Roseateles cavernae sp. nov., a Bacterium Isolated from Freshwater of the Old Huanglong Cave in Yunnan Province, South-West China

A novel bacteria, designated as YIM B04394T, was isolated from a freshwater sample collected from the Old Huanglong Cave in Kunming, Yunnan province, South-west China. The cells of this strain were Gram negative and rod shaped. The strain was found to be aerobic, oxidase positive, and weakly catalase positive, grew at 10-40℃ (optimum, 28 °C), pH 6.0-8.0 (optimum, pH 7.0), and low NaCl concentrations (up to 5.0%). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain YIM B04394T clustered with Roseateles species. The DNA-DNA and ANI relatedness values of strain YIM B04394T with the related species R. toxinivorans DSM 16998 T and R. saccharophilus DSM 25082 T were 21.50-22.9%% and 76.47-76.93%, respectively. The predominant fatty acids included C16:1ω6c and/or C16:1 ω7c and C16:0. Ubiquinone- 8 was detected as the respiratory quinone, and the major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, and an unknown phospholipid. The DNA G + C content was 67.89%. Based on phylogenomic and phylogenetic analyses, combined with phenotypic and chemotaxonomic characterizations, this strain represents a novel Roseateles species for which the name Roseateles cavernae sp. nov. is proposed. The type strain is YIM B04394T (= NBRC 115775 T = KCTC 92438 T = CCTCC AB2021502T).

Three Novel Bacterial Species, Roseateles flavus sp. nov., Roseateles paludis sp. nov., and Roseateles hydrophilus sp. nov., Isolated from Various Water-Related Environments

A polyphasic study was conducted to determine the taxonomic positions of three bacterial strains, designated as strains 2.12 T, DJS-2-20 T, and UHG3T, isolated from the water of an agricultural water pipe, wetland, and artificial lake, respectively. These strains were Gram-stain-negative, rod-shaped, and oxidase positive. The fatty acid profiles of all three strains revealed that the major fatty acids (> 10%) were C16:0 and summed features 3 (comprising C16:1ω6c and/or C16:1ω7c), with strain UHG3T additionally featuring C16:0 3-OH as its main fatty acid. Phosphatidylethanolamine was the major polar lipid. Ubiquinone 8 (Q-8) was the only respiratory quinone detected. The genomic G + C contents were 68.5% for strain 2.12 T, 68% for strain DJS-2-20 T, and 69% for strain UHG3T. Strains 2.12 T, DJS-2-20 T, and UHG3T had the closest 16S rRNA gene sequence similarity with R. subflavus APW6T (98.5%), R. puraquae CCUG 52769 T (98.2%), and R. puraquae CCUG 52769 T (99.4%), respectively. The pairwise amino acid identity, average nucleotide identity, and digital DNA-DNA hybridization values for strains 2.12 T, DJS-2-20 T, and UHG3T with its closely related type strain of the species were below the species delineation thresholds. The genotypic and phenotypic characteristics observed in this study indicated that strains 2.12 T (= KACC 23730 T = TBRC 19013 T), DJS-2-20 T (= KACC 23731 T = TBRC 19014 T), and UHG3T (= KACC 22636 T = TBRC 16347 T) represent three novel Roseateles species, for which we propose the names Roseateles flavus sp. nov., Roseateles paludis sp. nov., and Roseateles hydrophilus sp. nov., respectively.

