Biokinetics of Protein Degrading Clostridium cadaveris and Clostridium sporogenes in Batch and Continuous Mode of Operations

Abstract

A quantitative real-time polymerase chain reaction (QPCR) was applied to estimate biokinetic coefficients of Clostridium cadaveris and Clostridium sporogenes, which utilize protein as carbon source. Experimental data on changes in peptone concentration and 16S rRNA gene copy numbers of C. cadaveris and C. sporogenes were fitted to model. The fourth-order Runge-Kutta approximation with non-linear least squares analysis was employed to solve the ordinary differential equations to estimate biokinetic coefficients. The maximum specific growth rate (mu(max)), half-saturation concentration (K-s), growth yield and decay coefficient (K-d) of C. cadaveris and C.sporogenes were 0.73 +/- 0.05 and 1.35 +/- 0.32 h(-1), 6.07 +/- 1.52 and 5.67 +/- 1.53 g/l, 2.25 +/- 0.75 x 10(19) and 7.92 +/- 3.71 x10(9) coples/g, 0.002 +/- 0.003 and 0.002 +/- 0.001 h(-1), respectively. The theoretical specific growth rate of C. sporogenes always exceeded that of C. cadaveris at peptone concentration higher than 3.62 g/l. When the influent peptone concentration was 5.0 g/l, the concentration of C.cadaveris gradually decreased to the steady value of 2.9 x 10(10) coples/ml at 4 h Hydraulic retention time (HRT), which indicates a 67.1% reduction of the initial population, but the wash out occurred at HRTs of 1.9 and 3.2 h. The 16S rRNA gene copy numbers of C. sporogenes gradually decreased to steady values ranging from 1.1 x 10(10) to 2.9 x 10(10) coples/ml. C. sporogenes species was predicted to wash out at an HRT of 1.6 h.