Highest 16S rRNA Gene Similarity Research Articles

Exploring Biocontrol Agents From Microbial Keystone Taxa Associated to Suppressive Soil: A New Attempt for a Biocontrol Strategy.

Recent studies have observed differing microbiomes between disease-suppressive and disease-conducive soils. However, it remains unclear whether the microbial keystone taxa in suppressive soil are critical for the suppression of diseases. Bacterial wilt is a common soil-borne disease caused by Ralstonia solanacearum that affects tobacco plants. In this study, two contrasting tobacco fields with bacterial wilt disease incidences of 0% (disease suppressive) and 100% (disease conducive) were observed. Through amplicon sequencing, as expected, a high abundance of Ralstonia was found in the disease-conducive soil, while large amounts of potential beneficial bacteria were found in the disease-suppressive soil. In the fungal community, an abundance of the Fusarium genus, which contains species that cause Fusarium wilt, showed a positive correlation (p < 0.001) with the abundance of Ralstonia. Network analysis revealed that the healthy plants had more complex bacterial networks than the diseased plants. A total of 9 and 13 bacterial keystone taxa were identified from the disease-suppressive soil and healthy root, respectively. Accumulated abundance of these bacterial keystones showed a negative correlation (p < 0.001) with the abundance of Ralstonia. To complement network analysis, culturable strains were isolated, and three species belonging to Pseudomonas showed high 16S rRNA gene similarity (98.4–100%) with keystone taxa. These strains displayed strong inhibition on pathogens and reduced the incidence of bacterial wilt disease in greenhouse condition. This study highlighted the importance of keystone species in the protection of crops against pathogen infection and proposed an approach to obtain beneficial bacteria through identifying keystone species, avoiding large-scale bacterial isolation and cultivation.

Hymenobacter busanensis sp. nov., radiation-resistant species isolated from soil in South Korea.

Two bacterial strains designated as MA3T and BT182 were isolated from a soil sample in South Korea. Cells of the two strains were Gram-stain-negative, non-motile, rod-shaped and formed red colonies on R2A agar at 25°C. The 16S rRNA genes of the two strains shared a sequence similarity of 99.8%. Both strains shared the highest 16S rRNA gene similarity of 96.8% with Hymenobacter edaphi NLT, followed by Hymenobacter paludis KBP-30T (96.3%), Hymenobacter coalescens WW84T (96.3%) and Hymenobacter gummosus ANT-18T (96.3%). Growth was observed at 15-37°C (optimum 30°C), pH 6-8 (optimum pH 7) and in the presence up to 1% NaCl. The genome size of strains MA3T and BT182 is 4.9Mb and 4.8Mb, respectively. The genomic G + C content of both strains is 62.0mol%. The main polar lipid of the strains was phosphatidylethanolamine, the only respiratory quinone detected was menaquinone-7 and the major fatty acids were anteiso-C15:0, iso-C15:0, summed feature 4 (iso-C17:1 I/anteiso-C17:1 B) and summed feature 3 (C16:1 ω6c/C16:1 ω7c), supporting the affiliation of these strains with the genus Hymenobacter. Based on the phylogenetic, genotypic, phenotypic and chemotaxonomic data, strains MA3T and BT182 represent a novel species of the genus Hymenobacter, for which the name Hymenobacter busanensis is proposed. The type strain is MA3T (= KCTC 72631T = NBRC 114193T).

Nocardia aurantiaca sp. nov., isolated from soil in Thailand.

A novel actinomycete strain, CT2-14T, belonging to the genus Nocardia, was isolated from a soil sample collected from Phichit Province, Thailand. The taxonomic position of the strain was characterized using a polyphasic approach. The strain grew at 15-40 °C (optimum, 28-37 °C), pH 6-11 (optimum, pH 6-8) and on an International Streptomyces Project 2 with 4 % (w/v) NaCl agar plate. Meso-diaminopimelic acid was detected in the cell-wall peptidoglycan. Ribose, arabinose and galactose were detected in its whole-cell hydrolysates. Mycolic acids were present. The strain contained C16 : 0, summed feature 3, C17 : 0 10-methyl and C18 : 1 ω9c as the major fatty acids and MK-8(H4ω-cycl) as the major menaquinone. The major polar lipids were phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylinositol mannosides. Strain CT2-14T showed the highest 16S rRNA gene similarity to Nocardia veterana JCM 11307T (98.4 %), Nocardia africana JCM 11438T (98.2 %) and Nocardia kruczakiae JCM 13032T (98.0 %). The draft genome of strain CT2-14T was 7.37 Mb with 6685 coding sequences with an average G+C content of 67.9 mol %. Based on the phylogenomic tree analysis, the strain was closely related to Nocardia niigatensis NBRC 100131T. On the basis of polyphasic and genome analyses, strain CT2-14T represented a novel species of the genus Nocardia for which the name Nocardia aurantiaca sp. nov. is proposed. The type strain is CT2-14T (=JCM 33775T=TISTR 2838T).

