The liquid membrane bilayers generated by cytochrome-C have been shown to exhibit the phenomenon ... more The liquid membrane bilayers generated by cytochrome-C have been shown to exhibit the phenomenon of photo-osmosis. Data on the variation of photo-osmotic velocity with wavelength and intensity of the exciting light and concentration and the choice of redox chemicals are reported.
Isolated phycobilisome (PBS) sub-assemblies have been widely subjected to X-ray crystallography a... more Isolated phycobilisome (PBS) sub-assemblies have been widely subjected to X-ray crystallography analysis to obtain greater insights into the structure-function relationship of this light harvesting complex. Allophycocyanin (APC) is the phycobiliprotein always found in the PBS core complex. Phycocyanobilin (PCB) chromophores, covalently bound to conserved Cys residues of αand βsubunits of APC, are responsible for solar energy absorption from phycocyanin and for transfer to photosynthetic apparatus. In the known APC structures, heterodimers of αand βsubunits (known as αβ monomers) assemble as trimer or hexamer. We here for the first time report the crystal structure of APC isolated from a marine cyanobacterium (Phormidium sp. A09DM). The crystal structure has been refined against all the observed data to the resolution of 2.51 Å to R work (R free ) of 0.158 (0.229) with good stereochemistry of the atomic model. The Phormidium protein exists as a trimer of αβ monomers in solution and in crystal lattice. The overall tertiary structures of αand βsubunits, and trimeric quaternary fold of the Phormidium protein resemble the other known APC structures. Also, configuration and conformation of the two covalently bound PCB chromophores in the marine APC are same as those observed in fresh water cyanobacteria and marine red algae. More hydrophobic residues, however, constitute the environment of the chromophore bound to α-subunit of the Phormidium protein, owing mainly to amino acid substitutions in the marine protein.
Phycobilisomes present in cyanobacteria are photosynthetic macromolecular protein complexes that ... more Phycobilisomes present in cyanobacteria are photosynthetic macromolecular protein complexes that are categorized into three types - phycoerythrins (high energy), phycocyanin (intermediate energy) and allophycocyanin (low energy). Structurally, they consist of α and β protein subunits and open chain tetrapyrrole prosthetic group (bilin chromophore), known for its antioxidant properties and therapeutic potential against a variety of physiological ailments. Phycoerythrins (C-PE) were purified from cyanobacterial strains Phormidium sp. A27DM and Halomicronema sp. A32DM and their respective apoptotic potentials were assessed on A549 human lung carcinoma cells. Both strains of cyanobacteria were cultured and the C-PE from each strain was extracted, quantified and characterized. C-PE accounted for a dose dependent decrement in cell viability, mitochondrial membrane potential and an increment in lactate dehydrogenase release. Higher doses of C-PE (of both strains) accounted for loss of cell viability and nuclear pycnosis. These findings were further substantiated with flow cytometry that revealed a cell arrest at G0/G1 phase and a high percentage of cells undergoing apoptosis following C-PE treatment. These results confirm the efficacy of C-PE from Phormidium sp. or Halomicronema sp. in triggering apoptotic cell death. This study is the first to report on apoptotic property of C-PE against A549 human lung carcinoma cells and warrants further studies to establish its anti-cancer potential.
Polyvinyl alcohol (PVA)-boric acid method has been utilized for entrapment of Candida rugosa lipa... more Polyvinyl alcohol (PVA)-boric acid method has been utilized for entrapment of Candida rugosa lipase. Immobilized lipase was used to produce ethyl butyrate, a flavour ester showing 80.2% conversion in 72 h. Lipase in PVA-boric acid beads possessed the ability to synthesize variety of esters and was stable in various organic solvents with varying log P value from 2 to 8 under incubation at 50°C for 1 h.The immobilized lipase showed nearly full retention of activity even after 8 cycles of use, the activity then gradually decreased reaching to 56% conversion efficiency after 20 cycles and possesses a shelf-life of 10 months. The thermostability of the lipase increased three times upon immobilization. The immobilized enzyme possessed 40% higher activity compared to its free counterpart.
