Dehalogenation of a gaseous effluent by dehydrated whole cells in a solid/gas reactor: A study of catalyst stability

Dehydrated cells of recombinant Escherichia coli producing a halidohydrolase have been used as catalyst for the continuous hydrolysis of gaseous 1-chlorobutane. Viability was not required for catalysis but a low stability was observed. At 40 degrees C and water activity of 0.7, this behavior could be explained by two main phenomena. Thermal denaturation induced the irreversible inactivation of 55% of the catalyst during the first 16 h of reaction, whereas accumulation of HCl acidified the medium and led to a reversible decrease in enzyme activity. Damage caused by the release of proteases during catalyst preparation did not seem to be a major factor. Since neither 1-chlorobutane nor 1-butanol accumulated in the bioreactor, the decrease in activity was not due to the accumulation of these compounds.