Tepidibaculum saccharolyticum gen. nov., sp. nov. a moderately thermophilic, anaerobic, spore-forming bacterium isolated from a terrestrial hot spring

Bengtsoniella intestinalis gen. nov., sp. nov., a member of the family Oscillospiraceae, isolated from the hindgut of the marine herbivorous fish Kyphosus sydneyanus

A Gram-stain-negative, non-spore-forming, rod-shaped, obligately anaerobic bacterium, designated strain BP47G, was isolated from the hindgut of a silver drummer (Kyphosus sydneyanus) fish collected from the Hauraki Gulf, New Zealand. Phylogenetic analysis based on the 16S rRNA gene sequence of the isolate indicated that it belonged to the family Oscillospiraceae in the phylum Bacillota. The gene sequence of BP47G was most similar to Oscillibacter valericigenes with 95.23% sequence identity. Isolate BP47G grew on agar medium containing mannitol and fish gut fluid as the sole carbon sources. Clear colonies of ~1 mm diameter grew within a week at 20-28 °C (optimum 28 °C) and pH 7.1-8.5 (optimum 8.5). BP47G tolerated the addition to the medium of up to 1% NaCl. Formate and butyrate were the major fermentation products. The major cellular fatty acids were C12:0, C13:0, iso-C14:0, C16:0 and C16:1 cis 7. Genomic analyses comparing BP47G with its closest relatives indicated low genomic relatedness based on the average nucleotide identity, average amino acid identity, percentage of conserved protein and in silico DNA-DNA hybridization. Supported by the phenotypic and taxonomic characteristics observed in this study, a novel genus and species Bengtsoniella intestinalis gen. nov., sp. nov. is proposed for isolate BP47G (=ICMP 24688=JCM 35770).

Coprobacter secundus subsp. similis subsp. nov. and Solibaculum mannosilyticum gen. nov., sp. nov., isolated from human feces

An obligately anaerobic, Gram-stain-negative, rod-shaped bacterium, designated strain 2CBH44^T , was isolated from the fecal sample of a healthy Japanese man. This strain was initially assigned as a novel species of the genus Coprobacter based on the 16S rRNA gene sequence similarities compared with other Coprobacter species. The 16S rRNA gene sequence analysis revealed strain 2CBH44^T had relatively low 16S rRNA gene sequence similarity (97.5%) to Coprobacter secundus 177^T . However, strain 2CBH44^T showed 96.9% average nucleotide identity value with C. secundus 177^T , indicating that strain 2CBH44^T and C. secundus 177^T belong to the same species. On the other hand, the digital DNA-DNA hybridization value between strain 2CBH44^T and C. secundus 177^T was 73.5%, indicating that strain 2CBH44^T is a subspecies of C. secundus. Another anaerobic, Gram-stain-variable, rod-shaped bacterium, designated strain 12CBH8^T , was also isolated from human feces. Strain 12CBH8^T had significantly low 16S rRNA gene sequence similarities (<92.0%) to the validated bacterial species within the family Oscillospiraceae. The percentage of conserved protein values between the genome of strain 12CBH8^T and that of the validated related taxa were <50%, suggesting that strain 12CBH8^T belongs to a novel genus. On the basis of the collected data, strain 2CBH44^T represents a novel subspecies of C. secundus, for which the name Coprobacter secundus subsp. similis subsp. nov. (type strain 2CBH44^T  = JCM 34079^T  = DSM 111570^T ) is proposed. Strain 12CBH8^T represents a novel species of a novel genus, for which the name Solibaculum mannosilyticum gen. nov., sp. nov. (type strain 12CBH8^T  = JCM 34081^T  = DSM 111571^T ) is proposed.

Gut Bacteria Shared by Children and Their Mothers Associate with Developmental Level and Social Deficits in Autism Spectrum Disorder

The gut microbiota of autism spectrum disorder (ASD) children differs from that of children without ASD. The maternal gut microbiota impacts offspring gut microbiota. However, the relationship between the development of ASD and gut bacteria shared between children and their mothers remains elusive. Our study recruited 76 children with ASD and 47 age- and gender-matched children with typical development (TD), as well as the mothers of both groups, and investigated their gut microbiota using amplicon sequence variants (ASVs). The gut microbiota of ASD children was altered compared with that of children with TD, while no significant alterations were found in their mothers. We established 30 gut bacterial coabundance groups (CAGs) and found the relative abundances of CAG15 and CAG16 significantly decreased in ASD children. CAG15 showed a positive correlation with developmental level. The proportion of ASD children who shared either one of the two Lachnospiraceae ASVs from CAG15 with their mothers was significantly lower than that of children with TD. Moreover, we found that CAG12, CAG13, and CAG18 negatively correlated with the severity of social deficits in ASD children. ASD children who shared any one of the four (two Ruminococcaceae, one Lachnospiraceae, and one Collinsella) ASVs in CAG13 and CAG18 with their mothers showed a lower level of social deficits than ASD children that did not share those with their mothers. These data demonstrate that these shared gut bacteria in ASD children are associated with their developmental level and social deficits. This work provides a new direction toward understanding the role of the gut microbiota in the pathogenesis and development of ASD. (This study has been registered in the Chinese Clinical Trial Registry under number ChiCTR-RPC-16008139.)IMPORTANCE Gut microbiota may contribute to the pathogenesis and development of autism spectrum disorder. The maternal gut microbiota influences offspring gut microbial structure and composition. However, the relationship between the clinical symptoms of autism spectrum disorder and the gut bacteria shared between children and their mothers is not yet known. In our study, the gut microbiota of children with autism spectrum disorder differed from that of children with typical development, but there were no differences in the gut microbiota of their mothers. More importantly, gut bacteria shared between children with autism spectrum disorder and their mothers were related to developmental disabilities and social deficits. Thus, our study suggests that these shared gut bacteria may play an important role in the development of autism spectrum disorder. This provides a new direction for future studies aiming to explore the role of the gut microbiota in autism spectrum disorder.

Characterization of Thermophilic Microorganisms in the Geothermal Water Flow of El Chichón Volcano Crater Lake

This study reports for the first time the isolation, identification and characterization of lipase-producing thermophilic strain from the geothermal water of the El Chichón volcano crater lake. Two strains were identified by 16S rRNA sequencing as Geobacillus jurassicus CHI2 and Geobacillus stearothermophilus CHI1. Results showed that G. jurassicus CHI2 is Gram-positive, able to ferment maltose, fructose and sucrose and to hydrolyze starch and casein; while G. stearothermophilus CHI1 showed to be Gram-variable, able to ferment maltose and fructose and to hydrolyze starch. Colonies of both strains presented irregular shape, umbilicated elevation of gummy texture and cells presented flagellar movement to survive in fluids with high temperature and mass gradients due to complex phenomena of heat and mass transfer present in the geothermal fluids. Lipase production for G. stearothermophilus CHI1 was also evaluated. It was found that this strain possesses a growth associated with extracellular lipase production with a high activity of 143 U/mL at 8.3 h of incubation time, superior to the activities reported for other microorganisms of genus Geobacillus; for this reason, it can be said that the thermal flow of the El Chichón volcano crater lake can be a useful source of lipase-producing thermophilic bacteria.