Abstract
Glucose (xylose) isomerase (GI) is one of the most important industrial enzymes. It is used widely to catalyze the reversible conversion of D-glucose to D-fructose in vivo . The latter is used on a wide scale in the production of the high fructose corn syrup (HFCS) from corn starch. The great need of a thermostable GI, which is still active at higher temperatures (up to 90°C), opened the door to screen more microorganisms for the production of a more efficient industrial enzyme. Whole cells of 50 thermotole-rant/thermophilic bacterial isolates were used to evaluate their potential to produce GI when they were grown in broth medium (pH 7.0) containing D-xylose as a sole carbon source. Klebsiella and Pseudomonas showed the highest enzyme activity of 0.7; Bacillus came second with an activity of 0.3; while Acetobacter and Staphylococcus showed moderate activity of 0.3 for both, and Clostridium , Corynebacterium and Enterobacter showed the lowest enzyme activity of 0.2 each. The results reveal the need for optimizing the conditions for enhancing the production of the enzyme from Klebsiella and Pseudomonas isolates. Key words : Glucose isomerase, xylose isomerase, enzyme activity, Klebsiella , Pseudomonas .
Highlights
Glucose isomerase (GI) is a widely distributed enzyme in bacteria; it is used in industry to catalyze the reversible conversion of D-glucose to D-fructose in vivo, which in turn enters the process of the production of the high fructose corn syrup (HFCS) from corn starch
The aim of this study was to find out suitable thermotolerant/thermophilic isolated bacteria that have the capability for the production of a thermostable, and neutral or slightly acidic Glucose (xylose) isomerase (GI) which will be of great benefit in the industrial production of HFCS
This is helpful for food industries since it will provide the field with high glucose isomerase producer thermotolerant/thermophilic microorganisms
Summary
Glucose isomerase (GI) is a widely distributed enzyme in bacteria; it is used in industry to catalyze the reversible conversion of D-glucose to D-fructose in vivo, which in turn enters the process of the production of the high fructose corn syrup (HFCS) from corn starch. Consumer foods and products typically use HFCS as a sweetener This process is facing a challenge of applying high temperature and alkaline pH (Bucke, 1983) in order to maintain a higher equilibrium concentration of fructose, faster reaction rate, and decreased viscosity of the substrate in the product stream (Tewari et al, 1985). The aim of this study was to find out suitable thermotolerant/thermophilic isolated bacteria that have the capability for the production of a thermostable, and neutral or slightly acidic GI which will be of great benefit in the industrial production of HFCS This is helpful for food industries since it will provide the field with high glucose isomerase producer thermotolerant/thermophilic microorganisms
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