Gudongella oleilytica gen. nov., sp. nov., an aerotorelant bacterium isolated from Shengli oilfield and validation of family Tissierellaceae

Isolation of a methyl-reducing methanogen outside the Euryarchaeota

Methanogenic archaea are main contributors to methane emissions, and have a crucial role in carbon cycling and global warming. Until recently, methanogens were confined to Euryarchaeota, but metagenomic studies revealed the presence of genes encoding the methyl coenzyme M reductase complex in other archaeal clades1-4, thereby opening up the premise that methanogenesis is taxonomically more widespread. Nevertheless, laboratory cultivation of these non-euryarchaeal methanogens was lacking to corroborate their potential methanogenic ability and physiology. Here we report the isolation of a thermophilic archaeon LWZ-6 from an oil field. This archaeon belongs to the class Methanosuratincolia (originally affiliated with 'Candidatus Verstraetearchaeota') in the phylum Thermoproteota. Methanosuratincola petrocarbonis LWZ-6 is a strict hydrogen-dependent methylotrophic methanogen. Although previous metagenomic studies speculated on the fermentative potential of Methanosuratincolia members, strain LWZ-6 does not ferment sugars, peptides or amino acids. Its energy metabolism is linked only to methanogenesis, with methanol and monomethylamine as electron acceptors and hydrogen as an electron donor. Comparative (meta)genome analysis confirmed that hydrogen-dependent methylotrophic methanogenesis is a widespread trait among Methanosuratincolia. Our findings confirm that the diversity of methanogens expands beyond the classical Euryarchaeota and imply the importance of hydrogen-dependent methylotrophic methanogenesis in global methane emissions and carbon cycle.

Preliminary evaluation of electricity recovery from palm oil mill effluent by anion exchange microbial fuel cell

This study assessed the viability of an anion-exchange microbial fuel cell (MFC) for extracting electricity from palm oil mill effluent (POME), a major pollutant in palm-oil producing regions due to increasing demand. The MFC incorporated a tubular membrane electrode assembly (MEA) with an air core, featuring a carbon-painted carbon-cloth cathode, an anion exchange membrane (AEM), and a nonwoven graphite fabric (NWGF) anode. An additional carbon brush (CB) anode was placed adjacent to the tubular MEA. The MFC operated under semi-batch conditions with POME replacement every 7 days. Results showed superior performance of the AEM, with the highest power density (Pmax) observed in POME-treated MFCs. Current and power density increased with CB addition; the best chemical oxygen demand (COD) removal efficiency reached 73 %, decreasing from 1249 to 332 mg/L with three CBs. The Pmax was 0.18 W/m-2(-|-) with 1000 mg/L COD and three CBs, dropping to 0.0031 W/m-2(-|-) without CB and at 410 mg/L COD. Anode resistance, calculated using organic matter supplementation, COD, and anode surface area, decreased with increased COD or surface area, improving electricity production. AEM and CB compatibility synergistically enhanced MFC performance, offering potential for POME wastewater treatment and energy recovery.

Description of a moderately acidotolerant and aerotolerant anaerobic bacterium Acidilutibacter cellobiosedens gen. nov., sp. nov. within the family Acidilutibacteraceae fam. nov., and proposal of Sporanaerobacteraceae fam. nov. and Tepidimicrobiaceae fam. nov

A Gram-stain positive, moderately thermophilic, acidotolerant and aerotolerant anaerobic bacterium, designated JN-28 ^T, was isolated from the pit mud of Chinese strong-flavor liquor. Growth was observed at 25-50 °C and pH 5.5-8.0 in the presence of 0-25 g l^-1 NaCl (optimally at 45 °C, pH 6.0, without NaCl). Strain JN-28 ^T was heterotrophic, requiring yeast extract for growth. The major cellular fatty acids were iso-C_15:0 and C_14:0. The DNA G + C content of genomic DNA was 33.54 mol%. The strain was resistant to vancomycin (10 mg l^-1). Genome analysis revealed the presence of genes involved in the response to mild acid stress and oxidative stress, and resistance to vancomycin. 16S rRNA gene-based phylogenetic analysis showed that strain JN-28 ^T shares ≤ 89.3 % sequence similarity with its closest relatives Sporanaerobacter acetigenes DSM 13106 ^T and other members in the order Tissierellales. Based on phenotypic and phylogenetic characteristics, Acidilutibacter cellobiosedens gen. nov., sp. nov. is proposed for the new genus and novel species with the type strain JN-28 ^T (=CCAM 418 ^T = JCM 39087 ^T). Further phylogenetic and phylogenomic analyses suggested strain JN-28 ^T represents a novel family within the order Tissierellales, for which Acidilutibacteraceae fam. nov. is proposed. In addition, the family Tissierellaceae was reclassified, Sporanaerobacteraceae fam. nov. and Tepidimicrobiaceae fam. nov. were formally proposed. Emended description of the family Tissierellaceae is also provided.

