T. N. R. Srinivas

Bacterial diversity and bioprospecting for cold-active lipases, amylases and proteases, from culturable bacteria of kongsfjorden and Ny-alesund, Svalbard, Arctic.

Culturable bacterial diversity of seven marine sediment samples of Kongsfjorden and a sediment and a soil sample from Ny-Ålesund, Svalbard, Arctic was studied. The bacterial abundance in the marine sediments of Kongsfjorden varied marginally (0.5xa0×xa0103–1.3xa0×xa0104 cfu/g sediment) and the bacterial number in the two samples collected from the shore of Ny-Ålesund also was very similar (0.6xa0×xa0104 and 3.4xa0×xa0104, respectively). From the nine samples a total of 103 bacterial isolates were obtained and these isolates could be grouped in to 47 phylotypes based on the 16S rRNA gene sequence belonging to 4 phyla namely Actinobacteria, Bacilli, Bacteroidetes and Proteobacteria. Representatives of the 47 phylotypes varied in their growth temperature range (4–37°C), in their tolerance to NaCl (0.3–2xa0M NaCl) and growth pH range (2–11). Representatives of 26 phylotypes exhibited amylase and lipase activity either at 5 or 20°C or at both the temperatures. A few of the representatives exhibited amylase and/or lipase activity only at 5°C. None of the phylotypes exhibited protease activity. Most of the phylotypes (38) were pigmented. Fatty acid profile studies indicated that short chain fatty acids, unsaturated fatty acids, branched fatty acids, the cyclic and the cis fatty acids are predominant in the psychrophilic bacteria.

Bacterial diversity and bioprospecting for cold-active enzymes from culturable bacteria associated with sediment from a melt water stream of Midtre Lov´enbreen glacier, an Arctic glacier

Culturable bacterial diversity of Midtre Lovenbreen glacier, an Arctic glacier, was studied using 12 sediment samples collected from different points, along a transect, from the snout of Midtre Lovenbreen glacier up to the convergence point of the melt water stream with the sea. Bacterial abundance appeared to be closer to the convergence point of the glacial melt water stream with the sea than at the snout of the glacier. A total of 117 bacterial strains were isolated from the sediment samples. Based on 16S rRNA gene sequence analyses, the isolates (n=117) could be categorised in to 32 groups, with each group representing a different taxa belonging to 4 phyla (Actinobacteria, Bacilli, Flavobacteria and Proteobacteria). Representatives of the 32 groups varied in their growth temperature range (4-37 degrees C), in their tolerance to NaCl (0.1-1M NaCl) and in the growth pH range (2-13). Only 14 of 32 representative strains exhibited amylase, lipase and (or) protease activity and only one isolate (AsdM4-6) showed all three enzyme activities at 5 and 20 degrees C respectively. More than half of the isolates were pigmented. Fatty acid profile studies indicated that short-chain fatty acids, unsaturated fatty acids, branched fatty acids, cyclic and cis fatty acids are predominant in the psychrophilic bacteria.

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 diversity of soil in the vicinity of Pindari glacier, Himalayan mountain ranges, India, using culturable bacteria and soil 16S rRNA gene clones.

Three 16S rRNA gene clone libraries (P1L, P4L and P8L) were constructed using three soil samples (P1S, P4S and P8S) collected near Pindari glacier, Himalayas. The three libraries yielded a total of 703 clones. Actinobacteria, Firmicutes and Proteobacteria were common to the three libraries. In addition to the above P1L and P8L shared the phyla Acidobacteria, Bacteroidetes, Gemmatimonadetes and Planctomycetes. Phyla Chlamydiae, Chlorobi, Chloroflexi, Dictyoglomi, Fibrobacteres, Nitrospirae, Verrucomicrobia, candidate division SPAM and candidate TM7s TM7a phylum were present only in P1L. Rarefaction analysis indicated that the bacterial diversity in P4S and P8S soil samples was representative of the sample. Principal component analysis (PCA) revealed that P1S and P8S were different from P4S soil sample. PCA also indicated that arsenic content, pH, Cr and altitude influence the observed differences in the percentage of specific OTUs in the three 16S rRNA gene clone libraries. The observed bacterial diversity was similar to that observed for other Himalayan and non-polar cold habitats. A total of 40 strains of bacteria were isolated from the above three soil samples and based on the morphology 20 bacterial strains were selected for further characterization. The 20 bacteria belonged to 12 different genera. All the isolates were psychro-, halo- and alkalitolerant. Amylase and urease activities were detected in majority of the strains but lipase and protease activities were not detected. Long chain, saturated, unsaturated and branched fatty acids were predominant in the psychrotolerant bacteria.

