004

出　　处：《应用与环境生物学报》2024年第5期1006-1014,共9页Chinese Journal of Applied and Environmental Biology

基　　金：国家自然科学基金项目(42207161,42177115);浙江省自然科学基金项目(LTGS23D030001)资助。

摘　　要：利用微生物的碳延长过程用于高经济产物己酸的生成是一项绿色环保的可持续技术,然而产己酸菌的底物代谢路径复杂导致目标产物己酸的选择性不高,而最近研究表明炭材料可以作为提升菌株产酸性能的一种有效策略.因此探讨活性炭(activated charcoal,AC)和生物炭(biochar,BC)对己酸巨球菌(Megasphaera hexanoica)生长代谢和产酸性能的影响.结果显示,AC组显著促进了底物乳酸的氧化过程,伴随其生物量的明显增多(最大生物量提升27.2%),而BC组则显著地提升己酸的产量(由2.5 g/L提升至4.3 g/L).通过分析产物分布及底物碳通量,揭示了AC加速了丙酮酸途径中乙酰辅酶A向细胞合成的碳流量(碳通量由10.6%提升至19.5%),而BC则促进了乙酰辅酶A向乙酸及逆β氧化循环过程中的丁酸、己酸的合成(碳通量由37.2%提升至61.1%).与之对应,AC的乳酸消耗比滴度极大提高(由4.17 g/g提升至5.56 g/g)和己酸生成比滴度的极大下降(由3.08 g/g减少至1.72 g/g),BC则恰好相反.进一步,关键的代谢指标活性NADH、EPS、丙酮酸脱氢酶和乙酸激酶验证了这一推论,即AC组中负责催化丙酮酸氧化为乙酰辅酶A的丙酮酸脱氢酶活性提升了77.9%,而BC组中负责催化乙酰辅酶A向逆β氧化过程转化的乙酸激酶活性提升了41.6%.本研究表明AC和BC对己酸巨球菌的生长代谢和产酸性能有不同的影响机制,为发酵领域中的己酸合成的提升策略提供了一定的理论参考和技术支撑.(图5表1参37)Utilizing the carbon chain elongation process of microorganisms to generate hexanoic acid,an important economic product,is a green and sustainable technology.The complex substrate metabolism pathway of hexanoic acid-producing bacteria leads to low selectivity of the target product hexanoic acid.Recent studies showed that charcoal materials can enhance the acid generation by these strains.In the present study,we investigated the effects of activated charcoal(AC)and biochar(BC)on the growth,metabolism,and acidproducing performance of Megasphaera hexanoica.We explored the effects of different concentrations of AC and BC on hexanoic acid production,biomass,and key enzyme activities.The results showed that in the AC group,oxidation of the lactic acid substrate was significantly promoted,accompanied by a significant increase in its biomass(27.2% increase in maximum biomass).In contrast,in the BC group,the production of hexanoic acid was significantly enhanced(from 2.5 to 4.3 g/L).Analysis of the product distribution and substrate carbon fluxes revealed that AC accelerated the carbon flux of acetyl coenzyme A to cellular synthesis in the pyruvate pathway(carbon flux elevated from 10.6% to 19.5%),whereas BC promoted the synthesis of butyric and hexanoic acids from acetyl coenzyme A to acetate and during the reverse β-oxidation cycle(carbon flux elevated from 37.2% to 61.1%).This result corresponded to the large increase in the specific titer of lactate consumption(elevated from 4.17 to 5.56 g/g)and a great decrease in the specific titer of hexanoic acids production(reduced from 3.08 to 1.72 g/g)in the presence of AC,with the opposite effects observed for BC.Further,the key metabolic index activities NADH,extracellular polymers,pyruvate dehydrogenase,and acetate kinase verified this inference.The activity of pyruvate dehydrogenase,which is responsible for catalyzing oxidation of pyruvate to acetyl coenzyme A,was elevated by 77.9% in the AC group.In contrast,the activity of acetate kinase,which is responsible for catalyzi

关 键 词：活性炭 生物炭 己酸巨球菌 碳通量 乙酰辅酶A 

分 类 号：TQ921[轻工技术与工程—发酵工程]