To improve anaerobic digestion(AD)efficiency of rice straw,solid alkaline CaO and the liquid fraction of digestate(LFD)were used as pretreatment agents of rice straw.The results showed that AD performance of rice stra...To improve anaerobic digestion(AD)efficiency of rice straw,solid alkaline CaO and the liquid fraction of digestate(LFD)were used as pretreatment agents of rice straw.The results showed that AD performance of rice straw with CaOLFD pretreatment was optimal in different pretreatment methods of the CaO+LFD,CaOLFD,LFD+CaO,CaO,and LFD.The maximum methane yield(314 ml(g VS)^(-1))and the highest VFAs concentration(14851 mg·L^(-1) on day 3)of the CaOLFD pretreatment group were 81%and 118%higher than that of the control group,respectively.Under the action of solid alkaline CaO,the bacteria of Clostridium,Atopostipes,Sphaerochaeta,Tissierella,Thiopseudomonas,Rikenellaceae,and Sedimentibacter could build up co-cultures with the archaeal of Methanosaeta,Methanobacterium,and Methanosarcina performing direct interspecies electron transfer(DIET)and improving AD performance of rice straw.Therefore,the combined pretreatment using CaO and LFD could not only pretreat rice straw but also stimulate co-cultures of microorganism to establish DIET enhancing AD efficiency.展开更多
Direct interspecies electron transfer(DIET)may be most important in methanogenic environments,but mechanistic studies of DIET to date have primarily focused on cocultures in which fumarate was the terminal electron ac...Direct interspecies electron transfer(DIET)may be most important in methanogenic environments,but mechanistic studies of DIET to date have primarily focused on cocultures in which fumarate was the terminal electron acceptor.To better understand DIET with methanogens,the transcriptome of Geobacter metallireducens during DIET‐based growth with G.sulfurreducens reducing fumarate was compared with G.metallireducens grown in coculture with diverse Methanosarcina.The transcriptome of G.metallireducens cocultured with G.sulfurreducens was significantly different from those with Methanosarcina.Furthermore,the transcriptome of G.metallireducens grown with Methanosarcina barkeri,which lacks outer‐surface c‐type cytochromes,differed from those of G.metallireducens cocultured with M.acetivorans or M.subterranea,which have an outer‐surface c‐type cytochrome that serves as an electrical connect for DIET.Differences in G.metallireducens expression patterns for genes involved in extracellular electron transfer were particularly notable.Cocultures with c‐type cytochrome deletion mutant strains,ΔGmet_0930,ΔGmet_0557 andΔGmet_2896,never became established with G.sulfurreducens but adapted to grow with all three Methanosarcina.Two porin–cytochrome complexes,PccF and PccG,were important for DIET;however,PccG was more important for growth with Methanosarcina.Unlike cocultures with G.sulfurreducens and M.acetivorans,electrically conductive pili were not needed for growth with M.barkeri.Shewanella oneidensis,another electroactive microbe with abundant outer‐surface c‐type cytochromes,did not grow via DIET.The results demonstrate that the presence of outer‐surface c‐type cytochromes does not necessarily confer the capacity for DIET and emphasize the impact of the electron‐accepting partner on the physiology of the electron‐donating DIET partner.展开更多
