Biodegradation of Phenol by Actinobacillus Sp.: Mathematical Interpretation and Effect of Some Growth Conditions
Titel:
Biodegradation of Phenol by Actinobacillus Sp.: Mathematical Interpretation and Effect of Some Growth Conditions
Auteur:
Khleifat, Khaled M.
Verschenen in:
Bioremediation journal
Paginering:
Jaargang 11 (2007) nr. 3 pagina's 103-112
Jaar:
2007-07
Inhoud:
Models of the cultivation process of Actinobacillus sp. cells in two media, rich (NB) and minimal (M9) that includes phenol as a sole carbon source, have not been described in the available literature. For these reasons, several single-substrate inhibition models (Monod, Andrew, and Tesseir) were investigated in order to determine the mathematical expression of Actinobacillus sp. growth rate. The experimental data for both nutrient broth and M9 media were fitted to the above models mentioning that Andrews' model best fits these data adequately for both media with regression coefficient of 0.973 and 0.962, respectively. The maximum predicted growth rate by this model is 0.37 h- 1 for both media obtained when the initial concentration of phenol is 100 mg/L. The half-saturation concentration constant, KP, is 1.00 mg/L, which represents the phenol concentration when μ is equal to half μmax. On the other hand, the inhibition constant, Kp is 13,000.00 mg/L for broth medium and 12,000 mg/L for M9 medium, which is a measure of sensitivity to inhibition by inhibitory substances. When cells are grown in nutrient broth and minimal media, the rate of cell production with time can be expressed by the Reccati and Voltera models. Voltera model better fits in the case of M9 minimal medium plus phenol as sole carbon source. The pH of 7, the incubation temperature of 35°C to 37°C, and the agitation rate of 150 rpm are the optimal conditions for achieving the higher percentage of phenol degradation by Actinobacillus sp. Succinic acid and glycine as carbon and nitrogen source, respectively, were the most efficient of the cosubstrates (out of 10 substrates tested) for removal of phenol on an mg/L basis.
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