Journal of Microbiology and Biotechnology, Apr 1, 2008
In our previous study, a surfactant-coated Candida rugosa lipase immobilized in microemulsion-bas... more In our previous study, a surfactant-coated Candida rugosa lipase immobilized in microemulsion-based organogels was exploited for the synthesis of ethyl isovalerate. In the present study, we are focusing on the effective reuse of lipase immobilized in microemulsion-based organogels (MBGs) in terms of retainment of the catalytic activity. As water is one of the co-products in esterification reactions, the removal of water becomes a priority to allow the reaction to work in the forward direction and to prevent back hydrolysis. Taking this fact into consideration, the lipase-containing microemulsion-based organogels were given pretreatment and/or several intermittent treatments with dry reverse micellar solution of AOT in organic solvent during repeated cycles of ester synthesis. The pretreated MBGs with dry reverse micellar solution exhibited lower water content and higher initial rates of esterification in comparison with untreated freshly prepared MBGs. The esterification efficiency of untreated MBGs started decreasing after 5 cycles of reuse and was almost completely lost by the end of the 8th cycle. In contrast, pretreated MBGs exhibited a gradual decrease in esterification efficiency after 5 cycles and retained about 80% of the initial activity at the end of the 8th cycle. The intermittent treatment of MBGs after every 3 cycles resulted in enhanced reusability of immobilized lipase for up to 9 cycles without significant loss in esterification activity, after which it resulted in a slow decrease in activity with about 27% lower activity at the end of the 12th cycle. Furthermore, the treatment conditions such as concentration of AOT in liquid dessicant and time of treatment were optimized with respect to our system. The granulated MBGs proved to be better in terms of initial esterification rates (1.2- fold) as compared with the pelleted MBGs.
The aim of this study was to treat the wastewater collected from equalization tank of Common Effl... more The aim of this study was to treat the wastewater collected from equalization tank of Common Effluent Treatment Plant (CETP), which was a mixture of waste coming from 525 small-scale industries manufacturing textile and dyestuff intermediate, pigments and pharmaceuticals. Initially a pretreatment using ferric chloride and lime was carried out to increase the biodegradability (BOD(5)/COD) of the effluent, which showed color removal of 74% and COD reduction of 75% at a concentration of 10 and 4 g/L. respectively. The biological treatment system using anaerobic fixed film reactor was investigated as secondary treatment. A mixture of bacterial consortium DMAB and cowdung slurry was used for the formation of biofilm. The effect of hydraulic retention time (HRT) and organic loading rate (OLR) on the efficiency of treatment of anaerobic reactor was analysed. Subsequent aerobic treatment after anaerobic step using aerobic culture Pseudomonas aeroginosa helped in further removal of COD and color. Formation of aromatic amines during anaerobic treatment was mineralized by sequential aerobic treatment.
A semi-synthetic designed medium (SDM), containing azo dyes, salts and other additives, was treat... more A semi-synthetic designed medium (SDM), containing azo dyes, salts and other additives, was treated in a laboratory-scale upflow microaerophilic fixed-film bioreactor (UMFB) at various hydraulic retention times (HRT) in order to obtain efficient COD removal and decolorization using consortium VIE6. Grau's second order and modified Stover-Kincannon substrate removal kinetic models were the best fitting models for the steady-state experimental data of UMFB. The efficacy of microaerophilic process to treat SDM at varying shock-loads (high dye and salt concentrations) was assessed simultaneously. The best organic matter removal efficiency, measured as Chemical Oxygen Demand (COD), was 98 % and decolorization was 99 % at 2 d HRT. UMFB endured shock-loads of dye and salts up to 500 mg L -1 and 80 g L -1 , respectively, at 2 d HRT. Bio-film configured system operating in UMFB, having charcoal as supporting material, showed overall better efficiency in treating SDM, and even after reactor completion, the bio-film remained in immobilized form showed its stability to withstand the toxic shock loads. In addition, metabolites produced during microaerophilic processes were determined along with community dynamics of consortium VIE6. The role of each organism in a community was elucidated based on their dominance in the effluent at 2 d HRT. Moreover, phytotoxicity analysis of SDM and its bio-degraded products after treatment showed acute decline in the toxicity of metabolites as compared to SDM.