Creation of a functional duckweed holobiont to reduce nutrient competition with microalgae for high-yield biomass production

Duckweed has been highlighted as an appropriate biomass for low-carbon industries because of its significantly high production rate and multiple resource value. However, the outbreak of microalgae is a practical issue that decreases duckweed production yield. This study demonstrated that the growth of the duckweed Lemna aequinoctialis from factory wastewater was enhanced by colonization with indigenous plant growth-promoting bacteria (PGPB), whereas the growth of a duckweed competitor microalga, Coelastrella sp. KC10, from the same wastewater was reduced by indigenous microalgal growth-inhibiting bacteria (MGIB). Finally, a quadruple co-culture of a synthetic duckweed holobiont, L. aequinoctialis colonized by both KLaR20 (PGPB) and KLaR16 (MGIB), and Coelastrella sp. KC10 successfully recovered the duckweed production level by 117.5% in frond number and 84.5% in dry weight compared to those in the absence of microalgae. This case study demonstrates for the first time that duckweed holobionts can be reconstructed and enforced to antagonize growth competitor microalgae.

Pelomonas baiyunensis sp. nov., Pelomonas candidula sp. nov., Pelomonas dachongensis sp. nov., Pelomonas lactea sp. nov., Pelomonas margarita sp. nov., Pelomonas nitida sp. nov., Pelomonas parva sp. nov. and Roseateles rivi sp. nov., isolated from streams in China

Eight Gram-stain-negative, aerobic and motile strains (BYS78WT, BYS87WT, BYS96WT, BYS180WT, DC23WT, DXS20WT, LKC17WT and LYH14WT) were isolated from streams in China and showed the highest 16S rRNA gene sequence similarities with the species of genus Pelomonas. The calculated average nucleotide identity, digital DNA-DNA hybridization and average amino acid sequence identity values among these eight strains and other closely related strains were less than 89.8, 39.1 and 89.4 %, respectively, indicating that each of the eight strains should represent an independent novel species. The further reconstructed phylogenomic tree showed that seven isolated strains clustered closely with the Pelomonas strains. Only strain BYS180WT clustered with the Roseateles strains. The phylogenomic tree also showed that the taxonomic status of the recently published species (Paucibacter sediminis, Roseateles aquae, 'Roseateles caseinilyticus', 'Roseateles cellulosilyticus', Roseateles subflavus and Roseateles violae) was questionable. 'R. caseinilyticus' and 'R. cellulosilyticus' should be reassigned to the genus Pelomonas as Pelomonas caseinilytica P7T (=KACC 22504T=TBRC 15694T) and Pelomonas cellulosilytica P8T (=KACC 22505T=TBRC 15695T), respectively. P. sediminis, R. aquae, R. subflavus and R. violae should be reassigned to the genus Kinneretia as Kinneretia sediminis, Kinneretia aquae, Kinneretia subflava and Kinneretia violae, respectively. Combining the above descriptions, strains BYS78WT, BYS87WT, BYS96WT, DC23WT, DXS20WT, LKC17WT and LYH14WT should represent seven novel species of the genus Pelomonas, for which the names Pelomonas baiyunensis sp. nov. (type strain BYS87WT=GDMCC 1.4090T=KCTC 8151T), Pelomonas candidula sp. nov. (type strain BYS78WT=GDMCC 1.4089T=KCTC 8152T), Pelomonas dachongensis sp. nov. (type strain DC23WT=GDMCC 1.4087T=KCTC 8148T), Pelomonas lactea sp. nov. (type strain DXS20WT=GDMCC 1.4088T=KCTC 8147T), Pelomonas margarita sp. nov. (type strain LKC17WT=GDMCC 1.4086T=KCTC 8146T), Pelomonas nitida sp. nov. (type strain BYS96WT=GDMCC 1.4091T=KCTC 8150T) and Pelomonas parva sp. nov. (type strain LYH14WT=GDMCC 1.4276T=KCTC 8301T) are proposed, respectively. Strain BYS180WT should represent a novel species of the genus Roseateles, for which the name Roseateles rivi sp. nov. (type strain BYS180WT=GDMCC 1.4098T=KCTC 8149T) is proposed.

