Pavan Kumar Pindi

Janibacter hoylei sp. nov., Bacillus isronensis sp. nov. and Bacillus aryabhattai sp. nov., isolated from cryotubes used for collecting air from the upper atmosphere

Three novel bacterial strains, PVAS-1(T), B3W22(T) and B8W22(T), were isolated from cryotubes used to collect air samples at altitudes of between 27 and 41 km. Based on phenotypic characteristics, chemotaxonomic features, DNA-DNA hybridization with the nearest phylogenetic neighbours and phylogenetic analysis based on partial 16S rRNA gene sequences (PVAS-1(T), 1196 nt; B3W22(T), 1541 nt; B8W22(T), 1533 nt), the three strains were identified as representing novel species, and the names proposed are Janibacter hoylei sp. nov. (type strain PVAS-1(T) =MTCC 8307(T) =DSM 21601(T) =CCUG 56714(T)), Bacillus isronensis sp. nov. (type strain B3W22(T) =MTCC 7902(T) =JCM 13838(T)) and Bacillus aryabhattai sp. nov. (type strain B8W22(T) =MTCC 7755(T) =JCM 13839(T)).

Vertical distribution of bacteria in a lake sediment from Antarctica by culture-independent and culture-dependent approaches

Bacterial diversity of the subsurface (18-22 cm), middle (60-64 cm) and bottom (100-104 cm) of a 136-cm-long sediment core sampled from a freshwater lake in Antarctica was determined by the culturable approach, T-RFLP and 16S rRNA gene clone libraries. Using the culturable approach, 41 strains were isolated and, based on phylogenetic analysis, they could be categorized into 14 groups. Representatives of the 14 groups varied in their growth temperature range (4-30 °C), in their tolerance to NaCl (0-2 M NaCl) and in the growth pH range (5-11). Eleven of fourteen representative strains exhibited either amylase, lipase, protease and (or) urease activities at 4 °C. Bacterial diversity at the phyla level using T-RFLP and 16S rRNA clone libraries was similar and clones were affiliated with Proteobacteria, Bacteroidetes, Actinobacteria and Firmicutes. TRFs affiliated with Spirochaetes were detected only by the T-RFLP approach and clones affiliated with Caldiserica only in the clone libraries. Stratification of bacteria along the depth of the sediment was observed both with the T-RFLP and the 16S rRNA gene clone library methods, and results indicated that stratification was dependent on the nature of the organism, aerobic or anaerobic. For instance, aerobic Janthinobacterium and Polaromonas were confined to the surface of the sediment, whereas anaerobic Caldisericum was present only in the bottom portion of the core. It may be concluded that the bacterial diversity of an Antarctic lake sediment core sample varies throughout the length of the core depending on the oxic-anoxic conditions of the sediment. Furthermore, these psychrophilic bacteria, due to their ability to produce extracellular cold active enzymes, might play a key role in the transformation of complex organic compounds.

Bacterial biodiversity from Roopkund Glacier, Himalayan mountain ranges, India

The bacterial diversity of two soil samples collected from the periphery of the Roopkund glacial lake and one soil sample from the surface of the Roopkund Glacier in the Himalayan ranges was determined by constructing three 16S rRNA gene clone libraries. The three clone libraries yielded a total of 798 clones belonging to 25 classes.Actinobacteria was the most predominant class (>10% of the clones) in the three libraries. In the library from the glacial soil, class Betaproteobacteria (24.2%) was the most predominant. The rarefaction analysis indicated coverage of 43.4 and 41.2% in the samples collected from the periphery of the lake thus indicating a limited bacterial diversity covered; at the same time, the coverage of 98.4% in the glacier sample indicated most of the diversity was covered. Further, the bacterial diversity in the Roopkund glacier soil was low, but was comparable with the bacterial diversity of a few other glaciers. The results of principal component analysis based on the 16S rRNA gene clone library data, percentages of OTUs and biogeochemical data revealed that the lake soil samples were different from the glacier soil sample and the biogeochemical properties affected the diversity of microbial communities in the soil samples.

Exiguobacterium soli sp. nov., a psychrophilic bacterium from the McMurdo Dry Valleys, Antarctica

A novel psychrophilic bacterium, designated strain DVS 3Y(T), was isolated from a moraine sample from the McMurdo Dry Valleys, Antarctica. Phenotypic and chemotaxonomic characteristics and data from a phylogenetic analysis based on 16S rRNA gene sequences indicated that strain DVS 3Y(T) was related to the genus Exiguobacterium. Strain DVS 3Y(T) exhibited >97 % gene sequence similarity with respect to Exiguobacterium acetylicum DSM 20416(T) (97.4 %), Exiguobacterium oxidotolerans DSM 17272(T) (97.4 %), Exiguobacterium indicum IAM 15368(T) (97.6 %), Exiguobacterium undae DSM 14481(T) (98.2 %), Exiguobacterium sibiricum DSM 17290(T) (98.6 %) and Exiguobacterium antarcticum DSM 14480(T) (99.6 %). However, the levels of DNA-DNA relatedness between strain DVS 3Y(T) and E. acetylicum DSM 20416(T), E. oxidotolerans JCM 12280(T), E. indicum IAM 15368(T), E. undae DSM 14481(T), E. sibiricum DSM 17290(T) and E. antarcticum DSM 14480(T) were less than 70 % (52, 25, 16, 33, 16 and 38 %, respectively). Strain DVS 3Y(T) also differed from these six closely related species in a number of phenotypic traits. Phenotypic, chemotaxonomic and phylogenetic data suggest that strain DVS 3Y(T) represents a novel species of the genus Exiguobacterium, for which the name Exiguobacterium soli sp. nov. is proposed. The type strain is DVS 3Y(T) (=MTCC 4816(T)=JCM 14376(T)).

