Apibacter raozihei sp. nov. isolated from bat feces of Hipposideros and Taphozous spp

A review on recent taxonomic updates of gut bacteria associated with social bees, with a curated genomic reference database

Honeybees and bumblebees play a crucial role as essential pollinators. The special gut microbiome of social bees is a key factor in determining the overall fitness and health of the host. Although bees harbor relatively simple microbial communities at the genus level, recent studies have unveiled significant genetic divergence and variations in gene content within each bacterial genus. However, a comprehensive and refined genomics-based taxonomic database specific to social bee gut microbiomes remains lacking. Here, we first provided an overview of the current knowledge on the distribution and function of social bee gut bacteria, as well as the factors that influence the gut population dynamics. We then consolidated all available genomes of the gut bacteria of social bees and refined the species-level taxonomy, by constructing a maximum-likelihood core genome phylogeny and calculating genome-wide pairwise average nucleotide identity. On the basis of the refined species taxonomy, we constructed a curated genomic reference database, named the bee gut microbe genome sequence database (BGM-GDb). To evaluate the species-profiling performance of the curated BGM-GDb, we retrieved a series of bee gut metagenomic data and inferred the species-level composition using metagenomic intra-species diversity analysis system (MIDAS), and then compared the results with those obtained from a prebuilt MIDAS database. We found that compared with the default database, the BGM-GDb excelled in aligned read counts and bacterial richness. Overall, this high-resolution and precise genomic reference database will facilitate research in understanding the gut community structure of social bees.

Update on Novel Taxa and Revised Taxonomic Status of Bacteria Isolated from Nondomestic Animals Described in 2018 to 2021

Revisions and new additions to bacterial taxonomy can have a significant widespread impact on clinical practice, infectious disease epidemiology, veterinary microbiology laboratory operations, and wildlife conservation efforts. The expansion of genome sequencing technologies has revolutionized our knowledge of the microbiota of humans, animals, and insects. Here, we address novel taxonomy and nomenclature revisions of veterinary significance that impact bacteria isolated from nondomestic wildlife, with emphasis being placed on bacteria that are associated with disease in their hosts or were isolated from host animal species that are culturally significant, are a target of conservation efforts, or serve as reservoirs for human pathogens.

The Threat of Potentially Pathogenic Bacteria in the Feces of Bats

Bats have attracted global attention because of their zoonotic association with severe acute respiratory syndrome coronavirus (SARS-CoV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Previous and ongoing studies have predominantly focused on bat-borne viruses; however, the prevalence or abundance of bat-borne pathogenic bacteria and their potential public health significance have largely been neglected. For the first time, this study used both metataxonomics (16S rRNA marker gene sequencing) and culturomics (traditional culture methods) to systematically evaluate the potential public health significance of bat fecal pathogenic bacteria. To this end, fecal samples were obtained from five bat species across different locations in China, and their microbiota composition was analyzed. The results revealed that the bat microbiome was most commonly dominated by Proteobacteria, while the strictly anaerobic phylum Bacteroidetes occupied 35.3% of the relative abundance in Rousettus spp. and 36.3% in Hipposideros spp., but less than 2.7% in the other three bat species (Taphozous spp., Rhinolophus spp., and Myotis spp.). We detected 480 species-level phylotypes (SLPs) with PacBio sequencing, including 89 known species, 330 potentially new species, and 61 potentially higher taxa. In addition, a total of 325 species were identified by culturomics, and these were classified into 242 named species and 83 potentially novel species. Of note, 32 of the 89 (36.0%) known species revealed by PacBio sequencing were found to be pathogenic bacteria, and 69 of the 242 (28.5%) known species isolated by culturomics were harmful to people, animals, or plants. Additionally, nearly 40 potential novel species which may be potential bacterial pathogens were identified. IMPORTANCE Bats are one of the most diverse and widely distributed groups of mammals living in close proximity to humans. In recent years, bat-borne viruses and the viral zoonotic diseases associated with bats have been studied in great detail. However, the prevalence and abundance of pathogenic bacteria in bats have been largely ignored. This study used high-throughput sequencing techniques (metataxonomics) in combination with traditional culture methods (culturomics) to analyze the bacterial flora in bat feces from different species of bats in China, revealing that bats are natural hosts of pathogenic bacteria and carry many unknown bacteria. The results of this study can be used as guidance for future investigations of bacterial pathogens in bats.

