Brytella acorum gen. nov., sp. nov., a novel acetic acid bacterium from sour beverages.

Polyphasic taxonomic and comparative genomic analyses revealed that a series of lambic beer isolates including strain LMG 32668T and the kombucha isolate LMG 32879 represent a novel species among the acetic acid bacteria, with Acidomonas methanolica as the nearest phylogenomic neighbor with a valid name. Overall genomic relatedness indices and phylogenomic and physiological analyses revealed that this novel species was best classified in a novel genus for which we propose the name Brytella acorum gen. nov., sp. nov., with LMG 32668T (=CECT 30723T) as the type strain. The B. acorum genomes encode a complete but modified tricarboxylic acid cycle, and complete pentose phosphate, pyruvate oxidation and gluconeogenesis pathways. The absence of 6-phosphofructokinase which rendered the glycolysis pathway non-functional, and an energy metabolism that included both aerobic respiration and oxidative fermentation are typical metabolic characteristics of acetic acid bacteria. Neither genome encodes nitrogen fixation or nitrate reduction genes, but both genomes encode genes for the biosynthesis of a broad range of amino acids. Antibiotic resistance genes or virulence factors are absent.

A phylogenomic and comparative genomic analysis of Commensalibacter, a versatile insect symbiont.

BACKGROUND: To understand mechanisms of adaptation and plasticity of pollinators and other insects a better understanding of diversity and function of their key symbionts is required. Commensalibacter is a genus of acetic acid bacterial symbionts in the gut of honey bees and other insect species, yet little information is available on the diversity and function of Commensalibacter bacteria. In the present study, whole-genome sequences of 12 Commensalibacter isolates from bumble bees, butterflies, Asian hornets and rowan berries were determined, and publicly available genome assemblies of 14 Commensalibacter strains were used in a phylogenomic and comparative genomic analysis. RESULTS: The phylogenomic analysis revealed that the 26 Commensalibacter isolates represented four species, i.e. Commensalibacter intestini and three novel species for which we propose the names Commensalibacter melissae sp. nov., Commensalibacter communis sp. nov. and Commensalibacter papalotli sp. nov. Comparative genomic analysis revealed that the four Commensalibacter species had similar genetic pathways for central metabolism characterized by a complete tricarboxylic acid cycle and pentose phosphate pathway, but their genomes differed in size, G + C content, amino acid metabolism and carbohydrate-utilizing enzymes. The reduced genome size, the large number of species-specific gene clusters, and the small number of gene clusters shared between C. melissae and other Commensalibacter species suggested a unique evolutionary process in C. melissae, the Western honey bee symbiont. CONCLUSION: The genus Commensalibacter is a widely distributed insect symbiont that consists of multiple species, each contributing in a species specific manner to the physiology of the holobiont host.

Aristophania vespae gen. nov., sp. nov., isolated from wasps, is related to Bombella and Oecophyllibacter, isolated from bees and ants.

Acetic acid bacteria (family Acetobacteraceae) are found in the gut of most insects. Two clades are currently recognized: Commensalibacter-Entomobacter and Bombella-Oecophyllibacter. The latter group is only found in hymenopteran insects and the described species have been isolated from bees and ants. In this study, two new strains DDB2-T1T (=KACC 21507T=LMG 31759T) and DM15PD (=CCM 9165=DSM 112731=KACC 22353=LMG 32454) were isolated from wasps collected in the Republic of Korea and Germany, respectively. Molecular and phenotypic analysis revealed that the strains are closely related, with 16S rRNA gene sequences showing 100 % identity and genomic average nucleotide identity (ANI) values ≥99 %. The closest related species based on type strain 16S rRNA gene sequences are Swingsia samuiensis, Acetobacter peroxydans, Bombella favorum and Bombella intestini (94.8-94.7% identity), whereas the closest related species based on type strain genome analysis are Saccharibacter floricola and Bombella intestini (ANI values of 68.8 and 68.2 %, respectively). The reconstruction of a phylogenomic tree based on 107 core proteins revealed that the branch leading to DDB2-T1T and DM15PD is localized between Oecophyllibacter and Saccharibacter-Bombella. Further genomic distance metrics such as ANI, percentage of conserved proteins and alignment fraction values were consistent with these strains belonging to a new genus. The key phenotypic characteristics were one MALDI-TOF-MS peak (m/z=4601.9±2.0) and the ability to produce acid from d-arabinose. Based on this polyphasic approach, including phylogenetics, phylogenomics, genome distance calculations, ecology and phenotypic characteristics, we propose to name the novel strains Aristophania vespae gen. nov., sp. nov., with the type strain DDB2-T1T (=KACC 21507T=LMG 31759T).