厌氧消化是将生物质废弃物进行资源化利用的有效途径之一。然而,复杂的原料性质以及反应器高负荷的运行条件会使厌氧消化过程产生多种抑制效应,易导致反应器运行不稳定,产气效率低等问题。因此,提升厌氧消化反应器运行性能、减缓抑制效...厌氧消化是将生物质废弃物进行资源化利用的有效途径之一。然而,复杂的原料性质以及反应器高负荷的运行条件会使厌氧消化过程产生多种抑制效应,易导致反应器运行不稳定,产气效率低等问题。因此,提升厌氧消化反应器运行性能、减缓抑制效应成为当前的研究热点。区别于以氢气和甲酸为媒介的间接种间电子传递(Mediated Interspecies Electron Transfer,MIET)过程,微生物间的直接种间电子传递(Direct Interspecies Electron Transfer,DIET)能够在菌群间直接进行电子转移,传递效率更高。DIET的建立有助于强化厌氧反应的稳定性,提高反应效率,减缓抑制效应。基于此,该文总结了DIET的研究进展,分析了主要的种间电子传递机制,探讨了DIET对不同类型抑制效应的缓解作用,归纳了DIET潜在微生物的富集效果;在此基础上展望了DIET在减缓厌氧消化抑制效应方面的重点研究方向和应用前景。展开更多
微生物种间电子传递(Interspecies electron transfer,IET)是指电子供体微生物与电子受体微生物之间通过直接或间接方式传递电子形成互营生长关系,从而共同完成单一微生物不能完成的代谢过程的现象。IET分为间接种间电子传递(MediatedIE...微生物种间电子传递(Interspecies electron transfer,IET)是指电子供体微生物与电子受体微生物之间通过直接或间接方式传递电子形成互营生长关系,从而共同完成单一微生物不能完成的代谢过程的现象。IET分为间接种间电子传递(MediatedIET,MIET)和直接种间电子传递(Direct IET,DIET)。其中,前者一般需要氢、甲酸、核黄素等作为电子载体,而后者是指微生物间通过纳米导线、氧化还原蛋白、导电颗粒等进行直接电子交换。DIET是最新发现的IET方式,DIET的发现改变了微生物互营代谢必须依赖氢/甲酸等能量载体的传统认识。本文在论述MIET的同时,重点阐述了DIET的三种介导机制,列举了参与IET的典型微生物种类,系统介绍了IET在厌氧消化产甲烷、甲烷厌氧氧化、微生物脱氯等重要环境过程中的作用机制及应用潜力,并展望了微生物种间电子传递的未来研究方向。本综述有助于加深对微生物IET发生机制的认识,为理解微生物IET在自然界碳氮等元素循环、温室气体排放、污染物降解等关键生物地球化学过程中的作用提供理论基础,为IET的实际工程应用提供可能。展开更多
本研究构建了以丁酸为唯一碳源的厌氧消化反应器,利用16SrRNA基因测序技术分析氯四环素(Chlortetracycline,CTC)单独抑制及CTC与颗粒活性炭(Granular active carbon,GAC)协同作用下,互营丁酸氧化微生物群落结构的动态变化,探究环境胁迫...本研究构建了以丁酸为唯一碳源的厌氧消化反应器,利用16SrRNA基因测序技术分析氯四环素(Chlortetracycline,CTC)单独抑制及CTC与颗粒活性炭(Granular active carbon,GAC)协同作用下,互营丁酸氧化微生物群落结构的动态变化,探究环境胁迫下微生物之间的相互作用及其对CTC及CTC和GAC协同作用的响应。结果表明,原始反应器群落中,已知的互营丁酸氧化菌Syntrophomonas(11.6%)和乙酸营养型产甲烷古菌Methanosaeta(48.5%)分别在细菌和古菌群落中占主导优势。添加40mg/L和50mg/LCTC条件下,甲烷产量分别降低40.4%和49.3%。Syntrophomonas对CTC表现出耐受性,但与其呈正相关联系的细菌(如unclassified Firmicutes和unclassified Comamonadaceae)以及乙酸氧化菌Tepidanaerobacter活性被CTC明显抑制,从而影响丁酸降解率,同时造成代谢产物积累,导致产甲烷量降低。单独添加GAC以及在40mg/L和50mg/LCTC抑制下添加GAC,甲烷产量分别降低2.9%、48.5%和64.7%。共现网络分析结果显示,添加GAC明显增强了Geobacter以及与其呈正相关联系的细菌(Azonexus等)的活性。而产甲烷古菌Methanosaeta和Methanoculleus与Azonexus等大部分细菌呈负相关,因此,添加GAC可能间接影响了产甲烷古菌的活性。展开更多
基金supported by the National Key Research&Development Program of Ministry of Science and Technology of the People’s Republic of China(grant number 2018YFC1900901).
文摘To improve anaerobic digestion(AD)efficiency of rice straw,solid alkaline CaO and the liquid fraction of digestate(LFD)were used as pretreatment agents of rice straw.The results showed that AD performance of rice straw with CaOLFD pretreatment was optimal in different pretreatment methods of the CaO+LFD,CaOLFD,LFD+CaO,CaO,and LFD.The maximum methane yield(314 ml(g VS)^(-1))and the highest VFAs concentration(14851 mg·L^(-1) on day 3)of the CaOLFD pretreatment group were 81%and 118%higher than that of the control group,respectively.Under the action of solid alkaline CaO,the bacteria of Clostridium,Atopostipes,Sphaerochaeta,Tissierella,Thiopseudomonas,Rikenellaceae,and Sedimentibacter could build up co-cultures with the archaeal of Methanosaeta,Methanobacterium,and Methanosarcina performing direct interspecies electron transfer(DIET)and improving AD performance of rice straw.Therefore,the combined pretreatment using CaO and LFD could not only pretreat rice straw but also stimulate co-cultures of microorganism to establish DIET enhancing AD efficiency.
基金This study was supported by the Army Research Office and was accomplished under grant number W911NF‐17‐1‐0345.
