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- 저자 : Rishiram Ramanan (검색결과 10 건)
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Ramanan, Rishiram,Tran, Quynh-Giao,Cho, Dae-Hyun,Jung, Jae-Eun,Kim, Byung-Hyuk,Shin, Sang-Yoon,Choi, Sae-Hae,Liu, Kwang-Hyeon,Kim, Dae-Soo,Lee, Seon-Jin,Crespo, José,L.,Lee, Hee-Gu,Oh, Hee-Mock American Society of Plant Biologists 2018 PLANT PHYSIOLOGY - Vol.177 No.3
<P>Phosphatidylinositol 3-kinase signaling influences biofuel yields in algae by regulating membrane lipid hydrolysis, lipogenesis, tricarboxylic acid cycle, and mitochondrial ATP synthesis.</P><P>Algae undergo a complete metabolic transformation under stress by arresting cell growth, inducing autophagy and hyper-accumulating biofuel precursors such as triacylglycerols and starch. However, the regulatory mechanisms behind this stress-induced transformation are still unclear. Here, we use biochemical, mutational, and “omics” approaches to demonstrate that PI3K signaling mediates the homeostasis of energy molecules and influences carbon metabolism in algae. In <I>Chlamydomonas reinhardtii</I>, the inhibition and knockdown (KD) of algal class III PI3K led to significantly decreased cell growth, altered cell morphology, and higher lipid and starch contents. Lipid profiling of wild-type and PI3K KD lines showed significantly reduced membrane lipid breakdown under nitrogen starvation (−N) in the KD. RNA-seq and network analyses showed that under −N conditions, the KD line carried out lipogenesis rather than lipid hydrolysis by initiating de novo fatty acid biosynthesis, which was supported by tricarboxylic acid cycle down-regulation and via acetyl-CoA synthesis from glycolysis. Remarkably, autophagic responses did not have primacy over inositide signaling in algae, unlike in mammals and vascular plants. The mutant displayed a fundamental shift in intracellular energy flux, analogous to that in tumor cells. The high free fatty acid levels and reduced mitochondrial ATP generation led to decreased cell viability. These results indicate that the PI3K signal transduction pathway is the metabolic gatekeeper restraining biofuel yields, thus maintaining fitness and viability under stress in algae. This study demonstrates the existence of homeostasis between starch and lipid synthesis controlled by lipid signaling in algae and expands our understanding of such processes, with biotechnological and evolutionary implications.</P>
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Ramanan, Rishiram,Vinayagamoorthy, Nadimuthu,Sivanesan, Saravana Devi,Kannan, Krishnamurthi,Chakrabarti, Tapan The Korean Society of Phycology 2012 ALGAE Vol.27 No.4
Carbon concentrating mechanisms play a vital role in photosynthesis in microalgae and cyanobacteria especially in the proper functioning of Rubisco and assimilation of carbon via the Calvin cycle. This study evaluates the role of carbon dioxide on carbon concentrating mechanism (CCM) in a cynaobacteria, Spirulina platensis and a microalga, Chlorella sp. 786. The study organisms were grown in both atmospheric (control sample, 0.035%) and high (exposed sample, 10%) $CO_2$ concentrations. Second dimension (2D) electrophoresis revealed a huge difference in the protein profiles of both organisms suggesting the induction of CCM related proteins in the sample maintained at atmospheric $CO_2$ concentration and the repression of CCM related proteins in the sample maintained at 10% $CO_2$. Liquid chromatography-mass spectroscopy analysis revealed the presence of two important $C_i$ transporter proteins in the control sample of S. platensis, namely ferredoxin-$NADP^+$ reductase and ATP binding cassette (ABC) transport system protein. These proteins were only expressed in the control sample and were downregulated or not expressed at all in the exposed sample. Consequently, this study conclusively proves that CCMs are only inducted at low $CO_2$ concentrations and are not functional at high $CO_2$ concentration.
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Rishiram Ramanan,Nadimuthu Vinayagamoorthy,Saravana Devi Sivanesan,Krishnamurthi Kannan,Tapan Chakrabarti 한국조류학회I 2012 ALGAE Vol.27 No.4
Carbon concentrating mechanisms play a vital role in photosynthesis in microalgae and cyanobacteria especially in the proper functioning of Rubisco and assimilation of carbon via the Calvin cycle. This study evaluates the role of carbon dioxide on carbon concentrating mechanism (CCM) in a cynaobacteria, Spirulina platensis and a microalga, Chlorella sp. 786. The study organisms were grown in both atmospheric (control sample, 0.035%) and high (exposed sample, 10%)CO2 concentrations. Second dimension (2D) electrophoresis revealed a huge difference in the protein profiles of both organisms suggesting the induction of CCM related proteins in the sample maintained at atmospheric CO2 concentration and the repression of CCM related proteins in the sample maintained at 10% CO2. Liquid chromatography-mass spectroscopy analysis revealed the presence of two important Ci transporter proteins in the control sample of S. platensis,namely ferredoxin-NADP+ reductase and ATP binding cassette (ABC) transport system protein. These proteins were only expressed in the control sample and were downregulated or not expressed at all in the exposed sample. Consequently,this study conclusively proves that CCMs are only inducted at low CO2 concentrations and are not functional at high CO2concentration.
