Biodegradation of propanol and isopropanol by a mixed microbial consortium

The aerobic biodegradation of high concentrations of 1-propanol and 2-propanol (IPA) by a mixed microbial consortium was investigated. Solvent concentrations were one order of magnitude greater than any previously reported in the literature. The consortium utilized these solvents as their sole carbon source to a maximum cell density of 2.4 x 10⁹ cells ml^-1. Enrichment experiments with propanol or IPA as carbon sources were carried out in batch culture and maximum specific growth rates (µ(max)) calculated. At 20 °C, µ(max) values were calculated to be 0.0305 h^-1 and 0.1093 h^-1 on 1% (v/v) IPA and 1-propanol, respectively. Growth on propanol and IPA was carried out between temperatures of 10 °C and 45 °C. Temperature shock responses by the microbial consortium at temperatures above 45 °C were demonstrated by considerable cell flocculation. An increase in propanol substrate concentration from 1% (v/v) to 2% (v/v) decreased the µ(max) from 0.1093 h^-1 to 0.0715 h^-1. Maximum achievable biodegradation rates of propanol and IPA were 6.11 x 10^-3% (v/v) h^-1 and 2.72 x 10^-3% (v/v) h^-1, respectively. Generation of acetone during IPA biodegradation commenced at 264 h and reached a maximum concentration of 0.4% (v/v). The results demonstrate the potential of mixed microbial consortia in the bioremediation of solvent-containing waste streams.