文摘Direct interspecies electron transfer(DIET)may be most important in methanogenic environments,but mechanistic studies of DIET to date have primarily focused on cocultures in which fumarate was the terminal electron acceptor.To better understand DIET with methanogens,the transcriptome of Geobacter metallireducens during DIET‐based growth with G.sulfurreducens reducing fumarate was compared with G.metallireducens grown in coculture with diverse Methanosarcina.The transcriptome of G.metallireducens cocultured with G.sulfurreducens was significantly different from those with Methanosarcina.Furthermore,the transcriptome of G.metallireducens grown with Methanosarcina barkeri,which lacks outer‐surface c‐type cytochromes,differed from those of G.metallireducens cocultured with M.acetivorans or M.subterranea,which have an outer‐surface c‐type cytochrome that serves as an electrical connect for DIET.Differences in G.metallireducens expression patterns for genes involved in extracellular electron transfer were particularly notable.Cocultures with c‐type cytochrome deletion mutant strains,ΔGmet_0930,ΔGmet_0557 andΔGmet_2896,never became established with G.sulfurreducens but adapted to grow with all three Methanosarcina.Two porin–cytochrome complexes,PccF and PccG,were important for DIET;however,PccG was more important for growth with Methanosarcina.Unlike cocultures with G.sulfurreducens and M.acetivorans,electrically conductive pili were not needed for growth with M.barkeri.Shewanella oneidensis,another electroactive microbe with abundant outer‐surface c‐type cytochromes,did not grow via DIET.The results demonstrate that the presence of outer‐surface c‐type cytochromes does not necessarily confer the capacity for DIET and emphasize the impact of the electron‐accepting partner on the physiology of the electron‐donating DIET partner.
文摘厌氧消化是将生物质废弃物进行资源化利用的有效途径之一。然而,复杂的原料性质以及反应器高负荷的运行条件会使厌氧消化过程产生多种抑制效应,易导致反应器运行不稳定,产气效率低等问题。因此,提升厌氧消化反应器运行性能、减缓抑制效应成为当前的研究热点。区别于以氢气和甲酸为媒介的间接种间电子传递(Mediated Interspecies Electron Transfer,MIET)过程,微生物间的直接种间电子传递(Direct Interspecies Electron Transfer,DIET)能够在菌群间直接进行电子转移,传递效率更高。DIET的建立有助于强化厌氧反应的稳定性,提高反应效率,减缓抑制效应。基于此,该文总结了DIET的研究进展,分析了主要的种间电子传递机制,探讨了DIET对不同类型抑制效应的缓解作用,归纳了DIET潜在微生物的富集效果;在此基础上展望了DIET在减缓厌氧消化抑制效应方面的重点研究方向和应用前景。
文摘微生物种间电子传递(Interspecies electron transfer,IET)是指电子供体微生物与电子受体微生物之间通过直接或间接方式传递电子形成互营生长关系,从而共同完成单一微生物不能完成的代谢过程的现象。IET分为间接种间电子传递(MediatedIET,MIET)和直接种间电子传递(Direct IET,DIET)。其中,前者一般需要氢、甲酸、核黄素等作为电子载体,而后者是指微生物间通过纳米导线、氧化还原蛋白、导电颗粒等进行直接电子交换。DIET是最新发现的IET方式,DIET的发现改变了微生物互营代谢必须依赖氢/甲酸等能量载体的传统认识。本文在论述MIET的同时,重点阐述了DIET的三种介导机制,列举了参与IET的典型微生物种类,系统介绍了IET在厌氧消化产甲烷、甲烷厌氧氧化、微生物脱氯等重要环境过程中的作用机制及应用潜力,并展望了微生物种间电子传递的未来研究方向。本综述有助于加深对微生物IET发生机制的认识,为理解微生物IET在自然界碳氮等元素循环、温室气体排放、污染物降解等关键生物地球化学过程中的作用提供理论基础,为IET的实际工程应用提供可能。
文摘本研究构建了以丁酸为唯一碳源的厌氧消化反应器,利用16SrRNA基因测序技术分析氯四环素(Chlortetracycline,CTC)单独抑制及CTC与颗粒活性炭(Granular active carbon,GAC)协同作用下,互营丁酸氧化微生物群落结构的动态变化,探究环境胁迫下微生物之间的相互作用及其对CTC及CTC和GAC协同作用的响应。结果表明,原始反应器群落中,已知的互营丁酸氧化菌Syntrophomonas(11.6%)和乙酸营养型产甲烷古菌Methanosaeta(48.5%)分别在细菌和古菌群落中占主导优势。添加40mg/L和50mg/LCTC条件下,甲烷产量分别降低40.4%和49.3%。Syntrophomonas对CTC表现出耐受性,但与其呈正相关联系的细菌(如unclassified Firmicutes和unclassified Comamonadaceae)以及乙酸氧化菌Tepidanaerobacter活性被CTC明显抑制,从而影响丁酸降解率,同时造成代谢产物积累,导致产甲烷量降低。单独添加GAC以及在40mg/L和50mg/LCTC抑制下添加GAC,甲烷产量分别降低2.9%、48.5%和64.7%。共现网络分析结果显示,添加GAC明显增强了Geobacter以及与其呈正相关联系的细菌(Azonexus等)的活性。而产甲烷古菌Methanosaeta和Methanoculleus与Azonexus等大部分细菌呈负相关,因此,添加GAC可能间接影响了产甲烷古菌的活性。
