The phylogenetic position of the budding bacteria Blastobacter aggregatus and Gemmobacter aquatilis gen., nov. sp. nov

Gemmobacter denitrificans sp. nov., a denitrifying bacterium, isolated from pond water for Litopenaeus vannamei

A novel Gram-stain-negative strain, designated JM10B15T, was isolated from pond water for Litopenaeus vannamei collected from Jiangmen City, Guangdong province, south PR China. Cells of the strain were aerobic, rod-shaped, and motile by lateral flagella. JM10B15T could grow at 15-40 °C, pH 6.0-9.5, and in 0-3.0 % NaCl, with optimal growth at 25-35 °C, pH 7.5-8.5, and in 0 % NaCl, respectively. Furthermore, this strain grew well on Reasoner's 2A agar but not on nutrient broth agar or Luria-Bertani agar. JM10B15T was a denitrifying bacterium capable of removing nitrites and nitrates, and three key functional genes, nasA, nirS, and nosZ, were identified in its genome. The results of phylogenetic analyses based on the 16S rRNA gene and genome sequences indicated that JM10B15T belonged to the genus Gemmobacter. JM10B15T showed the highest 16S rRNA sequence similarity to Gemmobacter lutimaris YJ-T1-11T (98.8 %), followed by Gemmobacter aquatilis IFAM 1031T (98.6 %) and Gemmobacter serpentinus HB-1T (98.1 %). The average nucleotide identity and digital DNA-DNA hybridization values between JM10B15T and the other type strains of genus Gemmobacter were 78.1-82.1 % and 18.4-22.1 %, respectively. The major fatty acids of strain JM10B15T were summed feature 8 (C18 : 1  ω6c and/or C18 : 1  ω7c) and C18 : 1  ω7c 11-methyl. In addition, the major respiratory quinone of this novel strain was Q-10, and the predominant polar lipids were phosphatidylglycerol, phosphatidylethanolamine, four unidentified phospholipids, three unidentified lipids, and an unidentified aminophospholipid. Results of analyses of the phylogenetic, genomic, physiological, and biochemical characteristics indicated that JM10B15T represents a novel species of the genus Gemmobacter, for which the name Gemmobacter denitrificans sp. nov. is proposed. The type strain is JM10B15T (=GDMCC 1.4148T=KCTC 8140T).

Abyssibius alkaniclasticus gen. nov., sp. nov., a novel member of the family Rhodobacteraceae, isolated from the Mariana Trench

A Gram-stain-negative bacterium with rod-shaped or irregular cells approximately 0.5-0.9×2.0-3.8 µm in size, designated as 960558^T, was isolated from sediment sampled in the Mariana Trench. Strain 960558^T grows at 4-37 °C (optimum, 28 °C), pH 6-7 (optimum, pH 7) and in the presence of 1-5 % (w/v) NaCl (optimum, 3 %). Strain 960558^T utilizes tetradecane or hexadecane as a sole carbon and energy source, respectively. Phylogenetic trees based on 16S rRNA gene sequences and phylogenomic reconstruction revealed a close phylogenetic relationship between strain 960558^T and members of the family Rhodobacteraceae by forming a separate branch within the type species of closely related genera. The validly published species that is most closely related to strain 960558^T is Planktotalea lamellibrachiae JAM 119^T, which has the highest 16S rRNA gene sequence similarity (93.47 %). Ubiquinone 10 is the predominant ubiquinone, while C_16 : 0, 11-methyl C_18 : 1  ω7c and C_18 : 1  ω7c and/or C_18 : 1  ω6c are the predominant fatty acids (>10 %). Additionally, phosphatidylglycerol, glycolipids, diphosphatidylglycerol, unidentified polar lipids and unidentified aminolipids are the major polar lipids. The DNA G+C content of strain 960558^T is 61 %. Average nucleotide identity and digital DNA-DNA hybridization results of strain 960558^T with other type strains are <70.2 and 22.1 %, respectively. Based on its phylogenetic, chemotaxonomic and other phenotypic properties, strain 960558^T is considered to represent a novel genus and species within the family Rhodobacteraceae, for which the name Abyssibius alkaniclasticus gen. nov., sp. nov. is proposed. The type strain of Abyssibius alkaniclasticus is 960558^T (=KCTC 82619^T=MCCC 1K04727^T).

