The low diverse gastric microbiome of the jellyfish Cotylorhiza tuberculata is dominated by four novel taxa.

Cotylorhiza tuberculata is an important scyphozoan jellyfish producing population blooms in the Mediterranean probably due to pelagic ecosystem's decay. Its gastric cavity can serve as a simple model of microbial-animal digestive associations, yet poorly characterized. Using state-of-the-art metagenomic population binning and catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH), we show that only four novel clonal phylotypes were consistently associated with multiple jellyfish adults. Two affiliated close to Spiroplasma and Mycoplasma genera, one to chlamydial 'Candidatus Syngnamydia', and one to bacteroidetal Tenacibaculum, and were at least one order of magnitude more abundant than any other bacteria detected. Metabolic modelling predicted an aerobic heterotrophic lifestyle for the chlamydia, which were found intracellularly in Onychodromopsis-like ciliates. The Spiroplasma-like organism was predicted to be an anaerobic fermenter associated to some jellyfish cells, whereas the Tenacibaculum-like as free-living aerobic heterotroph, densely colonizing the mesogleal axis inside the gastric filaments. The association between the jellyfish and its reduced microbiome was close and temporally stable, and possibly related to food digestion and protection from pathogens. Based on the genomic and microscopic data, we propose three candidate taxa: 'Candidatus Syngnamydia medusae', 'Candidatus Medusoplasma mediterranei' and 'Candidatus Tenacibaculum medusae'.

Prokaryotic microbiota in the digestive cavity of the jellyfish Cotylorhiza tuberculata.

The microbiota associated to the gastric cavity of four exemplars of the jellyfish Cotylorhiza tuberculata has been studied by means of cultured-dependent and -independent methods. The pyrosequencing approach rendered a very reduced diversity of Bacteria with four major groups shared by the four exemplars that made up to 95% of the total diversity. The culturing approach recovered low abundant organisms and some of them also detected by the pyrosequencing approach. The major key organisms were related to the genera Spiroplasma, Thalassospira, Tenacibaculum (from the pyrosequencing data), and Vibrio (from the cultivable fraction). Altogether the results indicate that C. tuberculata harbors an associated microbiota of very reduced diversity. On the other hand, some of the major key players may be potential pathogens and the host may serve as dispersal mechanism.

Description of Bacillus toyonensis sp. nov., a novel species of the Bacillus cereus group, and pairwise genome comparisons of the species of the group by means of ANI calculations.

Strain BCT-7112(T) was isolated in 1966 in Japan from a survey designed to obtain naturally occurring microorganisms as pure cultures in the laboratory for use as probiotics in animal nutrition. This strain, which was primarily identified as Bacillus cereus var toyoi, has been in use for more than 30 years as the active ingredient of the preparation TOYOCERIN(®), an additive for use in animal nutrition (e.g. swine, poultry, cattle, rabbits and aquaculture). Despite the fact that the strain was initially classified as B. cereus, it showed significant genomic differences from the type strains of the B. cereus group that were large enough (ANI values below 92%) to allow it to be considered as a different species within the group. The polyphasic taxonomic study presented here provides sufficient discriminative parameters to classify BCT-7112(T) as a new species for which the name Bacillus toyonensis sp. nov. is proposed, with BCT-7112(T) (=CECT 876(T); =NCIMB 14858(T)) being designated as the type strain. In addition, a pairwise comparison between the available genomes of the whole B. cereus group by means of average nucleotide identity (ANI) calculations indicated that besides the eight classified species (including B. toyonensis), additional genomospecies could be detected, and most of them also had ANI values below 94%. ANI values were on the borderline of a species definition only in the cases of representatives of B. cereus versus B. thuringiensis, and B. mycoides and B. weihenstephanensis.

Breoghania corrubedonensis gen. nov. sp. nov., a novel alphaproteobacterium isolated from a Galician beach (NW Spain) after the Prestige fuel oil spill, and emended description of the family Cohaesibacteraceae and the species Cohaesibacter gelatinilyticus.

A Gram-negative bacterium designated UBF-P1(T) was isolated from an enrichment culture established in nutrient supplemented artificial sea water with pyrene as a carbon source, and inoculated with a marine fuel oil-degrading consortium obtained from a sand sample collected from the beach of Corrubedo (A Coruña, Galicia, Spain) after the Prestige accidental oil spill. Phylogenetic analysis based on the almost complete 16S rRNA gene sequence affiliated strain UBF-P1(T) with the family Cohaesibacteraceae, Cohaesibacter gelatinilyticus (DSM 18289(T)) being the closest relative species with 92% sequence similarity. Cells were irregular rods, motile, strictly aerobic, catalase and oxidase positive. Ubiquinone 10 was the major respiratory lipoquinone. The major polar lipids comprised diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), phosphatidylmonomethylethanolamine (PME), and phosphatidylcholine (PC). The major fatty acids detected were C(18:1)ω7c, C(19:0) cycloω8c, and C(16:0). The G+C content of strain UBF-P1(T) was 63.9 mol%. The taxonomic comparison with the closest relative based on genotypic, phenotypic and chemotaxonomic characteristics supported that strain UBF-P1(T) could be classified as a novel genus and species, for which the name Breoghania corrubedonensis gen. nov., sp. nov. is proposed. The type strain of this new taxon is UBF-P1(T) (CECT 7622, LMG 25482, DSM 23382).