Upper circumpolar deep water influences microbial functional gene composition and diversity along the southern Central Indian Ridge and eastern Southwest Indian Ridge.

Deep sea microbial communities play a significant role in global biogeochemical processes. However, the depth-wise metabolic potential of microbial communities in hydrothermally influenced Central Indian Ridge (CIR) and Southwest Indian Ridge (SWIR) remains elusive. In this study, a comprehensive functional microarray-based approach was used to understand factors influencing the metabolic potential of microbial communities and depth-driven differences in microbial functional gene composition in CIR and SWIR.

Molecular identification of deep-sea blind lobster (Crustacea: Decapoda: Polychelidae) from the Central Indian Ridge.

The deep-sea blind lobster A. Milne-Edwards, 1880 was collected at a water depth of 3433 m and is reported for the first time from the Central Indian Ridge (CIR). The species was identified based on morphological examination and supported by mitochondrial Cytochrome Oxidase Subunit I (mtCOI) gene.

Changes in morphology and metabolism enable Mn-oxidizing bacteria from mid-oceanic ridge environment to counter metal-induced stress.

Mn-oxidizing potential of two metal-tolerant bacterial strains - Halomonas meridiana and Marinobacter algicola isolated from the South West Indian Ridge waters were compared at varying concentrations of Mn (II), i.e., 1, 10, and 100 μmol and mmol L .

Astrobiological implications of dim light phototrophy in deep-sea red clays.

Red clays of Central Indian Basin (CIB) under influence of trace of Rodriguez Triple Junction exhibited chemoautotrophy, low temperature hydrothermal alterations and photoautotrophic potential. Seamount flank TVBC-08, hosting such signatures revealed dominance of aerobic anoxygenic phototroph Erythrobacter, with 93% of total 454 pyrosequencing tags. Subsequently, enrichments for both aerobic (Erythrobacter) and anaerobic anoxygenic phototrophs (green and purple sulphur bacteria) under red and white LED light illumination, with average irradiance 30.

Grazing of particle-associated bacteria-an elimination of the non-viable fraction.

Quantification of bacteria being grazed by microzooplankton is gaining importance since they serve as energy subsidies for higher trophic levels which consequently influence fish production. Hence, grazing pressure on viable and non-viable fraction of free and particle-associated bacteria in a tropical estuary controlled mainly by protist grazers was estimated using the seawater dilution technique. In vitro incubations over a period of 42h showed that at the end of 24h, growth coefficient (k) of particle-associated bacteria was 9 times higher at 0.

An appraisal of biological responses and network of environmental interactions in non-mining and mining impacted coastal waters.

The coastal waters of Goa and Ratnagiri lying on the West coast of India are influenced by terrestrial influx. However, Goa is influenced anthropogenically by iron-ore mining, while Ratnagiri is influenced by deposition of heavy minerals containing iron brought from the hinterlands. We hypothesize that there could be a shift in biological response along with changes in network of interactions between environmental and biological variables in these mining and non-mining impacted regions, lying 160 nmi apart.

Bacterial diversity in relatively pristine and anthropogenically-influenced mangrove ecosystems (Goa, India).

To appreciate differences in benthic bacterial community composition at the relatively pristine Tuvem and the anthropogenically-influenced Divar mangrove ecosystems in Goa, India, parallel tag sequencing of the V6 region of 16S rDNA was carried out. We hypothesize that availability of extraneously-derived anthropogenic substrates could act as a stimulatant but not a deterrent to promote higher bacterial diversity at Divar. Our observations revealed that the phylum Proteobacteria was dominant at both locations comprising 43-46% of total tags.

Nitrogen-limited mangrove ecosystems conserve N through dissimilatory nitrate reduction to ammonium.

Earlier observations in mangrove sediments of Goa, India have shown denitrification to be a major pathway for N loss. However, percentage of total nitrate transformed through complete denitrification accounted for <0-72% of the pore water nitrate reduced. Here, we show that up to 99% of nitrate removal in mangrove sediments is routed through dissimilatory nitrate reduction to ammonium (DNRA).

Denitrification prevails over anammox in tropical mangrove sediments (Goa, India).

