Selvaraj Poonguzhali

Mucilaginibacter gossypii sp. nov. and Mucilaginibacter gossypiicola sp. nov., plant-growth-promoting bacteria isolated from cotton rhizosphere soils.

Two isolates from rhizosphere soil of cotton, designated Gh-67(T) and Gh-48(T), which produced large amounts of extracellular polysaccharide and possessed plant-growth-promoting traits, were characterized phenotypically and genotypically. The strains were Gram-negative and cells were non-motile rods that grew optimally at 28°C and grew between pH 4 and 7. 16S rRNA gene sequence analysis of strains Gh-67(T) and Gh-48(T) placed them in the genus Mucilaginibacter, with pairwise sequence similarity between them and type strains from related genera ranging from 93.9 to 98.2u200a%. The major fatty acids were iso-C₁₅:₀, C₁₆:₀ and summed feature 3 (C₁₆:₁ω7c and/or iso-C₁₅:₀ 2-OH). The strains contained MK-7 as the major isoprenoid quinone. The DNA G+C contents of strains Gh-67(T) and Gh-48(T) were 46.7 and 44.2 mol%, respectively. The low DNA-DNA hybridization value (18u200a%) and a number of phenotypic differences between strains Gh-48(T) and Gh-67(T) indicated that they represent two separate species. Results of phenotypic, phylogenetic and genotypic analysis revealed that the strains were separated from the species of Mucilaginibacter described to date. Therefore, strains Gh-67(T) and Gh-48(T) represent novel species of Mucilaginibacter, for which we propose the names Mucilaginibacter gossypii sp. nov. (type strain Gh-67(T) =NCIMB 14470(T) =KCTC 22380(T)) and Mucilaginibacter gossypiicola sp. nov. (type strain Gh-48(T) =NCIMB 14471(T) =KCTC 22379(T)).

Enterobacter arachidis sp. nov., a plant-growth-promoting diazotrophic bacterium isolated from rhizosphere soil of groundnut.

A methylotrophic nitrogen-fixing bacterial strain, Ah-143(T), isolated from the rhizosphere soil of field-grown groundnut was analysed by a polyphasic taxonomic approach. Comparative 16S rRNA gene sequence analysis combined with rpoB gene sequence analysis allocated strain Ah-143(T) to the family Enterobacteriaceae, with Enterobacter radicincitans and Enterobacter cowanii as the closest relatives. The strain is Gram-stain-negative, non-spore-forming, aerobic and motile, having straight rod-shaped cells with a DNA G+C content of approximately 53.2 mol%. The strain utilizes methanol as a carbon source and the mxaF gene was closely related to the mxaF gene of members of the genus Methylobacterium. The fatty acid profile consisted of C(16 : 0), C(17 : 0) cyclo, C(18 : 1)omega7c, summed feature 2 (iso-C(16 : 1) I and/or C(14 : 0) 3-OH) and summed feature 3 (iso-C(15 : 0) 2-OH and/or C(16 : 1)omega7c) as the major components. DNA-DNA relatedness of strain Ah-143(T) with its close relatives was less than 20 %. On the basis of the phylogenetic analyses, DNA-DNA hybridization data, and unique physiological and biochemical characteristics, it is proposed that the strain represents a novel species of the genus Enterobacter and should be named Enterobacter arachidis sp. nov. The type strain is Ah-143(T) (=NCIMB 14469(T) =KCTC 22375(T)).

Microbacterium azadirachtae sp. nov., a plant-growth-promoting actinobacterium isolated from the rhizoplane of neem seedlings