Description of Leifsonia kafniensis sp. nov. and Leifsonia antarctica sp. nov.

Strains KFC-22(T) and SPC-20(T) are yellow-pigmented, Gram-positive, aerobic, non-motile, rod-shaped bacteria that were isolated from a soil sample near the Kafni glacier in the Himalayan mountain ranges in India, and from a spade core sediment sample from the Antarctic Ocean at Larsemann Hill, respectively. In both cases, the cell-wall peptidoglycan contained 2,4-diaminobutyric acid as the diamino acid, anteiso-C(15 : 0), anteiso-C(17 : 0) and iso-C(16 : 0) were the predominant fatty acids and MK-11 was the major isoprenoid quinone in the cell membrane. On the basis of the above-mentioned characteristics, both strains can be assigned to the genus Leifsonia. The strains share 16S rRNA gene sequence similarity of 97.7 % and DNA relatedness of only 10 %, indicating that they represent different species. A blast analysis indicated that Leifsonia pindariensis PON10(T) was the closest phylogenetic neighbour of strains SPC-20(T) and KFC-22(T), showing 16S rRNA gene sequence similarities of 97.3 and 97.7 %, respectively. However, at the whole-genome level, strains KFC-22(T) and SPC-20(T) shared 42 and 11 % DNA-DNA relatedness, respectively, with L. pindariensis PON10(T). In addition, both strains exhibited several phenotypic differences with respect to L. pindariensis PON10(T). Thus, on the basis of the differences that the two strains exhibited with respect to L. pindariensis, both were identified as representing novel species of the genus Leifsonia, for which the names Leifsonia kafniensis sp. nov. (type strain KFC-22(T) =NCCB 100216(T) =LMG 24362(T)) and Leifsonia antarctica sp. nov. (type strain SPC-20(T) =NCCB 100227(T) =LMG 24541(T)) are proposed.

Importance of trmE for Growth of the Psychrophile Pseudomonas syringae at Low Temperatures

ABSTRACT Transposon mutagenesis of Pseudomonas syringae Lz4W, a psychrophilic bacterium capable of growing at temperatures between 2 and 30°C, yielded 30 cold-sensitive mutants, and CSM1, one of these cold-sensitive mutants, was characterized. Growth of CSM1 was retarded when it was cultured at 4°C but not when it was cultured at 22°C and 28°C compared to the growth of wild-type cells, indicating that CSM1 is a cold-sensitive mutant of P. syringae Lz4W. The mutated gene in CSM1 was identified as trmE (coding for tRNA modification GTPase), and evidence is provided that this gene is induced at low temperatures. Further, the cold-inducible nature of the trmE promoter was demonstrated. In addition, the transcription start site and the various regulatory elements of the trmE promoter, such as the −10 region, −35 region, UP element, cold box, and DEAD box, were identified, and the importance of these regulatory elements in promoter activity were confirmed. The importance of trmE in rapid adaptation to growth at low temperatures was further highlighted by plasmid-mediated complementation that alleviated the cold-sensitive phenotype of CSM1.

Arthrobacter antarcticus sp. nov., isolated from an Antarctic marine sediment

A bacterial strain, SPC26(T), was isolated from a sediment sample of the Southern Ocean off Antarctica. The strain was Gram-staining- and catalase-positive and contained lysine and alanine in the cell-wall peptidoglycan. The major cellular fatty acids were anteiso-C₁₅:₀ (54.92 %), iso-C₁₅:₀ (11.47 %), anteiso-C₁₇:₀ (6.48 %) and anteiso-C₁₅:₁ (6.38 %) and the major menaquinones were MK-8, MK-9 and MK-10. The major polar lipids were phosphatidylethanolamine and diphosphatidylglycerol. The G+C content was 68 ± 0.5 mol%. Based on 16S rRNA gene sequence similarities, the nearest phylogenetic neighbours of strain SPC26(T) were identified as Arthrobacter gangotriensis Lz1y(T) (98.8 %), A. sulfureus DSM 20167(T) (98.6 %), A. psychrophenolicus DSM 15454(T) (97.9 %) and A. kerguelensis KGN15(T) (97.5). With these strains, strain SPC26(T) exhibited DNA-DNA relatedness values of 36, 21, 12 and 10 %, respectively. Therefore, on the basis of 16S rRNA gene sequence comparisons, phylogenetic analysis, phenotypic characteristics and DNA-DNA relatedness, it is proposed that strain SPC26(T) represents a novel species of Arthrobacter, for which the name Arthrobacter antarcticus sp. nov. is proposed, with strain SPC26(T) (=LMG 24542(T) =NCCB 100228(T)) as the type strain.