Sunxiuqinia indica sp. nov., isolated from deep sea.

A Gram-stain-negative, facultative anaerobic, red-pigmented, rod-shaped and non-motile strain (RC1_OXG_1FT) was isolated from deep sea water of the Indian Ocean. It was able to grow at pH 5-8 (optimum, pH 7), at 5-37 °C (optimum, 30 °C), and at salinity (% NaCl, w/v) of 0.5-5 % (optimum, 1-2 %). Catalase- and oxidase-positive. It had highest 16S rRNA gene similarity (96.7 %) to 'Sunxiuqinia dokdonensis' DH1T, followed by Sunxiuqinia faeciviva JAM-BA0302T (96.6 %), Sunxiuqinia elliptica CGMCC 1.9156T (96.2 %), Sunxiuqinia rutila HG677T (96.0 %) and species (less than 92.3 %) of other genera. It belongs to the genus Sunxiuqinia within the phylum Bacteroidetes, based on the phylogenetic analysis. The results of digital DNA-DNA hybridization and average nucleotide identity analyses indicated that the strain belonged to a novel species. Its genome size is 5,250, 885 bp, with DNA G+C content of 40.5 mol%. Genome analysis revealed that the strain possessed many genes involved in polysaccharide degradation, especially hemicellulose degradation, indicating that the strain could maintain its normal metabolism by using recalcitrant organic matter in the oligotrophic deep sea environment. Its principal fatty acids were anteiso-C15 : 0 and iso-C15 : 0 and the major polar lipids were phosphatidylethanolamine, two unidentified glycolipids, three unidentified phospholipids and two unidentified polar lipids. The isoprenoid quinone was MK-7. Based on the phenotypic, chemotaxonomic and genotypic data, the strain represents a novel species within the genus Sunxiuqinia, for which the name Sunxiuqinia indica sp. nov. is proposed. The type strain is RC1_OXG_1FT (=MCCC 1A13858T=KCTC 62805T).

Pusillimonas maritima sp. nov., isolated from surface seawater

Two Gram-stain-negative, short rod-shaped and non-flagellated strains, designated 17-4AT and L52-1-41, were isolated from the surface seawater of the Indian Ocean and South China Sea, respectively. The 16S rRNA genes of the two strains shared sequence similarity of 99.45 %. Strain 17-4AT shared the highest 16S rRNA gene similarity of 98.02 % with Pusillimonas caeni EBR-8-1T, followed by Pusillimonas noertemannii BN9T (97.47 %), Pusillimonas soli MJ07T (96.93 %), Parapusillimonas granuli Ch07T (96.68 %), Pusillimonas ginsengisoli DCY25T (96.65 %), Eoetvoesia caeni PB3-7BT (96.63 %), Paracandidimonas caeni 24T (96.34 %), Castellaniella defragrans 54PinT (96.28 %) and Pusillimonas harenae B201T (96.05 %). L52-1-41 shared the highest 16S rRNA gene similarity of 97.74 % with Pusillimonas caeni EBR-8-1T, followed by Pusillimonas noertemannii BN9T (97.47 %), Pusillimonas soli MJ07T (96.65 %), Parapusillimonas granuli Ch07T (96.41 %), Pusillimonas ginsengisoli DCY25T (96.37 %), Eoetvoesia caeni PB3-7BT (96.35 %), Pusillimonas harenae B201T (96.28 %), and Paracandidimonas caeni 24T (96.06 %). The results of phylogenetic analyses indicated that 17-4AT and L52-1-41 formed a stable, distinct and highly supported lineage affiliated to the genus Pusillimonas. The results of the digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) analyses indicated that they represented a single species. They featured similar genomic DNA G+C contents of 53.2-53.4 mol%. Activities of catalase and oxidase were negative for both strains. The fatty acids patterns of 17-4AT and L52-1-41 were most similar, mostly comprised of C16 : 0, C17 : 0cyclo, C18 : 0, C18 : 1ω9c and summed feature 8 (C18 : 1ω7c and/or C18 : 1 ω6c). The major polar lipids of the two strains were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and unidentified aminolipids. The respiratory quinone of the two strains was Q-8. Hence, on the basis of the phenotypic, chemotaxonomic and genotypic data presented in this study, we proposed the classification of both strains as representatives of a novel species named Pusillimonas maritima sp. nov., with the type strain 17-4AT (=MCCC 1A12670T=KCTC 62121T=NBRC 113794T), and another strain L52-1-41 (=MCCC 1A05046=KCTC 52313).

