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Kinetic studies of α‐galactosidase‐containing mold pellets on PNPG hydrolysis
Author(s) -
Kobayashi Harumi,
Suzuki Hideo
Publication year - 1976
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/bit.260180104
Subject(s) - thiele modulus , substrate (aquarium) , chemistry , pellets , pellet , diffusion , hydrolysis , chromatography , kinetics , enzymatic hydrolysis , reaction rate , reaction rate constant , product inhibition , enzyme , analytical chemistry (journal) , non competitive inhibition , organic chemistry , thermodynamics , materials science , mass transfer , catalysis , composite material , oceanography , physics , quantum mechanics , geology
Little is known about techniques for applying untreated microbial cells containing enzymes directly to industrial processes as a biocatalyst. The kinetic behavior of α‐galactosidase‐containing spherical pellets which are formed naturally under given conditions in a submerged culture of Mortierella vinacea was studied on the hydrolysis of PNPG ( p ‐nitrophenyl–α– D ‐galactopyranoside). The effect of intraparticle diffusion on the overall reaction rate was assessed by the use of an effectiveness factor, which was calculated by the approximate solution to the equation derived from the mass balance within a pellet. The experimental effectiveness factors were found to be represented as a single function of the modified Thiele modulus, including such parameters as pellet size, enzyme concentration in the pellet, and substrate concentration. As the diffusional effect became more significant, the marked substrate inhibition as seen for a five enzyme disappeared gradually. The effect of product inhibition on the pellets was much weaker than that for a free enzyme at a given substrate concentration. In the region of diffusion controlled reaction, it was found that the rate is proportional to the square root of the enzyme concentration in the pellet. In addition, similarly to what was reported previously for a free enzyme, the reaction in a batch system was found to be approximately representable as simple first‐order kinetics in which the rate constant was dependent on the initial substrate concentration.