Biodegradation of low-density polyethylene by mixed fungi composed of Alternaria sp. and Trametes sp. isolated from landfill sites.

With the development of industry and modern manufacturing, nondegradable low-density polyethylene (LDPE) has been widely used, posing a rising environmental hazard to natural ecosystems and public health. In this study, we isolated a series of LDPE-degrading fungi from landfill sites and carried out LDPE degradation experiments by combining highly efficient degrading fungi in pairs. The results showed that the mixed microorganisms composed of Alternaria sp. CPEF-1 and Trametes sp. PE2F-4 (H-3 group) had a greater degradation effect on heat-treated LDPE (T-LDPE). After 30 days of inoculation with combination strain H-3, the weight loss rate of the T-LDPE film was approximately 154% higher than that of the untreated LDPE (U-LDPE) film, and the weight loss rate reached 0.66 ± 0.06%. Environmental scanning electron microscopy (ESEM) and Fourier transform infrared spectroscopy (FTIR) were used to further investigate the biodegradation impacts of T-LDPE, including the changes on the surface and depolymerization of the LDPE films during the fungal degradation process. Our findings revealed that the combined fungal treatment is more effective at degrading T-LDPE than the single strain treatment, and it is expected that properly altering the composition of the microbial community can help lessen the detrimental impact of plastics on the environment.

Lacibacter sediminis sp. nov., isolated from contaminated freshwater sediment.

Two Gram-stain-negative bacterial strains, S13-6-6 and S13-6-22T, were isolated from sediment sample collected at a water depth of 4 m from Lake Hongze, Jiangsu Province, PR China. The cells of strains S13-6-6 and S13-6-22T were non-spore-forming, aerobic, non-motile and formed orange colonies on R2A agar. Comparative 16S rRNA gene sequence studies revealed a clear affiliation of the two strains with he phylum Bacteroidota, and revealed the highest pairwise sequence similarities with Lacibacter daechungensis H32-4T (97.8 %), Lacibacter cauensis NJ-8T (97.8 %), Lacibacter luteus TTM-7T (97.4 %) and Lacibacter nakdongensis SS2-56T (97.4 %). The results of phylogenetic analysis based on 16S rRNA gene sequences indicated that the strains formed a clear phylogenetic lineage with the genus Lacibacter. The major fatty acids were identified as iso-C15 : 1G, iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) (>10 %), and the respiratory quinone was identified as menaquinone MK-7. The polar lipids consisted of phosphatidylethanolamine, two unidentified aminolipids, an unidentified phospholipid and six unidentified lipids. The genomic DNA G+C content was determined to be 40.2 mol% (HPLC) for strain S13-6-6 and 40.3 % (genome) for strain S13-6-22T. The combined genotypic and phenotypic data indicated that strains S13-6-6 and S13-6-22T represent a novel species of the genus Lacibacter, for which the name Lacibacter sediminis sp. nov. is proposed. The type strain is S13-6-22T (=CGMCC 1.17450T =JCM 35802T).

Description of Hymenobacter sediminicola sp. nov., isolated from contaminated sediment.

A polyphasic taxonomic study was conducted on two Gram-negative, non-sporulating, non-motile bacterial strains, S2-20-2T and S2-21-1, isolated from a contaminated freshwater sediment in China. Comparative 16S rRNA gene sequence studies revealed a clear affiliation of two strains with Bacteroidetes, which showed the highest pairwise sequence similarities with Hymenobacter duratus BT646T (99.3%), Hymenobacter psychrotolerans Tibet-IIU11T (99.3%), Hymenobacter kanuolensis T-3T (97.6%), Hymenobacter swuensis DY53T (96.9%), Hymenobacter tenuis POB6T (96.8%), Hymenobacter seoulensis 16F7GT (96.7%), and Hymenobacter rigui KCTC 12533T (96.5%). The phylogenetic analysis based on 16S rRNA gene sequences showed that two strains formed a clear phylogenetic lineage with the genus Hymenobacter. Major fatty acids were identified as iso-C15:0, anteiso-C15:0, and summed feature 3 (C16:1 ω6c and/or C16:1 ω7c/t) and summed feature 4 (iso-C17:1 I and/or anteiso-C17:1 B). Major cellular polar lipids were identified as phosphatidylethanolamine, three unidentified aminolipids, an unidentified aminophosopholipid and an unidentified lipid. The respiratory quinone was detected as MK-7 and the genomic DNA G + C content was determined to be 57.9% (genome) for type strain S2-20-2T and 57.7 mol% (HPLC) for strain S2-21-1. The observed ANI and dDDH values between strain S2-20-2T and its closely related strains were 75.7-91.4% and 21.2-43.9%, respectively. Based on physiological, biochemical, genetic and genomic characteristics, we propose that strains S2-20-2T and S2-21-1 represent a novel species of the genus Hymenobacter, for which the name Hymenobacter sediminicola sp. nov. is proposed. The type strain is S2-20-2T (= CGMCC 1.18734T = JCM 35801T).