Lacipirellula parvula gen. nov., sp. nov., representing a lineage of planctomycetes widespread in low-oxygen habitats, description of the family Lacipirellulaceae fam. nov. and proposal of the orders Pirellulales ord. nov., Gemmatales ord. nov. and Isosphaerales ord. nov.

Pirellula-like planctomycetes are ubiquitous aquatic bacteria, which are often detected in anoxic or micro-oxic habitats. By contrast, the taxonomically described representatives of these bacteria, with very few exceptions, are strict aerobes. Here, we report the isolation and characterization of the facultatively anaerobic planctomycete, strain PX69T, which was isolated from a boreal lake. Its 16S rRNA gene sequence is affiliated with the Pirellula-related Pir4 clade, which is dominated by environmental sequences retrieved from a variety of low-oxygen habitats. Strain PX69T was represented by ellipsoidal cells that multiplied by budding and grew on sugars, some polysaccharides and glycerol. Anaerobic growth occurred by means of fermentation. Strain PX69T grew at pH 5.5–7.5 and at temperatures between 10 and 30°C. The major fatty acids were C18:1ω9c, C16:0 and C16:1ω7c; the major intact polar lipid was dimethylphosphatidylethanolamine. The complete genome of strain PX69T was 6.92Mb in size; DNA G+C content was 61.7mol%. Among characterized planctomycetes, the highest 16S rRNA gene similarity (90.4%) was observed with ‘Bythopirellula goksoyri’ Pr1d, a planctomycete from deep-sea sediments. We propose to classify PX69T as a novel genus and species, Lacipirellula parvula gen. nov., sp. nov.; the type strain is strain PX69T (=KCTC 72398T=CECT 9826T=VKM B-3335T). This genus is placed in a novel family, Lacipirellulaceae fam. nov., which belongs to the order Pirellulales ord. nov. Based on the results of comparative genome analysis, we also suggest establishment of the orders Gemmatales ord. nov. and Isosphaerales ord. nov. as well as an emendation of the order Planctomycetales.

An "olivomycin A" derivative from a sponge-associated Streptomyces sp. strain SP 85.

We isolated an actinobacterium, Streptomyces sp. strain SP 85 from the marine sponge Dysidea avara. Polyphasic identification of the microorganism showed that the strain SP 85 had high 16S rRNA gene similarity (99%) with Streptomyces olivaceus strain NBRC 12805, while some physiological and biochemical differences were observed. A cytotoxic compound, SP 85 was isolated from the active culture extract of the strain SP 85 by bioassay-guided purification over silica gel column chromatography, preparative TLC, and HPLC. The structure elucidation based on the spectroscopic analysis, including UV, ESI-MS, and 13C NMR data revealed that SP 85 compound is an analog of anti-tumor drug, "olivomycin A". The SP 85 compound showed high cytotoxic activity against three human cancer cell lines, including SW480, HepG2, and MCF7 with IC50 values of 16, 93, and 78nM, respectively. SP 85 exhibited significantly (2-10 times) higher cytotoxicity against the tumor cell lines in comparison with HUVECs as the normal cell line, which also induced apoptosis in the tested cancerous cell line. This is the first report on the production of an "olivomycin A" derivative by a sponge-associated Streptomyces, showing the great potential of sponge-associated actinobacteria in producing cytotoxic natural products.