Three liquid phases (viz. aqueous, nonaqueous, and reverse micelles) were scrutinized as medium f... more Three liquid phases (viz. aqueous, nonaqueous, and reverse micelles) were scrutinized as medium for attachment of the enzyme Candida rugosa lipase (CRL) onto multiwalled carbon nanotubes (CNTs). The nanotubes were functionalized to attain carboxyl and amino groups on their surfaces before enzyme conjugation. Transmission electron microscopy and Fourier transformation infrared spectroscopic studies were used for characterization of the nanotubes during the course of functionalization. High enzyme loadings associated with the functionalized CNTs were observed when reverse micelles were used as the attachment medium. In addition, high activity in terms of ester synthesis in organic solvents was also observed while using those preparations. The nanobioconjugates prepared using reverse micelles were found to be highly sturdy and exhibited appreciable operational stability of around 95 ± 3% at 20th cycle (in case of carboxylated nanotubes) and 90 ± 5% at 10th cycle (in case of aminated nanotubes) for esterification. This shows the potential application of reverse micelles as the attachment medium for surface active enzymes such as CRL onto CNTs.
Lipase from Candida rugosa was coated with surfactants and immobilized on silica to catalyze este... more Lipase from Candida rugosa was coated with surfactants and immobilized on silica to catalyze esterification reaction to produce ethyl butyrate, a flavour ester. Various surfactants were tested amongst which non-ionic surfactant performed better than cationic surfactant, whereas ...
This paper describes the improvement of anaerobic digestion processdue to the addition of various... more This paper describes the improvement of anaerobic digestion processdue to the addition of various surfactants and adsorbents in differentcombinations. Among the different combinations tested mixtureof silica gel (2000 mg litreJ) and sodium lauryl sulphate (300 mg lirre") showed maximum enhancement in gas productionas well as methanecontent indicating better process perfcinnance.
International Journal of Hydrogen Energy, Apr 1, 1993
We report a new observation: the phenomenon of photoosmosis due to liquid membrane bilayers gener... more We report a new observation: the phenomenon of photoosmosis due to liquid membrane bilayers generated by phycoerythrin on a supporting membrane. The magnitude of light-induced volume flow depends upon the intensity and wavelength of the exciting light, temperature and nature and concentration of electron donors and electron acceptors. When phycoerythrin is combined with bacteriorhodopsin the rate of photoosmotic velocity is much greater than that generated by the individual pigment.
Journal of Colloid and Interface Science, Oct 1, 1992
... References. Photoosmosis through Liquid Membrane Bilayers Generated by Mixture of Bacteriorho... more ... References. Photoosmosis through Liquid Membrane Bilayers Generated by Mixture of Bacteriorhodopsin and Cyanocobalamin DATTA MADAMWAR1 AND NIKKI JAIN Postgraduate ... 3. Tien, HT, "Bilayer Liquid MembraneTheory and Practice," p. 361. Dekker, New York, 1974. ...
TO obtain enriched methane content and improve the anaerobic digestion of a mixture of cattle dun... more TO obtain enriched methane content and improve the anaerobic digestion of a mixture of cattle dung f poultry waste and cheese whey, with enriched methane content, the effect of various surfactants was studied. Among the surfactants tested, Tween 80 and sodium lauryl sulphate showed the maximum enhancement in gas production as well as methane content, indicating better process performance. The Tween 80 dosed digester (300 JJL/L) produced about 3.5 L gas/L of digester/d with 70% methane. Results also indicated increased percent COD reduction in the presence of Tween 80. Keywords.
The crystallographic analysis of a marine cyanobacterium (Phormidium sp. A09DM) phycoerythrin (PE... more The crystallographic analysis of a marine cyanobacterium (Phormidium sp. A09DM) phycoerythrin (PE) that shows distinct sequence features compared with known PE structures from cyanobacteria and red algae is reported. Phormidium PE was crystallized using the sitting-drop vapour-diffusion method with ammonium sulfate as a precipitant. Diffraction data were collected on the protein crystallography beamline at the Indus-2 synchrotron. The crystals diffracted to about 2.1 A ˚resolution at 100 K. The crystals, with an apparent hexagonal morphology, belonged to space group P1, with unit-cell parameters a = 108.