Roseateles microcysteis sp. nov., Isolated from Co-cultivation of Microcystis aeruginosa and Myriophyllum spicatum

A novel rod-shaped, Gram-stain-negative bacterial strain MS17T was obtained from a co-culture of Microcystis aeruginosa and Myriophyllum spicatum. The examination of the 16S ribosomal RNA gene sequence showed a significant degree of similarity between strain MS17T and Paucibacter sediminis S2-9T (98.4%), Roseateles violae PFR6T (98.1%), 'Roseateles cellulosilyticus' P8T (98.0%), Roseateles aquae APW11T (97.9%), Roseateles oligotrophus CHU3T (97.7%), Roseateles saccharophilus DSM 654T (97.6%), Kinneretia aquatilis CR182T (97.7%), Pelomonas aquatica CCUG 52575T (97.6%), and Roseateles toxinivorans 2C20T (97.0%). Between strain MS17T and the type strains of closely related species, digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values were below 21.9% and 78.48%. The respiratory quinone was ubiquinone Q-8. The main fatty acids (> 10.0%) were C15:1 ω6c, C16:0, C17:0, and summed feature 3 (C16:1 ω7c and/or C16:1 ω6c). The polar lipids comprised phosphatidylethanolamine, unidentified phospholipid, phosphatidylglycerol, unidentified aminophospholipid, unidentified aminolipid, and three unidentified lipids. The genomic G + C content was 65.9%. According to phenotypic characteristics, phylogenetic relationships, and chemotaxonomic data, strain MS17T has been categorized as a newly discovered species belonging to the Roseateles genus, and the name Roseateles microcysteis sp. nov. is suggested. It exhibits distinct biochemical properties that differentiate it from closely related species. The type strain is MS17T (=KCTC 8001T = LMG 33142T).

Roseateles subflavus sp. nov. and Roseateles aquae sp. nov., isolated from artificial pond water and Roseateles violae sp. nov., isolated from a Viola mandshurica root

Two novel strains, designated APW6T and APW11T, were isolated from artificial pond water, and one novel strain, designated PFR6T, was isolated from a Viola mandshurica root. These strains were found to be Gram-negative, rod-shaped, motile by means of flagella, and oxidase-positive. Growth conditions of the type strains were as follows: APW6T, 15-43 °C (optimum, 28 °C), pH 6.0-12.0 (optimum, pH 7.0), with no salinity; APW11T, 4-35 °C (optimum, 25 °C), pH 6.0-11.0 (optimum, pH 9.0), with 0-1 % NaCl (w/v, optimum 0 %); PFR6T, 10-38 °C (optimum 28 °C), pH 6.0-12.0 (optimum, pH 7.0), with 0-2 % NaCl (w/v; optimum, 0 %). Strains APW6T, APW11T, and PFR6T belonged to the genus Roseateles, having the most 16S rRNA gene sequence similarity to Roseateles saccharophilus DSM 654T (98.1 %), Roseateles oligotrophus CHU3T (98.7 %), and Roseateles puraquae CCUG 52769T (98.1 %). The estimated genome sizes of APW6T, APW11T, and PFR6T were 50 50 473, 56 70 008, and 52 16 869 bp, respectively and the G+C contents were 69.5, 66, and 68.5 mol%. The digital DNA-DNA hybridization, average amino acid identity, and average nucleotide identity values among the novel strains and related taxa were all lower than 22.4, 74.7, and 78.9 %, respectively. The predominant cellular fatty acids (>10 %) of all strains were summed feature 3 (comprising C16 : 1  ω6c and/or C16 : 1  ω7c) and C16 : 0. PFR6T also had summed feature 8 (comprising C18 :  1  ω7c and/or C18 :  1  ω6c) as a major fatty acid. The polar lipid profile of all strains contained phosphatidylethanolamine, phosphoaminoglycolipid, and phosphoglycolipid. The distinct phylogenetic, physiological, and chemotaxonomic features reported in this study indicate that strains APW6T, APW11T, and PFR6T represent novel species within the genus Roseateles, for which the names Roseateles subflavus sp. nov., with the type strain APW6T (=KACC 22877T=TBRC 16606T), Roseateles aquae sp. nov., with the type strain APW11T (=KACC 22878T=TBRC 16607T), and Roseateles violae sp. nov (=KACC 23257T=TBRC 17653T) are respectively proposed.

