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Retention and regeneration of native NAD(H) in noncharged ultrafiltration membrane reactors: Application to l‐lactate and gluconate production
Author(s) -
Obón José María,
Manjón Arturo,
Iborra José Luis
Publication year - 1998
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/(sici)1097-0290(19980305)57:5<510::aid-bit2>3.0.co;2-j
Subject(s) - nad+ kinase , ultrafiltration (renal) , lactate dehydrogenase , chemistry , dehydrogenase , chromatography , cofactor , membrane , enzyme , biochemistry , bovine serum albumin
NAD(H) was retained in a noncharged ultrafiltration membrane reactor for the simultaneous and continuous production of l ‐lactate and gluconate with coenzyme regeneration. Polyethyleneimine (PEI), a 50‐kDa cationic polymer, achieved coenzyme retentions above 0.8 for PEI/NAD(H) molar ratios higher than 5. The ionic strength of the inlet medium caused a decrease of NAD(H) retention that can be counterbalanced by an initial addition of 1% bovine serum albumin (BSA). Continuous reactor performance in the presence of PEI and BSA showed that NAD(H), glucose dehydrogenase, and lactate dehydrogenase were retained by 10‐kDa ultrafiltration membranes; l ‐lactate and gluconate were produced at conversions higher than 95%. PEI enhanced the thermal stability of the enzymes used and increased the catalytic efficiency of glucose dehydrogenase, while no effect was found on the kinetic parameters of lactate dehydrogenase. A model that implements the kinetic equations of the two enzymes describes the reactor behavior satisfactorily. In brief, the use of PEI to retain NAD(H) is a new interesting approach to be widely applied in continuous synthesis with the large number of known dehydrogenases. ©1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 510‐517, 1998.