This explains some of the differences seen in previous lower resolution structures determined at ... more This explains some of the differences seen in previous lower resolution structures determined at two different pH values (Kumar et al. in Photosyn Res 129:17-28, 2016).
International Biodeterioration & Biodegradation, Mar 1, 2014
ABSTRACT Endoglucanase production was carried out using in-house isolate Aspergillus terreus on r... more ABSTRACT Endoglucanase production was carried out using in-house isolate Aspergillus terreus on rice straw under solid state fermentation. An increase of 1.25-fold endoglucanase production was obtained under optimized conditions using response surface methodology. The enzyme was purified to homogeneity by gel filtration chromatography. Its molecular weight was determined as 28.18 kDa by gel filtration and 29.13 kDa on SDS-PAGE. The enzyme displayed maximum activity at 50 °C and pH 4.8. It was stable for 240 min at 50 °C and 120 min at 60 °C but rapidly inactivated at 70 °C. The purified enzyme was specific towards carboxymethyl-cellulose but showed no activity for cellobiose or xylan. Maximum velocity (Vmax) and KM were 16.15 μmol min−1 mg−1 and 12.01 mg ml−1, respectively. AgNO3, KCl, NaCl, and MnSO4 were found to inhibit enzyme activity while CaCl2 and ZnSO4 activated the enzyme. Internal peptide mass fingerprinting analysis identified that the protein belongs to GH12 superfamily endoglucanases. External supplementation of the purified enzyme to the crude cellulase showed 38.7% increase in saccharification efficiency of the delignified rice straw compared to the crude cellulase alone. The results demonstrated that the addition of GH 12 family purified endoglucanase to the crude cellulase can efficiently convert lignocellulosic biomass to fermentable sugars.
The liquid membrane bilayers generated by cytochrome-C have been shown to exhibit the phenomenon ... more The liquid membrane bilayers generated by cytochrome-C have been shown to exhibit the phenomenon of photo-osmosis. Data on the variation of photo-osmotic velocity with wavelength and intensity of the exciting light and concentration and the choice of redox chemicals are reported.
Isolated phycobilisome (PBS) sub-assemblies have been widely subjected to X-ray crystallography a... more Isolated phycobilisome (PBS) sub-assemblies have been widely subjected to X-ray crystallography analysis to obtain greater insights into the structure-function relationship of this light harvesting complex. Allophycocyanin (APC) is the phycobiliprotein always found in the PBS core complex. Phycocyanobilin (PCB) chromophores, covalently bound to conserved Cys residues of αand βsubunits of APC, are responsible for solar energy absorption from phycocyanin and for transfer to photosynthetic apparatus. In the known APC structures, heterodimers of αand βsubunits (known as αβ monomers) assemble as trimer or hexamer. We here for the first time report the crystal structure of APC isolated from a marine cyanobacterium (Phormidium sp. A09DM). The crystal structure has been refined against all the observed data to the resolution of 2.51 Å to R work (R free ) of 0.158 (0.229) with good stereochemistry of the atomic model. The Phormidium protein exists as a trimer of αβ monomers in solution and in crystal lattice. The overall tertiary structures of αand βsubunits, and trimeric quaternary fold of the Phormidium protein resemble the other known APC structures. Also, configuration and conformation of the two covalently bound PCB chromophores in the marine APC are same as those observed in fresh water cyanobacteria and marine red algae. More hydrophobic residues, however, constitute the environment of the chromophore bound to α-subunit of the Phormidium protein, owing mainly to amino acid substitutions in the marine protein.