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Purification and Characterization of a Novel Plant-type Carbonic Anhydrase from Bacillus subtilis
Rishiram Ramanan,Krishnamurthi Kannan,Nadimuthu Vinayagamoorthy,Saravana Devi Sivanesan,Kunga Mohan Ramkumar,Tapan Chakrabarti 한국생물공학회 2009 Biotechnology and Bioprocess Engineering Vol.14 No.1
Carbonic anhydrase enzyme, one of the fastest known enzymes, remains largely unexplored in prokaryotes when compared to its mammalian counterparts despite its ubiquity. In this study, the enzyme has been purified from Bacillus subtilis SA3 using sequential Sephadex G-75 chromatography, DEAE cellulose chromatography, and sepharose-4B-L-tyrosine-sulphanilamide affinity chromatography and characterized to provide additional insights into its properties. The apparent molecular mass of carbonic anhydrase obtained by SDS-PAGE was found to be approximately 37 kDa. Isoelectric focusing of the purified enzyme revealed an isoelectric point (pI) of around 6.1 when compared with marker. The presence of metal ions such as Zn2+, Co2+, Cu2+, Fe3+, Mg2+, and anion SO4- increased enzyme activity while strong inhibition was observed in the presence of Hg2+, Cl-, HCO3-, and metal chelator EDTA. The optimum pH and temperature for the enzyme were found to be 8.3 and 37℃, respectively. Enzyme kinetics with p-nitrophenyl acetate as substrate at pH 8.3 and 37℃ determined the Vmax and Km values of the enzyme to be 714.28 μmol/mg protein/min and 9.09 mM, respectively. The Ki value for acetazolamide was 0.22 mM, compared to 0.099 mM for sulphanilamide. The results from N-terminal amino acid sequencing imply the purified protein is a putative beta-carbonic anhydrase with close similarities to CAs from plants, microorganisms.
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Phycosphere bacterial diversity in green algae reveals an apparent similarity across habitats
Ramanan, Rishiram,Kang, Zion,Kim, Byung-Hyuk,Cho, Dae-Hyun,Jin, Long,Oh, Hee-Mock,Kim, Hee-Sik Elsevier 2015 Algal research Vol.8 No.-
<P><B>Abstract</B></P> <P>Phytoplankton and bacteria play the foremost role in primary production and often act in unison in biogeochemical cycling. Studies conducted so far are inconclusive on species specificity of phycosphere bacteria as the overarching function of specific clades of algae-associated bacteria, for instance <I>Roseobacter</I> in sulfur cycling, is widely held. In this study, we attempt to demonstrate the diversity of phycosphere bacteria in phylogenetically divergent unialgal green algae from vastly different environmental samples like soil, freshwater, marine, and wastewater with diatom and cyanobacteria as an outgroup. Diversity analyses using Differential Gel Gradient Electrophoresis (DGGE) revealed the predominant presence of bacteria belonging to Bacteroidetes phylum (46% of all strains). 454 pyrosequencing of selected strains from different habitats not only confirmed the presence of Bacteroidetes (33.1% of total reads) but also revealed the presence of bacteria belonging to α-Proteobacteria (52.6%), all in close association with their host. Majority of those symbiotic bacteria have been classified as Plant Growth Promoting Bacteria (PGPB) including prominent Sphingomonads and Rhizobacter. Results suggest that although host algae might encourage species specific interactions, specific functional traits are prerequisite for proximal adhesion in nutrient-rich phycosphere. While Bacteroidetes is known to have significant role in nutrient cycling through degradation of plant and algal macromolecules and for its attached growth, PGPB have proven symbiosis with plants and the overwhelming presence of these bacteria in green algae points to possible co-evolution.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Phycosphere bacterial diversity of 11 algal strains from different habitats by DGGE. </LI> <LI> DGGE & pyrosequencing revealed the dominance of α-Proteobacteria and Bacteroidetes. </LI> <LI> Algal-bacterial interactions might not be species specific. </LI> <LI> Algae might prefer certain bacterial clades with specific functional traits. </LI> <LI> Results of this study has ecological and biotechnological implications. </LI> </UL> </P>
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Nutrient Removal and Biofuel Production in High Rate Algal Pond Using Real Municipal Wastewater
( Byung Hyuk Kim ),( Zion Kang ),( Rishiram Ramanan ),( Jong Eun Choi ),( Dae Hyun Cho ),( Hee Mock Oh ),( Hee Sik Kim ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.8
This study evaluated the growth and nutrient removal ability of an indigenous algal consortium on real untreated municipal wastewater in a high rate algal pond (HRAP). The HRAP was operated semicontinuously under different hydraulic retention times (HRT: 2, 4, 6, and 8 days). The average removal efficiencies of chemical oxygen demand, and total nitrogen and phosphate of real municipal wastewater were maintained at 85.44 ± 5.10%, 92.74 ± 5.82%, and 82.85 ± 8.63%, respectively, in 2 day HRT. Algae dominated the consortium and showed high settling efficiency (99%), and biomass and lipid productivity of 0.500 ± 0.03 g/l/day and 0.103 ± 0.0083 g/l/day (2day HRT), respectively. Fatty acid methyl ester analysis revealed a predominance of palmitate (C16:0), palmitoleate (C16:1), linoleate (C18:2), and linolenate (C18:3). Microalgal diversity analyses determined the presence of Chlorella, Scenedesmus, and Stigeoclonium as the dominant microalgae. The algal consortium provides significant value not only in terms of energy savings and nutrient removal but also because of its bioenergy potential as indicated by the lipid content (20-23%) and FAME profiling.
