Food and dietary water intake and their utilization in the new multivoltine breeds of silkworm Bo... more Food and dietary water intake and their utilization in the new multivoltine breeds of silkworm Bombyx marl L., viz. BL - 23, BL -24 and PM as control ted ad Ilbitum on M 5 mulberry leaf during 5th instar at the temperature of 26 ′ 1°C and 75 ′ 5% R.H. are reported. In the new multivoltine breeds, the larval duration was significantly shorter from 3.25 (BL - 23) to 3.50 (BL -24) days than the Pure Mysore race. The decrement in dry food consumed, food assimilated, assimilation efficiency, food oxidized, feeding rete, assimilation rate and metabolic rate was noticed in the new breeds when compared with the control. However, the conversion efficiencies (K 1 & K 2 ) and water retention efficiency were significantly higher in the new breeds. Due to higher conversion efficiencies, the larval biomass accumulation and cocoon conversion efficiencies were higher in the new breeds. The causative factors responsible for these changes have been discussed.
A detailed investigation of choline chloride-lactic acid (ChCl-LA)-based deep eutectic solvent (D... more A detailed investigation of choline chloride-lactic acid (ChCl-LA)-based deep eutectic solvent (DES) extraction of lignin nanoparticles from herbaceous biomass (wheat straw) was conducted. It was found that DES can extract high purity lignin (up to 94.8%) with a high yield (up to 81.5% from air-dried samples and 85.9% from oven-dried samples) from wheat straw. The cleavages of ether bonds in lignin, as well as the linkages between lignin and hemicelluloses during DES treatments at different conditions, were analyzed. The effects of reaction time, treatment temperature and water content in wheat straw on lignin yield, purity, and chemical structure were determined. The water content in biomass was found to affect the hydrogen bond interaction between lignin and DES, which was a key factor influencing the lignin extraction yield and chemical properties of separated lignin. The lignin extracted from wheat straw by DES consists of well-dispersed nanoparticles with a narrow size distribution peaking at 70–90 nm. The mechanism of ChCl-LA-based DES depolymerization and extraction of lignin from wheat straw is discussed.
Nitrogen supply is critical to the synthesis of intracellular PHA in various bacteria. However, t... more Nitrogen supply is critical to the synthesis of intracellular PHA in various bacteria. However, the specific role of the nitrogen in synthesizing PHA from benzoate, a lignin model compound use for the study of bacteria catabolism of aromatics, is still not clear. In this study, two culture conditions were maintained for Pseudomonas putida KT2440 to produce PHA using benzoate as a carbon source. Under nitrogen-limited and surplus conditions, the accumulation of PHA was to 37.3% and 0.25% of cell dry weight, respectively. A model fit to the kinetics of biomass growth and PHA accumulation showed good agreement with data. GC-MS and NMR showed that PHA contained six hydroxyl fatty acid monomers under nitrogen-limited conditions, while two monomers were identified under nitrogen surplus conditions. The average molecular weight of PHA increased after the nitrogen source was exhausted. These results provide a promising strategy for optimization of lignin to PHA yields.
Sericulturists in the vicinity of Bangalore city irrigate their mulberry gardens with Vrishabhava... more Sericulturists in the vicinity of Bangalore city irrigate their mulberry gardens with Vrishabhavathy stream water, which is polluted with domestic and industrial wastes from the city. To investigate the effect of pollutants on silkworm crops, a detailed field survey was conducted to study the cocoon yield pattern of the crops raised on mulberry irrigated with wastewater as against irrigation by bore/open wells. The villages along the stream were grouped into five test batches at about a distance of km from each other. The seasonal yield data with relevant information were collected through questionnaires from 117 rearers using stream water and 35 rearers using bore/open wells, the latter serving as control group. The average yield for 100 layings was 46 to 57 kg in the control group whereas in test groups, it ranged between 34 to 51 kg in the first test group and 22 to 38 kg in the rest. The difference in yield was kg depending on the season between control and test batches. In summ...
Journal of Industrial Microbiology & Biotechnology, 2007
Aspergillus strains are being considered as potential hosts for recombinant heterologous protein ... more Aspergillus strains are being considered as potential hosts for recombinant heterologous protein production because of their excellent extracellular enzyme production characteristics. However, Aspergillus proteases are problematic in that they modify and degrade the heterologous proteins in the extracellular medium. In previous studies we observed that media adjustments and maintenance of a filamentous morphology greatly reduced protease activity and that a low concentration of the aspartic protease inhibitor pepstatin inhibited the latter protease activity to the extent of approximately 90%. In this paper we report that when the serine protease inhibitor chymostatin is used in combination with pepstatin 99-100% of total protease activity in Aspergillus cultures is inhibited. In protease assays a concentration of 30 microM chymostatin combined with 0.075 microM pepstatin was required for maximum inhibition. Inhibitor concentrations of chymostatin and pepstatin of 120 and 0.3 microM, respectively, when added to Aspergillus cultures, has no significant effect on biomass production, glucose utilization or culture pH pattern. The potential of using these protease inhibitors in cultures of recombinant Aspergillus strains producing heterologous proteins will now be investigated to determine if the previously observed recombinant protein denaturing effects of Aspergillus proteases can be negated.