Microbacterium strain AI-S262(T) was isolated from the rhizoplane of neem seedlings in the Botanical garden of Tamilnadu Agricultural University, Coimbatore, India, and subjected to phenotypic, chemotaxonomic and genetic characterization. Cells of this strain were Gram-stain-positive, motile, non-spore-forming, short rods and formed light-yellow-pigmented colonies on nutrient agar. Strain AI-S262(T) contained MK-12 and MK-13 as the main respiratory quinones, anteiso-C(15 : 0), anteiso-C(17 : 0) and iso-C(16 : 0) as the predominant fatty acids, peptidoglycan-type B2beta with glycolyl residues, and had a DNA G+C content of 69.5 mol%. A phylogenetic analysis based on 16S rRNA gene sequences showed 98.0-98.6 % pair-wise similarity with respect to close relatives in the genus Microbacterium. DNA-DNA hybridization experiments revealed a low level of DNA-DNA relatedness (less than 39%) between strain AI-S262(T) and its closest relatives. Data from DNA-DNA hybridization and phenotypic analyses supported the conclusion that strain AI-S262(T) represents a novel species in the genus Microbacterium, for which the name Microbacterium azadirachtae sp. nov. is proposed. The type strain is AI-S262(T) (=JCM 15681(T) =LMG 24772(T) =KCTC 19668(T)).

Flavobacterium glycines sp. nov., a facultative methylotroph isolated from the rhizosphere of soybean.

An aerobic, yellow-pigmented, facultatively methylotrophic, Gram-staining-negative, non-spore-forming bacterium, designated strain Gm-149(T), was isolated from the rhizosphere of cultivated soybean in India. Cells were motile by gliding. The predominant cellular fatty acids were iso-C(15 : 0), summed feature 3 (comprising iso-C(15 : 0) 2-OH and/or C(16 : 1) ω 7c), C(16 : 0) 3-OH and anteiso-C(15 : 0), and the major isoprenoid quinone was MK-6. The G+C content of the genomic DNA of strain Gm-149(T) was 35.6 mol%. Comparative 16S rRNA gene sequence analysis showed that strain Gm-149(T) formed a distinct phyletic line within the genus Flavobacterium. Based on levels of pairwise 16S rRNA gene sequence similarity, strain Gm-149(T) was related most closely to the type strain of Flavobacterium daejeonense (97.1 %), but the level of DNA-DNA relatedness between these two strains was about 11.2 %. On the basis of phenotypic and genotypic data, strain Gm-149(T) is considered to represent a novel species of the genus Flavobacterium, for which the name Flavobacterium glycines sp. nov. is proposed. The type strain is Gm-149(T) (=ICMP 17618(T)=NBRC 105008(T)).

Arachidicoccus rhizosphaerae gen. nov., sp. nov., a plant-growth-promoting bacterium in the family Chitinophagaceae isolated from rhizosphere soil

Three novel bacterial strains, designated Vu-144(T), Vu-7 and Vu-35, were isolated on minimal medium from rhizosphere soil of field-grown cowpea and subjected to a taxonomic study using a polyphasic approach. Cells of the strains were Gram-stain-negative, non-motile, non-spore-forming, coccoid rods, and formed non-pigmented colonies. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain Vu-144(T) was affiliated with an uncultivated lineage of the phylum Bacteroidetes. Its closest phylogenetic neighbour was the recently described species Niastella populi, a member of the family Chitinophagaceae, with just 90.7 % sequence similarity to the type strain. The only isoprenoid quinone detected was menaquinone 7 (MK-7). The fatty acid profiles showed large amounts of iso-C15 : 0, iso-C17 : 0 3-OH and iso-C15 : 1 G and minor amounts of summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH), C16 : 0 and other fatty acids, allowing the differentiation of the strains from other genera. The G+C content of the genomic DNA of the three strains ranged from 43.1 to 44.3 mol%. In addition to phosphatidylethanolamine, the major polar lipids were three unidentified aminophospholipids (APL1-APL3), two unidentified phospholipids (PL1, PL2) and three unidentified lipids (UL1-UL3). Biochemical test patterns also differed from those of Niastella populi and members of other genera. All three isolates showed plant-growth-promoting properties, e.g. the ability to produce indole-3-acetic acid and NH3 and to solubilize phosphate, utilized 1-aminocyclopropane 1-carboxylate (ACC) as a sole source of nitrogen and possessed the ACC deaminase enzyme. The novel isolates readily colonized roots and stimulated growth of tomato and cowpea under glasshouse conditions. Inoculated plants showed a 45-60 % increase in dry matter weight with respect to uninoculated controls. On the basis of the evidence from our polyphasic study, isolate Vu-144(T) represents a novel genus and species in the family Chitinophagaceae, for which the name Arachidicoccus rhizosphaerae gen. nov., sp. nov. is proposed. The type strain of Arachidicoccus rhizosphaerae is Vu-144(T) (u200a= KCTC 22378(T)u200a= NCIMB 14473(T)).

