Production of Biobutanol by Clostridium Acetobutylicum

The socio-economic scenario of the third millennium revives the interest in production of biofuel for transport purposes by fermentation processes and the butanol appears to be a promising candidate. Present contribution reports about results of a research activity aiming at investigating the feasibility of the acetone-butanol-ethanol (ABE) production by Clostridium acetobutylicum ATCC824, adopting biofilm reactors for the process intensification. The kinetics of the ABE production process has been assessed by free C. acetobutylicum in batch reactors and in a CSTR equipped with a microfiltration unit. Solutions of lactose – concentration ranging between 10 and 100 g/L - were adopted. Tests carried out under batch conditions show that: i) cells growth is constant for lactose concentration (CL) smaller than 100 g/L; ii) the butanol specific production rate (rB) as a function of CL may be represented by a Monod-like kinetics; iii) the selectivity of butanol with respect to total solvents increases with CL and stabilizes at about 72%W for CL larger than 30 g/L. Preliminary tests carried out under continuous conditions show that the process takes advantage from the steady state operation under solventogenic conditions. The rB is larger in the CSTR than in the STR, when compared at the same CL.