RESULTS:

To examine the possible physiological significance of Mrp a multi-subunit cation/proton antiporter from Vibrio cholerae a chromosomal deletion Δmrp of V. cholerae was constructed and characterized. The resulting mutant showed a consistent early growth defect in LB broth that became more evident at elevated pH of the growth medium and increasing Na+ or K+ loads. After 24 h incubation these differences disappeared likely due to the concerted effort of other cation pumps in the mrp mutant. Phenotype MicroArray analyses revealed an unexpected systematic defect in nitrogen utilization in the Δmrp mutant that was complemented by using the mrpA′-F operon on an arabinose-inducible expression vector. Deletion of the mrp operon also led to hypermotility observable on LB and M9 semi-solid agar. Surprisingly Δmrp mutation resulted in wild-type biofilm formation in M9 despite a growth defect but the reverse was true in LB. Furthermore the Δmrp strain exhibited higher susceptibility to amphiphilic anions. These pleiotropic phenotypes of the Δmrp mutant demonstrate how the chemiosmotic activity of Mrp contributes to the survival potential of V. cholerae despite the presence of an extended battery of cation/proton antiporters of varying ion selectivity and pH profile operating in the same membrane.

A Gram-stain-negative rod-shaped catalase- and oxidase-positive facultatively anaerobic and motile bacterium designated strain SZDIS-1T was isolated from pigpen sawdust bedding in Xiamen Fujian Province China. Cells grew at 10–50 °C pH 6.0–9.0 up to 12 % (w/v) NaCl resisted vibriostatic agent O/129 and were negative for gelatin and alginate hydrolysis. No growth on thiosulfate citrate bile salts sucrose agar medium. Based on 16S rRNA gene sequences and multilocus sequence analysis this strain should be assigned to the genus Vibrio with the closest relatives being Vibrio aphrogenes CA-1004T (97.7 % 16S rRNA gene sequence pairwise similarity) Vibrio algivorus SA2T (96.6 %) Vibrio casei WS 4539T (96.3 %) Vibrio rumoiensis S-1T (96.1 %) and Vibrio litoralis MANO22DT (95.5 %) but separate from them by large distances in different phylogenetic trees. Based on whole genome analysis the orthologous average nucleotide identity and in silico DNA–DNA hybridization values against the five relatives were 76.1–78.7 and 20.1–28.7 %. The major fatty acids were summed feature 3 (C16 : 1 ω7c/C16 : 1 ω6c) C16 : 0 summed feature 2 (one or more of C12 : 0 aldehyde C14 : 0 3OH and/or iso-C16 : 1) and summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c). The DNA G+C content was 43.0 mol% from whole genomic sequence analysis. Therefore phylogenetic genotypic phenotypic and chemotaxonomic characteristics showed that the isolate represented a novel species of the genus Vibrio for which the name Vibrio gangliei sp. nov. is proposed. The type strain is SZDIS-1T (=DSM 104291T=CGMCC 1.15236T).

Cyanobacteria is an ancient phylum of oxygenic photosynthetic microorganisms found in almost all environments of Earth. In recent years the taxonomic placement of some cyanobacterial strains including those belonging to the genus Nostoc sensu lato have been reevaluated by means of a polyphasic approach. Thus 16S rRNA gene phylogeny and 16S–23S internal transcribed spacer (ITS) secondary structures coupled with morphological ecological and physiological data are considered powerful tools for a better taxonomic and systematics resolution leading to the description of novel genera and species. Additionally underexplored and harsh environments such as saline–alkaline lakes have received special attention given they can be a source of novel cyanobacterial taxa. Here a filamentous heterocytous strain Nostocaceae CCM-UFV059 isolated from Laguna Amarga Chile was characterized applying the polyphasic approach; its fatty acid profile and physiological responses to salt (NaCl) were also determined. Morphologically this strain was related to morphotypes of the Nostoc sensu lato group being phylogenetically placed into the typical cluster of the genus Desmonostoc. CCM-UFV059 showed identity of the 16S rRNA gene as well as 16S–23S secondary structures that did not match those from known described species of the genus Desmonostoc as well as distinct ecological and physiological traits. Taken together these data allowed the description of the first strain of a member of the genus Desmonostoc from a saline–alkaline lake named Desmonostoc salinum sp. nov. under the provisions of the International Code of Nomenclature for algae fungi and plants. This finding extends the ecological coverage of the genus Desmonostoc contributing to a better understanding of cyanobacterial diversity and systematics.