Paucibacter sediminis sp. nov., isolated from sediment in a freshwater pond

A Gram-stain-negative, aerobic, oxidase-positive, weakly catalase-positive, motile by means of a single polar flagellum, rod-shaped bacterium designated as strain S2-9T was isolated from sediment sampled in Wiyang pond, Republic of Korea. Growth of this strain was observed at 10-40 °C (optimum, 35 °C) and pH 5.5-9.5 (optimum, pH 7.0-8.0) and in the presence of 0-0.5 % NaCl in Reasoner's 2A broth. The major fatty acids (>10 %) of strain S2-9T were C16 : 0 and summed feature 3 (comprising a mixture of C16 : 1  ω7c and/or C16 : 1  ω6c). Ubiquinone-8 was detected as the respiratory quinone. The major polar lipids were phosphatidylethanolamine and phosphatidylglycerol. Strain S2-9T showed the highest 16S rRNA gene sequence similarity to Paucibacter oligotrophus CHU3T (98.7 %), followed by 'Paucibacter aquatile' CR182 (98.4 %), all type strains of Pelomonas species (98.1-98.3 %), Mitsuaria chitosanitabida NBRC 102408T (97.9 %), Kinneretia asaccharophila KIN192T (97.8 %), Mitsuaria chitinivorans HWN-4T (97.4 %), and Paucibacter toxinivorans 2C20T (97.4 %). Phylogenetic trees based on the 16S rRNA gene and whole-genome sequences showed that strain S2-9T formed a tight phylogenetic lineage with Paucibacter species (CHU3T, CR182, and 2C20T). Average nucleotide identity and digital DNA-DNA hybridization values between strain S2-9T and Paucibacter strains were 76.6-79.3% and 19.5-21.5 %, respectively. The genomic DNA G+C content of strain S2-9T was 68.3 mol%. Notably, genes responsible for both sulphur oxidation and reduction and denitrification were found in the genome of strain S2-9T, suggesting that strain S2-9T is involved in the nitrogen and sulphur cycles in pond ecosystems. Based on the polyphasic taxonomic results, strain S2-9T represents a novel species of the genus Paucibacter, for which the name Paucibacter sediminis sp. nov. is proposed. The type strain is S2-9T (= KACC 22267T= JCM 34541T).

Roseateles amylovorans sp. nov., isolated from freshwater

A Gram-stain-negative, rod-shaped, amylolytic bacterial strain, designated as bsSlp3-1T, was isolated from the Slepian water system, a freshwater reservoir. Strain bsSlp3-1T was found to be aerobic, oxidase-positive and catalase-negative, grew at 5-37 °C (optimum, 28 °C), pH 5.0-9.5 (optimum, pH 7.0) and low NaCl concentration (up to 1.0 %). Comparative analysis of 16S rRNA gene sequence similarity revealed that strain bsSlp3-1T clustered with Roseateles species and is closely related to Roseateles depolymerans KCTC 42856T (98.7 %) and Roseateles terrae CCUG 52222T (98.6 %). Whole-genome comparisons using average nucleotide identity and digital DNA-DNA hybridization values suggested that strain bsSlp3-1T represents a novel species within the genus Roseateles and is most closely related to Roseateles aquatilis CCUG 48205T (81.2 and 25.6 %, respectively). The genome of strain bsSlp3-1T consisted of a single circular chromosome with size 6 289 366 bp and DNA G+C content of 66.8 mol%. The predominant cellular fatty acids of bsSlp3-1T were cis-9-hexadecanoic and hexadecenoic acids. According to the data obtained in this work, strain bsSlp3-1T represents a novel Roseateles species for which the name Roseateles amylovorans sp. nov. is proposed. The type strain is bsSlp3-1T (=BIM B-1768T=NBIMCC 9098T=VKM B-3671T).