Bhargavaea cecembensis gen. nov., sp. nov., isolated from the Chagos-Laccadive ridge system in the Indian Ocean

A novel Gram-positive, rod-shaped, non-motile, non-spore-forming bacterium, strain DSE10(T), was isolated from a deep-sea sediment sample collected at a depth of 5904 m from the Chagos-Laccadive ridge system in the Indian Ocean. Cells of strain DSE10(T) were positive for catalase, oxidase, urease and lipase activities and contained iso-C(14 : 0), iso-C(15 : 0), iso-C(16 : 0) and anteiso-C(15 : 0) as the major fatty acids. The major respiratory quinones were MK-6 and MK-8 and the major lipids were phosphatidylglycerol and diphosphatidylglycerol. The cell-wall peptidoglycan contained diaminopimelic acid as the diagnostic diamino acid. A blast sequence similarity search based on 16S rRNA gene sequences indicated that the genera Planococcus, Planomicrobium, Bacillus and Geobacillus were the nearest phylogenetic neighbours to the novel isolate with gene sequence similarities ranging from 94.9 to 95.2 %. Phylogenetic analyses using neighbour-joining, minimum-evolution and maximum-parsimony methods indicated that strain DSE10(T) formed a deeply rooted lineage distinct from the clades represented by the genera Planococcus, Planomicrobium, Bacillus and Geobacillus. Further, strain DSE10(T) could be distinguished from the above-mentioned genera based on the presence of signature nucleotides G, A, C, T, C, A, G, C and T at positions 182, 444, 480, 492, 563, 931, 1253, 1300 and 1391, respectively, in the 16S rRNA gene sequence. Based on the phenotypic and phylogenetic characteristics determined in this study, strain DSE10(T) was assigned as the type species of a new genus, Bhargavaea gen. nov., as Bhargavaea cecembensis sp. nov. The type strain of Bhargavaea cecembensis gen. nov., sp. nov. is DSE10(T) (=LMG 24411(T)=JCM 14375(T)). The genomic DNA G+C content of strain DSE10(T) is 59.5+/-2.5 mol%.

Identification of opportunistic pathogenic bacteria in drinking water samples of different rural health centers and their clinical impacts on humans.

International drinking water quality monitoring programs have been established in order to prevent or to reduce the risk of contracting water-related infections. A survey was performed on groundwater-derived drinking water from 13 different hospitals in the Mahabubnagar District. A total of 55 bacterial strains were isolated which belonged to both gram-positive and gram-negative bacteria. All the taxa were identified based on the 16S rRNA gene sequence analysis based on which they are phylogenetically close to 27 different taxa. Many of the strains are closely related to their phylogenetic neighbors and exhibit from 98.4 to 100% sequence similarity at the 16S rRNA gene sequence level. The most common group was similar to Acinetobacter junii (21.8%) and Acinetobacter calcoaceticus (10.9%) which were shared by 7 and 5 water samples, respectively. Out of 55 isolates, only 3 isolates belonged to coliform group which are Citrobacter freundii and Pantoea anthophila. More than half (52.7%, 29 strains) of the phylogenetic neighbors which belonged to 12 groups were reported to be pathogenic and isolated from clinical specimens. Out of 27 representative taxa are affiliated have eight representative genera in drinking water except for those affiliated with the genera Exiguobacterium, Delftia, Kocuria, and Lysinibacillus.

Plant growth regulation of Bt-cotton through Bacillus species

Deccan plateau in India periodically experiences droughts due to irregular rain fall and the soil in many parts of the region is considered to be poor for farming. Plant growth promoting rhizobacteria are originally defined as root-colonizing bacteria, i.e., Bacillus that cause either plant growth promotion or biological control of plant diseases. The study aims at the isolation of novel Bacillus species and to assess the biotechnological potential of the novel species as a biofertilizer, with respect to their plant growth promoting properties as efficient phosphate-solubilizing bacteria. Seven different strains of Bacillus were isolated from cotton rhizosphere soil near boys’ hostel of Palamuru University which belongs to Deccan plateau. Among seven isolated strains, Bacillus strain-7 has shown maximum support for good growth of eight cotton cultivars. This bacterial species is named Bacillus sp. PU-7 based on the phenotypic and phylogenetic analysis. Among eight cotton cultivars, Mahyco has shown high levels of IAA, proteins, chlorophyll, sugars and low level of proline. Efficacy of novel Bacillus sp. PU-7 with Mahyco cultivar has been checked experimentally at field level in four different cotton grown agricultural soils. The strains supported plant growth in almost all the cases, especially in the deep black soil, with a clear evidence of maximum plant growth by increased levels of phytohormone production and biochemical analysis, followed by shallow black soil. Hence, it is inferred that the novel isolate can be used as bioinoculant in the cotton fields.