THE BIOOXIDATION OF METHANOL, ETHANOL AND ISOPROPANOL BY A DEFINED CO-CULTURE AT ELEVATED-TEMPERATURES

The introduction of more imaginative enrichment and isolation procedures has permitted the isolation of pure cultures of thermotolerant methylotrophic bacteria, a group that was previously unknown. One potential application for such bacteria is in the aerobic biotreatment of petrochemical industry wastewaters at elevated temperatures. Here, the growth and biooxidation characteristics of one such bacterium, Bacillus sp. NCIB 12522, in co-culture with a Gram-negative thermophilic non-methylotrophic solvent utilizing bacterium, NA 17, on a mixture of methanol, ethanol and isopropanol, under both steady and transient state continuous flow culture conditions are reported. The results indicate that at dilution rates <0.2 h-1 effective biooxidation can be achieved at temperatures between 50° and 57 °C. As a result of step increases in bioreactor feed concentrations, the fraction of the methylotroph present in the co-culture changed according to whether the methanol or the ethanol concentrations were increased, but when isopropanol was increased, no change in the methylotroph fraction occurred between the initial and final steady states. © 1990 Springer-Verlag.