New Multidrug Efflux Systems in a Microcystin-Degrading Bacterium Blastomonas fulva and Its Genomic Feature.

A microcystin-degrading bacterial strain, Blastomonas fulva T2, was isolated from the culture of a microalgae Microcystis. The strain B. fulva T2 is Gram-stain-negative, non-motile, aerobic, non-spore-forming and phototrophic. The cells of B. fulva T2 are able to grow in ranges of temperature from 15 to 37 °C, with a pH of 6 to 8 and a salinity of 0 to 1% NaCl. Here, we sequenced the complete genome of B. fulva T2, aiming to better understand the evolutionary biology and the function of the genus Blastomonas at the molecular level. The complete genome of B. fulva T2 contained a circular chromosome (3,977,381 bp) with 64.3% GC content and a sizable plasmid (145.829 bp) with 60.7% GC content which comprises about 3.5% of the total genetic content. A total of 3842 coding genes, including 46 tRNAs and 6 rRNAs, were predicted in the genome. The genome contains genes for glycolysis, citric acid cycle, Entner-Doudoroff pathways, photoreaction center and bacteriochlorophylla synthesis. A 7.9 K gene cluster containing mlrA, mlrB, mlrC and mlrD1,2,3,4 of microcystin-degrading enzymes was identified. Notably, eight different efflux pumps categorized into RND, ABC and MFS types have been identified in the genome of strain T2. Our findings should provide new insights of the alternative reaction pathway as well as the enzymes which mediated the degradation of microcystin by bacteria, as well as the evolution, architectures, chemical mechanisms and physiological roles of the new bacterial multidrug efflux system.

Development and Applications of CRISPR/Cas9-Based Genome Editing in Lactobacillus.

Lactobacillus, a genus of lactic acid bacteria, plays a crucial function in food production preservation, and probiotics. It is particularly important to develop new Lactobacillus strains with superior performance by gene editing. Currently, the identification of its functional genes and the mining of excellent functional genes mainly rely on the traditional gene homologous recombination technology. CRISPR/Cas9-based genome editing is a rapidly developing technology in recent years. It has been widely applied in mammalian cells, plants, yeast, and other eukaryotes, but less in prokaryotes, especially Lactobacillus. Compared with the traditional strain improvement methods, CRISPR/Cas9-based genome editing can greatly improve the accuracy of Lactobacillus target sites and achieve traceless genome modification. The strains obtained by this technology may even be more efficient than the traditional random mutation methods. This review examines the application and current issues of CRISPR/Cas9-based genome editing in Lactobacillus, as well as the development trend of CRISPR/Cas9-based genome editing in Lactobacillus. In addition, the fundamental mechanisms of CRISPR/Cas9-based genome editing are also presented and summarized.

Paraconexibacter algicola gen. nov., sp. nov., a novel actinobacterium isolated from a eutrophic lake during the end of cyanobacterial harmful algal blooms, and proposal of Paraconexibacteraceae fam. nov. in the order Solirubrobacterales.