Food and dietary water intake and their utilization in the new multivoltine breeds of silkworm Bo... more Food and dietary water intake and their utilization in the new multivoltine breeds of silkworm Bombyx marl L., viz. BL - 23, BL -24 and PM as control ted ad Ilbitum on M 5 mulberry leaf during 5th instar at the temperature of 26 ′ 1°C and 75 ′ 5% R.H. are reported. In the new multivoltine breeds, the larval duration was significantly shorter from 3.25 (BL - 23) to 3.50 (BL -24) days than the Pure Mysore race. The decrement in dry food consumed, food assimilated, assimilation efficiency, food oxidized, feeding rete, assimilation rate and metabolic rate was noticed in the new breeds when compared with the control. However, the conversion efficiencies (K 1 & K 2 ) and water retention efficiency were significantly higher in the new breeds. Due to higher conversion efficiencies, the larval biomass accumulation and cocoon conversion efficiencies were higher in the new breeds. The causative factors responsible for these changes have been discussed.
A detailed investigation of choline chloride-lactic acid (ChCl-LA)-based deep eutectic solvent (D... more A detailed investigation of choline chloride-lactic acid (ChCl-LA)-based deep eutectic solvent (DES) extraction of lignin nanoparticles from herbaceous biomass (wheat straw) was conducted. It was found that DES can extract high purity lignin (up to 94.8%) with a high yield (up to 81.5% from air-dried samples and 85.9% from oven-dried samples) from wheat straw. The cleavages of ether bonds in lignin, as well as the linkages between lignin and hemicelluloses during DES treatments at different conditions, were analyzed. The effects of reaction time, treatment temperature and water content in wheat straw on lignin yield, purity, and chemical structure were determined. The water content in biomass was found to affect the hydrogen bond interaction between lignin and DES, which was a key factor influencing the lignin extraction yield and chemical properties of separated lignin. The lignin extracted from wheat straw by DES consists of well-dispersed nanoparticles with a narrow size distribution peaking at 70–90 nm. The mechanism of ChCl-LA-based DES depolymerization and extraction of lignin from wheat straw is discussed.
Nitrogen supply is critical to the synthesis of intracellular PHA in various bacteria. However, t... more Nitrogen supply is critical to the synthesis of intracellular PHA in various bacteria. However, the specific role of the nitrogen in synthesizing PHA from benzoate, a lignin model compound use for the study of bacteria catabolism of aromatics, is still not clear. In this study, two culture conditions were maintained for Pseudomonas putida KT2440 to produce PHA using benzoate as a carbon source. Under nitrogen-limited and surplus conditions, the accumulation of PHA was to 37.3% and 0.25% of cell dry weight, respectively. A model fit to the kinetics of biomass growth and PHA accumulation showed good agreement with data. GC-MS and NMR showed that PHA contained six hydroxyl fatty acid monomers under nitrogen-limited conditions, while two monomers were identified under nitrogen surplus conditions. The average molecular weight of PHA increased after the nitrogen source was exhausted. These results provide a promising strategy for optimization of lignin to PHA yields.
Sericulturists in the vicinity of Bangalore city irrigate their mulberry gardens with Vrishabhava... more Sericulturists in the vicinity of Bangalore city irrigate their mulberry gardens with Vrishabhavathy stream water, which is polluted with domestic and industrial wastes from the city. To investigate the effect of pollutants on silkworm crops, a detailed field survey was conducted to study the cocoon yield pattern of the crops raised on mulberry irrigated with wastewater as against irrigation by bore/open wells. The villages along the stream were grouped into five test batches at about a distance of km from each other. The seasonal yield data with relevant information were collected through questionnaires from 117 rearers using stream water and 35 rearers using bore/open wells, the latter serving as control group. The average yield for 100 layings was 46 to 57 kg in the control group whereas in test groups, it ranged between 34 to 51 kg in the first test group and 22 to 38 kg in the rest. The difference in yield was kg depending on the season between control and test batches. In summ...
Journal of Industrial Microbiology & Biotechnology, 2007
Aspergillus strains are being considered as potential hosts for recombinant heterologous protein ... more Aspergillus strains are being considered as potential hosts for recombinant heterologous protein production because of their excellent extracellular enzyme production characteristics. However, Aspergillus proteases are problematic in that they modify and degrade the heterologous proteins in the extracellular medium. In previous studies we observed that media adjustments and maintenance of a filamentous morphology greatly reduced protease activity and that a low concentration of the aspartic protease inhibitor pepstatin inhibited the latter protease activity to the extent of approximately 90%. In this paper we report that when the serine protease inhibitor chymostatin is used in combination with pepstatin 99-100% of total protease activity in Aspergillus cultures is inhibited. In protease assays a concentration of 30 microM chymostatin combined with 0.075 microM pepstatin was required for maximum inhibition. Inhibitor concentrations of chymostatin and pepstatin of 120 and 0.3 microM, respectively, when added to Aspergillus cultures, has no significant effect on biomass production, glucose utilization or culture pH pattern. The potential of using these protease inhibitors in cultures of recombinant Aspergillus strains producing heterologous proteins will now be investigated to determine if the previously observed recombinant protein denaturing effects of Aspergillus proteases can be negated.
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Papers by Aftab Ahamed