Acetobacter vaccinii sp. nov., a novel acetic acid bacterium isolated from blueberry fruit (Vaccinium corymbosum L.).

Strain C17-3T was isolated from blueberry fruits collected from a farmland located in Damyang-gun, Jeollanam-do, Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequences allocated strain C17-3T to the genus Acetobacter, where it occupied a rather isolated line of descent with Acetobacter ghanensis 430AT and Acetobacter lambici LMG 27439T as the nearest neighbours (98.9 % sequence similarity to both species). The highest average nucleotide identity and digital DNA-DNA hybridization values were 76.3 % and 21.7 % with Acetobacter garciniae TBRC 12339T; both values were well below the cutoff values for species delineation. Cells are strictly aerobic, Gram-stain-negative rods, catalase-positive and oxidase-negative. The DNA G+C content calculated from the genome sequence was 59.2 %. Major fatty acids were summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c) and C19 : 0cyclo ω8c. The major isoprenoid quinone was ubiquinone 9. On the basis of the results of phylogenetic analyses, phenotypic features and genomic comparisons, it is proposed that strain C17-3T represents a novel species of the genus Acetobacter and the name Acetobacter vaccinii sp. nov. is proposed. The type strain is C17-3T (= KACC 21233T = LMG 31758T).

Gluconacetobacter dulcium sp. nov., a novel Gluconacetobacter species from sugar-rich environments.

A phylogenomic analysis based on 107 single-copy core genes revealed that three strains from sugar-rich environments, i.e. LMG 1728T, LMG 1731 and LMG 22058, represented a single, novel Gluconacetobacter lineage with Gluconacetobacter liquefaciens as nearest validly named neighbour. OrthoANIu and digital DNA-DNA hybridization analyses among these strains and Gluconacetobacter type strains confirmed that the three strains represented a novel Gluconacetobacter species. Biochemical characteristics and MALDI-TOF mass spectra allowed differentiation of this novel species from the type strains of G. liquefaciens and other closely related Gluconacetobacter species. We therefore propose to classify strains LMG 1728T, LMG 1731 and LMG 22058 in the novel species Gluconacetobacter dulcium sp. nov., with LMG 1728T (=CECT 30142T) as the type strain.

Novel acetic acid bacteria from cider fermentations: Acetobacter conturbans sp. nov. and Acetobacter fallax sp. nov.

Strains LMG 1627T, LMG 1636T and LMG 1637 were all isolated from cider fermentations in the 1940s and 1950s. A recent study based on MALDI-TOF MS and dnaK gene sequence analyses suggested they represented novel Acetobacter species. In the present study, we determined the whole-genome sequences of these strains and analysed their phenotypic and chemotaxonomic characteristics. A phylogenomic analysis based on 107 single-copy core genes revealed that they represented a single Acetobacter lineage with Acetobacter aceti, Acetobacter sicerae, Acetobacter musti and Acetobacter oeni, Acetobacter estunensis and with Acetobacter nitrogenifigens as an outgroup to this cluster. OrthoANIu value and dDDH analyses among these and other Acetobacter type strains confirmed that these three strains represented two novel Acetobacter species, which could be differentiated from other closely related type strains of Acetobacter by different phenotypic tests, such as ketogenesis from glycerol. We therefore propose to classify strain LMG 1627T in the novel species Acetobacter conturbans sp. nov., with LMG 1627T (=NCIMB 8945T) as the type strain, and to classify strains LMG 1636T and LMG 1637 in the novel species Acetobacter fallax sp. nov., with LMG 1636T (=NCIMB 8956T) as the type strain.

Effect of Sequential Acclimation to Various Carbon Sources on the Proteome of Acetobacter senegalensis LMG 23690T and Its Tolerance to Downstream Process Stresses.