Inhibition of AHL-mediated quorum sensing to control biofilm thickness in microbial fuel cell by using Rhodococcus sp. BH4

Anode biofilm thickness is a key point for high and sustainable power generation in microbial fuel cells (MFCs). Over time, the formation of a thicker biofilm on anode electrode hinders the power generation performance of MFC by causing a longer electron transfer path and the accumulation of undesirable components in anode biofilm. To overcome these limitations, we used a novel strategy named quorum quenching (QQ) for the first time in order to control the biofilm thickness on the anode surface by inactivation of signal molecules among microorganisms. For this purpose, the isolated QQ bacteria (Rhodococcus sp. BH4) were immobilized into alginate beads (20, 40, and 80 mg/10 ml sodium alginate) and added to the anode chamber of MFCs. The MFC exhibited the best electrochemical activity (1924 mW m^-2) with a biofilm thickness of 26 μm at 40 mg Rhodococcus sp. BH4/10 ml sodium alginate. The inhibition of signal molecules in anode chamber reduced the production of extracellular polymeric substance (EPS) by preventing microbial communication amonganode microorganisms. Microscopic observations revealed that anode biofilm thickness and the abundance of dead bacteria significantly decreased with an increase in Rhodococcus sp. BH4 concentration in MFCs. Microbiome diversity showed an apparent difference among the microbial community structures of anode biofilms in MFCs containing vacant and Rhodococcus sp. BH4 beads. The data revealed that the QQ strategy is an efficient application for improving MFC performance and may shed light on future studies.

Genomic Insights into Denitrifying Methane-Oxidizing Bacteria Gemmobacter fulva sp. Nov., Isolated from an Anabaena Culture

The genus Gemmobacter grows phototrophically, aerobically, or anaerobically, and utilizes methylated amine. Here, we present two high-quality complete genomes of the strains con4 and con5^T isolated from a culture of Anabaena. The strains possess sMMO (soluble methane monooxygenase)-oxidizing alkanes to carbon dioxide. Functional genes for methane-oxidation (prmAC, mimBD, adh, gfa, fdh) were identified. The genome of strain con5^T contains nirB, nirK, nirQ, norB, norC, and norG genes involved in dissimilatory nitrate reduction. The presence of nitrite reductase gene (nirK) and the nitric-oxide reductase gene (norB) indicates that it could potentially use nitrite as an electron acceptor in anoxic environments. Taxonomic investigations were also performed on two strains through polyphasic methods, proposing two isolates as a novel species of the genus Gemmobacter. The findings obtained through the whole genome analyses provide genome-based evidence of complete oxidation of methane to carbon dioxide. This study provides a genetic blueprint of Gemmobacter&nbsp;fulva con5^T and its biochemical characteristics, which help us to understand the evolutionary biology of the genus Gemmobacter.

Comparative genomics analyses indicate differential methylated amine utilization trait within members of the genus Gemmobacter

Methylated amines are ubiquitous in the environment and play a role in regulating the earth's climate via a set of complex biological and chemical reactions. Microbial degradation of these compounds is thought to be a major sink. Recently we isolated a facultative methylotroph, Gemmobacter sp. LW-1, an isolate from the unique environment Movile Cave, Romania, which is capable of methylated amine utilization as a carbon source. Here, using a comparative genomics approach, we investigate how widespread methylated amine utilization is within members of the bacterial genus Gemmobacter. Seven genomes of different Gemmobacter species isolated from diverse environments, such as activated sludge, fresh water, sulphuric cave waters (Movile Cave) and the marine environment were available from the public repositories and used for the analysis. Our results indicate that methylamine utilization is a distinctive feature of selected members of the genus Gemmobacter, namely G. aquatilis, G. lutimaris, G. sp. HYN0069, G. caeni and G. sp. LW-1 have the genetic potential while others (G. megaterium and G. nectariphilus) have not.

Gemmobacter aquarius sp. nov., Runella rosea sp. nov. and Flavobacterium fluviale sp. nov., isolated from the Namhangang River system

Three bacterial strains, namely HYN0069T, HYN0085T and HYN0086T, were isolated from freshwater samples taken from the Namhangan River system in Korea. 16S rRNA gene sequence similarities and phylogenetic tree topologies indicated that the three strains belonged to the genera Gemmobacter , Runella and Flavobacterium by showing the highest sequence similarities with Gemmobacter straminiformis (98.4 %), Runella aurantiaca (98.3 %) and Flavobacterium chungangense (98.1 %). No bacterial species with validly published names showed 98.7 % or higher sequence similarity with the novel isolates. The average nucleotide identities between the genome sequences of the three new isolates and the three closest neighbours were 80.2–92.0 %, all below the threshold for bacterial species delineation (95–96 %). Many biochemical and physiological features also discriminated the isolates from previously known species of the genera Gemmobacter , Runella and Flavobacterium . Based on the phylogenetic and phenotypic data presented in this study, we suggest three novel species with the following names: Gemmobacter aquarius sp. nov. (type strain HYN0069T=KACC 19488T=NBRC 113115T), Runella rosea sp. nov. (type strain HYN0085T=KACC 19490T=NBRC 113116T) and Flavobacterium fluviale sp. nov. (type strain HYN0086T=KACC 19489T=NBRC 113117T).