Leifsonia soli sp. nov., a yellow-pigmented actinobacterium isolated from teak rhizosphere soil.

Two yellow-pigmented, Gram-stain-positive, aerobic, motile, short rod-shaped bacteria were isolated from natural teak tree rhizosphere soil and their taxonomic positions were determined by using a polyphasic approach. Comparative 16S rRNA gene sequence analysis showed that strains TG-S248(T) and TG-S240 formed a distinct phyletic line within the genus Leifsonia. 16S rRNA gene sequence analysis of strain TG-S248(T) with sequences from Leifsonia shinshuensis DB 102(T), L. poae VKM Ac-1401(T), L. naganoensis DB 103(T), L. aquatica DSM 20146(T) and L. xyli subsp. cynodontis JCM 9733(T) revealed pairwise similarities ranging from 98.7 to 99.1 %. The major fatty acids were anteiso-C(15 : 0), anteiso-C(17 : 0) and iso-C(16 : 0). The G+C content of the DNA of the type strain was 69.4 mol%. DNA-DNA hybridization experiments revealed low levels of DNA-DNA relatedness (32 % or less) between strain TG-S248(T) and its closest relatives. Based on differences in phenotypic and genotypic characteristics, strain TG-S248(T) (=LMG 24767(T) =JCM 15679(T)) is designated the type strain of a novel species of the genus Leifsonia, for which the name Leifsonia soli sp. nov. is proposed.

Methylobacterium pseudosasicola sp. nov. and Methylobacterium phyllostachyos sp. nov., isolated from bamboo leaf surfaces.

Two strains of Gram-negative, methylotrophic bacteria, isolated because of their abilities to promote plant growth, were subjected to a polyphasic taxonomic study. The isolates were strictly aerobic, motile, pink-pigmented, facultatively methylotrophic, non-spore-forming rods. The chemotaxonomic characteristics of the isolates included the presence of C18 : 1ω7c as the major cellular fatty acid. The DNA G+C contents of strains BL36(T) and BL47(T) were 69.4 and 69.8 mol%, respectively. 16S rRNA gene sequence analysis of strains BL36(T) and BL47(T) placed them under the genus Methylobacterium, with the pairwise sequence similarity between them and the type strains of closely related species ranging from 97.2 to 99.0%. On the basis of their phenotypic and phylogenetic distinctiveness and the results of DNA-DNA hybridization analysis, the isolates represent two novel species within the genus Methylobacterium, for which the names Methylobacterium pseudosasicola sp. nov. (type strain BL36(T)u200a= NBRC 105203(T)u200a= ICMP 17621(T)) and Methylobacterium phyllostachyos sp. nov. (type strain BL47(T)u200a= NBRC 105206(T)u200a= ICMP 17619(T)) are proposed.

Duganella sacchari sp. nov. and Duganella radicis sp. nov., two novel species isolated from rhizosphere of field-grown sugar cane.

Two strains, designated Sac-22(T) and Sac-41(T), were isolated from rhizosphere soil and rhizoplane of field-grown sugar cane clone Co86032. Comparative 16S rRNA gene sequence analysis showed a clear affiliation of these two bacteria with the class Betaproteobacteria, their closest relatives being Pseudoduganella violaceinigra and Duganella zoogloeoides with 16S rRNA gene sequence pairwise similarities of 96.4-97.2u200a% to the two novel strains. Strains Sac-22(T) and Sac-41(T) shared a 16S rRNA gene sequence similarity value of 97.6u200a%. Cells of the two strains were Gram-reaction-negative, aerobic, motile and rod-shaped. Ubiquinone (Q-8) was the respiratory quinone and the predominant polar lipids consisted of phosphatidylglycerol and phosphatidylethanolamine. The main cellular fatty acids were C16u200a:u200a0, C16u200a:u200a1ω7c/iso-C15u200a:u200a0 2-OH, C17u200a:u200a0 cyclo, C10u200a:u200a0 3-OH and C12u200a:u200a0. The DNA G+C content of the genomic DNA was 56.4 mol% for strain Sac-22(T) and 54.9 mol% for strain Sac-41(T). Based on the results of 16S rRNA gene sequence analysis and physiological and biochemical characterization, that differentiated strains Sac-22(T) and Sac-41(T) from all recognized species of the genus Duganella, it was concluded that strains represent two novel species in the genus Duganella for which the names Duganella sacchari sp. nov. (type strain Sac-22(T)u200a=u200aKCTC 22381(T)u200a=u200aNCIMB 14475(T)) and Duganella radicis sp. nov. (type strain Sac-41(T)u200a=u200aKCTC 22382(T)u200a=u200aNCIMB 14476(T)) are proposed.