Acetic acid bacteria are very vulnerable to environmental changes; hence, they should get acclimated to different kinds of stresses when they undergo downstream processing. In the present study, Acetobacter senegalensis LMG 23690T, a thermo-tolerant strain, was acclimated sequentially to different carbon sources including glucose (condition Glc), a mixture of glucose and ethanol (condition EtOH) and a mixture of glucose and acetic acid (condition GlcAA). Then, the effects of acclimation on the cell proteome profiles and some phenotypic characteristics such as growth in culture medium containing ethanol, and tolerance to freeze-drying process were evaluated. Based on the obtained results, despite the cells acclimated to Glc or EtOH conditions, 86% of acclimated cells to GlcAA condition were culturable and resumed growth with a short lag phase in a culture medium containing ethanol and acetic acid. Interestingly, if A. senegalensis LMG 23690T had been acclimated to condition GlcAA, 92% of cells exhibited active cellular dehydrogenases, and 59% of cells were culturable after freeze-drying process. Proteome profiles comparison by 2D-DiGE and MS analysis, revealed distinct physiological status between cells exposed to different acclimation treatments, possibly explaining the resulting diversity in phenotypic characteristics. Results of proteome analysis by 2D-DiGE also showed similarities between the differentially expressed proteins of acclimated cells to EtOH condition and the proteome of acclimated cells to GlcAA condition. Most of the differentially regulated proteins are involved in metabolism, folding, sorting, and degradation processes. In conclusion, acclimation under appropriate sub-lethal conditions can be used as a method to improve cell phenotypic characteristics such as viability, growth under certain conditions, and tolerance to downstream processes.

Characterization of novel Gluconobacter species from fruits and fermented food products: Gluconobacter cadivus sp. nov., Gluconobacter vitians sp. nov. and Gluconobacter potus sp. nov.

Strains LMG 1744T, LMG 1745, LMG 31484T, LMG 1764T and R-71646 were isolated from rotting fruits and fermented food products. A phylogenomic analysis based on 107 single-copy core genes revealed that they grouped in a Gluconobacter lineage comprising Gluconobacter oxydans, Gluconobacter roseus, Gluconobacter sphaericus, Gluconobacter kanchanaburiensis, Gluconobacter albidus, Gluconobacter cerevisiae, Gluconobacter kondonii and Gluconobacter aidae. OrthoANIu and digital DNA hybridization analyses demonstrated that these five strains represented three novel Gluconobacter species, which could be differentiated from the type strains of closely related Gluconobacter species by multiple phenotypic characteristics. We therefore propose to classify strains LMG 1744T and LMG 1745 in the novel species Gluconobacter cadivus sp. nov., with LMG 1744T (=CECT 30141T) as the type strain; to classify strain LMG 31484T as the novel species Gluconobacter vitians sp. nov., with LMG 31484T (=CECT 30132T) as the type strain; and to classify strains LMG 1764T and R-71646 in the novel species Gluconobacter potus sp. nov., with LMG 1764T (=CECT 30140T) as the type strain.

Entomobacter blattae gen. nov., sp. nov., a new member of the Acetobacteraceae isolated from the gut of the cockroach Gromphadorhina portentosa.

A novel bacterium designated G55GPT and pertaining to the family Acetobacteraceae was isolated from the gut of the Madagascar hissing cockroach Gromphadorhina portentosa. The Gram-negative cells were rod-shaped and non-motile. The complete 16S rRNA sequence of the strain G55GPT showed the highest pairwise similarity to Gluconacetobacter johannae CFN-Cf-55T (95.35 %), suggesting it represents a potential new genus of the family Acetobacteraceae. Phylogenetic analysis based on 16S rRNA gene and 106 orthologous housekeeping protein sequences revealed that G55GPT forms a monophyletic clade with the genus Commensalibacter, which thus far has also been isolated exclusively from insects. The G55GPT genome size was 2.70 Mbp, and the G+C content was 45.4 mol%, which is lower than most acetic acid bacteria (51-68 mol%) but comparable to Swingsia samuiensis AH83T (45.1 mol%) and higher than Commensalibacter intestini A911T (36.8 mol%). Overall genome relatedness indices based on gene and protein sequences strongly supported the assignment of G55GPT to a new genus within the family Acetobacteraceae. The percentage of conserved proteins, which is a useful metric for genus differentiation, was below 54 % when comparing G55GPT to type strains of acetic acid bacteria, thus strongly supporting our hypothesis that G55GPT is a member of a yet-undescribed genus. The fatty acid composition of G55GPT differed from that of closely related acetic acid bacteria, particularly given the presence of C19 : 1 ω9c/ω11c and the absence of C14 : 0 and C14 : 0 2-OH fatty acids. Strain G55GPT also differed in terms of metabolic features such as its ability to produce acid from d-mannitol, and its inability to produce acetic acid from ethanol or to oxidize glycerol to dihydroxyacetone. Based on the results of combined genomic, phenotypic and phylogenetic characterizations, isolate G55GPT (=LMG 31394T=DSM 111244T) is considered to represent a new species in a new genus, for which we propose the name Entomobacter blattae gen. nov., sp. nov.