Substrate and water adsorption phenomena in a gas/solid enzymatic reactor

Kerasina Dimoula (1) , Martina Pohl (2) , Jochen Büchs (3) , Antje C Spiess (3)

1 Aachener Verfahrenstechnik - Biochemical Engineering
2 Institute of Molecular Enzyme Technology-Research Center Jülich
3 Aachener Verfahrenstechnik - Biochemical Engineering

The adsorption of water and substrates to dry deposited alcohol dehydrogenase from Lactobacillus brevis (LBADH) is studied in a continuous enzymatic gas/solid reactor. This work is aiming at obtaining a deeper and more thorough understanding of the enzyme microenvironment in the gas/solid system of acetophenone reduction with concomitant oxidation of 2-propanol. Extensive water adsorption studies showed that the effect of sucrose in the enzyme preparation on the water adsorption isotherm is significant for water activities exceeding 0.5 and reaches a factor 2 with respect to bead mass at aw=0.9. Significant hysteresis during water desorption is identified, resulting g in up to 0.6 mgwater/mgprotein, for lyophilized enzyme preparation and up to 10 mgwater/mgprotein for deposited enzyme preparation The adsorption of the substrates is quantified here for the first time. Whereas the adsorption of the main substrate, acetophenone, may reach a significant level of up to 6 mg/mgprotein, at an acetophenone activity of 0.32, the secondary substrate, 2-propanol is not adsorbed at a detectable degree. The presence of water leads to a decrease of the adsorbed amount of acetophenone, by approximately 25%, at a water activity of 0.54.

Mots clés: Life Sciences

Kerasina Dimoula, Martina Pohl, Jochen Büchs, Antje C Spiess. Substrate and water adsorption phenomena in a gas/solid enzymatic reactor. Biotechnology Journal, 2009, 4 (6), pp.712-n/a. ⟨10.1002/biot.200800291⟩. ⟨hal-00480829⟩