Bacillus rhizosphaerae sp. nov., an novel diazotrophic bacterium isolated from sugarcane rhizosphere soil.

A Gram-positive, non-pigmented, rod-shaped, diazotrophic bacterial strain, designated SC-N012T, was isolated from rhizosphere soil of sugarcane and was subjected to a polyphasic taxonomic study. The strain exhibited phenotypic properties that included chemotaxonomic characteristics consistent with its classification in the genus Bacillus. Sequence analysis of the 16S rRNA gene of SC-N012T revealed the closest match (98.9% pair wise similarity) with Bacillus clausii DSM 8716T. However, DNA–DNA hybridization experiments indicated low levels of genomic relatedness (32%) with this strain. The major components of the fatty acid profile are iso-C15:0, anteiso-C15:0, iso-C17:0 and anteiso-C17:0. The diagnostic cell-wall diamino acid was meso-diaminopimelic acid. The G+C content of the genomic DNA is 43.0xa0mol%. The lipids present in strain SC-N012T are diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol and two unknown phospholipids. Their predominant respiratory quinone was MK-7. Studies of DNA-DNA relatedness, morphological, physiological and chemotaxonomic analyses and phylogenetic data based on 16S rRNA gene sequencing allowed strain SC-N012T to be described as members of novel species of the genus Bacillus, for which the name Bacillus rhizosphaerae sp. nov. is proposed. The type strain is SC-N012T (=DSM 21911Txa0=xa0NCCB 100267T).

Rhodanobacter glycinis sp. nov., a yellow-pigmented gammaproteobacterium isolated from the rhizoplane of field-grown soybean.

A novel, yellow-pigmented bacterium, designated strain MO64(T), was isolated from the rhizoplane of field-grown soybean, collected from an experimental plot at Coimbatore, India. Cells were Gram-reaction-negative, motile, non-spore-forming rods that produced yellow-pigmented colonies on R2A agar. Phylogenetic analysis, based on 16S rRNA gene sequences, showed that strain MO64(T) belonged to the genus Rhodanobacter. Strain MO64(T) was related most closely to Rhodanobacter ginsengisoli GR17-7(T) (98.0% 16S rRNA gene sequence similarity), Rhodanobacter spathiphylli B39(T) (97.9%), Rhodanobacter panaciterrae LnR5-47(T) (97.7%), Rhodanobacter terrae GP18-1(T) (97.6%), Rhodanobacter soli DCY45(T) (97.3%) and Rhodanobacter caeni MJ01(T) (97.2%); levels of similarity to the type strains of all other recognized species of the genus Rhodanobacter were less than 97.0%. Chemotaxonomic data (Q-8 as the predominant ubiquinone, and iso-C(16u200a:u200a0), iso-C(15u200a:u200a0), C(17u200a:u200a0) cyclo, iso-C(17u200a:u200a1)ω9c, iso-C(17u200a:u200a0) and iso-C(11u200a:u200a0) as the major fatty acids) also supported the affiliation of strain MO64(T) with the genus Rhodanobacter. The G+C content of the genomic DNA was 64 mol%. The results of DNA-DNA hybridization and phenotypic analysis showed that strain MO64(T) can be distinguished from all known species of the genus Rhodanobacter and therefore represents a novel species of the genus, for which the name Rhodanobacter glycinis sp. nov. is proposed. The type strain is MO64(T) (u200a=u200aICMP 17626(T)u200a=u200aNBRC 105007(T)).