A novel bacterium, strain Seoho-28T, was isolated from a shallow eutrophic lake during the end of cyanobacterial harmful algal blooms and was characterized taxonomically and phylogenetically. Strain Seoho-28T was a Gram-stain-negative, aerobic, rod-shaped and non-motile bacterium. The strain grew optimally with 0 % NaCl and at 25-30 °C on Reasoner's 2A medium. The phylogenetic analysis based on 16S rRNA gene sequences positioned the novel strain among the order Solirubrobacterales, but sequence similarities to known species were less than 94.7 %. The genomic DNA G+C content of the strain Seoho-28T was 74.2 mol%. Genomic comparisons of strain Seoho-28T with families in the order Solirubrobacterales were made using the Genome-to-Genome Distance Calculator, average nucleotide identity and average amino acid identity analyses (values indicated ≤14.9, ≤73.5 and ≤57.8 %, respectively). Strain Seoho-28T contained C16 : 0-iso, C18 : 1 ω9c and C16 : 0 as major fatty acids and MK-7 (H4) as the major quinone. Strain Seoho-28T contained diphosphatidylglycerol, phosphatidylinositol and an unidentified phospholipid as major polar lipids. Meso- and ll-diaminopimelic acids were the diagnostic diamino acids in the cell-wall peptidoglycan. Based on the genotypic, chemotaxonomic and phenotypic results, strain Seoho-28T represents a novel genus and species, Paraconexibacter algicola gen. nov., sp. nov., which belongs to a new family Paraconexibacteraceae in the order Solirubrobacterales and the class Thermoleophilia. The type strain is Seoho-28T (=KCTC 39791T=JCM 31881T).

Lysobacter profundi sp. nov., isolated from freshwater sediment and reclassification of Lysobacter panaciterrae as Luteimonas panaciterrae comb. nov.

A polyphasic taxonomic study was carried out on strains CHu50b-3-2T and CHu40b-3-1 isolated from a 67 cm-long sediment core collected from the Daechung Reservoir at a water depth of 17 m, Daejeon, Republic of Korea. The cells of the strains were Gram-stain-negative, non-spore-forming, non-motile and rod-shaped. Comparative 16S rRNA gene sequence studies showed a clear affiliation of two strains with γ-Proteobacteria, which showed the highest pairwise sequence similarities to Lysobacter hankyongensis KTce-2T (96.5 %), Lysobacter pocheonensis Gsoil193T (96.3 %), Lysobacter ginsengisoli Gsoil 357T (96.1 %), Lysobacter solanacearum T20R-70T (96.1 %), Lysobacter brunescens KCTC 12130T (95.4 %) and Lysobacter capsici YC5194T (95.3 %). The phylogenetic analysis based on 16S rRNA gene sequences showed that the strains formed a clear phylogenetic lineage with the genus Lysobacter. The major fatty acids were identified as summed feature 9 (iso-C17 : 1 ω9c and/or C18 : 1 10-methyl), iso-C15 : 0, iso-C16 : 0 and iso-C17 : 0. The respiratory quinone was identified as ubiquinone Q-8. The major polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine and an unidentified phospholipid. The genomic DNA G+C content was determined to be 66.8 mol% (genome) for strain CHu50b-3-2T and 66.4 mol% (HPLC) for strain CHu40b-3-1. Based on the combined genotypic and phenotypic data, we propose that strains CHu50b-3-2T and CHu40b-3-1 represent a novel species of the genus Lysobacter, for which the name Lysobacter profundi sp. nov. is proposed. The type strain is CHu50b-3-2T (=KCTC 72973T=CCTCC AB 2019129T). Besides Lysobacter panaciterrae Gsoil 068T formed a phylogenetic group together with strain Luteimonas aquatica RIB1-20T (EF626688) that is clearly separated from all other known Lysobacter strains. Based on the phylogenetic relationships together with fatty acid compositions, Lysobacter panaciterrae Gsoil 068T should be reclassified as a member of the genus Luteimonas: Luteimonas aquatica comb. nov. (type strain Gsoil 068T=KCTC 12601T=DSM 17927T).

Caulobacter soli sp. nov., isolated from soil sampled at Jiri Mountain, Republic of Korea.

