Cysteine-Accelerated Methanogenic Propionate Degradation in Paddy Soil Enrichment.
Propionate degradation is a critical step during the conversion of complex organic matter under methanogenic conditions, and it requires a syntrophic cooperation between propionate-oxidizing bacteria and methanogenic archaea. Increasing evidences suggest that interspecies electron transfer for syntrophic metabolism is not limited to the reducing equivalents of hydrogen and formate. This study tested the ability of an electron shuttle to mediate interspecies electron transfer in syntrophic methanogenesis. We found that cysteine supplementation (100, 400, and 800 μM) accelerated CH4production from propionate in paddy soil enrichments. Of the concentrations tested, 100 μM cysteine was the most effective at enhancing propionate degradation to CH4, and the rates of CH4production and propionate degradation were increased by 109 and 79%, respectively, compared with the cysteine-free control incubations. We eliminated the possibility that the stimulatory effect of cysteine on methanogenesis was attributable to the function of cysteine as a methanogenic substrate in the presence of propionate. The potential catalytic effect involved cysteine serving as an electron carrier to mediate interspecies electron transfer in syntrophic propionate oxidization. The redox potential of cystine/cysteine, which is dependent on the concentration, might be more suitable to facilitate interspecies electron transfer between syntrophic partners at a concentration of 100 μM. Pelotomaculum, obligately syntrophic, propionate-oxidizing bacteria, and hydrogenotrophic methanogens of the family Methanobacteriaceae are predominant in cysteine-mediated methanogenic propionate degradation. The stimulatory effect of cysteine on syntrophic methanogenesis offers remarkable potential for improving the performance of anaerobic digestion and conceptually broaden strategies for interspecies electron transfer in syntrophic metabolism.
Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-environmental and Soil Sciences, No. 808 Tianyuan Road, Guangzhou, 510650, China.
Li
L
Zhuang
Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-environmental and Soil Sciences, No. 808 Tianyuan Road, Guangzhou, 510650, China.
Jinlian
J
Ma
Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-environmental and Soil Sciences, No. 808 Tianyuan Road, Guangzhou, 510650, China. tangjia@soil.gd.cn.
Jia
0000-0002-2701-5814
J
Tang
Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-environmental and Soil Sciences, No. 808 Tianyuan Road, Guangzhou, 510650, China.
Ziyang
Z
Tang
Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-environmental and Soil Sciences, No. 808 Tianyuan Road, Guangzhou, 510650, China.
Shungui
S
Zhou
D000693:Anaerobiosis; D001105:Archaea / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D001419:Bacteria / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D001673:Biodegradation, Environmental / Q000187:drug effects*; D003545:Cysteine / Q000008:administration & dosage / Q000494:pharmacology*; D019641:DNA, Archaeal / Q000032:analysis / Q000302:isolation & purification; D004269:DNA, Bacterial / Q000032:analysis / Q000302:isolation & purification; D004579:Electron Transport / Q000187:drug effects; D005561:Formates / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism; D007700:Kinetics; D008697:Methane / Q000032:analysis / Q000378:metabolism*; D017013:Methanobacteriaceae / Q000378:metabolism; D059013:Microbial Consortia / Q000235:genetics; D010084:Oxidation-Reduction; D010802:Phylogeny; D011422:Propionates / Q000032:analysis / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017421:Sequence Analysis; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology
D019641:DNA, Archaeal; D004269:DNA, Bacterial; D005561:Formates; D011422:Propionates; D012336:RNA, Ribosomal, 16S; D012987:Soil; C030544:formic acid; D006859:Hydrogen; D003545:Cysteine; D008697:Methane
Cysteine; Electron shuttle; Methanogenesis; Propionate degradation; Syntrophic interaction