Microbacterium chengjingii sp. nov. and Microbacterium fandaimingii sp. nov., isolated from bat faeces of Hipposideros and Rousettus species

Four aerobic, Gram-stain-positive, rod-shaped bacteria (HY60^T, HY54, HY82^T and HY89) were isolated from bat faeces of Hipposideros and Rousettus species collected in PR China. Phylogenetic analyses based on 16S rRNA gene sequences indicated that the four novel strains formed two separate but adjacent subclades close to Microbacterium agarici CGMCC 1.12260^T (97.6-97.7 % similarity), Microbacterium humi JCM 18706^T (97.3-97.5 %) and Microbacterium lindanitolerans JCM 30493^T (97.3-97.4 %). The 16S rRNA gene sequence similarity was 98.3 % between strains HY60^T and HY82^T, and identical within strain pairs HY60^T/HY54 and HY82^T/HY89. The DNA G+C contents of strains HY60^T and HY82^T were 61.9 and 63.3 mol%, respectively. The digital DNA-DNA hybridization and average nucleotide identity values between each novel strain and their closest relatives were all below the 70 % and 95-96 % thresholds for species delimitation, respectively. All four novel strains contained anteiso-C_{15 : 0}, anteiso-C_{17 : 0}, iso-C_{16 : 0} and iso-C_{15 : 0} as the main fatty acids, MK-11 and MK-12 as the major respiratory quinones, and diphosphatidylglycerol, phosphatidylglycerol and one unidentified glycolipid as the predominant polar lipids. The cell-wall peptidoglycan was of B type and contained alanine, glutamate, glycine and ornithine. The acyl type of the muramic acid was glycolyl. The whole-cell sugars were rhamnose and ribose. Based on the foregoing polyphasic analyses, it was concluded that the four uncharacterized strains represented two novel species of the genus Microbacterium, for which the names Microbacterium chengjingii sp. nov. [type strain HY60^T (=CGMCC 1.17468^T=GDMCC 1.1951^T=KACC 22102^T)] and Microbacterium fandaimingii sp. nov. [type strain HY82^T (=CGMCC 1.17469^T=GDMCC 1.1949^T=KACC 22101^T)] are proposed, respectively.

Agromyces laixinhei sp. nov. isolated from bat feces in China

Three rod-shaped, Gram-stain-positive, and catalase-positive, phenotypically closely related isolates (HY052T, HY050, and HY045) were obtained from fecal samples collected from bats in Guangxi province and Chongqing city of China. Circular, smooth, light-yellow colonies appeared on brain heart infusion plate after 24-48 h incubation at 28°C. The optimal pH for growth was between 6.0 and 7.5. Based on 16S rRNA, the three isolates were phylogenetically related to Agromyces terreus DS-10T, Agromyces aureus AR33T, Agromyces salentinus 20-5T, Agromyces allii UMS-62T, Agromyces lapidis CD55T, and Agromyces italicus CD1T. Moreover, based on 296 core genes, the phylogenomic tree indicated that the three isolates clustered together, closest to Agromyces cerinus VKM Ac-1340T and Agromyces fucosus VKM Ac-1345T but separated distantly from other Agromyces species. The average nucleotide identity values between strain HY052T and other Agromyces species ranged from 79.3% to 87.9%, lower than the 95-96% threshold. Furthermore, the genome of strain HY052T contains a circular chromosome of 3,437,203 bp with G + C content of 69.0 mol%. Main fatty acids were anteiso-C15:0 and anteiso-C17:0. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, and unidentified glycolipids. Rhamnose, ribose, and glucose were the primary cell wall sugars. The major peptidoglycan amino acids included alanine, glutamic acid, glycine, and 2,4-diaminobutyric acid. An additional remarkable difference from other Agromyces species is that MK-12 was the sole menaquinone in strain HY052T. Based on results from the polyphasic characterizations performed in this study, our isolates are proposed to be members of a novel species in genus Agromyces, named Agromyces laixinhei. The type strain is HY052T (= CGMCC 1.17175T = JCM 33695T).