A Gram-stain-negative, yellow-pigmented, aerobic, non-spore-forming, motile with a single polar flagellum and rod-shaped bacterium, Ji-3-8T, was isolated from a soil sample taken from Jiri Mountain, Republic of Korea. Comparative 16S rRNA gene sequence studies showed the isolate had clear affiliation with Alphaproteobacteria and the closest relatedness to Caulobacter rhizosphaerae KCTC 52515T, Caulobacter henricii ATCC 15253T, Caulobacter segnis ATCC 21756T, Caulobacter hibisci THG-AG3.4T, Caulobacter flavus RHGG3T and Caulobacter vibrioides CB51T showing 99.1, 98.9, 97.7, 97.6, 97.5 and 97.4 % 16S rRNA gene sequence similarity, respectively, and 94.7-96.5 % to the remaining species of genus Caulobacter. The predominant ubiquinone was Q-10 and the major fatty acids were C18 : 1 ω7c 11-methyl, C16 : 0, summed feature 8 (C18 : 1 ω6c and/or C18 : 1 ω7c) and summed feature 3 (C16 : 1 ω6c and/or C16 : 1 ω7c). The major polar lipids were found to be phosphatidylglycerol, two unidentified phosphoglycolipid and two unidentified glycolipids. The G+C content of the genomic DNA of strain Ji-3-8T was 68.1 mol%. Average nucleotide identity and digital DNA-DNA hybridization values of strain Ji-3-8T with C. rhizosphaerae KCTC 52515T, C. henricii ATCC 15253T, C. segnis ATCC 21756T, C. flavus RHGG3T and C. vibrioides were 79.7-87.7% and 23.0-34.3%, respectively. Based on the polyphasic evidence, it is proposed that strain Ji-3-8T forms a novel species in the genus Caulobacter, for which the name Caulobacter soli sp. nov. is proposed. The type strain is Ji-3-8T (=CCTCC AB 2019389T=KCTC 72990T).

Genomic insights into a novel species Rhodoferax aquaticus sp. nov., isolated from freshwater.

A novel non-phototrophic member of the genus Rhodoferax was obtained from freshwater. The purpose of this study was to analyse the genome of a nonphototrophic strain and propose a new species based on its phylogenetic, genomic, physiological and chemotaxonomic characteristics. The results of phylogenetic analysis based on 16S rRNA gene sequences supports that the strain, designated Gr-4T, has a close relationship to the genus Rhodoferax. The observed average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain Gr-4T and its closest related strains were 72.3-74.6 % and 21.9-22.8 %, respectively. These values were much lower than the species separation thresholds for ANI or dDDH of 95-96 and 70 %, respectively, and in fact fall in the intergeneric range. Strain Gr-4T does not contain RuBisCO-related genes, but does contain GS/GOGAT pathway-related genes enabling nitrate ammonification. A polyphasic study and a genomic-level investigation were done to establish the taxonomic status of strain Gr-4T. Based on the phylogenetic, genomic and physiological differences, it is proposed that the isolate be classified to the genus Rhodoferax as Rhodoferax aquaticus sp. nov. with isolate Gr-4T (=KCTC 32394T=JCM 19166T) as the type strain.

Lacisediminimonas profundi gen. nov., sp. nov., a member of the family Oxalobacteraceae isolated from freshwater sediment.

A novel Gram-stain-negative bacterial strain, CHu64-6-4T, was isolated from a 67-cm-long sediment core collected from the Daechung Reservoir at a water depth of 17 m, Daejeon, Republic of Korea. The cells of strain CHu64-6-4T were aerobic nonmotile and formed colorless colonies on R2A agar. The phylogenetic analysis based on 16S rRNA gene sequencing indicated that the strain formed a separate lineage within the family Oxalobacteraceae, exhibiting 97.2% and 97.1% 16S rRNA gene sequence similarities to Glaciimonas singularis and Paraherbaspirillum soli, respectively. Strain CHu64-6-4T showed less than 74.4% average nucleotide identity compared to the type strains of related genera within the family Oxalobacteraceae. In the UPGMA dendrogram based on the ANI values of genomic sequences, strain CHu64-6-4T formed an evolutionary lineage independent of the genera Glaciimonas and some other taxa. The chemotaxonomic results showed Q-8 as the predominant respiratory ubiquinone, phosphatidylglycerol, diphosphatidylglycerol, and phosphatidylethnolamine as the major polar lipids, Summed Feature 3 (C16:1ω7c and/or iso-C15:0 2-OH), C16:0, and C18:1ω7c as the major fatty acids, and a DNA G+C content of 62.1 mol%. The combined genotypic and phenotypic data showed that strain CHu64-6-4T could be distinguished from all genera within the family Oxalobacteraceae and represents a novel genus, Lacisediminimonas profundi gen. nov., with the name Lacisediminimonas profundi sp. nov., in the family Oxalobacteraceae. The type strain is CHu64-6-4T (=KCTC 62287T=JCM 32676T).

