Biodegradation of isopropanol in a three phase fixed bed bioreactor: start up and acclimation using a previously-enriched microbial culture.
The aerobic biodegradation of high liquid phase concentrations of 2-propanol (IPA) by a previously enriched solvent-tolerant bacterial consortium within a 1.9 l fed-batch three phase fixed bed bioreactor was investigated. Solvent concentrations of up to 7.9 g l(-1) were investigated. Previously enriched solvent-tolerant bacterial cells were immobilised onto porous glass cylinders as a means obioprocess intensification. Bioreactor start-up and acclimation was studied anacetone concentration tracked as an indicator of IPA utilization, as the sole carbon source within a minimal salts medium (MSM). The initial batch treatment of IPA exhibited a biodegradation rate of 0.11 g l(-1) h(-1) prior to biofilm formation Biofilm growth during the second batch treatment was consistent with an increase in metabolic activity and an IPA biodegradation rate of 0.34 g l(-1), followed by a reduction of biodegradation rate to a constant value of 0.078 g l(-1) h(-1) after 650 h. A maximum acetone generation rate of 1.3 g l(-1) h(-1) was obtained during the fourth IPA addition although the maximum acetone biodegradation rate of 0.38 g l(-1) h(-1) was observed during the initial IPA addition. It is proposed that the metabolic lag resulting from switching from alcohol dehydrogenase to acetone carboxylase is a major rate-limiting step in the deep oxidation of IPA to acetone. The results demonstrate the potential of a previously enriched solvent-tolerant bacterial consortium in fixed bed bioreactor systems, for the aerobic treatment of concentrated solvent-containing wastestreams.
Bustard
M T
MT
Department of Mechanical and Chemical Engineering, Heriot-Watt University, Edinburgh, UK.
Meeyoo
V
V
Wright
P C
PC
D019840:2-Propanol / Q000378:metabolism*; D000096:Acetone / Q000378:metabolism; D001420:Bacteria, Aerobic / Q000502:physiology*; D001673:Biodegradation, Environmental; D018441:Biofilms; D007700:Kinetics; D012997:Solvents / Q000378:metabolism*; D014865:Waste Disposal, Fluid / Q000379:methods; D018508:Water Purification / Q000379:methods*
D012997:Solvents; D000096:Acetone; D019840:2-Propanol