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Raghukumar S.,Myko Technology Pvt. Ltd. | Damare V.S.,National Institute of Oceanography of India
Botanica Marina | Year: 2011

This review summarizes increasing evidence for the role of Labyrinthulomycetes in marine ecosystems gathered over the last six decades. It focuses on their diversity, habitats, biomass, productivity and overall role in food webs and remi-neralization. Earlier studies contributed enormously to the cultured diversity of Labyrinthulomycetes. In recent years, their uncultured diversity has been demonstrated in exotic environments like the deep sea and anoxic waters. These findings emphasize the need for novel culture methods to grow these organisms. Many species seem to be substrate-specific in their occurrence. Their commensalistic or mutua-listic occurrence in marine invertebrates deserves attention. The biomass of Labyrinthulomycetes in the water column may often match or even exceed that of bacteria, although such occurrences seem to be seasonal. There is a major knowledge gap on their productivity and turnover in the water column. The high biomass and production of several degradative enzymes indicate their importance as reminera-lizers in the ocean. However, the mechanisms by which they overcome bacterial competition are not clear. It is likely that they occupy special habitats, such as marine aggregates. One role of the Labyrinthulomycetes suggested in this review, based on preliminary experiments, is that of ''left-over scavenging'', following bacterial growth. © 2011 by Walter de Gruyter. Source


Damare V.S.,National Institute of Oceanography of India | Raghukumar S.,Myko Technology Pvt. Ltd.
Ecological Research | Year: 2015

Labyrinthulomycetes are unicellular eukaryotes known for their ability to synthesize polyunsaturated fatty acids that are essential for growth and development of zooplankton. But relationship of these microorganisms with microzooplankton and their trophic status in food chain remains unexplored. Hence grazing losses of these protists were studied in coastal and oceanic waters. Traditional dilution plot experiments to study consumption of natural phytoplankton (herbivory) and bacteria (bacterivory) by microzooplankton were carried out, incorporating a modification to unravel their preying on Labyrinthulomycetes. It was incorporation of fluorescently-labeled Labyrinthulomycetes cells. Experiments in oceanic waters displayed grazing on phytoplankton and bacteria at all the three times of study while that on Labyrinthulomycetes at only one time out of the three. There was no significant grazing on phytoplankton in coastal waters and microzooplankton grazed on Labyrinthulomycetes and bacteria. When grazing was studied with respect to time, significant grazing on bacteria occurred in the first 6 h and on Labyrinthulomycetes occurred towards the end of 24 h of incubation. Grazing on natural Labyrinthulomycetes population instead of fluorescently-labeled cells also revealed that they were grazed. Overall, the grazing experiments demonstrated that microzooplankton can exert positive grazing pressure on Labyrinthulomycetes, though during certain times only, signalizing the probable ‘top-down control’ of Labyrinthulomycetes by microzooplankton during those times. Labyrinthulomycetes may therefore constitute an important part of microbial loop in the marine ecosystem by utilizing dissolved and particulate organic matter due to osmoheterotrophic mode of nutrition and in turn supplying it to the next trophic level viz., the microzooplankton. © 2015, The Ecological Society of Japan. Source


Pratibha J.,Myko Technology Pvt. Ltd. | Bhat D.J.,Goa University | Raghukumar S.,Myko Technology Pvt. Ltd.
Mycotaxon | Year: 2011

Anaselenosporella indica and Arachnophora goanensis, two new species of anamorphic fungi isolated from decaying plant litter collected from the forest of Goa, India, are described and illustrated. Anaselenosporella indica, found growing on dead twig of an unidentified plant, is characterized by polyblastic, sympodial, discrete, conidiogenous cells and cylindrical, rarely curved, aseptate, hyaline conidia. Arachnophora goanensis, collected from dry decaying bark of an unidentified tree, is characterized by blastic pigmented stauroconidia and blastic hyaline fusiform synanamorphic conidia. Two other species from the monotypic genera Catenosynnema and Cheiromyceopsis are also reported for the first time from India. © 2011 Publishing Technology. Source


Pratibha J.,Myko Technology Pvt. Ltd. | Raghukumar S.,Myko Technology Pvt. Ltd. | Bhat D.J.,Goa University
Mycotaxon | Year: 2010

Two new species of hyphomycetes isolated from decaying plant litter collected from Goa, India, are described and illustrated. Dendryphiopsis goanensis, found on decaying bark of an unidentified tree, is characterized by mostly polytretic, integrated, discrete, terminal, and intercalary conidiogenous cells. Stauriella indica, collected from decaying spathe of coconut tree, is characterized by sub-hyaline, spinulate, staurosporous conidia with 15-20 cells. © 2010. Mycotaxon, Ltd. Source


Damare V.S.,National Institute of Oceanography of India | Damare S.,National Institute of Oceanography of India | Ramanujam P.,Vellore Institute of Technology | Meena R.M.,National Institute of Oceanography of India | Raghukumar S.,Myko Technology Pvt. Ltd.
Microbial Ecology | Year: 2013

The relationship of the marine heterokont stramenopilan protists, the aplanochytrids, with the zooplankton was studied in coastal waters. The aplanochytrids were fed to the zooplankton specimens and observed for grazing by two different approaches: [1] using fluorescently-labeled prey approach and [2] using internal transcribed spacer-based molecular probe and in situ hybridization approach. The aplanochytrid cells were detected in the guts as well as fecal pellets of the zooplankton, thus serving as prey to them. Aplanochytrids were consistently isolated from zooplankton specimens. The isolates did not produce a wide array of enzymes, implicating that they may not play a major role in degradation of zooplankton exoskeleton. They were found to produce only protease considerably and sometimes lipase too. The amplified rDNA restriction analysis showed similar patterns, suggesting that most of the isolates might be same strains of Aplanochytrium spp. The existence of aplanochytrids with the zooplankton in marine waters points towards their probable association either as predator-prey or as commensalistic rather than saprophytic type of association. © 2013 Springer Science+Business Media New York. Source

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