title: Conductive iron oxide minerals accelerate syntrophic cooperation in methanogenic benzoate degradation.
abstract: Recent studies have suggested that conductive iron oxide minerals can facilitate syntrophic metabolism of the methanogenic degradation of organic matter, such as ethanol, propionate and butyrate, in natural and engineered microbial ecosystems. This enhanced syntrophy involves direct interspecies electron transfer (DIET) powered by microorganisms exchanging metabolic electrons through electrically conductive minerals. Here, we evaluated the possibility that conductive iron oxides (hematite and magnetite) can stimulate the methanogenic degradation of benzoate, which is a common intermediate in the anaerobic metabolism of aromatic compounds. The results showed that 89-94% of the electrons released from benzoate oxidation were recovered in CH4 production, and acetate was identified as the only carbon-bearing intermediate during benzoate degradation. Compared with the iron-free controls, the rates of methanogenic benzoate degradation were enhanced by 25% and 53% in the presence of hematite and magnetite, respectively. This stimulatory effect probably resulted from DIET-mediated methanogenesis in which electrons transfer between syntrophic partners via conductive iron minerals. Phylogenetic analyses revealed that Bacillaceae, Peptococcaceae, and Methanobacterium are potentially involved in the functioning of syntrophic DIET. Considering the ubiquitous presence of iron minerals within soils and sediments, the findings of this study will increase the current understanding of the natural biological attenuation of aromatic hydrocarbons in anaerobic environments.
authors.affiliation: Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650, China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhuang
authors.affiliation: Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Tang
authors.affiliation: Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650, China.
authors.forename: Yueqiang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650, China.
authors.forename: Min
authors.initials: M
authors.lastname: Hu
authors.affiliation: Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650, China. Electronic address: sgzhou@soil.gd.cn.
authors.forename: Shungui
authors.initials: S
authors.lastname: Zhou
mesh_terms: D000085:Acetates / Q000378:metabolism; D001406:Bacillaceae / Q000235:genetics / Q000378:metabolism; D001565:Benzoates / Q000378:metabolism*; D001673:Biodegradation, Environmental; D005290:Ferric Compounds / Q000378:metabolism*; D052203:Ferrosoferric Oxide / Q000378:metabolism*; D019766:Genes, Archaeal / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics; D008697:Methane / Q000378:metabolism*; D017014:Methanobacterium / Q000235:genetics / Q000378:metabolism; D010459:Peptococcaceae / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D000085:Acetates; D001565:Benzoates; D005290:Ferric Compounds; D012336:RNA, Ribosomal, 16S; C000499:ferric oxide; D008697:Methane; D052203:Ferrosoferric Oxide
keywords: Direct interspecies electron transfer; Iron oxides; Methanogenic benzoate degradation; Syntrophy