Roseateles albus sp. nov., Roseateles koreensis sp. nov. and Janthinobacterium fluminis sp. nov., isolated from freshwater at Jucheon River, and emended description of Roseateles aquaticus comb. nov

Three Gram-stain-negative, facultatively anaerobic, rod-shaped, catalase-positive, oxidase-negative bacterial strains were designated as hw1T, hw8T and hw3T. Strains hw1T, hw8T and hw3T grew at 15-28 °C (optimum, 25 °C), 15-35 °C (optimum, 30 °C) and 4-28 °C (optimum, 20 °C), respectively, and at pH 7.0-12.0 (optimum, pH 9.0), pH 6.0-11.0 (optimum, pH 9.0) and 5.0-12.0 (optimum, pH 7.0), respectively. Additionally, strains hw1T and hw8T only grew when the NaCl concentration was 0 %, while strain hw3T grew at between 0 and 0.5 % (w/v; optimum, 0 %). The average nucleotide identity (ANI) values between strains hw1T, hw8T and the Roseateles type strains ranged from 73.8 to 84.2 %, while the digital DNA-DNA hybridization (dDDH) values ranged from 19.7 to 27.5 %. The ANI values between strain hw3T and the Janthinobacterium type strains ranged from 78.7 to 80.7 %, while dDDH values ranged from 22.3 to 23.0 %. The draft genomes of strains hw1T, hw8T and hw3T consisted of 5.5, 4.4 and 5.9 Mbp, with DNA G+C contents of 61.7, 61.8 and 66.0 mol%, respectively. The results of the dDDH, ANI, phylogenetic, biochemical and physiological analyses indicated that the novel strains were distinct from other members of their genera. Thus, we proposed the names Roseateles albus sp. nov. (type strain hw1T= KACC 22887T= TBRC 16613T), Roseateles koreensis sp. nov. (type strain hw8T= KACC 22885T= TBRC 16614T) and Janthinobacterium fluminis sp. nov. (type strain hw3T= KACC 22886T= TBRC 16615T).

Impact of nutrients and trace elements on freshwater microbial communities in Croatia: identifying bacterial bioindicator taxa

Since aquatic microbial communities promptly respond to environmental changes, it is now evident that they can complement traditional taxa such as fish, macroinvertebrates and algae as bioindicators of water quality. The aim of this study was to correlate the physico-chemical parameters of water with the microbial community structure and the occurrence of putative bioindicator taxa. Thirty-five water samples were collected throughout Croatia and their physico-chemical parameters, including the concentration of trace elements using the high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS), and the composition of the microbial communities by high-throughput sequencing of the 16S rRNA marker gene, were analysed in parallel. Partial least squares regression (PLS-R) modelling revealed that a number of microbial taxa were positively correlated with some of the water parameters. For example, some taxa from the phylum Proteobacteria were positively correlated with the ion content of the water (e.g. Erythrobacter, Rhodobacteraceae, Alteromonadaceae), while some Firmicutes taxa, such as the well-known faecal indicators Enterococcus and Clostridium, were correlated with nutrient content (ammonium and total phosphorus). Among the trace elements, uranium was positively correlated with a highest number of microbial taxa. The results obtained will aid in development of protocols for eDNA-based biological assessment of water quality.