A bacterial strain designated 32AT was isolated from the skin of an Anderson’s salamander (Ambystoma andersoni) and subjected to a comprehensive taxonomic study. The strain was Gram-stain-negative rod-shaped non-motile oxidase- and urease-negative and catalase-positive. 16S rRNA gene sequence comparisons placed the strain in the genus Luteolibacter with highest sequence similarities to Luteolibacter pohnpeiensis A4T-83T (95.2%) Luteolibacter gellanilyticus CB-286403T (95.1%) and Luteolibacter cuticulihirudinis E100T (94.9%). Genomic sequence analysis revealed a size of 5.3 Mbp a G+C-content of 62.2 mol% and highest ANI values with Luteolibacter luteus (71.2%) Luteolibacter yonseiensis (71.4%) and L. pohnpeiensis (69.5%). In the polyamine pattern 13-diaminopropane and spermidine were predominant. The diagnostic diamino acid of the peptidoglycan was meso-diaminopimelic acid. The quinone system was composed of the major menaquinones MK-9 and MK-10. Major polar lipids were diphosphatidylglycerol phosphatidylglycerol phosphatidylethanolamine the unidentified aminolipid AL2 the unidentified phospholipid PL2 and the unidentified aminophospholipid APL1. The fatty acid profile contained major amounts of iso-C14:0 iso-C16:0 C16 : 0 and C16 : 1 ω9c. In addition C14 : 0 C15:0 anteiso-C15 : 0 summed feature 2 (C14 : 0 3OH and/or iso-C16 : 0 I) and the hydroxylated fatty acids iso-C14 : 0 3OH iso-C16 : 0 3OH and C16 : 0 3-OH were detected. Physiologically strain 32AT is distinguishable from its next relatives. Based on phylogenetic genomic physiological and chemotaxonomic data strain 32AT represents a novel species of the genus Luteolibacter for which we propose the name Luteolibacter ambystomatis sp. nov. The type strain is 32AT (=CCM 9141T=LMG 32214T).

A bacterial strain designated 26BT which had been isolated from the cloaca of a toad-headed turtle was subjected to a comprehensive taxonomic study. Comparison of 16S rRNA gene sequences demonstrated that strain 26BT is a member of the family Neisseriaceae . Based on highest similarity values Neisseria animaloris DSM 21642T (95.15 %) Alysiella filiformis ATCC 15532T (95.06 %) Uruburuella testudinis 07_OD624T (94.71 %) Uruburuella suis CCUG 47806T (94.66 %) and Alysiella crassa DSM 2578T (94.64 %) were identified as the closest relatives. Average nucleotide identity values based on the blast algorithm (ANIb) indicated that U. suis (76.10/76.17 %) Neisseria shayeganii 871T (74.34/74.51 %) Stenoxybacter acetivorans (73.30/73.41 %) N. animaloris (72.98/72.80) % A. filiformis (71.14/71.21 %) and A. crassa (70.53/71.15 %) are the next closest relatives. Like ANIb genome-based phylogeny did not suggest the affiliation of strain 26BT with any established genus. The polyamine pattern consisted of the major compounds putrescine 13-diaminopropane and spermidine and the major quinone was ubiquinone Q-8. In the polar lipid profile diphosphatidylglycerol phosphatidylglycerol phosphatidylethanolamine and an ornithine lipid were predominant. The fatty acid profile contained predominantly C16 : 1 ω7c C12 : 0 C14 : 0 C16 : 0 and C12 : 0 3OH. The size of the genome was 2.91 Mbp and the genomic G+C content was 54.0 mol%. Since these data do not demonstrate an unambiguous association with any established genus we here propose the novel genus Paralysiella with the type species Paralysiella testudinis gen. nov. sp. nov. The type strain is 26BT (=CCM 9137T=LMG 32212T).

A bacterial strain D-1/1aT isolated from a medieval wall painting of the chape of Herberstein (Styria Austria) was characterized by a polyphasic approach. Strain D-1/1aT shared 98.1% 16S rRNA sequence similarity to Agrococcus jenensis. The chemotaxonomic characteristics including polar lipid pattern whole cell sugars quinone system polyamine pattern cell wall composition and fatty acid profile were in good agreement with those of Agrococcus jenensis. The G+C content of the DNA was determined to be 74 mol%. The value of 47% DNA reassociation obtained after DNA-DNA hybridization between DNA of Agrococcus jenensis and strain D-1/1aT as well as differences in the amino acid composition of the peptidoglycan and in physiological characteristics demonstrate that the isolate represents a new species of the genus Agrococcus. The name Agrococcus citreus sp. nov. is proposed for the new species harbouring isolate D-1/1aT. The type strain is DSM 12453T.

Because large brains are energetically expensive they are associated with metabolic traits that facilitate energy availability across vertebrates. However the biological underpinnings driving these traits are not known. Given its role in regulating host metabolism in disease studies we hypothesized that the gut microbiome contributes to variation in normal cross-vertebrate species differences in metabolism including those associated with the brain’s energetic requirements. By inoculating germ-free mice with the gut microbiota (GM) of three primate species – two with relatively larger brains and one with a smaller brain – we demonstrated that the GM of larger-brained primates shifts host metabolism towards energy use and production while that of smaller-brained primates stimulates energy storage in adipose tissues. Our findings establish a causal role of the GM in normal cross-host species differences in metabolism associated with relative brain size and suggest that the GM may have been an important facilitator of metabolic changes during human evolution that supported encephalization.