Histidinibacterium lentulum gen. nov., sp. nov., a marine bacterium from the culture broth of marine microalga Picochlorum sp. 122.

A Gram-stain-negative, non-spore-forming, aerobic, motile, ovoid or short rod shaped bacterium, designed strain B17T, was isolated from the culture broth of Picochlorum sp. 122. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain B17T forms a stable cluster with Oceanicolagranulosus MCCC 1A10589T (with the highest 16S rRNA gene similarity of 95.8 %) and Roseisalinusantarcticus DSM 11466T in the family Rhodobacteraceae. The only detected respiratory quinone was Q-10. The major cellular fatty acids were C18 : 1 ω7c/ω6c, C17 : 1iso I/anteiso B and C16 : 0. The major polar lipids were phosphatidylglycerol, diphosphatidylglycerol, an unidentified phospholipid and two unidentified lipids. The genome G+C content was 69 mol%. Characteristics, such as a long lag phase, being motile with single polar flagellum, no aminolipid content, and little or no C18 : 1ω7c11-methyl and C19 : 0cyclo ω8c content could significantly distinguish strain B17T from its closely related type strains. Therefore strain B17T is suggested to represent a new species in a new genus, for which Histidinibacterium lentulum gen. nov., sp. nov. is proposed. The type strain B17T (=MCCC 1K03225T=KCTC 52553T).

Chryseolinea flava sp. nov., a new species of Chryseolinea isolated from soil.

A pale yellow bacterial strain, designated SDU1-6T, was isolated from a soil sample collected in the Jinan campus of Shandong University, Shandong Province, PR China. The strain was aerobic, motile, Gram-stain-negative and rod-shaped. Cellular growth occurred at 13-37 °C, pH 5.0-10.0 and with 0-0.1 % (w/v) NaCl, and the optimal growth was at 25 °C and pH 7.5. SDU1-6T had the highest 16S rRNA gene similarity of 95.42 % with Chryseolinea serpens DSM 24574T. The genome was 6 542 746 bp in length with 43.5 mol% DNA G+C content. The major fatty acids of SDU1-6T were C16 : 1ω5 and iso-C15 : 0, the major menaquinone was menaquinone-7 (MK-7) and the major polar lipid was phosphatidylethanolamine. On the basis of the polyphasic evidence and the 16S rRNA gene sequence, SDU1-6T represents a novel species of the genus Chryseolinea, for which the name Chryseolineaflava sp. nov. is proposed. The type strain is SDU1-6T (=CGMCC 1.13492T=JCM 32520T).

Metabolism of Toxic Sugars by Strains of the Bee Gut Symbiont Gilliamella apicola.

ABSTRACTSocial bees collect carbohydrate-rich food to support their colonies, and yet, certain carbohydrates present in their diet or produced through the breakdown of pollen are toxic to bees. The gut microbiota of social bees is dominated by a few core bacterial species, including the Gram-negative species Gilliamella apicola. We isolated 42 strains of G. apicola from guts of honey bees and bumble bees and sequenced their genomes. All of the G. apicola strains share high 16S rRNA gene similarity, but they vary extensively in gene repertoires related to carbohydrate metabolism. Predicted abilities to utilize different sugars were verified experimentally. Some strains can utilize mannose, arabinose, xylose, or rhamnose (monosaccharides that can cause toxicity in bees) as their sole carbon and energy source. All of the G. apicola strains possess a manO-associated mannose family phosphotransferase system; phylogenetic analyses suggest that this was acquired from Firmicutes through horizontal gene transfer. The metabolism of mannose is specifically dependent on the presence of mannose-6-phosphate isomerase (MPI). Neither growth rates nor the utilization of glucose and fructose are affected in the presence of mannose when the gene encoding MPI is absent from the genome, suggesting that mannose is not taken up by G. apicola strains which harbor the phosphotransferase system but do not encode the MPI. Given their ability to simultaneously utilize glucose, fructose, and mannose, as well as the ability of many strains to break down other potentially toxic carbohydrates, G. apicola bacteria may have key roles in improving dietary tolerances and maintaining the health of their bee hosts.