Community characteristics of autotrophic CO2-fixing bacteria in karst wetland groundwaters with different nitrogen levels

Karst wetlands are important in the global carbon and nitrogen cycles as well as in security of water resources. Huixian wetland (Guilin) is the largest natural karst wetland in China. In recent years, groundwater nitrogen pollution has increasingly affected the wetland ecosystem integrity due to anthropogenic activities. In this study, it was hypothesized that autotrophic microbial diversity is impacted with the advent of pollution, adversely affecting autotrophs in the carbon and nitrogen cycles. Autotrophic microbes have important roles in abating groundwater nitrogen pollution. Thus, it is of great significance to study the characteristics of autotrophic bacterial communities and their responses to environmental parameters in nitrogen-polluted karst groundwaters. The abundances of the Calvin-Benson cycle functional genes cbbL and cbbM as well as the autotrophic CO2-fixing bacterial communities were characterized in the karst groundwater samples with different levels of nitrogen pollution. The cbbM gene was generally more abundant than the cbbL gene in the groundwater samples. The cbbL gene abundance was significantly positively correlated with dissolved inorganic nitrogen (DIN) concentration (P < 0.01). In the autotrophic CO2-fixing bacterial communities, Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria of the phylum Proteobacteria were predominant. At the genus level, Rubrivivax and Methylibium were the dominant cbbL gene containing genera, while Halothiobacillus and Endothiovibrio were the dominant genera for the cbbM gene. The abundance of autotrophic CO2-fixing bacterial communities increased but their diversity decreased with the inflow of nitrogen into the karst groundwater system. The community structure of autotrophic CO2-fixing bacteria in the groundwaters was also significantly affected by environmental factors such as the carbonic anhydrase (CA) activity, dissolved inorganic carbon (DIC) concentration, temperature, and oxidation-reduction potential (ORP). Nitrogen inflow significantly changed the characteristics of autotrophic CO2-fixing bacterial communities in the karst groundwaters. Some key genera such as Nitrosospira and Thiobacillus were clearly abundant in the karst groundwaters with high nitrogen levels. Their respective roles in nitrification and denitrification impact nitrogen removal in this ecosystem. The findings in this study provide an important reference for biological abatement of nitrogen pollution in the karst groundwater system.

Complete Genome Sequences of Kinneretia sp. Strain XES5, Shinella sp. Strain XGS7, and Vogesella sp. Strain XCS3, Isolated from Xenopus laevis Skin

Here, we report the genome sequences of three bacterial isolates, Kinneretia sp. strain XES5, Shinella sp. strain XGS7, and Vogesella sp. strain XCS3, which were cultured from skin of adult female laboratory-bred Xenopus laevis.

Complete Genome Sequence of Kinneretia sp. Strain DAIF2, Isolated from a Freshwater Pond

Kinneretia sp. strain DAIF2 was isolated from a eutrophic freshwater pond. The genome consists of a single chromosome (6,010,585 bp) with a GC content of 69.3%. The whole-genome-based phylogeny of DAIF2 revealed a closest relation to the genus Kinneretia.

Reclassification of 'Polyangium brachysporum' DSM 7029 as Schlegelella brevitalea sp. nov

Strain DSM 7029, isolated from a soil sample in Greece, can produce antitumour glidobactins, and has been found, as a heterologous host, to produce useful nonribosomal peptide synthetase-polyketide synthase hybrid molecules known as epothilones. This strain was originally named 'Polyangium brachysporum' of the family Polyangiaceae and the order Myxococcales. However, phylogenetic analysis of the 16S rRNA gene sequence of strain DSM 7029 indicated that it was clustered with members of Schlegelella. Significant growth occurred at 25-42 °C, pH 5.0-10.0 and in the presence of 0-0.2 % (w/v) NaCl. The predominant ubiquinone was Q-8. The major fatty acids were C_16 : 1ω7c/C_16 : 1ω6c, C_16 : 0 and C_18 : 1ω7c. The G+C content of genomic DNA was 67.51 mol%. The strain was clearly distinguishable from other neighbouring Schlegelella members and genera Caldimonas and Zhizhongheella, using phylogenetic analysis, fatty acid composition data and a range of physiological and biochemical characteristics and genome analysis. Therefore, strain DSM 7029 represents a novel species of the genus Schlegelella, for which the name Schlegelella brevitalea sp. nov. is proposed.