Falsigemmobacter faecalis gen. nov. sp. nov., isolated from faeces of Rhinopithecus roxellanae, and reclassification of Gemmobacter intermedius as Falsigemmobacter intermedius comb. nov

Strain YIM 102744-1^T was isolated from Rhinopithecus roxellanae fecal sample collected at Yunnan Wild Animal Park, Yunnan province, PR China. Cells were Gram-stain-negative, aerobic, non-motile and irregular rods. Optimal growth occurred in the presence of 0-1.0% (w/v) NaCl, at pH 7.0-8.0, and at 30 °C. The predominant ubiquinone was Q-10. The major cellular fatty acids (> 10.0%) were C_18:1ω7c and C_16:1ω7c/C_16:1ω6c. The dominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine. The DNA G + C content was 62.4 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that YIM 102744-1^T belonged to the family Rhodobacteraceae and shared the highest similarity with the type strain Gemmobacter intermedius 119/4^T (96.6%). In addition, phylogenetic trees indicated that strain YIM 102744-1^T formed a distinct clade together with the closest relative G. intermedius 119/4^T. Based on the results of polyphasic taxonomic analysis, strain YIM 102744-1^T is considered to represent a novel species within a new genus Falsigemmobacter, for which the name Falsigemmobacter faecalis gen. nov., sp. nov. is proposed. The type strain of Falsigemmobacter faecalis is YIM 102744-1^T(= KCTC 52106^T = CCTCC AB 2016031^T). Because Gemmobacter intermedius 119/4^T formed a branch with YIM 102744-1 in the phylogenetic trees and was clearly separated from the other members within the genus Gemmobacter, it is also proposed to transfer into the genus Falsigemmobacter as Falsigemmobacter intermedius comb. nov. (type strain 119/4^T = CIP 110795^T = LMG 28215^T = CCM 8510^T). The type species of the genus Falsigemmobacter is Falsigemmobacter intermedius gen. nov., comb. nov.

Gemmobacter serpentinus sp. nov., isolated from conserved forages

A Gram-stain-negative, long-rod-shaped and facultative aerobic bacterium, designated HB-1T, was isolated from a round hay bale at the Kansas State University Beef Stocker Unit. The results of phylogenetic analysis of 16S rRNA gene sequences indicated that strain HB-1T clustered within the genus Gemmobacter and its closest relatives were Gemmobacter aquaticus A1-9T (98.0 %), Gemmobacter lutimaris YJ-T1-11T (98.0 %), Gemmobacter fontiphilus JS43T (97.8 %), Gemmobacter aquatilis DSM 3857T (97.5 %) and Gemmobacter lanyuensis Orc-4T (96.9 %). Additional phylogenomic analysis also indicated that strain HB-1T belongs to the genus Gemmobacter . The draft genome of strain HB-1T had a total length of 4.23 Mbp and contained 4071 protein-coding genes. The average nucleotide identity values between the genomes of strain HB-1T and the three most-related type strains ranged from 77.5 to 78.1 %. The DNA G+C content of strain HB-1T was 63.7 mol%. The novel strain grew at 10–37 °C, pH 5–10 and with 0–2 % NaCl. Oxidase and catalase activities were positive. Cells were 0.3–0.4 µm wide, 3.0–7.0 µm long and usually found in pairs or chains of cells. The major respiratory quinone of strain HB-1T was Q-10 (90 %), with a minor amount of Q-9 (10 %). The major fatty acids were C18 : 1  ω7c (54.6 %) and C16 : 0 (18.2 %). On the basis of phenotypic, phylogenetic and chemotaxonomic data, strain HB-1T (=DSM 109828T=ATCC TSD-211T) is considered to represent a novel species of the genus Gemmobacter , for which the name Gemmobacter serpentinus sp. nov. is proposed.

Analysis of 1,000+ Type-Strain Genomes Substantially Improves Taxonomic Classification of Alphaproteobacteria

The class Alphaproteobacteria is comprised of a diverse assemblage of Gram-negative bacteria that includes organisms of varying morphologies, physiologies and habitat preferences many of which are of clinical and ecological importance. Alphaproteobacteria classification has proved to be difficult, not least when taxonomic decisions rested heavily on a limited number of phenotypic features and interpretation of poorly resolved 16S rRNA gene trees. Despite progress in recent years regarding the classification of bacteria assigned to the class, there remains a need to further clarify taxonomic relationships. Here, draft genome sequences of a collection of genomes of more than 1000 Alphaproteobacteria and outgroup type strains were used to infer phylogenetic trees from genome-scale data using the principles drawn from phylogenetic systematics. The majority of taxa were found to be monophyletic but several orders, families and genera, including taxa recognized as problematic long ago but also quite recent taxa, as well as a few species were shown to be in need of revision. According proposals are made for the recognition of new orders, families and genera, as well as the transfer of a variety of species to other genera and of a variety of genera to other families. In addition, emended descriptions are given for many species mainly involving information on DNA G+C content and (approximate) genome size, both of which are confirmed as valuable taxonomic markers. Similarly, analysis of the gene content was shown to provide valuable taxonomic insights in the class. Significant incongruities between 16S rRNA gene and whole genome trees were not found in the class. The incongruities that became obvious when comparing the results of the present study with existing classifications appeared to be caused mainly by insufficiently resolved 16S rRNA gene trees or incomplete taxon sampling. Another probable cause of misclassifications in the past is the partially low overall fit of phenotypic characters to the sequence-based tree. Even though a significant degree of phylogenetic conservation was detected in all characters investigated, the overall fit to the tree varied considerably.