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( Zion Kang ),( Byung Hyuk Kim ),( Rishiram Ramanan ),( Jong Eun Choi ),( Ji Won Yang ),( Hee Mock Oh ),( Hee Sik Kim ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.1
Open raceway ponds are cost-efficient for mass cultivation of microalgae compared with photobioreactors. Although low-cost options like wastewater as nutrient source is studied to overcome the commercialization threshold for biodiesel production from microalgae, a cost analysis on the use of wastewater and other incremental increases in productivity has not been elucidated. We determined the effect of using wastewater and wavelength filters on microalgal productivity. Experimental results were then fitted into a model, and cost analysis was performed in comparison with control raceways. Three different microalgal strains, Chlorella vulgaris AG10032, Chlorella sp. JK2, and Scenedesmus sp. JK10, were tested for nutrient removal under different light wavelengths (blue, green, red, and white) using filters in batch cultivation. Blue wavelength showed an average of 27% higher nutrient removal and at least 42% higher chemical oxygen demand removal compared with white light. Naturally, the specific growth rate of microalgae cultivated under blue wavelength was on average 10.8% higher than white wavelength. Similarly, lipid productivity was highest in blue wavelength, at least 46.8% higher than white wavelength, whereas FAME composition revealed a mild increase in oleic and palmitic acid levels. Cost analysis reveals that raceways treating wastewater and using monochromatic wavelength would decrease costs from 2.71 to 0.73 $/kg biomass. We prove that increasing both biomass and lipid productivity is possible through cost-effective approaches, thereby accelerating the commercialization of low-value products from microalgae, like biodiesel.
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( Byung-hyuk Kim ),( Jong-eun Choi ),( Kichul Cho ),( Zion Kang ),( Rishiram Ramanan ),( Doo-gyung Moon ),( Hee-sik Kim ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.4
The high rate algal ponds (HRAP) powered and mixed by a paddlewheel have been widely used for over 50 years to culture microalgae for the production of various products. Since light incidence is limited to the surface, water depth can affect microalgal growth in HRAP. To investigate the effect of water depth on microalgal growth, a mixed microalgal culture constituting three major strains of microalgae including Chlorella sp., Scenedesmus sp., and Stigeoclonium sp. (CSS), was grown at different water depths (20, 30, and 40 cm) in the HRAP, respectively. The HRAP with 20cm of water depth had about 38% higher biomass productivity per unit area (6.16 ± 0.33 g·m<sup>-2</sup>·d<sup>-1</sup>) and required lower nutrients and energy consumption than the other water depths. Specifically, the algal biomass of HRAP under 20c m of water depth had higher settleability through larger floc size (83.6% settleability within 5 min). These results indicate that water depth can affect the harvesting process as well as cultivation of microalgae. Therefore, we conclude that water depth is an important parameter in HRAP design for mass cultivation of microalgae.
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Ramesh Kakarla,최정운,윤진호,김병혁,허진아,이수진,조대현,Rishiram Ramanan,김희식 한국미생물학회 2018 The journal of microbiology Vol.56 No.1
Increased lipid accumulation of algal cells as a response to environmental stress factors attracted much attention of researchers to incorporate this stress response into industrial algal cultivation process with the aim of enhancing algal lipid productivity. This study applies high-salinity stress condition to a two-phase process in which microalgal cells are initially grown in freshwater medium until late exponential phase and subsequently subjected to high-salinity condition that induces excessive lipid accumulation. Our initial experiment revealed that the concentrated culture of Chlorella sorokiniana HS1 exhibited the intense fluorescence of Nile red at the NaCl concentration of 60 g/L along with 1 g/L of supplemental bicarbonate after 48 h of induction period without significantly compromising cultural integrity. These conditions were further verified with the algal culture grown for 7 days in a 1 L bottle reactor that reached late exponential phase; a 12% increment in the lipid content of harvested biomass was observed upon inducing high lipid accumulation in the concentrated algal culture at the density of 5.0 g DW/L. Although an increase in the sum of carbohydrate and lipid contents of harvested biomass indicated that the external carbon source supplemented during the induction period increased overall carbon assimilation, a decrease in carbohydrate content suggested the potential reallocation of cellular carbon that promoted lipid droplet formation under high-salinity stress. These results thus emphasize that the two-phase process can be successfully implemented to enhance algal lipid productivity by incorporating high-salinity stress conditions into the pre-concentrated sedimentation ponds of industrial algal production system.
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