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.

Comparison of bacterial diversity in proglacial soil from Kafni Glacier, Himalayan Mountain ranges, India, with the bacterial diversity of other glaciers in the world

Two 16S rRNA gene clone libraries (KF and KS) were constructed using two soil samples (K7s and K8s) collected near Kafni Glacier, Himalayas. The two libraries yielded a total of 648 clones. Phyla Actinobacteria, Bacteroidetes, Chloroflexi Firmicutes, Proteobacteria, Spirochaetae, Tenericutes and Verrucomicrobia were common to the two libraries. Phyla Acidobacteria, Chlamydiae and Nitrospirae were present only in KF library, whereas Lentisphaerae and TM7 were detected only in KS. In the two libraries, clones belonging to phyla Bacteroidetes and Proteobacteria were the most predominant. Principal component analysis (PCA) revealed that KF and KS were different and arsenic content influenced the differences in the percentage of OTUs. PCA indicated that high water content in the K8s sample results in high total bacterial count. PCA also indicated that bacterial diversity of KF and KS was similar to soils from the Pindari Glacier, Himalayas; Samoylov Island, Siberia; Schrimacher Oasis, Antarctica and Siberian tundra. The eleven bacterial strains isolated from the above two soil samples were phylogenetically related to six different genera. All the isolates were psychro-, halo- and alkalitolerant. Amylase, lipase and urease activities were detected in the majority of the strains. Long chain, saturated, unsaturated and branched fatty acids were predominant in the psychrotolerant bacteria.

Nitritalea halalkaliphila gen. nov., sp. nov., an alkaliphilic bacterium of the family 'Cyclobacteriaceae', phylum Bacteroidetes

A novel Gram-negative, rod-shaped, non-motile bacterium, designated strain LW7(T), was isolated from a water sample collected at a depth of 4.5 m from Lonar Lake in Buldhana district, Maharastra, India. The cell suspension was dark-reddish orange due to the presence of carotenoids. The fatty acids were dominated by large amounts of iso-C₁₅:₀ (59.6u200a%) and iso-C₁₇:₀ 3-OH (8.9u200a%). Strain LW7(T) contained MK-4 and MK-5 as the major respiratory quinones and phosphatidylglycerol and phosphatidylethanolamine as the major phospholipids. 16S rRNA gene sequence analysis indicated that Belliella baltica, a member of family Cyclobacteriaceae (phylum Bacteroidetes), is the closest related species, with a sequence similarity of 94.0u200a% to the type strain. Other members of the family Cyclobacteriaceae had sequence similarities of < 93.3u200a%. Based on the above-mentioned phenotypic and phylogenetic characteristics, strain LW7(T) is proposed as a representative of a new genus and species, Nitritalea halalkaliphila gen. nov., sp. nov. The type strain of Nitritalea halalkaliphila is LW7(T) (=CCUG 57665(T) =JCM 15946(T) =NCCB 100279(T)). The genomic DNA G+C of strain LW7(T) is 49u2005mol%.

Cecembia lonarensis gen. nov., sp. nov., a haloalkalitolerant bacterium of the family Cyclobacteriaceae, isolated from a haloalkaline lake and emended descriptions of the genera Indibacter, Nitritalea and Belliella