Lacisediminihabitans profunda gen. nov., sp. nov., a member of the family Microbacteriaceae isolated from freshwater sediment.

A novel Gram-stain-positive bacterial strain, CHu50b-6-2T, was isolated from a 67-cm-long sediment core collected from the Daechung Reservoir at a water depth of 17 m, Daejeon, Republic of Korea. The cells of strain CHu50b-6-2T were aerobic non-motile and formed yellow colonies on R2A agar. The phylogenetic analysis based on 16S rRNA gene sequencing indicated that the strain formed a separate lineage within the family Microbacteriaceae, exhibiting 98.0%, 97.7% and 97.6% 16S rRNA gene sequence similarities to Glaciihabitans tibetensis KCTC 29148T, Frigoribacterium faeni KACC 20509T and Lysinibacter cavernae DSM 27960T, respectively. The phylogenetic trees revealed that strain CHu50b-6-2T did not show a clear affiliation to any genus within the family Microbacteriaceae. The chemotaxonomic results showed B1α type peptidoglacan containg 2, 4-diaminobutyric acid (DAB) as the diagnostic diamino acid, MK-10 as the predominant respiratory menaquinone, diphosphatidylglycerol, phosphatidylglycerol, and an unidentified glycolipid as the major polar lipids, anteiso-C15:0, iso-C16:0, and anteiso-C17:0 as the major fatty acids, and a DNA G + C content of 67.3 mol%. The combined genotypic and phenotypic data showed that strain CHu50b-6-2T could be distinguished from all genera within the family Microbacteriaceae and represents a novel genus, Lacisediminihabitans gen. nov., with the name Lacisediminihabitans profunda sp. nov., in the family Microbacteriaceae. The type strain is CHu50b-6-2T (= KCTC 49081T = JCM 32673T).

Description of novel members of the family Sphingomonadaceae: Aquisediminimonas profunda gen. nov., sp. nov., and Aquisediminimonas sediminicola sp. nov., isolated from freshwater sediment.

Two Gram-stain-negative bacterial strains, DS48-3T and CH68-4T, were isolated from freshwater sediment taken from the Daechung Reservoir, Republic of Korea. Cells of strains DS48-3T and CH68-4T were aerobic, non-motile, non-spore-forming and rod-shaped. Strain DS48-3T was isolated from a sediment surface sample at a depth of 48 m from the Daechung Reservoir and was most closely related to the genus Sphingopyxis according to 16S rRNA gene sequence analysis (94.5-95.9 % similarity). Strain CH68-4T was isolated from the very bottom of a 67-cm-long sediment core collected from Daechung Reservoir at a water depth of 17 m and was most closely related to the genus Sphingopyxis (16S rRNA gene sequence similarity of 93.7-95.0 %). Phylogenetic analysis based on 16S rRNA gene sequencing indicated that the two strains formed a separate lineage within the order Sphingomonadales showing similarity values below 95.9 % with their closest phylogenetic neighbours, and sharing 97.3 % similarity with each other. The combined genotypic and phenotypic data showed that strains DS48-3T and CH68-4T could be distinguished from all genera within the family Sphingomonadaceae and represented two distinct species of a novel genus, Aquisediminimonas profunda gen. nov., sp. nov. (type strain DS48-3T=KCTC 52068T=CCTCC AB 2018061T) and Aquisediminimonas sediminicola sp. nov. (type strain CH68-4T=KCTC 62205T=CCTCC AB 2018062T).

Nevskia lacus sp. nov., a gammaproteobacterium isolated from a eutrophic lake.