Phycobilisomes present in cyanobacteria are photosynthetic macromolecular protein complexes that ... more Phycobilisomes present in cyanobacteria are photosynthetic macromolecular protein complexes that are categorized into three types - phycoerythrins (high energy), phycocyanin (intermediate energy) and allophycocyanin (low energy). Structurally, they consist of α and β protein subunits and open chain tetrapyrrole prosthetic group (bilin chromophore), known for its antioxidant properties and therapeutic potential against a variety of physiological ailments. Phycoerythrins (C-PE) were purified from cyanobacterial strains Phormidium sp. A27DM and Halomicronema sp. A32DM and their respective apoptotic potentials were assessed on A549 human lung carcinoma cells. Both strains of cyanobacteria were cultured and the C-PE from each strain was extracted, quantified and characterized. C-PE accounted for a dose dependent decrement in cell viability, mitochondrial membrane potential and an increment in lactate dehydrogenase release. Higher doses of C-PE (of both strains) accounted for loss of cell viability and nuclear pycnosis. These findings were further substantiated with flow cytometry that revealed a cell arrest at G0/G1 phase and a high percentage of cells undergoing apoptosis following C-PE treatment. These results confirm the efficacy of C-PE from Phormidium sp. or Halomicronema sp. in triggering apoptotic cell death. This study is the first to report on apoptotic property of C-PE against A549 human lung carcinoma cells and warrants further studies to establish its anti-cancer potential.
Polyvinyl alcohol (PVA)-boric acid method has been utilized for entrapment of Candida rugosa lipa... more Polyvinyl alcohol (PVA)-boric acid method has been utilized for entrapment of Candida rugosa lipase. Immobilized lipase was used to produce ethyl butyrate, a flavour ester showing 80.2% conversion in 72 h. Lipase in PVA-boric acid beads possessed the ability to synthesize variety of esters and was stable in various organic solvents with varying log P value from 2 to 8 under incubation at 50°C for 1 h.The immobilized lipase showed nearly full retention of activity even after 8 cycles of use, the activity then gradually decreased reaching to 56% conversion efficiency after 20 cycles and possesses a shelf-life of 10 months. The thermostability of the lipase increased three times upon immobilization. The immobilized enzyme possessed 40% higher activity compared to its free counterpart.
Journal of Microbiology and Biotechnology, Apr 1, 2008
In our previous study, a surfactant-coated Candida rugosa lipase immobilized in microemulsion-bas... more In our previous study, a surfactant-coated Candida rugosa lipase immobilized in microemulsion-based organogels was exploited for the synthesis of ethyl isovalerate. In the present study, we are focusing on the effective reuse of lipase immobilized in microemulsion-based organogels (MBGs) in terms of retainment of the catalytic activity. As water is one of the co-products in esterification reactions, the removal of water becomes a priority to allow the reaction to work in the forward direction and to prevent back hydrolysis. Taking this fact into consideration, the lipase-containing microemulsion-based organogels were given pretreatment and/or several intermittent treatments with dry reverse micellar solution of AOT in organic solvent during repeated cycles of ester synthesis. The pretreated MBGs with dry reverse micellar solution exhibited lower water content and higher initial rates of esterification in comparison with untreated freshly prepared MBGs. The esterification efficiency of untreated MBGs started decreasing after 5 cycles of reuse and was almost completely lost by the end of the 8th cycle. In contrast, pretreated MBGs exhibited a gradual decrease in esterification efficiency after 5 cycles and retained about 80% of the initial activity at the end of the 8th cycle. The intermittent treatment of MBGs after every 3 cycles resulted in enhanced reusability of immobilized lipase for up to 9 cycles without significant loss in esterification activity, after which it resulted in a slow decrease in activity with about 27% lower activity at the end of the 12th cycle. Furthermore, the treatment conditions such as concentration of AOT in liquid dessicant and time of treatment were optimized with respect to our system. The granulated MBGs proved to be better in terms of initial esterification rates (1.2- fold) as compared with the pelleted MBGs.
