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Articles by Sathyanarayana N. Gummadi
Total Records ( 4 ) for Sathyanarayana N. Gummadi
  Sathyanarayana N. Gummadi and D. Sunil Kumar
  Production of pectic lyases (PL and PGL) from Debaryomyces nepalensis has been optimized in submerged fermentation using Plackett-Burman design and response surface methodology. Four of the eleven fermentation variables (yeast extract, galactose, lemon peel and temperature) tested by Plackett-Burman design showed significant effect on both pectin lyase and pectate lyase production. The four screened variables were further optimized by central composite design. The optimal values of yeast extract, galactose, lemon peel powder and temperature for PL production was found to be 1.885, 0.956, 2.39% and 31.5°C and for PGL was at 2.5, 0.55, 2.4% and 32.7°C, respectively. The optimum activities of PL and PGL were found to be 10.73 and 8.73 U mL-1 after optimization which shows a 2.5 and 2.9 fold increase in PL and PGL production, respectively. This is the first time an optimization was done for production of PL and PGL by yeast Debaryomyces nepalensis. This could be an alternative to fungal pectolytic enzymes.
  Sathyanarayana N. Gummadi and Sawan Kumar
  The effect of temperature and salts on the growth of halotolerant yeast, Debaryomyces nepalensis was studied by growing cells in shake flask on rotary shaker and cell growth was measured. Specific growth rate (μ) of D. nepalensis increased with increase in temperature from 15 to 35 °C and then decreased with increase in temperature beyond 35 °C when grown in presence and absence of different salts. At 40 °C, both NaCl and KCl at 1.0 M concentration enhanced the specific growth rate. D. nepalensis showed synergistic effect on thermal and salt stress when grown at 35-40 °C (0.5 M NaCl) and 30-40 °C (0.5 and 1.0 M KCl). The organism was able to revert its specific growth rate when temperature was shifted from 20 °C to its optimum temperature for growth (30 °C) only in the presence of salts, which was not observed in the absence of salts. However, the same phenomenon was not observed when the temperature was shifted from 40 to 30 °C. Decrease in activation energy was observed for growth at salt concentration beyond 0.5 M of NaCl and KCl.
  Rajesh Kanna , Sathyanarayana N. Gummadi and G. Suresh Kumar
  Microbial compounds that exhibit pronounced surface and emulsifying activities are classified as biosurfactants. The effect of carbon and nitrogen sources and other physiological parameters affecting the biosurfactant production by Pseudomonas putida MTCC 2467 was studied. Different carbon and nitrogen sources were tested for biosurfactant production using minimal medium and it has been found that sucrose and ammonium sulphate were found to be the best carbon and nitrogen source. The effect of initial pH was studied by varying pH from 5.0-8.0 and maximum biosurfactant production, 2.8 g L-1 was achieved at an optimum pH of 8.0. The biosurfactant production was also monitored by measuring the liquid surface tension and interfacial tension and the results showed that the medium surface tension reduced from 74-35 mN m-1. The stability of biosurfactant was determined by varying pH, temperature, salinity and metal ions found that biosurfactant was stable at alkaline pH and higher temperature range suggesting that biosurfactant was highly stable, purified and checked for protein and lipid content and characterized by FTIR spectroscopy.
  Sathyanarayana N. Gummadi and D. Sunil Kumar
  Response surface methodology was used to study the effect of microbiological parameters, viz., plate age, inoculum age and amount of inoculum on production of pectin lyase and pectate lyase. Individual optimum values of plate age, inoculum age and amount of inoculum were found to be 31.5 h, 12 h and 5.3% (v/v), respectively for PL and 27 h, 14 h and 4.2% (v/v), respectively for PGL. At optimal conditions of PL 12.7 and 10.5 U mL-1 of PL and PGL was produced and at optimal conditions of PGL 12.2 and 10.4 U mL-1 of PL and PGL was obtained. Since, there is no much difference in PL and PGL production at two different optimal conditions, it can be concluded that enzyme production is not affected in the range of optimal conditions obtained in this study. Hence, the individual optimal values of microbiological parameters for PL or PGL can be used to develop seed culture for maximum production of both PL and PGL. At optimal conditions the production of PL and PGL was increased by 1.2 fold, respectively.
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