Biodegradation kinetics and interactions of styrene and ethylbenzene as single and dual substrates for a mixed bacterial culture

This study examined biodegradation kinetics of styrene and ethylbenzene as representatives of alkenylbenzenes andmono-alkylbenzenes, respectively. the compounds were studied independently and as binary mixtures using a series ofaerobic batch degradation experiments introduced by acclimatized mix culture. initial concentration of styrene andethylbenzene in the liquid phase vacillated from 0 to 220 mg/l. the andrew model was applied for the biodegradationof individual substrates and the estimated constants of the equation for styrene and ethylbenzene were ?max = 0.1581,0.2090 (1/h), ks =25.91, 37.77 (mg/l), ki =13.15, 62.62 (mg/l), respectively. the accomplished parameters from singlesubstrate degradation tests were used to predict possible interaction factors achieved from dual substrate experiments.the sum kinetics with interaction parameters (skip) model and the purely competitive enzyme kinetics model wereemployed to evaluate any interactions. the skip model was found to accurately describe these interactions. moreover, itwas revealed that ethylbenzene plays an influential role on styrene consumption (e.g. ie,s = 1.64) compared to styrenewhich has insignificant inhibitory effect on ethylbenzene usage (e.g. is,e =0.4) . the active site differences for styrene andethylbenzene biodegradation and the pathway variations for biodegradation are among the major potential reasons forfailure of the estimation that occurred in purely competitive kinetics model. this study is the first to calculate theinteractions between styrene and ethylbenzene.