Mariprofundus micogutta sp. nov., a novel iron-oxidizing zetaproteobacterium isolated from a deep-sea hydrothermal field at the Bayonnaise knoll of the Izu-Ogasawara arc, and a description of Mariprofundales ord. nov. and Zetaproteobacteria classis nov.

A novel iron-oxidizing chemolithoautotrophic bacterium, strain ET2T, was isolated from a deep-sea sediment in a hydrothermal field of the Bayonnaise knoll of the Izu-Ogasawara arc. Cells were bean-shaped, curved short rods. Growth was observed at a temperature range of 15-30°C (optimum 25°C, doubling time 24h) and a pH range of 5.8-7.0 (optimum pH 6.4) in the presence of NaCl at a range of 1.0-4.0% (optimum 2.75%). The isolate was a microaerophilic, strict chemolithoautotroph capable of growing using ferrous iron and molecular oxygen (O2) as the sole electron donor and acceptor, respectively; carbon dioxide as the sole carbon source; and either ammonium or nitrate as the sole nitrogen source. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that the new isolate was related to the only previously isolated Mariprofundus species, M. ferrooxydans. Although relatively high 16S rRNA gene similarity (95%) was found between the new isolate and M. ferrooxydans, the isolate was distinct in terms of cellular fatty acid composition, genomic DNA G+C content and cell morphology. Furthermore, genomic comparison between ET2T and M. ferrooxydans PV-1 indicated that the genomic dissimilarity of these strains met the standard for species-level differentiation. On the basis of its physiological and molecular characteristics, strain ET2T (=KCTC 15556T=JCM 30585 T) represents a novel species of Mariprofundus, for which the name Mariprofundus micogutta is proposed. We also propose the subordinate taxa Mariprofundales ord. nov. and Zetaproteobacteria classis nov. in the phylum Proteobacteria.

Corynebacterium guangdongense sp. nov., isolated from a contaminated plate

A novel Gram-reaction-positive, non-motile and facultatively anaerobic bacterium, designated strain S01T, was isolated from a nutrient agar plate kept on a laboratory clean bench at Guangdong Institute of Microbiology, PR China, which was contaminated from an unknown source. Strain S01T was found to be catalase-positive and oxidase-negative. Similarity searches revealed that the strain shared the highest 16S rRNA gene similarity with Corynebacterium humireducens MFC-5T (95.9 %). However, phylogenetic analysis based on the 16S rRNA gene sequences showed that strain S01T was closely related to Corynebacteriumdoosanense JCM 17317T (94.8 %) and Corynebacterium maris JCM 17018T (94.8 %). The major fatty acids were C18:1ω9c, C16:0, 10-methyl C18:0 and C18:0. The respiratory quinones predominantly consisted of MK-8(H2), with small amounts of MK-8 and MK-9(H2). Polar lipids contained phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, an unidentified aminolipid, two unidentified glycolipids and two unidentified lipids. Mycolic acids were present. The cell-wall peptidoglycan contained meso-diaminopimelic acid and the major cell-wall sugars were galactose, arabinose and glucose. The genomic DNA G+C content of strain S01T was 70.7±0.1 mol%. The results of phenotypic, phylogenetic and chemotaxonomic analyses indicated that strain S01T represents a novel species of the genus Corynebacterium, for which the name Corynebacterium guangdongense sp. nov. is proposed. The type strain is S01T (=GDMCC 1.1022T=CCTCC AB 2015423T=KCTC 39608T).

Paracoccus angustae sp. nov., isolated from soil.

A Gram-stain-negative, coccus-shaped, aerobic bacterium, strain E6T, was isolated from soil. 16S rRNA gene sequence analysis revealed a cluster containing strain E6T and Paracoccus sediminis CMB17T (the highest 16S rRNA gene similarity of 97.2 %). The other strains investigated showed 16S rRNA gene sequence similarities of less than 97 % to strain E6T. The DNA–DNA relatedness between strain E6T and P. sediminis DSM 26170T was 59.2 %. Strain E6T also shows some differences compared with other Paracoccus strains such as motility and inability to utilize lactate and propionate as sole carbon sources. The major fatty acids of strain E6T were C18 : 1ω7c and C18 : 0 and ubiquinone-10 was the only respiratory quinone. Strain E6T had diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, an unknown aminolipid and an unknown glycolipid as major polar lipids. The genomic DNA G+C content was 68.1 mol%. On the basis of phenotypic and genotypic characteristics, strain E6T is concluded to represent a novel species of the genus Paracoccus, for which the name Paracoccus angustae sp. nov. is proposed. The type strain is E6T ( = KCTC 42473T = CCTCC AB 2015056T).

