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Kinetics and thermodynamics of glucoamylase inhibition by lactate during fermentable sugar production from food waste
Author(s) -
Qiang Wang Xiao,
Hui Wang Qun,
Ying Liu Ying,
Zhi Ma Hong,
Ming Wang Xu
Publication year - 2010
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.2355
Subject(s) - bioconversion , hydrolysis , chemistry , aspergillus niger , food waste , food science , sugar , reducing sugar , nuclear chemistry , biochemistry , fermentation , waste management , engineering
BACKGROUND: Glucoamylase hydrolysis is a key step in the bioconversion of food waste with complicated composition. This work investigated the effect of lactate on glucoamylase from Aspergillus niger UV‐60, and inhibition mechanisms of glucoamylase by lactate during food waste hydrolysis. RESULTS: For 125 min hydrolysis of food waste (10%, dry basis), reducing sugars produced in the absence of lactate were 15%, 26% and 56% more than those produced in the presence of 24 g L −1 lactate at 60, 50 and 40 °C, respectively. Kinetic study showed that the type of glucoamylase inhibition by lactate was competitive, and K m (Michaelis‐Menten constent), V max (maximum initial velocity), K I (inhibition constant) were 103.2 g L −1 , 5.0 g L −1 min −1 , 100.6 g L −1 , respectively, for food waste hydrolysis at 60 °C and pH 4.6. Lactate also accelerated glucoamylase denaturation significantly. Activation energy of denaturation without inhibitor was 61% greater than that of denaturation with inhibitor (24 g L −1 lactate). Half‐lives ( t 1/2 ) without inhibitor were 7.6, 2.7, 2.6, 1.7 and 1.2 times longer than those with inhibitor at temperature 40, 45, 50, 55 and 60 °C, respectively. CONCLUSION: These results are helpful to process optimization of saccharification and bioconversion of food waste. Copyright © 2010 Society of Chemical Industry