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Highlights: [•] Substrate degradation with incorporation of maintenance energy expenditure has been modeled. [•] The biodegradation dynamics has been modeled in the two dual substrate systems. [•] Quantitative assessment of interaction parameters in two dual substrate systems. [•] p-Cresol degradation is difficult in presence of phenol whereas resorcinol shows reverse effect. [ABSTRACT FROM AUTHOR]

Abstract: Biodegradation of resorcinol and p-cresol using fungus Gliomastix indicus MTCC 3869 was investigated in batch culture experiments at 28°C temperature and pH of 6 in the medium up to the initial concentration of 1300mg/L and 700mg/L for resorcinol and p-cresol, respectively. Five specific growth kinetic models and five specific degradation rate models were fitted to the experimental data in order to get best fitted kinetic models. The variation of observed growth yield and maintenance energy requirement with the initial substrate concentration was also studied. The model for maintenance energy coefficient was fitted to the experimental data. The model parameters were: m 1 =0.0135h−1, k =0.054, μ max =0.132h−1 for resorcinol and m 1 =0.0229h−1, k =0.011, μ max =0.102h−1 for p-cresol. Two mathematical models comprising of two sets of ODE were solved simultaneously to get degradation profiles with time. The model with varying growth yield and maintenance energy was found to be most appropriate biodegradation model. [Copyright &y& Elsevier]

Abstract: Biodegradation of p-cresol by a pure culture of new filamentous fungal strain Gliomastix indicus was studied. The fungus strain was acclimatized to the higher concentration of 700mg/l of p-cresol in modified czapeck medium over a period of two months. The lag period was 24h. The shake flask batch experiments were carried out at temperature of 28°C and pH of 6 over a wide range of initial p-cresol concentration (10–700mg/l) keeping initial biomass concentration constant at 18.72mg/l. Experimentally it was observed that p-cresol was inhibitory type substrate and the inhibition effect of p-cresol became predominant above a concentration of 50mg/l. The kinetics of cell growth and p-cresol degradation were investigated. Six kinetic models (Haldane, Andrews, Webb, Yano, Aiba, and Teissier) were fitted to the experimental growth kinetic data. Models by Haldane, Andrews, Webb and Yano (correlation coefficient R 2 >0.99) were found to be most suitable models. In addition, the variation of observed yield coefficient Y X with specific growth rate μ g was investigated. The maintenance energy coefficient and true growth yield coefficient, were found to be 0.0227h−1 and 1.0708(mg/mg), respectively. The specific substrate utilization rate was represented in terms of specific biomass growth rate. The decay coefficient was found to be 0.0055h−1. The effect of pH and nitrogen source of medium on biodegradation of p-cresol was investigated as well. [Copyright &y& Elsevier]

Abstract: Biological degradation of phenol and catechol by a bacterial strain of Pseudomonas putida (MTCC 1194) in basal salt medium (BSM) was investigated in shake-flask experiments at 29.9±0.3°C and pH of approximately 7.1. The lyophilized cultures of P. putida (MTCC 1194) were revived and exposed to increasing concentrations of phenol, and catechol in shake-flasks. This bacterial strain could be acclimatized to the concentrations of 1000 and 500mg/l for phenol and catechol, respectively, over a period of three months. The higher the concentration of phenol or catechol, the longer was the lag period. The well-acclimatized culture of P. putida (MTCC 1194) degraded the initial phenol concentration of 1000mg/l and initial catechol concentration of 500mg/l completely in 162 and 94h, respectively. Both the phenol and catechol were observed to be the inhibitory compounds. Monod''s and linearized-Haldane''s model could not represent the growth kinetics over the studied concentration range. However, Haldane''s growth kinetics model could be fitted to the growth kinetics data well for the entire concentration range. Further, the decay coefficients have been found to be 0.0056 and 0.0067h-1 for the growth on phenol and catechol, respectively. Besides, the yield coefficient for the growth on phenol and catechol were found to be 0.65 and 0.50mg/mg, respectively. It is our view that the above information would be useful for modeling and designing the units treating phenol- and catechol-containing wastewaters. [Copyright &y& Elsevier]