Paucibacter oligotrophus sp. nov., isolated from fresh water, and emended description of the genus Paucibacter

A Gram-stain-negative, rod-shaped, non-spore forming, motile and strictly oxidative bacterium, strain CHU3T, was isolated from fresh water in the Daecheong Reservoir, South Korea. A comparison of the 16S rRNA gene sequence showed that the novel bacterium is closely related to Paucibacter toxinivorans 2C20T (=KCTC 42569T) with a sequence similarity value of 97.8 %, Pelomonas saccharophila DSM 654T (=KCTC 52256T) with 97.4 % similarity and Pelomonas aquatica CCUG 52575T (=KCTC 42961T) with 97.3 % similarity, respectively. The major fatty acids (>10 %) of the isolate were summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and C16 : 0. Ubiquinone-8 was detected as the respiratory quinone. The polar lipids contained diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylserine and an unidentified aminolipid. The DNA G+C content was 62.5 mol%. DNA-DNA hybridization experiments with PaucibactertoxinivoransKCTC 42569T (=2C20T), PelomonassaccharophilaKCTC 52256T (=DSM 654T) and PelomonasaquaticaKCTC 42961T (=CCUG 52575T) resulted in relatedness values of 20 % (reciprocal 11 %), 16 % (reciprocal 17 %) and 15 % (reciprocal 19 %), respectively. The phylogenetic analysis, DNA-DNA hybridization value, polar lipids, fatty acid composition and other physiological characteristics confirmed that strain CHU3T represents a novel species in the genus Paucibacter for which the name Paucibacter oligotrophus sp. nov. is proposed. The type strain is CHU3T (=KCTC 42519T=CICC 24092T). An emended description of the genus Paucibacter is also proposed on the basis of new data obtained in this study.

Piscinibacterium candidicorallinum gen. nov., sp. nov., a member of the order Burkholderiales isolated from a fish pond

A bacterial strain designated LYH-15T was isolated from a freshwater fish pond in Taiwan and characterized using a polyphasic taxonomy approach. Cells of LYH-15T were Gram-staining-negative, aerobic, motile by means of a single polar flagellum, poly-β-hydroxybutyrate-containing, non-spore forming, straight rods and formed light-coral-colored colonies. Growth occurred at 15-40 °C (optimum, 30 °C), at pH 5.0-9.0 (optimum, pH 7.0) and with 0-0.5 % NaCl (optimum, 0 %). Phylogenetic analyses based on 16S rRNA gene sequences showed that LYH-15T forms a distinct phyletic line within the order Burkholderiales, with less than 94 % sequence similarity to its closest relatives with validly published names. The predominant fatty acids were summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c), C16 : 0 and C18 : 1ω7c. The major isoprenoid quinone was Q-8 and the DNA G+C content was 63.8 mol%. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and several uncharacterized lipids. The major polyamines were 2-hydroxyputrescine and putrescine. On the basis of the genotypic and phenotypic data, LYH-15T represents a novel species of a new genus in the order Burkholderiales, for which the name Piscinibacterium candidicorallinum gen. nov., sp. nov. is proposed. The type strain is LYH-15T (=BCRC 80969T=LMG 29480T=KCTC 52168T).

Understanding molecular identification and polyphasic taxonomic approaches for genetic relatedness and phylogenetic relationships of microorganisms

The major proportion of earth's biological diversity is inhabited by microorganisms and they play a useful role in diversified environments. However, taxonomy of microorganisms is progressing at a snail's pace, thus less than 1% of the microbial population has been identified so far. The major problem associated with this is due to a lack of uniform, reliable, advanced, and common to all practices for microbial identification and systematic studies. However, recent advances have developed many useful techniques taking into account the house-keeping genes as well as targeting other gene catalogues (16S rRNA, rpoA, rpoB, gyrA, gyrB etc. in case of bacteria and 26S, 28S, β-tubulin gene in case of fungi). Some uncultivable approaches using much advanced techniques like flow cytometry and gel based techniques have also been used to decipher microbial diversity. However, all these techniques have their corresponding pros and cons. In this regard, a polyphasic taxonomic approach is advantageous because it exploits simultaneously both conventional as well as molecular identification techniques. In this review, certain aspects of the merits and limitations of different methods for molecular identification and systematics of microorganisms have been discussed. The major advantages of the polyphasic approach have also been described taking into account certain groups of bacteria as case studies to arrive at a consensus approach to microbial identification.