Overall functional gene diversity of microbial communities in three full-scale activated sludge bioreactors.

Understanding microbial community composition is thought to be crucial for improving process functioning and stabilities of full-scale activated sludge reactors in wastewater treatment plants (WWTPs). However, functional gene compositions of microbial communities within them have not been clearly elucidated. To gain a complete picture of microbial community, in this study, GeoChip 4.2 was used to profile the overall functional genes of three full-scale activated sludge bioreactors, the 16S rRNA gene diversities of which had been unveiled by 454-pyrosequencing in our previous investigation. Triplicate activated sludge samples from each system were analyzed, with the detection of 38,507 to 40,654 functional genes. A high similarity of 77.3-81.2% shared functional genes was noted among the nine samples, verified by the high 16S rRNA gene similarity with shared operational taxonomic units (OTUs) constituting 66.4-70.0% of the detected sequences in each system. Correlation analyses showed that the abundances of a wide array of functional genes were associated with system performances. For example, the abundances of carbon degradation genes were strongly correlated to chemical oxygen demand (COD) removal efficiencies (r = 0.8697, P < 0.01). Lastly, we found that sludge retention time (SRT), influent total nitrogen concentrations (TN inf), and dissolved oxygen (DO) concentrations were key environmental factors shaping the overall functional genes. Together, the results revealed vast functional gene diversity and some links between the functional gene compositions and microbe-mediated processes.

Methylobacterium haplocladii sp. nov. and Methylobacterium brachythecii sp. nov., isolated from bryophytes

Pink-pigmented, facultatively methylotrophic bacteria, strains 87e(T) and 99b(T), were isolated from the bryophytes Haplocladium microphyllum and Brachythecium plumosum, respectively. The cells of both strains were Gram-reaction-negative, motile, non-spore-forming rods. On the basis of 16S rRNA gene sequence similarity, strains 87e(T) and 99b(T) were found to be related to Methylobacterium organophilum ATCC 27886(T) (97.1% and 97.7%, respectively). Strains 87e(T) and 99b(T) showed highest 16S rRNA gene similarity to Methylobacterium gnaphalii 23e(T) (98.3 and 99.0%, respectively). The phylogenetic similarities to all other species of the genus Methylobacterium with validly published names were less than 97%. Major cellular fatty acids of both strains were C(18:1)ω7c and C(18:0). The results of DNA-DNA hybridization, phylogenetic analyses based on 16S rRNA and cpn60 gene sequences, fatty acid profiles, whole-cell matrix-assisted, laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) analysis, and physiological and biochemical tests allowed genotypic and phenotypic differentiation of strains 87e(T) and 99b(T) from their phylogenetically closest relatives. We propose that strains 87e(T) and 99b(T) represent novel species within the genus Methylobacterium, for which the names Methylobacterium haplocladii sp. nov. (type strain 87e(T) =DSM 24195(T) =NBRC 107714(T)) and Methylobacterium brachythecii sp. nov. (type strain 99b(T) =DSM 24105(T) =NBRC 107710(T)) are proposed.

Classification of organisms previously reported as the SP and Stewart–Letscher groups, with descriptions of Necropsobacter gen. nov. and of Necropsobacter rosorum sp. nov. for organisms of the SP group

