Pelotomaculum terephthalicum sp. nov. and Pelotomaculum isophthalicum sp. nov.: two anaerobic bacteria that degrade phthalate isomers in syntrophic association with hydrogenotrophic methanogens

Abstract

An anaerobic phthalate isomer-degrading strain (JT(T)) that we previously isolated was characterized. In addition, a strictly anaerobic, mesophilic, syntrophic phthalate isomer-degrading bacterium, designated strain JI(T), was isolated and characterized in this study. Both were non-motile rods that formed spores. In both strains, the optimal growth was observed at temperatures around 37 degrees C and neutral pH. In syntrophic co-culture with the hydrogenotrophic methanogen Methanospirillum hungatei, both strains could utilize two or three phthalate isomers for growth, and produce acetate and methane as end products. Strain JT(T) was able to grow on isophthalate, terephthalate, and a number of low-molecular weight aromatic compounds, such as benzoate, hydroquinone, 2-hydroxybenzoate, 3-hydroxybenzoate, 2,5-dihydroxybenzoate, 3-phenylpropionate in co-culture with M. hungatei. It could also grow on crotonate, hydroquinone and 2,5-dihydroxybenzoate in pure culture. Strain JI(T) utilized all of the three phthalate isomers as well as benzoate and 3-hydroxybenzoate for growth in co-culture with M. hungatei. No substrates were, however, found to support the axenic growth of strain JI(T). Neither strain JT(T) nor strain JI(T) could utilize sulfate, sulfite, thiosulfate, nitrate, fumarate, Fe (III) or 4-hydroxybenzoate as electron acceptor. Phylogenetically, strains JT(T) and JI(T) were relatively close to the members of the genera Pelotomaculum and Cryptanaerobacter in 'Desulfotomaculum lineage I'. Physiological and chemotaxonomic characteristics indicated that the two isolates should be classified into the genus Pelotomaculum, creating two novel species for them. Here, we propose Pelotomaculum terephthalicum sp. nov. and Pelotomaculum isophthalicum sp. nov. for strain JT(T) and strain JI(T), respectively. The type strains are strains JT(T) (= DSM 16121(T )= JCM 11824(T )= NBRC 100523(T)) and JI(T) (= JCM 12282(T) = BAA-1053(T)) for P. terephthalicum and P. isophthalicum, respectively.

Multiple syntrophic interactions in a terephthalate-degrading methanogenic consortium

“…Several studies (Chan, 2000;Qiu et al, 2006;Imachi et al, 2008) have observed the existence of multiple bacterial populations in highly enriched methanogenic cultures degrading carbon substrates like formate, acetate, propionate and phthalate isomers. These observations were shown through a defined mixed culture (Dolfing et al, 2008), suggesting that syntrophic interactions in methanogenic enrichments are more complex than simple pairwise syntroph-methanogen relationships.…”

“…The syntrophic bacteria, however, are difficult to identify based on phylogenetic classification, and extremely difficult to obtain in pure culture. In the last decade, only three bacterial species that can degrade TA and its isomers have been successfully co-cultured with methanogens under mesophilic conditions (Qiu et al, 2006(Qiu et al, , 2008, and these isolates are different from those found under thermophilic conditions (Chen et al, 2004). This greatly limits the effort to understand the microbial interaction and function in the TA-degrading consortia.…”

Microbial dark matter ecogenomics reveals complex synergistic networks in a methanogenic bioreactor

“…Pelotomaculum and Syntrophorhabdus are known to syntrophically metabolize TA (Wu et al, 2001;Qiu et al, 2004Qiu et al, , 2006Qiu et al, , 2008. In this reactor specifically, Pelotomaculum syntrophically interacts with methanogens and predominates TA degradation (Chen et al, 2004).…”

Unique diversity content of a thermophilic anaerobic microbial consortium that utilizes propionate in a synthetic medium

“…This was possibly due to the characteristic feature of the corresponding organism, namely dependence on complex interactions established in the microbial community. Actually, the studies on Pelotomaculum, the genus known for its ability to degrade propionate, have shown that cultivation of this group of bacteria is difficult even under coculture with a specific archaeal strain (de Bok et al, 2005;Imachi et al, 2002;Qiu et al, 2006). Hence, we assumed that development of an appropriate mixed (commensal) culture condition may be useful to stably maintain propionate-degrading microorganisms and their activity.…”

“…The bacterium corresponding to EPE306 (band f ) was a member of Pelotomaculum, the genus known for its involvement in propionate metabolism (de Bok et al, 2005;Imachi et al, 2002;Qiu et al, 2006). The 16S rRNA gene sequences almost identical to that of EPE306 have been obtained in propionate-degrading enrichments ) and a thermophilic packed-bed bioreactor degrading garbage (Sasaki et al, 2007), although the corresponding bacterium has not yet been isolated.…”