The aim of this study was to treat the wastewater collected from equalization tank of Common Effl... more The aim of this study was to treat the wastewater collected from equalization tank of Common Effluent Treatment Plant (CETP), which was a mixture of waste coming from 525 small-scale industries manufacturing textile and dyestuff intermediate, pigments and pharmaceuticals. Initially a pretreatment using ferric chloride and lime was carried out to increase the biodegradability (BOD(5)/COD) of the effluent, which showed color removal of 74% and COD reduction of 75% at a concentration of 10 and 4 g/L. respectively. The biological treatment system using anaerobic fixed film reactor was investigated as secondary treatment. A mixture of bacterial consortium DMAB and cowdung slurry was used for the formation of biofilm. The effect of hydraulic retention time (HRT) and organic loading rate (OLR) on the efficiency of treatment of anaerobic reactor was analysed. Subsequent aerobic treatment after anaerobic step using aerobic culture Pseudomonas aeroginosa helped in further removal of COD and color. Formation of aromatic amines during anaerobic treatment was mineralized by sequential aerobic treatment.
A semi-synthetic designed medium (SDM), containing azo dyes, salts and other additives, was treat... more A semi-synthetic designed medium (SDM), containing azo dyes, salts and other additives, was treated in a laboratory-scale upflow microaerophilic fixed-film bioreactor (UMFB) at various hydraulic retention times (HRT) in order to obtain efficient COD removal and decolorization using consortium VIE6. Grau's second order and modified Stover-Kincannon substrate removal kinetic models were the best fitting models for the steady-state experimental data of UMFB. The efficacy of microaerophilic process to treat SDM at varying shock-loads (high dye and salt concentrations) was assessed simultaneously. The best organic matter removal efficiency, measured as Chemical Oxygen Demand (COD), was 98 % and decolorization was 99 % at 2 d HRT. UMFB endured shock-loads of dye and salts up to 500 mg L -1 and 80 g L -1 , respectively, at 2 d HRT. Bio-film configured system operating in UMFB, having charcoal as supporting material, showed overall better efficiency in treating SDM, and even after reactor completion, the bio-film remained in immobilized form showed its stability to withstand the toxic shock loads. In addition, metabolites produced during microaerophilic processes were determined along with community dynamics of consortium VIE6. The role of each organism in a community was elucidated based on their dominance in the effluent at 2 d HRT. Moreover, phytotoxicity analysis of SDM and its bio-degraded products after treatment showed acute decline in the toxicity of metabolites as compared to SDM.
Three liquid phases (viz. aqueous, nonaqueous, and reverse micelles) were scrutinized as medium f... more Three liquid phases (viz. aqueous, nonaqueous, and reverse micelles) were scrutinized as medium for attachment of the enzyme Candida rugosa lipase (CRL) onto multiwalled carbon nanotubes (CNTs). The nanotubes were functionalized to attain carboxyl and amino groups on their surfaces before enzyme conjugation. Transmission electron microscopy and Fourier transformation infrared spectroscopic studies were used for characterization of the nanotubes during the course of functionalization. High enzyme loadings associated with the functionalized CNTs were observed when reverse micelles were used as the attachment medium. In addition, high activity in terms of ester synthesis in organic solvents was also observed while using those preparations. The nanobioconjugates prepared using reverse micelles were found to be highly sturdy and exhibited appreciable operational stability of around 95 ± 3% at 20th cycle (in case of carboxylated nanotubes) and 90 ± 5% at 10th cycle (in case of aminated nanotubes) for esterification. This shows the potential application of reverse micelles as the attachment medium for surface active enzymes such as CRL onto CNTs.
Lipase from Candida rugosa was coated with surfactants and immobilized on silica to catalyze este... more Lipase from Candida rugosa was coated with surfactants and immobilized on silica to catalyze esterification reaction to produce ethyl butyrate, a flavour ester. Various surfactants were tested amongst which non-ionic surfactant performed better than cationic surfactant, whereas ...
This paper describes the improvement of anaerobic digestion processdue to the addition of various... more This paper describes the improvement of anaerobic digestion processdue to the addition of various surfactants and adsorbents in differentcombinations. Among the different combinations tested mixtureof silica gel (2000 mg litreJ) and sodium lauryl sulphate (300 mg lirre") showed maximum enhancement in gas productionas well as methanecontent indicating better process perfcinnance.