Metabolic characteristics of the species Variovorax paradoxus

This review outlines information about the Gram-negative, aerobic bacterium Variovorax paradoxus. The genomes of these species have G+C contents of 66.5-69.4 mol%, and the cells form yellow colonies. Some strains of V. paradoxus are facultative lithoautotrophic, others are chemoorganotrophic. Many of them are associated with important catabolic processes including the degradation of toxic and/or complex chemical compounds. The degradation pathways or other skills related to the following compounds, respectively, are described in this review: sulfolane, 3-sulfolene, 2-mercaptosuccinic acid, 3,3'-thiodipropionic acid, aromatic sulfonates, alkanesulfonates, amino acids and other sulfur sources, polychlorinated biphenyls, dimethyl terephthalate, linuron, 2,4-dinitrotoluene, homovanillate, veratraldehyde, 2,4-dichlorophenoxyacetic acid, anthracene, poly(3-hydroxybutyrate), chitin, cellulose, humic acids, metal-EDTA complexes, yttrium, rare earth elements, As(III), trichloroethylene, capsaicin, 3-nitrotyrosine, acyl-homoserine lactones, 1-aminocyclopropane-1-carboxylate, methyl tert-butyl ether, geosmin, and 2-methylisoborneol. Strains of V. paradoxus are also engaged in mutually beneficial interactions with other plant and bacterial species in various ecosystems. This species comprises probably promising strains for bioremediation and other biotechnical applications. Lately, the complete genomes of strains S110 and EPS have been sequenced for further investigations.

Aquabacterium limnoticum sp. nov., isolated from a freshwater spring

A Gram-negative, facultatively anaerobic, short-rod-shaped, non-motile and non-spore-forming bacterial strain, designated ABP-4(T), was isolated from a freshwater spring in Taiwan and was characterized using the polyphasic taxonomy approach. Growth occurred at 20-40 °C (optimum, 30-37 °C), at pH 7.0-10.0 (optimum, pH 7.0-9.0) and with 0-3% NaCl (optimum, 0%). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain ABP-4(T), together with Aquabacterium fontiphilum CS-6(T) (96.4% sequence similarity), Aquabacterium commune B8(T) (96.1%), Aquabacterium citratiphilum B4(T) (95.5%) and Aquabacterium parvum B6(T) (94.7%), formed a deep line within the order Burkholderiales. Strain ABP-4(T) contained summed feature 3 (comprising C(16:1) ω7c and/or C(16:1) ω6c), C(18:1) ω7c and C(16:0) as predominant fatty acids. The major cellular hydroxy fatty acid was C(10:0) 3-OH. The major isoprenoid quinone was Q-8 and the DNA G+C content was 68.6 mol%. The polar lipid profile consisted of a mixture of phosphatidylethanolamine, phosphatidylglycerol, phosphatidylserine, diphosphatidylglycerol and several uncharacterized phospholipids. The DNA-DNA relatedness of strain ABP-4(T) with respect to recognized species of the genus Aquabacterium was less than 70%. On the basis of the genotypic, chemotaxonomic and phenotypic data, strain ABP-4(T) represents a novel species in the genus Aquabacterium, for which the name Aquabacterium limnoticum sp. nov. is proposed. The type strain is ABP-4(T) (=BCRC 80167(T)=KCTC 23306(T)).