A novel Gram-stain negative, rod-shaped and motile bacterial strain, designated strain Seoho-38T, was isolated from a eutrophic lake in South Korea. Polyphasic taxonomic studies were performed to investigate the taxonomic position of the new isolate. The phylogenetic analysis based on the 16S rRNA gene sequences revealed that strain Seoho-38T formed a distinct cluster with Nevskia ramosa Soe1T, Nevskia persephonica G6M-30T, Nevskia soli GR15-1T, Nevskia terrae KIS13-15T and Nevskia aquatilis F2-63T with bootstrap resampling value of 100%. Of those Nevskia strains, the new isolate shows high sequence similarity with N. ramosa Soe1T (98.7%) and N. persephonica G6M-30T (97.2%), and values lower than 96.5% with the other type strains. The new isolate was observed to grow aerobically in 0-1.5% (w/v) NaCl (optimum 0%), at pH 7.0-9.0 (optimum pH 7.0) and temperature 15-36 °C (optimum 20-30 °C) on R2A medium. DNA-DNA relatedness values between strain Seoho-38T and the type strains of reference species in the genus Nevskia were < 24%. The genomic DNA G + C content was determined to be 67.4 mol%. Ubiquinone-8 (Q-8) (95%) and ubiquinone-7 (Q-7) (5%) were identified as the respiratory quinones. The cellular polar lipids were identified as diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, a phosphoaminolipid, two glycolipids, an aminolipid and four unidentified lipids. The major fatty acid components were found to include summed feature 3 (C16:1ω7c and/or C16:1ω6c), summed feature 8 (C18:0ω7c and/or C18:0ω6c), C16:0 and C14:0. Based on the above polyphasic evidence, strain Seoho-38T (= KCTC 52221T = JCM 31888T) represents a new species of the genus Nevskia, for which the name Nevskia lacus sp. nov. is proposed.

Description of Hymenobacter daejeonensis sp. nov., isolated from grass soil, based on multilocus sequence analysis of the 16S rRNA gene, gyrB and tuf genes.

A polyphasic taxonomic study was carried out on strains PB105T and PB108 isolated from a grass soil in Korea. The cells of the strains were Gram-stain negative, non-spore-forming, non-motile, and rod-shaped. Comparative 16S rRNA gene sequence studies showed a clear affiliation of these strains with Bacteroidetes, which showed high pairwise sequence similarities with Hymenobacter algoricola VUG-A23aT (99.2%), Hymenobacter fastidiosus VUG-A124aT (97.4%), and Hymenobacter daecheongensis Dae14T (96.9%). The phylogenetic analysis based on 16S rRNA gene sequences showed that the strains formed a clear phylogenetic lineage with the genus Hymenobacter. The major fatty acids were identified as C15:0 iso, C15:0 anteiso, C16:1 ω5c, C15:0 iso 3-OH, C17:0 iso 3-OH, summed feature 3 (C16:1 ω6c and/or C16:1 ω7c/t), and summed feature 4 (C17:1 anteiso B and/or C17:1 iso I). The major cellular polar lipids were identified as phosphatidylethanolamine, an unidentified aminolipid, and two unidentified lipids. The respiratory quinone was identified as MK-7 and the genomic DNA G+C content was determined to be 64.5 mol% for strain PB105T and 64.1 mol% for strain PB108. DNA-DNA hybridization value of type strain PB105T with H. algoricola VUG-A23aT was 32.3% (reciprocal 39.2). Based on the combined genotypic and phenotypic data, we propose that strains PB105T and PB108 represent a novel species of the genus Hymenobacter, for which the name Hymenobacter daejeonensis sp. nov. is proposed. The type strain is PB105T (= KCTC 52579T = JCM 31885T).

Silanimonas algicola sp. nov., isolated from laboratory culture of a bloom-forming cyanobacterium, Microcystis.

