Syed G. Dastager

Isolation and characterization of novel plant growth promoting Micrococcus sp NII-0909 and its interaction with cowpea

A phosphate-solubilizing bacterial strain NII-0909 isolated from the Western ghat forest soil in India was identified as Micrococcus sp on the basis of phenotypic characteristics, carbon source utilization pattern, fatty acid methyl esters analysis, and 16S rRNA gene sequence. The strain exhibited the plant growth-promoting attributes of phosphate solubilization, auxin production, 1-aminocyclopropane-1-carboxylate deaminase activity, and siderophore production. It was able to solubilize (122.4μg of Ca(3)PO(4) ml(-1)), and produce IAA (109μgml(-1)) at 30°C. P-solubilizing activity of the strain NII-0909 was associated with the release of organic acids and a drop in the pH of the NBRIP medium. HPLC analysis detected two organic acids in the course of P-solubilization. A significant increase in the growth of cow pea was recorded for inoculations under controlled conditions. Scanning electron microscopic study revealed the root colonization of strain on cow pea seedlings. These results demonstrate that isolates NII-0909 has the promising PGPR attributes to be develop as a biofertilizer to enhance soil fertility and promote the plant growth.

Pontibacter niistensis sp. nov., isolated from forest soil

A Gram-negative, rod-shaped bacterial strain, NII-0905(T) [corrected], that was motile by gliding was isolated from soil of a dense forest collected from the Western Ghats of India and its taxonomic position was established. Strain NII-0905(T) [corrected] contained MK-7 as the major menaquinone and anteiso-C(17 : 0), anteiso-C(15 : 0), iso-C(16 : 0) and iso-C(15 : 0) as the major cellular fatty acids. The DNA G+C content of strain NII-0905(T) [corrected] was 51.47 mol%. 16S rRNA gene sequence-based phylogenetic analysis confirmed the placement of strain NII-0905(T) [corrected] in the genus Pontibacter and strain NII-0905(T) [corrected] exhibited 93.9-96.3 % 16S rRNA sequence similarity with type strains of species of the genus Pontibacter. On the basis of genotypic and phenotypic evidence, strain NII-0905(T) [corrected] is considered to represent a novel species of the genus Pontibacter, for which the name Pontibacter niistensis sp. nov. is proposed. The type strain is NII-0905(T) [corrected](=NCIM 5339(T) =CCTCC AA 209057(T)).

Nocardioides sediminis sp. nov., isolated from a sediment sample

A strictly aerobic, motile, short-rod-shaped, Gram-positive-staining actinomycete strain, designated MSL-01(T), was isolated from a sediment sample from Bigeum Island of Korea. 16S rRNA gene sequence analysis revealed that the isolate MSL-01(T) belonged to the genus Nocardioides, with the highest sequence similarity to Nocardioides terrigena DS-17(T) (98.54 %), but the DNA-DNA relatedness to this type strain was 34 %. The physiological properties of strain MSL-01(T) differ from those of Nocardioides terrigena DS-17(T) and other species of Nocardioides. The diamino acid in the cell-wall peptidoglycan of strain MSL-01(T) is ll-diaminopimelic acid, the major menaquinone is MK-8(H(4)) and iso-C(16 : 0) is the major fatty acid component. The name Nocardioides sediminis sp. nov. is proposed for the novel species, with the type strain MSL-01(T) (=DSM 19263(T) =KCTC 19271(T)).

Isolation and characterization of plant growth-promoting strain Pantoea NII-186. From Western Ghat Forest soil, India

Aims:  To isolate plant growth‐promoting bacterium from Western Ghat forests in India.

Marmoricola bigeumensis sp. nov., a member of the family Nocardioidaceae.