Gemmobacter caeruleus sp. nov., a novel species originating from lake sediment

An aerobic, Gram-stain-negative, non-spore-forming and rod-shaped bacterial strain, designated N8T, was isolated from the interfacial sediment of Taihu Lake in PR China. The strain formed white to blue colonies on R2A agar. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain N8T represented a member of the genus Gemmobacter and was most closely related to Gemmobacter aquaticus A1-9T (97.97 %). The average nucleotide identity and digital DNA–DNAhybridization values between strain N8T and G. aquaticus A1-9T based on their whole genomes were 78.8 and 21.7 %, respectively. Q-10 was the main predominant ubiquinone. The major fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), C18 : 0 and C16 : 0. The G+C content of the genomic DNA was 66.1 mol%. The polar lipids comprised phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, one unidentified phospholipid, two unidentified glycolipids and two unidentified lipids. Based on its physiological, biochemical and chemotaxonomic characteristics, strain N8T represents a novel species of the genus Gemmobacter , for which the name Gemmobacter caeruleus sp. nov. is proposed. The type strain is N8T=(KACC 21307T=MCCC 1K04036T).

Tabrizicola alkalilacus sp. nov., isolated from alkaline Lake Dajiaco on the Tibetan Plateau

A novel Gram-stain-negative, aerobic, non-motile and rod-shaped bacterium was isolated from Lake Dajiaco on the Tibetan Plateau. Strain DJC^T grew without NaCl and tolerated up to 3 % (w/v) NaCl. Growth occurred at pH 6.0-10.0 (optimum, pH 7.0-8.0) and 15-37 °C (optimum, 25-30 °C). Vitamins were not required for growth. The main polar lipids of strain DJC^T were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The predominant respiratory quinone was Q-10. The major fatty acid was C_18 : 1ω7c. Genome sequencing revealed a genome size of 4.61 Mbp and a G+C content of 62.9 mol%. Analysis of 16S rRNA sequences showed that strain DJC^T belonged to the genus Tabrizicola, with the closest neighbour Tabrizicola aquatica RCRI19^T (97.5 %). DNA-DNA relatedness between strain DJC^T and the closest phylogenetically related strain T. aquatica RCRI19^T was 40.8 %. Stain DJC^T was clearly distinguished from the type strain mentioned above through phylogenetic analysis, DNA-DNA hybridization, fatty acid composition data and a range of physiological and biochemical characteristic comparisons. Based on its phenotypic and chemotaxonomic characteristics, strain DJC^T could be classified as a representative of a novel species of the genus for which the name Tabrizicola alkalilacus sp. nov. is proposed. The type strain is DJC^T (=CICC 24242^T=KCTC 62173^T).

Taxogenomics Resolves Conflict in the Genus Rhodobacter: A Two and Half Decades Pending Thought to Reclassify the Genus Rhodobacter

The genus Rhodobacter is taxonomically well studied, and some members are model organisms. However, this genus is comprised of a heterogeneous group of members. 16S rRNA gene-based phylogeny of the genus Rhodobacter indicates a motley assemblage of anoxygenic phototrophic bacteria (genus Rhodobacter) with interspersing members of other genera (chemotrophs) making the genus polyphyletic. Taxogenomics was performed to resolve the taxonomic conflicts of the genus Rhodobacter using twelve type strains. The phylogenomic analysis showed that Rhodobacter spp. can be grouped into four monophyletic clusters with interspersing chemotrophs. Genomic indices (ANI and dDDH) confirmed that all the current species are well defined, except Rhodobacter megalophilus. The average amino acid identity values between the monophyletic clusters of Rhodobacter members, as well as with the chemotrophic genera, are less than 80% whereas the percentage of conserved proteins values were below 70%, which has been observed among several genera related to Rhodobacter. The pan-genome analysis has shown that there are only 1239 core genes shared between the 12 species of the genus Rhodobacter. The polyphasic taxonomic analysis supports the phylogenomic and genomic studies in distinguishing the four Rhodobacter clusters. Each cluster is comprised of one to seven species according to the current Rhodobacter taxonomy. Therefore, to address this taxonomic discrepancy we propose to reclassify the members of the genus Rhodobacter into three new genera, Luteovulum gen. nov., Phaeovulum gen. nov. and Fuscovulum gen. nov., and provide an emended description of the genus Rhodobacter sensu stricto. Also, we propose reclassification of Rhodobacter megalophilus as a sub-species of Rhodobacter sphaeroides.