A novel Gram-staining-negative, rod-shaped, non-motile bacterium, designated strain LW9(T), was isolated from a water sample collected from Lonar Lake of Buldhana district, Maharashtra, India. Colonies and broth cultures were reddish orange due to the presence of carotenoid pigments. Strain LW9(T) was positive for catalase, ornithine decarboxylase and lysine decarboxylase activities and negative for gelatinase, oxidase, urease and lipase activities. The predominant fatty acids were iso-C(15 : 0) (31.3 %), iso-C(16 : 0) (9.3 %), anteiso-C(15 : 0) (7.3 %), iso-C(16 : 1) H (6.1 %), summed feature 3 (comprising C(16 : 1)ω7c/C(16 : 1)ω6c; 5.9 %), iso-C(17 : 1)ω9c (5.4 %) and iso-C(17 : 0) 3-OH (5.0 %). Strain LW9(T) contained MK-7 as the major respiratory quinone. The polar lipids consisted of phosphatidylethanolamine, two unidentified aminolipids and seven unidentified lipids. The DNA G+C content of strain LW9(T) was 40.5 mol%. 16S rRNA gene sequence analysis indicated that the type strains of Indibacter alkaliphilus and Aquiflexum balticum, two members of the family Cyclobacteriaceae (phylum Bacteroidetes) were the most closely related strains with sequence similarities of 93.0 and 94.0 %, respectively. Other members of the family Cyclobacteriaceae showed sequence similarities <93.0 %. Based on these phenotypic characteristics and on phylogenetic inference, strain LW9(T) is proposed as the representative of novel species in a new genus, Cecembia lonarensis gen. nov., sp. nov. The type strain of the type species, Cecembia lonarensis, is LW9(T) (= CCUG 58316(T) = KCTC 22772(T)). Emended descriptions of the genera Indibacter, Nitritalea and Belliella are also proposed.

Winogradskyella psychrotolerans sp. nov., a marine bacterium of the family Flavobacteriaceae isolated from Arctic sediment.

A novel Gram-negative, rod-coccus shaped, non-motile, strain, RS-3(T), was isolated from a sediment sample collected from the marine transect of Kongsfjorden, Ny-Ålesund, Svalbard, Arctic. Colonies and broth cultures were yellowish in colour due to the presence of carotenoids. Strain RS-3(T) was positive for oxidase, aesculinase, caseinase, gelatinase and urease activities and negative for amylase, catalase, lipase, lysine decarboxylase, ornithine decarboxylase, DNase and β-galactosidase activities. The predominant fatty acids were iso-C15u200a:u200a0 (18.0), anteiso-C15u200a:u200a0 (16.8), iso-C15u200a:u200a1 G (14.2), anteiso-C15u200a:u200a1 A (6.0) and iso-C15u200a:u200a0 3-OH (6.8). Strain RS-3(T) contained MK-6 (72.42u200a%) and MK-7 (27.58u200a%) as the major respiratory quinones and phosphatidylethanolamine, two unidentified aminolipids and two unidentified lipids make up the polar lipid composition. The DNA G+C content of strain RS-3(T) was 34.7±1.2 mol%. The 16S rRNA gene sequence analysis indicated that Winogradskyella pacifica and Winogradskyella thalassocola are the most closely related species with sequence similarities to the type strains of these species of 98.5 and 97.7u200a%, respectively. However, DNA-DNA hybridization with Winogradskyella pacifica KCTC 22997(T) and Winogradskyella thalassocola DSM 15363(T) showed a relatedness of 22 and 42.5u200a% with respect to strain RS-3(T). Based on the DNA-DNA hybridization values, phenotypic and chemotaxonomic characteristics and phylogenetic inference, strain RS-3(T) is proposed as a novel species of the genus Winogradskyella, for which the name Winogradskyella psychrotolerans sp. nov. is proposed. The type strain of Winogradskyella psychrotolerans sp. nov. is RS-3(T) (u200a=u200aCIP 110154(T)u200a=u200aNBRC 106169(T)). An emended description of the genus Winogradskyella is provided.

Antarctic ice core samples: culturable bacterial diversity.

Culturable bacterial abundance at 11 different depths of a 50.26 m ice core from the Tallaksenvarden Nunatak, Antarctica, varied from 0.02 to 5.8 × 10(3) CFU ml(-1) of the melt water. A total of 138 bacterial strains were recovered from the 11 different depths of the ice core. Based on 16S rRNA gene sequence analyses, the 138 isolates could be categorized into 25 phylotypes belonging to phyla Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria. All isolates had 16S rRNA sequences similar to previously determined sequences (97.2-100%). No correlation was observed in the distribution of the isolates at the various depths either at the phylum, genus or species level. The 25 phylotypes varied in growth temperature range, tolerance to NaCl, growth pH range and ability to produce eight different extracellular enzymes at either 4 or 18 °C. Iso-, anteiso-, unsaturated and saturated fatty acids together constituted a significant proportion of the total fatty acid composition.