A Gram-positive, aerobic strain, designated MSL-05T, was isolated from a soil sample collected from Bigeum Island, Korea, and its taxonomic position was investigated using a polyphasic approach. Cells of the novel strain were coccoid and occurred singly. The novel strain grew over a wide range of NaCl concentrations (0-7 %, w/v). The optimum growth temperature and pH were 28 degrees C and 7.2, respectively. Chemotaxonomic characteristics [peptidoglycan type, meso-diaminopimelic acid; major menaquinone, MK-8(H4); predominant fatty acids, i-C16 : 0, ai-C17 : 0, C16 : 0 and i-C14 : 0; DNA G+C content of 72.9 mol%] placed this organism within the genus Marmoricola. 16S rRNA gene sequence analysis confirmed this classification, but showed that the novel strain was distinct from its nearest neighbours. Strain MSL-05T was found in the same clade as the type strains of species of the genus Marmoricola and also shared low gene sequence similarity with Marmoricola aequoreus JCM 13812T (96.91 %) and Marmoricola aurantiacus DSM 12652T (95.39 %). Based on the results of phenotypic and phylogenetic analyses, it is proposed that the new isolate should be classified as a novel species in the genus Marmoricola, for which the name Marmoricola bigeumensis sp. nov. is proposed. The type strain is MSL-05T (=KCTC 19287T=DSM 19426T).

Nocardioides koreensis sp. nov., Nocardioides bigeumensis sp. nov. and Nocardioides agariphilus sp. nov., isolated from soil from Bigeum Island, Korea.

Three Gram-positive, coccoid to rod-shaped actinobacteria, designated strains MSL-09(T), MSL-19(T) and MSL-28(T), were isolated from a soil sample collected from Bigeum Island in Korea, and were subjected to a polyphasic taxonomic analysis. All three isolates grew optimally at pH 7.5-9.0 and 28-30 degrees C. 16S rRNA gene analysis revealed that all three strains belonged to the genus Nocardioides, with strains MSL-09(T), MSL-19(T) and MSL-28(T) respectively showing the highest sequence similarity to Nocardioides aquaticus DSM 11439(T) (96.25 %), Nocardioides aquiterrae GW-9(T) (95.75 %) and Nocardioides terrigena DS-17(T) (95.61 %). Chemotaxonomically, they contain LL-2,6-diaminopimelic acid in the cell-wall peptidoglycan, MK-8(H(4)) as the predominant menaquinone and diphosphatidylglycerol, phosphatidylglycerol and some unknown lipids as the polar lipids found in the cell wall. iso-C(16 : 0) is a major fatty acid. The G+C content of the DNA was respectively 69.9, 69.3 and 69.4 mol% for strains MSL-09(T), MSL-19(T) and MSL-28(T). Based on morphological, physiological, biochemical and chemotaxonomic characters presented in this study, the three strains represent novel species of the genus Nocardioides. The names Nocardioides koreensis sp. nov. (type strain MSL-09(T) =KCTC 19272(T) =DSM 19266(T)), Nocardioides bigeumensis sp. nov. (type strain MSL-19(T) =KCTC 19290(T) =DSM 19320(T)) and Nocardioides agariphilus sp. nov. (type strain MSL-28(T) =KCTC 19276(T) =DSM 19323(T)) are proposed.

Leifsonia kribbensis sp. nov., isolated from soil

A yellow-pigmented actinobacterium, designated strain MSL-13T, was isolated from a soil sample collected from Bigeum Island, Republic of Korea, and its taxonomic position was determined by using a polyphasic approach. Strain MSL-13T showed phenotypic and chemotaxonomic properties consistent with its classification in the genus Leifsonia. 16S rRNA gene sequence analysis of strain MSL-13T with sequences from Leifsonia naganoensis DB103T, Leifsonia aquatica DSM 20146T, Leifsonia xyli subsp. cynodontis JCM 9733T, Leifsonia poae VKM Ac-1401T and Leifsonia shinshuensis DB102T revealed similarities of 96.22, 96.19, 95.77, 95.44 and 95.37 %, respectively, with differences of 39-65 nt among 1483 total nucleotides aligned. Based on differences in phenotypic and genotypic characteristics, strain MSL-13T (=KCTC 19267T =DSM 19272T) is designated as the type strain of a novel species of the genus Leifsonia, for which the name Leifsonia kribbensis sp. nov. is proposed.

Cryobacterium mesophilum sp. nov., a novel mesophilic bacterium.