A Gram-stain-negative, aerobic, rod-shaped and motile bacterium, designated M23T, was isolated from a laboratory culture of a bloom-forming cyanobacterium, Microcystis, which was isolated from a eutrophic lake in Korea. The strain grew optimally without NaCl and at 25-30 °C on R2A agar medium. Phylogenetic analysis based on 16S rRNA gene sequences positioned the novel strain among the genus Silanimonas, with the highest similarity to Silanimonas lenta DSM 16282T (98.5 %). DNA-DNA relatedness between strain M23T and the closely related species in the genus Silanimonas was <30 %. Strain M23T contained iso-C15 : 0, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and iso-C16 : 0 as major fatty acids and ubiquinone-8 (Q-8) as the major quinone. Strain M23T contained diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylmethylethanolamine as major polar lipids. The DNA G+C content of strain M23T was 69.6 mol%. On the basis of the genotypic, chemotaxonomic and phenotypic data, strain M23T represents a novel species in the genus Silanimonas, for which the name Silanimonas algicola sp. nov. is proposed. The type strain is M23T (=KCTC 52219T=JCM 31889T).

Reyranella aquatilis sp. nov., an alphaproteobacterium isolated from a eutrophic lake.

A novel Gram-stain-negative, rod-shaped and non-motile bacterial strain, designated strain Seoho-37T, was isolated from a eutrophic lake in South Korea. Polyphasic studies were performed to investigate the taxonomic position of the new isolate. The isolate grew aerobically with 0-1.0 % (w/v) NaCl (optimum 0 %), at pH 6.0-10.0 (optimum pH 7.0-9.0) and at temperatures of 15-36 °C (optimum 25-30 °C) on R2A medium. In the phylogenetic analysis of 16S rRNA gene sequences, strain Seoho-37T formed a clear cluster with the strains of Reyranella graminifolii, Reyranella massiliensis and Reyranella soli with a bootstrap resampling value of 100 %. DNA-DNA relatedness between strain Seoho-37T and the type strains of each species in the genus Reyranella was <20 %. The genomic DNA G+C content of strain Seoho-37T was 66.5 mol%. Ubiquinone-10 (Q-10) and ubiquinone-9 (Q-9) were found as the respiratory quinones. The cellular polar lipids were identified as diphosphatidylglycerol, phosphatidylglycerol and phosphatidylmethylethanolamine. The major fatty acid components included C16 : 0, summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and C18 : 1 2-OH. Based on the above evidence from a polyphasic study, strain Seaho-37T represents a novel species of the genus Reyranella, for which the name Reyranella aquatilis sp. nov. is proposed. The type strain is Seoho-37T (=KCTC 52223T=JCM 31892T).

Asprobacter aquaticus gen. nov., sp. nov., a prosthecate alphaproteobacterium isolated from fresh water.

A novel Gram-negative bacterium strain, DRW22-8T, was isolated from fresh water taken at a depth of 22 m at Daechung Reservoir, Republic of Korea. The cells of strain DRW22-8T were aerobic and motile with a single polar flagellum or non-motile (stalked), and formed creamy-white colonies on R2A agar. The phylogenetic analysis based on 16S rRNA gene sequencing indicated that the strain formed a separate lineage within the order Rhodobacterales, showing similarity values under 91.8 % with its closest phylogenetic neighbours, Hirschia litorea, Hirschia baltica and Hirschia maritima. The chemotaxonomic results showed Q-10 as the predominant respiratory ubiquinone, three unidentified glycolipids, an unidentified lipid and phosphatidylglycerol as the major polar lipids, and C16 : 0, 11-methyl C18 : 1, C18 : 1 ω7c and/or C18 : 1 ω6c as the major fatty acids. The DNA G+C content was 64.4 mol%. The combined genotypic and phenotypic data showed that strain DRW22-8T could be distinguished from all genera within the family Hyphomonadaceae and represented a novel genus, Asprobacter gen. nov., with the name Asprobacter aquaticus sp. nov., in the family Hyphomonadaceae. The type strain is DRW22-8T (=KCTC 42356T=JCM 30469T).

Actinotalea caeni sp. nov., isolated from a sludge sample of a biofilm reactor.