To allow classification of bacteria previously reported as the SP group and the Stewart-Letscher group, 35 isolates from rodents (21), rabbits (eight), a dog and humans (five) were phenotypically and genotypically characterized. Comparison of partial rpoB sequences showed that 34 of the isolates were closely related, demonstrating at least 97.4 % similarity. 16S rRNA gene sequence comparison of 20 selected isolates confirmed the monophyly of the SP group and revealed 98.5 %-100 % similarity between isolates. A blast search using the 16S rRNA gene sequences showed that the highest similarity outside the SP group was 95.5 % to an unclassified rat isolate. The single strain, P625, representing the Stewart-Letscher group showed the highest 16S rRNA gene similarity (94.9-95.5 %) to members of the SP group. recN gene sequence analysis of 11 representative strains resulted in similarities of 97-100 % among the SP group strains, which showed 80 % sequence similarity to the Stewart-Letscher group strain. Sequence similarity values based on the recN gene, indicative for whole genome similarity, showed the SP group being clearly separated from established genera, whereas the Stewart-Letscher group strain was associated with the SP group. A new genus, Necropsobacter gen. nov., with only one species, Necropsobacter rosorum sp. nov., is proposed to include all members of the SP group. The new genus can be separated from existing genera of the family Pasteurellaceae by at least three phenotypic characters. The most characteristic properties of the new genus are that haemolysis is not observed on bovine blood agar, positive reactions are observed in the porphyrin test, acid is produced from (+)-L-arabinose, (+)-D-xylose, dulcitol, (+)-D-galactose, (+)-D-mannose, maltose and melibiose, and negative reactions are observed for symbiotic growth, urease, ornithine decarboxylase and indole. Previous publications have documented that both ubiquinones and demethylmenaquinone were produced by the proposed type strain of the new genus, Michel A/76(T), and that the major polyamine of representative strains (type strain not included) of the genus is 1,3-diaminopropane, spermidine is present in moderate amounts and putrescine and spermine are detectable only in minor amounts. The major fatty acids of strain Michel A/76(T) are C(14 : 0), C(16 : 0), C(16:1)ω7c and summed feature C(14 : 0) 3-OH/iso-C(16 : 1) I. This fatty acid profile is typical for members of the family Pasteurellaceae. The G+C content of DNA of strain Michel A/76(T) was estimated to be 52.5 mol% in a previous investigation. The type strain is P709(T) ( = Michel A/76(T) = CCUG 28028(T) = CIP 110147(T) = CCM 7802(T)).

Diversity of cultivable hydrogen-producing bacteria isolated from agricultural soils, waste water sludge and cow dung

This project aimed to study the diversity of cultivable hydrogen-producing bacteria, isolated from agricultural soils, waste water sludge and cow dung by analyzing 16S rRNA gene. Isolation performed anaerobically on nutrient agar using environmental samples as inoculum yielded 106 pure isolates. These isolates were tested for their capability to produce hydrogen. Then 16S rRNA gene of the 11 isolates having such ability were PCR amplified and subjected to restriction fragment length polymorphism (RFLP) analysis in order to group them into operational taxonomic units (OTUs). RFLP was evaluated for its ability to group the 1500–1600 bp PCR products into OTUs. Isolates were presumptively identified by analysis of partial 16S rRNA gene sequence data. Each OTU was found to be phylogenetically cohesive. The 11 isolates were put into 2 main groups. Group 1 composted of WS-2-2, AS_I-1 and AS_I-2 whose partial 16S rRNA genes showed similarity of 98–99% to members of the genus Paenibacillus. Group 2 composted of WS-4-2, Lao-1-2, WS-7-11, AS-1, AS-4, CD-5 and CD-6 having highest similarity of 98–99% to members of four genera in the family Enterobacteriacea. AS_I-2 which produced the highest amount of hydrogen gas of 2.70 ml had the highest 16S rRNA gene similarity of 99% to Paenibacillus polymixa.

Characterization of an O-desmethylangolensin-producing bacterium isolated from human feces

A bacterium that converted daidzein to O-desmethylangolensin was isolated from the feces of healthy humans. It was an obligately anaerobic, nonsporeforming, nonmotile and Gram-positive rod. The isolate used glucose, sucrose, raffinose, maltose, and fructose as carbon sources. It did not hydrolyze gelatin, esculin, or starch. The strain was urease, acid phosphatase, and arginine dihydrolase positive. It was catalase, oxidase, H(2)S, and indole negative. The major products of glucose fermentation were butyrate and lactate. Its mol% G+C was 51.2. The major cellular fatty acids were C(16:0) DMA, C(16:0), and C(16:0) aldehyde. The structural type of cell wall peptidoglycan was suggested to be A1gamma. The isolate was susceptible to beta-lactam, cefem, and macrolide antibiotics and resistant to aminoglycoside and quinolone antibiotics. The bacterium was related to Eubacterium ramulus ATCC29099(T), Eubacterium rectale ATCC33656(T), and species of the genus Roseburia, but the highest 16S rRNA gene similarity to these described species was only 94.4%, consistent with its being classified as a novel genus. Based on the above, the isolate, named strain SY8519, was identified as belonging to a novel genus in the Clostridium rRNA cluster XIVa.