Denitrification, anammox (Anx) and di-nitrogen fixation were examined in two mangrove ecosystems- the anthropogenically influenced Divar and the relatively pristine Tuvem. Stratified sampling at 2 cm increments from 0 to 10 cm depth revealed denitrification as the main process of N₂ production in mangrove sediments. At Divar, denitrification was ∼3 times higher than at Tuvem with maximum activity of 224.

Effects of composition of labile organic matter on biogenic production of methane in the coastal sediments of the Arabian Sea.

Coastal regions are potential zones for production of methane which could be governed by ecological/environmental differences or even sediment properties of a niche. In order to test the hypothesis that methanogenesis in most marine sediments could be driven more by proteins than by carbohydrates and lipid content of labile organic matter (LOM), incubation experiments were carried out with sediments from different environmental niches to measure methane production. The methane production rates were examined in relationship to the sediment biochemistry, i.

Cobalt immobilization by manganese oxidizing bacteria from the Indian ridge system.

Co immobilization by two manganese oxidizing isolates from Carlsberg Ridge waters (CR35 and CR48) was compared with that of Mn at same molar concentrations. At a lower concentration of 10 μM, CR35 and CR48 immobilized 22 and 23 fM Co cell(-1) respectively, which was 1.4 to 2 times higher than that of Mn oxidation, while at 10 mM the immobilization was 15-69 times lower than that of Mn.

Denitrification: an important pathway for nitrous oxide production in tropical mangrove sediments (Goa, India).

Net nitrous oxide production and denitrification activity were measured in two mangrove ecosystems of Goa, India. The relatively pristine site Tuvem was compared to Divar, which is prone to high nutrient input. Stratified sampling at 2-cm intervals within the 0- to 10-cm depth range showed that N2O production at both the locations decreased with depth.

Nitrate levels modulate denitrification activity in tropical mangrove sediments (Goa, India).

A study to examine the short-term effect of nitrate and organic carbon addition on denitrification activity was carried out on sediments from a mangrove ecosystem prone to anthropogenic activities (Divar, Goa, India). Laboratory microcosms were prepared using sediment sectioned at every 2-cm-depth interval from the surface to 10 cm. The incubations were subjected to varying nitrate amendments at concentrations ranging from 0, 5, 10, 20, 40 to 60 μmol l(-1) (up to three times more than measured in field).

Water quality and bacteriology in an aquaculture facility equipped with a new aeration system.

The HOBAS aeration system was tested to compare changes in environmental and bacteriological parameters in ponds growing Penaeus monodon during a single production cycle. The stocking density in the aerated pond was doubled to 12 post-larvae (PL) m(-2) in contrast to the non-aerated pond with 6 (PL) m(-2). Microbial abundance in the ponds ranged between 10(5-6) cells ml(-1).

Anoxia over the western continental shelf of India: bacterial indications of intrinsic nitrification feeding denitrification.

Studies on the Arabian Sea coastal anoxia have been of immense interest, but despite its ecological significance there is sparse understanding of the microbes involved. Hence, observations were carried out off Goa (15 degrees 30'N, 72 degrees 40'E to 15 degrees 30'N, 72 degrees 59'E) to understand the processes that mediate the changes in various inorganic nitrogen species in the water column during anoxia. Water column chemistry showed a clear distinct oxic environment in the month of April and anoxic condition in October.

Bacterial contribution to mitigation of iron and manganese in mangrove sediments.

The Mandovi and Chapora are two tropical estuaries lying in close geographic proximity on the west coast of India. Seasonal changes in down core variation of Fe, Mn and Total Organic Carbon (TOC) in the mangrove sediments adjoining these estuaries were studied to assess their influence on some of the representative benthic bacteria belonging to heterotrophic and autotrophic groups. Heterotrophic bacteria (HB) cultured on different nutrient concentrations (0.

Manganese oxidation by bacterial isolates from the Indian ridge system.

The abundance and activity of culturable manganese-oxidizing bacteria were assessed from near-bottom water samples of the tectonically active Carlsberg Ridge. Retrievable counts as colony forming units (CFU) on dilute nutrient agar medium (dilNA=2 gm l(-1) nutrient broth+2% agar) and on dilNA supplemented with 1, 2 and 3 mM MnCl(2).4H(2)O were in the order of 10(6) CFU l(-1).