Draft genomes and descriptions of Urmitella timonensis gen. nov., sp. nov. and Marasmitruncus massiliensis gen. nov., sp. nov., isolated from severely malnourished African children using culturomics

Two strains, designated as Marseille-P2918^T and Marseille-P3646^T, were isolated from a 14-week-old Senegalese girl using culturomics: Urmitella timonensis strain Marseille-P2918^T (= CSUR P2918, = DSM 103634) and Marasmitruncus massiliensis strain Marseille-P3646^T (= CSUR P3646, = CCUG72353). Both strains were rod-shaped, anaerobic, spore forming motile bacteria. The 16S rRNA gene sequences of strains Marseille-P2918^T (LT598554) and Marseille-P3646^T (LT725660) shared 93.25% and 94.34% identity with Tissierella praeacuta ATCC 25539^T and Anaerotruncus colihominis CIP 107754^T, their respective phylogenetically closest species with standing in nomenclature. Therefore, strain Marseille-P2918^T is classified within the family Tissierellaceae and order Tissierellales whereas strain Marseille-P3646^T is classified within the family Oscillospiraceae and order Eubacteriales. The genome of strain Marseille-P2918^T had a size of 2.13 Mb with a GC content of 50.52% and includes six scaffolds and six contigs, and that of strain Marseille-P3646^T was 3.76 Mbp long consisting of five contigs with a 50.04% GC content. The genomes of both strains presented a high percentage of genes encoding enzymes involved in genetic information and processing, suggesting a high growth rate and adaptability. These new taxa are extensively described and characterised in this paper, using the concept of taxono-genomic description.

Genome-wide analysis of Keratinibaculum paraultunense strain KD-1 T and its key genes and metabolic pathways involved in the anaerobic degradation of feather keratin

Keratinibaculum paraultunense strain KD-1 ^T (= JCM 18769 ^T = DSM 26752 ^T) is a strictly anaerobic rod-shaped bacterium. Under optimal conditions, feather keratin can be completely degraded by strain KD-1 within 24 h. Genomic sequencing showed that the genome was a single circular chromosome consisting of 2,307,997 base pairs (bp), with an average G + C content of 29.8% and no plasmids. A total of 2308 genes were annotated, accounting for 88.87% of the genomic sequence, and 1495 genes were functionally annotated. Among these, genes Kpa0144, Kpa0540, and Kpa0541 encoding the thioredoxin family members were identified, and may encode the potential disulfide reductases, with redox activity for protein disulfide bonds. Two potential keratinase-encoding genes, Kpa1675 and Kpa2139, were also identified, and corresponded to the ability of strain KD-1 to hydrolyze keratin. Strain KD-1 encoded genes involved in the heterotrophic metabolic pathways of 14 amino acids and various carbohydrates. The metabolic pathways for amino acid and carbohydrate metabolism were mapped in strain KD-1 based on KEGG annotations. The complete genome of strain KD-1 provided fundamental data for the further investigation of its physiology and genetics.

Soehngenia longivitae sp. nov., a Fermenting Bacterium Isolated from a Petroleum Reservoir in Azerbaijan, and Emended Description of the Genus Soehngenia

A methanogenic enrichment growing on a medium with methanol was obtained from a petroleum reservoir (Republic of Azerbaijan) and stored for 33 years without transfers to fresh medium. High-throughput sequencing of the V4 region of the 16S rRNA gene revealed members of the genera Desulfovibrio, Soehngenia, Thermovirga, Petrimonas, Methanosarcina, and Methanomethylovorans. A novel gram-positive, rod-shaped, anaerobic fermentative bacterium, strain 1933PT, was isolated from this enrichment and characterized. The strain grew at 13-55 °C (optimum 35 °C), with 0-3.0% (w/v) NaCl (optimum 0-2.0%) and in the pH range of 6.7-8.0 (optimum pH 7.0). The 16S rRNA gene sequence similarity, the average nucleotide identity (ANI) and in silico DNA-DNA hybridization (dDDH) values between strain 1933PT and the type strain of the most closely related species Soehngenia saccharolytica DSM 12858T were 98.5%, 70.5%, and 22.6%, respectively, and were below the threshold accepted for species demarcation. Genome-based phylogenomic analysis and physiological and biochemical characterization of the strain 1933PT (VKM B-3382T = KCTC 15984T) confirmed its affiliation to a novel species of the genus Soehngenia, for which the name Soehngenia longivitae sp. nov. is proposed. Genome analysis suggests that the new strain has potential in the degradation of proteinaceous components.