A rod-shaped, Gram-stain-positive, obligately anaerobic, xylan-degrading bacterium, SK-Y3, was isolated from oily-sludge of Shengli oilfield, China. Optimum growth occurred at 50 °C, at pH 7.5 and without addition of NaCl. The predominant cellular fatty acids of strain SK-Y3 were iso-C15 : 0, anteiso-C15 : 0 and iso-C17 : 0, and the main polar lipids were glycolipids (GL), lipids (L), phosphatidylglycerol (PG) and diphosphatidylglycerol (DPG); no respiratory quinones were detected. The genomic DNA G+C content was 37.2 mol%. Phylogenetic analysis of 16S rRNA gene sequences showed that strain SK-Y3 belongs to clostridial cluster III, exhibiting 91-92% sequence similarity to the most closely related species, namely Clostridium clariflavum, Clostridium straminisolvens and Acetivibrio cellulolyticus. Based on distinct physiological and phylogenetic differences from the aforementioned described taxa, strain SK-Y3 (=DSM 103557=ACCC 19952) is proposed as the type strain of a novel species of a new genus, Petroclostridium xylanilyticum gen. nov., sp. nov. Furthermore, analysis through 16S rRNA gene, ribosomal protein and whole genome sequences indicated that clostridial cluster III members should be reclassified into four novel genera for which the names Hungateiclostridium gen. nov., Thermoclostridium gen. nov., Ruminiclostridium gen. nov. and Pseudoclostridium gen. nov. are proposed. In combination with the genera Anaerobacterium, Cellulosibacter, Ercella, Fastidiosipila, Mageeibacillus, Pseudobacteroides, Petroclostridium and Saccharofermentans, clostridial cluster III members formed a monophyletic clade within the order Clostridiales but that was clearly distinguished from other Ruminococcaceae members, which is proposed as a novel family, Hungateiclostridiaceae fam. nov.
A novel Gram-positive, strictly anaerobic, spore-forming, rod-shaped bacterium, designated strain S11-3-10(T), was isolated from the pit mud used for Chinese Luzhou-flavor liquor production. Phylogenetic analysis based on 16S rRNA gene sequencing revealed that the strain formed a monophyletic clade with the closely related type strains of Clostridium cluster I and was most closely related to Clostridium amylolyticum JCM 14823(T) (94.38%). The temperature, pH, and NaCl range for growth was determined to be 20-45 °C (optimum 37 °C), 4.0-10.0 (optimum pH 7.3), and 0-3.0% (w/v), respectively. The strain was able to tolerate up to 7.5 % (v/v) ethanol. Yeast extract or peptone was found to be required for growth. Acids were found to be produced from glucose, mannose and trehalose. The major end products from glucose fermentation were identified as ethanol, acetate and hydrogen. The polar lipids were found to consist of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and unidentified phospholipids and polar lipids. The major fatty acids (>5%) were identified as iso-C(15:0), C(16:0), C(16:0)dma, C(14:0), anteiso-C(15:0) and iso-C(13:0). No respiratory quinone was detected. The diamino acid in the cell wall peptidoglycan was identified as meso-diaminopimelic acid and the whole-cell sugars were found to include galactose and glucose as major components. The DNA G+C content was determined to be 36.4 mol%. Based on the phylogenetic, chemotaxonomic and phenotypic evidence, the isolate is considered to represent a novel species of the genus Clostridium for which the name Clostridium swellfunianum sp. nov. is proposed. The type strain is S11-3-10(T) (=DSM 27788(T) = JCM 19606(T) = CICC 10730(T)).
BackgroundOver three-fifths of the world’s known crude oil cannot be recovered using state-of-the-art techniques, but microbial conversion of petroleum hydrocarbons trapped in oil reservoirs to methane is one promising path to increase the recovery of fossil fuels. The process requires cooperation between syntrophic bacteria and methanogenic archaea, which can be affected by sulfate-reducing prokaryotes (SRPs). However, the effects of sulfate on hydrocarbon degradation and methane production remain elusive, and the microbial communities involved are not well understood.ResultsIn this study, a methanogenic hexadecane-degrading enrichment culture was treated with six different concentrations of sulfate ranging from 0.5 to 25 mM. Methane production and maximum specific methane production rate gradually decreased to 44 and 56% with sulfate concentrations up to 25 mM, respectively. There was a significant positive linear correlation between the sulfate reduction/methane production ratio and initial sulfate concentration, which remained constant during the methane production phase. The apparent methanogenesis fractionation factor (α app) gradually increased during the methane production phase in each treatment, the α app for the treatments with lower sulfate (0.5–4 mM) eventually plateaued at ~1.047, but that for the treatment with 10–25 mM sulfate only reached ~1.029. The relative abundance levels of Smithella and Methanoculleus increased almost in parallel with the increasing sulfate concentrations. Furthermore, the predominant sulfate reducer communities shifted from Desulfobacteraceae in the low-sulfate cultures to Desulfomonile in the high-sulfate cultures.ConclusionThe distribution of hexadecane carbon between methane-producing and sulfate-reducing populations is dependent on the initial sulfate added, and not affected during the methane production period. There was a relative increase in hydrogenotrophic methanogenesis activity over time for all sulfate treatments, whereas the total activity was inhibited by sulfate addition. Both Smithella and Methanoculleus, the key alkane degraders and methane producers, can adapt to sulfate stress. Specifically, different SRP populations were stimulated at various sulfate concentrations. These results could help to evaluate interactions between sulfate-reducing and methanogenic populations during anaerobic hydrocarbon degradation in oil reservoirs.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-017-0895-9) contains supplementary material, which is available to authorized users.
Methanogenic archaea are main contributors to methane emissions, and thus play a crucial role in carbon cycling and global warming. Until recently, methanogens were confined to the phylum Euryarchaeota, but metagenomic studies revealed the presence of genes encoding the methyl coenzyme M reductase complex in other archaeal clades, thereby opening up the premise that methanogenesis is taxonomically more widespread. Nevertheless, laboratory cultivation of these non-Euryarchaeal methanogens was missing to allow the study of their physiology and to corroborate their potential methanogenic capability. Here we describe a thermophilic co-culture from an oil field, containing a single archaeon (strain LWZ-6) belonging to the proposed order Candidatus Verstraetearchaeia, together with a H2-producing Acetomicrobium sp. CY-2. Strain LWZ-6, for which we propose the name Verstraetearchaeum methanopetracarbonis, is a H2-dependent methylotrophic methanogen. Although previous metagenomic studies speculated on the fermentative potential of Verstraetearchaeial methanogens, strain LWZ-6 does not ferment sugars, peptides, and amino acids. Its energy metabolism is linked to methanogenesis, with methanol and monomethylamine as electron acceptors and H2 as electron donor. Comparative (meta)genome analysis revealed that H2-dependent methylotrophic methanogenesis is a shared trait among Verstraetearchaeia. Our findings corroborate that the diversity of methanogens expands beyond the classical Euryarchaeota and change our current conception of the global carbon cycle.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.