Paenibacillus tundrae sp. nov. and Paenibacillus xylanexedens sp. nov., psychrotolerant, xylan-degrading bacteria from Alaskan tundra

Eight psychrotolerant, xylan-degrading strains of bacteria that were catalase-positive, oxidase-negative and able to reduce nitrate to nitrite were isolated from soil beneath moist non-acidic and acidic tundra in northern Alaska. The DNA G+C contents for the strains ranged from 46.4-50.3 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that each strain belonged to the genus Paenibacillus. The highest level of 16S rRNA gene similarity was found between the eight strains and Paenibacillus amylolyticus NRRL NRS-290(T) (98.9-99.1 %). However, despite relatively high 16S rRNA gene similarity, DNA-DNA hybridization, repetitive elements genotyping and phenotypic analysis revealed that at least two of the strains differed from P. amylolyticus NRRL NRS-290(T). DNA-DNA hybridization values between strain A10b(T) and P. amylolyticus NRRL NRS-290(T) (4.3 %), between strain B22a(T) and P. amylolyticus NRRL NRS-290(T) (48.8 %) and between strain A10b(T) and strain B22a(T) (11.0 %) were below those recommended by the ad hoc committee for those belonging to the same species. Significant phenotypic features that differentiate these novel strains from P. amylolyticus included their inability to utilize l-arabinose and ability to utilize glycogen as sole carbon sources. Unlike strains 1B4a and B22a(T), strains A6a and A10b(T) produced ethanol as an end product of glucose fermentation, utilized acetic acid and 2,3-butanediol and did not utilize d-gluconic acid. MK-7 was the major isoprenoid quinone and anteiso-C(15 : 0) was the most abundant fatty acid for strains A10b(T) and B22a(T). On the basis of these results, strains A10b(T) and B22a(T) are each considered to represent a novel species of the genus Paenibacillus, for which the names Paenibacillus tundrae sp. nov. and Paenibacillus xylanexedens sp. nov. are proposed, respectively. The type strain of Paenibacillus tundrae sp. nov. is A10b(T) (=NRRL B-51094(T)=DSM 21291(T)). The type strain of Paenibacillus xylanexedens sp. nov. is B22a(T) (=NRRL B-51090(T)=DSM 21292(T)).

Mineral and iron oxidation at low temperatures by pure and mixed cultures of acidophilic microorganisms

An enrichment culture from a boreal sulfide mine environment containing a low-grade polymetallic ore was tested in column bioreactors for simulation of low temperature heap leaching. PCR-denaturing gradient gel electrophoresis and 16S rRNA gene sequencing revealed the enrichment culture contained an Acidithiobacillus ferrooxidans strain with high 16S rRNA gene similarity to the psychrotolerant strain SS3 and a mesophilic Leptospirillum ferrooxidans strain. As the mixed culture contained a strain that was within a clade with SS3, we used the SS3 pure culture to compare leaching rates with the At. ferrooxidans type strain in stirred tank reactors for mineral sulfide dissolution at various temperatures. The psychrotolerant strain SS3 catalyzed pyrite, pyrite/arsenopyrite, and chalcopyrite concentrate leaching. The rates were lower at 5 degrees C than at 30 degrees C, despite that all the available iron was in the oxidized form in the presence of At. ferrooxidans SS3. This suggests that although efficient At. ferrooxidans SS3 mediated biological oxidation of ferrous iron occurred, chemical oxidation of the sulfide minerals by ferric iron was rate limiting. In the column reactors, the leaching rates were much less affected by low temperatures than in the stirred tank reactors. A factor for the relatively high rates of mineral oxidation at 7 degrees C is that ferric iron remained in the soluble phase whereas, at 21 degrees C the ferric iron precipitated. Temperature gradient analysis of ferrous iron oxidation by this enrichment culture demonstrated two temperature optima for ferrous iron oxidation and that the mixed culture was capable of ferrous iron oxidation at 5 degrees C.