Use of Response Surface Methodology to Study the Combined Effect of Salt, pH, and Temperature on the Growth of Food-Spoiling Halotolerant Yeast, Debaryomyces nepalensis NCYC 3413 |
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Authors: | Pradeep Lal Sawan Kumar Sathyanarayana N Gummadi |
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Affiliation: | (1) Applied and Industrial Microbiology Laboratory, Department of Biotechnology, Indian Institute of Technology-Madras, Chennai, 600 036, India; |
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Abstract: | This paper reports the interaction of salt (NaCl and KCl), initial pH, and temperature and their effects on the specific growth
rate and lag phase of food spoiling halotolerant yeast, Debaryomyces nepalensis. The optimization of salt, initial pH, and temperature was carried out using response surface methodology based on central
composite design. The mathematical model showed that salt has a significant effect on specific growth rate and lag phase of
D. nepalensis. The optimal conditions of salt concentration, pH, and temperature of growth were found to be 0.3 M NaCl, 7.1, 26 °C and
0.6 M KCl, 5.6, 25°C, respectively. Under these conditions, a maximum specific growth rate of 0.41 and 0.5 h−1 was observed in medium containing NaCl and KCl, respectively. Lag phase can be increased most effectively either by increasing
salt concentrations or both by decreasing (≤20°C) or increasing the temperature (≥40°C) with moderate (1.5 M) or low salt
concentration (0.5 M), respectively. Results show that D. nepalensis need to generate weak acids to maintain the intracellular pH under pH and saline stress conditions. The results obtained
in this study will be helpful in using optimal conditions for the maximum growth of the strain for the production of certain
metabolites like organic acids and glycerol and designing food preservation procedures. |
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