International Journal of Hydrogen Energy, Apr 1, 1993
We report a new observation: the phenomenon of photoosmosis due to liquid membrane bilayers gener... more We report a new observation: the phenomenon of photoosmosis due to liquid membrane bilayers generated by phycoerythrin on a supporting membrane. The magnitude of light-induced volume flow depends upon the intensity and wavelength of the exciting light, temperature and nature and concentration of electron donors and electron acceptors. When phycoerythrin is combined with bacteriorhodopsin the rate of photoosmotic velocity is much greater than that generated by the individual pigment.
Journal of Colloid and Interface Science, Oct 1, 1992
... References. Photoosmosis through Liquid Membrane Bilayers Generated by Mixture of Bacteriorho... more ... References. Photoosmosis through Liquid Membrane Bilayers Generated by Mixture of Bacteriorhodopsin and Cyanocobalamin DATTA MADAMWAR1 AND NIKKI JAIN Postgraduate ... 3. Tien, HT, "Bilayer Liquid MembraneTheory and Practice," p. 361. Dekker, New York, 1974. ...
TO obtain enriched methane content and improve the anaerobic digestion of a mixture of cattle dun... more TO obtain enriched methane content and improve the anaerobic digestion of a mixture of cattle dung f poultry waste and cheese whey, with enriched methane content, the effect of various surfactants was studied. Among the surfactants tested, Tween 80 and sodium lauryl sulphate showed the maximum enhancement in gas production as well as methane content, indicating better process performance. The Tween 80 dosed digester (300 JJL/L) produced about 3.5 L gas/L of digester/d with 70% methane. Results also indicated increased percent COD reduction in the presence of Tween 80. Keywords.
The crystallographic analysis of a marine cyanobacterium (Phormidium sp. A09DM) phycoerythrin (PE... more The crystallographic analysis of a marine cyanobacterium (Phormidium sp. A09DM) phycoerythrin (PE) that shows distinct sequence features compared with known PE structures from cyanobacteria and red algae is reported. Phormidium PE was crystallized using the sitting-drop vapour-diffusion method with ammonium sulfate as a precipitant. Diffraction data were collected on the protein crystallography beamline at the Indus-2 synchrotron. The crystals diffracted to about 2.1 A ˚resolution at 100 K. The crystals, with an apparent hexagonal morphology, belonged to space group P1, with unit-cell parameters a = 108.
This explains some of the differences seen in previous lower resolution structures determined at ... more This explains some of the differences seen in previous lower resolution structures determined at two different pH values (Kumar et al. in Photosyn Res 129:17-28, 2016).
International Biodeterioration & Biodegradation, Mar 1, 2014
ABSTRACT Endoglucanase production was carried out using in-house isolate Aspergillus terreus on r... more ABSTRACT Endoglucanase production was carried out using in-house isolate Aspergillus terreus on rice straw under solid state fermentation. An increase of 1.25-fold endoglucanase production was obtained under optimized conditions using response surface methodology. The enzyme was purified to homogeneity by gel filtration chromatography. Its molecular weight was determined as 28.18 kDa by gel filtration and 29.13 kDa on SDS-PAGE. The enzyme displayed maximum activity at 50 °C and pH 4.8. It was stable for 240 min at 50 °C and 120 min at 60 °C but rapidly inactivated at 70 °C. The purified enzyme was specific towards carboxymethyl-cellulose but showed no activity for cellobiose or xylan. Maximum velocity (Vmax) and KM were 16.15 μmol min−1 mg−1 and 12.01 mg ml−1, respectively. AgNO3, KCl, NaCl, and MnSO4 were found to inhibit enzyme activity while CaCl2 and ZnSO4 activated the enzyme. Internal peptide mass fingerprinting analysis identified that the protein belongs to GH12 superfamily endoglucanases. External supplementation of the purified enzyme to the crude cellulase showed 38.7% increase in saccharification efficiency of the delignified rice straw compared to the crude cellulase alone. The results demonstrated that the addition of GH 12 family purified endoglucanase to the crude cellulase can efficiently convert lignocellulosic biomass to fermentable sugars.
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