A novel mesophilic, Gram-positive, cream- to pale yellow-pigmented, aerobic bacterium, designated MSL-15T, was isolated from a soil sample collected from Bigeum Island, South Korea. The cells were catalase-positive, motile and irregular rods. The diamino acid content of the cell-wall peptidoglycan was determined to be 2,4-diaminobutyric acid. Strain MSL-15T grew well between 20 and 28 degrees C, with optimum growth occurring at 25-28 degrees C. The major fatty acids were anteiso-C15 : 0, iso-C16 : 0, anteiso-C17 : 0 and iso-C15 : 0. The genomic DNA G+C content was 70.0 mol%. A phylogenetic analysis based on 16S rRNA gene sequences indicated that strain MSL-15T was associated with the genus Cryobacterium and exhibited 96.6 % sequence similarity to Cryobacterium psychrotolerans JCM 13925T and 94.8 % similarity to Cryobacterium psychrophilum JCM 1463T. Phenotypic, chemotaxonomic and phylogenetic data revealed that strain MSL-15T represents a novel species within the genus Cryobacterium, for which the name Cryobacterium mesophilum is proposed. The type strain is MSL-15T (=DSM 19267T=KCTC 19270T).

Leifsonia bigeumensis sp. nov., isolated from soil on Bigeum Island, Korea.

A Gram-positive, motile, mesophilic bacterium that formed yellowish-white, circular, convex, glistening colonies, strain MSL-27T, was isolated from a soil sample from Bigeum Island, Korea, and its taxonomic position was investigated by a polyphasic approach. Cells of strain MSL-27T are non-spore-forming, irregular rods, usually fragmenting into shorter rods or coccoid elements. The growth temperature and pH ranges are 20-37 degrees C and pH 6.0-12.0, with optimum growth at 28 degrees C and pH 8.0. MK-11 is the major menaquinone and dl-2,4-diaminobutyric acid is found in the cell-wall peptidoglycan. The major fatty acids are i-C16:0 (39 %), ai-C15:0 (36 %), ai-C17:0 (18 %) and i-C15:0 (2 %). The G+C content is 69.0 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain MSL-27T should be placed in the genus Leifsonia. Levels of similarity between the 16S rRNA gene sequence of strain MSL-27T and those of the type strains of the other members of the genus Leifsonia ranged from 95.8 to 96.7 %. Based on phenotypic characteristics, biochemical properties and chemotaxonomic features, strain MSL-27T (=KCTC 19268T =DSM 19322T) represents the type strain of a novel species of Leifsonia, for which the name Leifsonia bigeumensis sp. nov. is proposed.

Characterization of plant growth-promoting rhizobacterium Exiguobacterium NII-0906 for its growth promotion of cowpea (Vigna unguiculata)

A phosphate solubilizing and antagonistic bacterial strain, isolated from a Western Ghat forest soil in Kerala province, India (designated as NII-0906), showed cold tolerance and grew from 10 to 37°C (optimum temperature 30°C). It was a Gram-positive, rod shaped, 0.8–1.6 μm in size, and exhibited tolerance to a wide pH range (5–12; optimum 7.0) and salt concentration up to 7% (w/v). The isolate showed maximum similarity with Exiguobacterium marinum TF-80T based on 16S rRNA analysis. It solubilized tricalcium phosphate under in vitro conditions. The phosphate solubilization was estimated along a temperature range (5–40°C), and maximum activity (84.7 μg mL−1 day−1) was recorded at 30°C after 10 days of incubation. The phosphate solubilizing activity coincided with a concomitant decrease in pH of the medium. The isolate also exhibited antifungal activity against phytopathogenic fungi in Petri dish assays and produced siderophore and hydrogen cyanide. The strain’s plant growth promotion properties were demonstrated through a cowpea-based bioassay under greenhouse conditions. The bacterial inoculation resulted in significant increment in plant root, stem and as well as in plant biomass. Further, scanning electron microscopic study revealed the root colonization in cowpea. These results could offer potential perspective for the strain to be used as plant growth-promoting rhizobacteria, which could be used as an inoculant for regional crops.