Response of microbial community structure to pre-acclimation strategies in microbial fuel cells for domestic wastewater treatment

Microbial community structures and performance of air-cathode microbial fuel cells (MFCs) inoculated with activated sludge from domestic wastewater were investigated to evaluate the effects of three substrate pre-acclimation strategies: 1, serial pre-acclimation with acetate and glucose before supplying domestic wastewater; 2, one step pre-acclimation with acetate before supplying domestic wastewater; and 3, direct supply of domestic wastewater without any pre-acclimation. Strategy 1 showed much higher current generation (1.4mA) and Coulombic efficiency (33.5%) than strategies 2 (0.7mA and 9.4%) and 3 (0.9mA and 10.3%). Pyrosequencing showed that microbial communities were significantly affected by pre-acclimation strategy. Although Proteobacteria was the dominant phylum with all strategies, Actinobacteria was abundant when MFCs were pre-acclimated with glucose after acetate. Not only anode-respiring bacteria (ARB) in the genus Geobacter but also non-ARB belonging to the family Anaerolinaceae seemed to play important roles in air-cathode MFCs to produce electricity from domestic wastewater.

Halovulum dunhuangense gen. nov., sp. nov., isolated from a saline terrestrial spring

A bacterial strain, YYQ-30T, isolated from a mixed water–sand–sediment sample collected from a terrestrial spring located in Dunhuang, China, was characterized with respect to its morphology, physiology and taxonomy. Cells of the strain were Gram-stain-negative, aerobic, oxidase- and catalase-positive, non-flagellated, oval to rod-shaped (0.5–1.0 μm wide and 1.1–6.6 μm long) and divided by binary fission. Growth was observed in the presence of 0–10.0 % (w/v) NaCl with optimal growth at 0–3.0 %, at pH 6.0–9.0 (optimum pH 7.0–8.5) and at 10–45 °C (optimum 30–37 °C). The isolate could reduce nitrate to nitrite and hydrolyse aesculin and gelatin (weakly), but was unable to degrade Tween 80 or starch. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain YYQ-30T belongs to the family Rhodobacteraceae and forms a distinct lineage with the type strain of Albimonas donghaensis and forms a branch within a cluster constituted by the type strains of species of the genera Albimonas, Rhodovulum, Albidovulum, Haematobacter and Tropicimonas; levels of 16S rRNA gene sequence similarity between strain YYQ-30T and members of related genera ranged from 94.1 to 89.7  %. Strain YYQ-30T contained Q-10 as the predominant ubiquinone and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c; 70.0  %), C18 : 0 (9.5  %), summed feature 2 (one or more of C14  :  0 3-OH, iso-C16  :  1 I and C12  :  0 aldehyde; 6.9  %) and 11-methyl C18  :  1ω7c (6.0  %) as the principal fatty acids. The polar lipids comprised diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, three unidentified phospholipids, two unidentified aminolipids and five unknown lipids. The pufLM gene was detected. The G+C content of the genomic DNA was 71.7 mol%. Based on the phylogenetic, chemotaxonomic and phenotypic data obtained in this study, strain YYQ-30T is considered to represent a novel species in a new genus within the family Rhodobacteraceae, for which the name Halovulum dunhuangense gen. nov., sp. nov. is proposed. The type strain of Halovulum dunhuangense is YYQ-30T ( = LMG 27418T = MCCC 1A06483T).

Reclassification of Gemmobacter changlensis to a new genus as Cereibacter changlensis gen. nov., comb. nov

We propose a new genus to accommodate the phototrophic bacterium Gemmobacter changlensis [Chen W. M., Cho, N. T., Huang, W. C., Young, C. C. & Sheu, S. Y. (2013) Int J Syst Evol Microbiol 63, 470–478] based on multiple strain analysis. Differences in the major diagnostic properties such as ability to grow phototrophically, the presence of internal photosynthetic membranes, the light harvesting complexes, fatty acids, carotenoids, bacterial chlorophylls, polar lipid composition and some other phenotypic properties warrant the creation of a new genus, designated Cereibacter gen. nov., to accommodate the phototrophic members of the genus Gemmobacter , as represented by the type species Cereibacter changlensis comb. nov.