A polyphasic taxonomic study was carried out on strain EBR-4-2T isolated from a biofilm reactor in Korea. Cells of the strain were Gram-stain-positive, non-spore-forming, non-motile and rod-shaped. Comparative 16S rRNA gene sequence studies showed the clear affiliation of this strain to the Actinobacteria, and it had the highest pairwise sequence similarities with Actinotalea suaedae EGI 60002T (98.7 %), Actinotalea ferrariae CF5-4T (96.3 %) and Actinotalea fermentans DSM 3133T (96.2 %). Phylogenetic analysis based on the 16S rRNA gene sequences showed that the strain formed a clear phylogenetic lineage with the genus Actinotalea. The major fatty acids were identified as C15 : 0 anteiso, C16 : 0, C16 : 0 N alcohol, C15 : 1 anteiso A and C15 : 0 iso. The major cellular polar lipids were diphosphatidylglycerol, phosphatidylinositol mannoside, phosphatidylinositol and glycolipid. The peptidoglycan type was A4ß containing l-Orn-d-Glu. The whole-cell-wall sugars were glucose and ribose. The respiratory quinone was identified as menaquinone MK-10(H4), and the genomic DNA G+C content was determined to be 74.8 mol %. Based on evidence from this polyphasic study, it is proposed that strain EBR-4-2T should be designated as representing a novel species named Actinotalea caeni sp. nov. The type stain is EBR-4-2T (=KCTC 33604T=JCM 30447T).

Blastomonas fulva sp. nov., aerobic photosynthetic bacteria isolated from a Microcystis culture.

Two Gram-stain-negative, aerobic, non-motile, non-spore-forming and rod-shaped bacteria, designated strains T2T and T5, were isolated from a culture of Microcystis from Daejeon, Republic of Korea. Comparative 16S rRNA gene sequence studies placed the new isolates in the class Alphaproteobacteria and, notably, most closely related to Blastomonasaquatica PE 4-5T, Blastomonas natatoria DSM 3183T and Blastomonas ursincola KR-99T showing 99.4 %, 98.2 % and 97.9 % 16S rRNA gene sequence similarities, respectively. The two novel strains shared 100 % similarity with each other. The cells of strains T2T and T5 formed yellow colonies on R2A agar and contained Q-10 as the only ubiquinone, sphingoglycolipid, phosphatidylethanolamine, phosphatidylcholine, and phosphatidylglycerol as major polar lipids, and C17 : 1ω6c, summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), C17 : 1ω8c and C17 : 0 as the major fatty acids (>5 %). The DNA G+C content of the genomes was determined to be 64.2 mol% for strain T2T and 64.4 mol% for strain T5. The DNA-DNA hybridization values of strains T2T and T5 with B.aquatica PE 4-5T, B. natatoria DSM 3183T, and B. ursincola KR-99T were 19.7-42.4 %. Based on the combined genotypic and phenotypic data, we propose that strains T2T and T5 represent a novel species of the genus Blastomonas, for which the name Blastomonas fulvasp. nov. is proposed. The type strain is T2T (=KCTC 42354T=JCM 30467T).

Acidovorax lacteus sp. nov., isolated from a culture of a bloom-forming cyanobacterium (Microcystis sp.).

A novel Gram-negative, rod-shaped and motile bacterial strain, designated strain M36T, was isolated from a culture of a bloom-forming cyanobacterium, Microcystis sp., collected from a eutrophic lake in Korea. Its taxonomic position was investigated by using a polyphasic taxonomic approach. The isolate was found to grow aerobically at 15-42 °C (optimum 25 °C), pH 7.0-11.0 (optimum pH 8.0) and in the presence of 0-1.0% (w/v) NaCl (optimum 0% NaCl) on R2A medium. The phylogenetic analysis based on 16S rRNA gene sequences revealed that the strain M36T is closely related to Acidovorax anthurii DSM 16745T (98.1%), Acidovorax konjaci DSM 7481T (97.7%) and Acidovorax avenae DSM 7227T (97.0%) and also formed a clear phylogenetic lineage with other Acidovorax species. DNA-DNA relatedness between strain M36T and the closely related species of the genus Acidovorax was <30%. The major fatty acid components identified included summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), C16:0 and summed feature 8 (C18:0 ω7c and/or C18:0 ω6c). The DNA G+C content of strain M36T was determined to be 66.8 mol%. Based on above polyphasic evidence, strain M36T is concluded to represent a new species of genus Acidovorax, for which the name Acidovorax lacteus sp. nov. is proposed. The type strain is M36T (=KCTC 52220T = JCM 31890T).