Gemmobacter intermedius sp. nov., isolated from a white stork (Ciconia ciconia)

A cream-coloured, Gram-stain-negative, aerobic, non-motile, rod- to irregular shaped bacterium, strain 119/4T, was isolated from a choana swab of a white stork nestling on sheep blood agar. 16S rRNA gene sequence analysis and subsequent comparisons showed that it was a member of the family Rhodobacteraceae, showing 94.9 % similarity to the type strain of Gemmobacter tilapiae and 94.6 % similarity to that of Gemmobacter nectariphilus , but also similarly low sequence similarity to the type strains of Rhodobacter viridis (94.8 %), Rhodobacter veldkampii (94.6 %) and Paenirhodobacter enshiensis (94.6 %). Reconstruction of phylogenetic trees showed that strain 119/4T clustered close to species of the genus Gemmobacter . The quinone system contained high amounts of ubiquinone Q-10 with traces of Q-8, Q-9 and Q-11, and the fatty acid profile consisted mainly of C18 : 1ω7c, C16 : 1ω7c/iso-C15 : 0 2-OH and C10 : 0 3-OH. The predominant polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phoshatidylglycerol and phosphatidylcholine. Major polyamines were putrescine and spermidine. On the basis of 16S rRNA gene sequence analysis and chemotaxonomic and physiological data, strain 119/4T represents a novel species of the genus Gemmobacter , for which the name Gemmobacter intermedius sp. nov. is proposed. The type strain is 119/4T ( = CIP 110795T = LMG 28215T = CCM 8510T).

Gemmobacter megaterium sp. nov., isolated from coastal planktonic seaweeds

A Gram-stain-negative, non-motile and aerobic bacterium, designated CF17T, was isolated from coastal planktonic seaweeds, East China Sea. The isolate grew at 18–37 °C (optimum 25–28 °C), pH 6.5–9.0 (optimum 7.0–8.0) and with 0–5 % NaCl (optimum 1–2 %, w/v) and 0.5–10 % sea salts (optimum 2–3 %, w/v). Growth of strain CF17T could be stimulated prominently by supplementing the growth medium with the autoclaved supernatant of a culture of strain CF5, which was isolated from the same sample along with strain CF17T. The cell morphology of strain CF17T was a bean-shaped rod consisting of a swollen end and a long prostheca. The phylogenetic analysis of 16S rRNA gene sequences indicated that strain CF17T clustered with Gemmobacter nectariphilus DSM 15620T within the genus Gemmobacter . The DNA G+C content of strain CF17T was 61.4 mol%. The respiratory quinone was ubiquinone Q-10. The major fatty acids included C18 : 1ω7c and C18 : 0. The polar lipids of strain CF17T consisted of phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, two uncharacterized phospholipids, one uncharacterized aminolipid, three uncharacterized glycolipids and one uncharacterized lipid. On the basis of phenotypic, phylogenetic and chemotaxonomic data, strain CF17T ( = CGMCC 1.11024T = JCM 18498T) is considered to represent a novel species of the genus Gemmobacter , for which the name Gemmobacter megaterium sp. nov. is proposed.

Gemmobacter lanyuensis sp. nov., isolated from a freshwater spring

A bacterial strain designated Orc-4T was isolated from a freshwater spring in Taiwan and characterized using the polyphasic taxonomic approach. Cells of strain Orc-4T were facultatively anaerobic, Gram-reaction-negative, poly-β-hydroxybutyrate-accumulating, non-motile rods surrounded by a thick capsule and forming cream–white colonies. Growth occurred at 15–40 °C (optimum, 25–30 °C), at pH 6.0–9.0 (optimum, pH 7.0) and with 0–1 % NaCl (optimum, 0–0.5 %). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain Orc-4T belonged to the genus Gemmobacter within the family Rhodobacteraceae of the class Alphaproteobacteria and its most closely related neighbour was Gemmobacter fontiphilus JS43T with sequence similarity of 97.8 %. Strain Orc-4T contained C18 : 1ω7c as the predominant fatty acid. The major respiratory quinone was Q-10. The DNA G+C content of the genomic DNA was 63.5 mol%. The polar lipid profile consisted of a mixture of phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, one uncharacterized aminolipid and several uncharacterized phospholipids. The DNA–DNA relatedness of strain Orc-4T with respect to recognized species of the genus Gemmobacter was less than 48 %. On the basis of the genotypic, chemotaxonomic and phenotypic data, strain Orc-4T represents a novel species of the genus Gemmobacter , for which the name Gemmobacter lanyuensis sp. nov. is proposed. The type strain is Orc-4T ( = BCRC 80378T = LMG 26667T = KCTC 23714T).

Gemmobacter tilapiae sp. nov., a poly-β-hydroxybutyrate-accumulating bacterium isolated from a freshwater pond

A novel bacterium, designated strain Ruye-53T, was isolated from a freshwater pond used to rear tilapiine cichlid fish in Taiwan. The taxonomic position of the novel strain was determined using a polyphasic approach. Strain Ruye-53T was Gram-reaction-negative, aerobic, cream–white coloured, rod-shaped, non-motile and poly-β-hydroxybutyrate-accumulating. Growth occurred at 10–37 °C (optimum between 20 and 25 °C), at pH 6.0–9.0 (optimum between pH 8.0 and pH 9.0) and with 0–1 % (w/v) NaCl (optimum 0 %). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain Ruye-53T belonged to the genus Gemmobacter and that its most closely related neighbour was Gemmobacter aquatilis DSM 3857T (97.6 % sequence similarity). The novel strain’s predominant fatty acid was C18 : 1ω7c, its major respiratory quinone was Q-10 and its genomic DNA G+C content was 61.2 mol%. The polar lipid profile consisted of a mixture of phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, one uncharacterized aminolipid and four uncharacterized phospholipids. The DNA–DNA relatedness value between strain Ruye-53T and Gemmobacter aquatilis DSM 3857T was about 45.5 % (48.2±0.4 % in the reciprocal experiment). On the basis of the genotypic, chemotaxonomic and phenotypic data, strain Ruye-53T represents a novel species in the genus Gemmobacter , for which the name Gemmobacter tilapiae sp. nov. is proposed. The type strain is Ruye-53T ( = BCRC 80261T  = KCTC 23310T).

Description of Gemmobacter fontiphilus sp. nov., isolated from a freshwater spring, reclassification of Catellibacterium nectariphilum as Gemmobacter nectariphilus comb. nov., Catellibacterium changlense as Gemmobacter changlensis comb. nov., Catellibacterium aquatile as Gemmobacter aquaticus nom. nov., Catellibacterium caeni as Gemmobacter caeni comb. nov., Catellibacterium nanjingense as Gemmobacter nanjingensis comb. nov., and emended description of the genus Gemmobacter and of Gemmobacter aquatilis

A light-yellow-pigmented bacterial strain designated JS43T was isolated from a freshwater spring in Taiwan and was characterized using a polyphasic taxonomic approach. Cells of strain JS43T were Gram-negative-staining, facultatively anaerobic, rod-shaped, non-motile and non-spore-forming. Growth occurred at 10–30 °C (optimum, 25 °C), at pH 7.0–10.0 (optimum, pH 7.0–8.0) and with 0–0.5 % (w/v) NaCl (optimum, 0 %). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain JS43T was a member of the family Rhodobacteraceae of the class Alphaproteobacteria . Sequence similarities to type strains of the genera Gemmobacter and Catellibacterium were between 94.6 and 98.1 %. The highest sequence similarity was found with Gemmobacter aquatilis DSM 3857T. Strain JS43T contained C18 : 1ω7c as the predominant fatty acid (74.4 %). The major isoprenoid quinone was Q-10 and the DNA G+C content was 69.3 mol%. The polar lipid profile consisted of a mixture of phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, two uncharacterized aminolipids and three uncharacterized phospholipids. The DNA–DNA relatedness values of strain JS43T with respect to the phylogenetically related Gemmobacter aquatilis DSM 3857T, Catellibacterium aquatile A1-9T and Catellibacterium caeni DCA-1T were less than 70 %. The taxonomic relationship between members of the genera Gemmobacter and Catellibacterium was clarified by means of a direct experimental comparison. Based on phylogenetic, chemotaxonomic and phenotypic data, we propose that all species currently classified in the genus Catellibacterium should be transferred to the genus Gemmobacter . The following new combinations are proposed: Catellibacterium nectariphilum is reclassified as Gemmobacter nectariphilus comb. nov. (type strain, AST4T = DSM 15620T = JCM 11959T = NBRC 100046T), Catellibacterium changlense as Gemmobacter changlensis comb. nov. (type strain, JA139T = CCUG 53722T = DSM 18774T = JCM 14338T), Catellibacterium aquatile as Gemmobacter aquaticus nom. nov. (type strain, A1-9T = CGMCC 1.7029T = NBRC 104254T), Catellibacterium caeni as Gemmobacter caeni comb. nov. (type strain, DCA-1T = CGMCC 1.7745T = DSM 21823T) and Catellibacterium nanjingense as Gemmobacter nanjingensis comb. nov. (type strain, Y12T = CCTCC AB 2010218T = KCTC 23298T). Emended descriptions of the genus Gemmobacter and of Gemmobacter aquatilis are also presented. Strain JS43T could be distinguished from recognized species of the genera Gemmobacter and Catellibacterium . It is suggested, on the basis of genotypic and phenotypic characteristics, that strain JS43T ( = BCRC 80082T = LMG 25376T) represents a novel species for which the name Gemmobacter fontiphilus is proposed.

Rhizobium rosettiformans sp. nov., isolated from a hexachlorocyclohexane dump site, and reclassification of Blastobacter aggregatus Hirsch and Müller 1986 as Rhizobium aggregatum comb. nov

A Gram-negative, rod-shaped, motile, aerobic bacterial strain, W3T, was isolated from hexachlorocyclohexane (HCH)-contaminated groundwater from Lucknow, India, and its taxonomic position was determined using a polyphasic approach. Strain W3T shared highest 16S rRNA gene sequence similarity of 97.8 % with Rhizobium selenitireducens B1T, followed by Rhizobium daejeonense L61T (97.7 %), Rhizobium radiobacter ATCC 19358T (97.5 %) and Blastobacter aggregatus IFAM 1003T (97.2 %). Strain W3T formed a monophyletic clade with Blastobacter aggregatus IFAM 1003T ( = DSM 1111T) in the cluster of species of the genus Rhizobium. Phylogenetic analyses of strain W3T using atpD and recA gene sequences confirmed the phylogenetic arrangements obtained by using 16S rRNA gene sequences. Hence, the taxonomic characterization of B. aggregatus DSM 1111T was also undertaken. Strains W3T and B. aggregatus DSM 1111T contained summed feature 8 (18 : 1ω7c and/or 18 : 1ω6c; 65.4 and 70.8 %, respectively) as the major fatty acid, characteristic of the genus Rhizobium. DNA–DNA relatedness of strain W3T with Rhizobium selenitireducens LMG 24075T, Rhizobium daejeonense DSM 17795T, Rhizobium radiobacter DSM 30147T and B. aggregatus DSM 1111T was 42, 34, 30 and 34 %, respectively. The DNA G+C contents of strain W3T and B. aggregatus DSM 1111T were 62.3 and 62.7 mol%, respectively. A nifH gene encoding dinitrogenase reductase was detected in strain W3T but not in B. aggregatus DSM 1111T. Based on the results obtained by phylogenetic and chemotaxonomic analyses, phenotypic characterization and DNA–DNA hybridization, it is concluded that strain W3T represents a novel species of the genus Rhizobium, for which the name Rhizobium rosettiformans sp. nov. is proposed (type strain W3T  = CCM 7583T  = MTCC 9454T). It is also proposed that Blastobacter aggregatus Hirsch and Müller 1986 be transferred to the genus Rhizobium as Rhizobium aggregatum comb. nov. (type strain IFAM 1003T  = DSM 1111T  = ATCC 43293T).

Reclassification of 'Blastobacter viscosus' 7d and 'Blastobacter aminooxidans' 14a as Xanthobacter viscosus sp. nov. and Xanthobacter aminoxidans sp. nov

On the basis of morphological, physiological and genotypic properties 'Blastobacter viscosus' 7d and 'Blastobacter aminooxidans' 14a are proposed as new species of the genus Xanthobacter, Xanthobacter viscosus (type strain 7dT =VKM B-2253T =ATCC BAA-298T) and Xanthobacter aminoxidans corrig. (type strain 14aT =VKM B-2254T =ATCC BAA-299T).

A phylogenetic survey of budding, and/or prosthecate, non-phototrophic eubacteria: membership of Hyphomicrobium, Hyphomonas, Pedomicrobium, Filomicrobium, Caulobacter and "dichotomicrobium" to the alpha-subdivision of purple non-sulfur bacteria

The phylogenetic position of various budding and/or or prosthecate Gram-negative eubacteria was determined by different methods. Members of the genera Hyphomicrobium, Filomicrobium, Pedomicrobium were investigated by 16S rRNA cataloguing, a 1373 nucleotide long portion of the 16S rRNA was sequenced from Hyphomicrobium vulgare and the 5S rRNAs were analyzed from two Hyphomicrobium strains, Hyphomonas polymorpha and Caulobacter crescentus. Comparison with published sequences indicated a membership of all of these organisms to the alpha subdivision of purple bacteria. While C. crescentus and Hyphomonas polymorpha constitute separate individual lines of descent, the position of a coherent cluster embracing Hyphomicrobium, Pedomicrobium and Filomicrobium is not yet settled. 16S rRNA cataloguing indicate the presence of a distinct line equivalent to other subgroups in its phylogenetic depth. 5S rRNA analysis, on the other hand, groups Hyphomicrobium vulgare and strain IFAM 1761 with members of subgroup alpha-2 (Rhodopseudomonas palustris, Nitrobacter winogradskyi and relatives). In contrast to the present classification, Pedomicrobium ferrugineum and Filimicrobium fusiforme are more closely related to certain Hyphomicrobium strains than these are related among each other. Budding mode of reproduction and prosthecate morphology are dominating morphological features of members of the alpha subdivision. These characteristics may gain diagnostic significance in a future formal description of this subdivision and its subgroups as a higher rank.