Abstract
BackgroundPlatform chemicals are essential to industrial processes. Used as starting materials for the manufacture of diverse products, their cheap availability and efficient sourcing are an industrial requirement. Increasing concerns about the depletion of natural resources and growing environmental consciousness have led to a focus on the economics and ecological viability of bio-based platform chemical production. Contemporary approaches include the use of immobilized enzymes that can be harnessed to produce high-value chemicals from waste.ResultsIn this study, an engineered glucose dehydrogenase (GDH) was optimized for gluconic acid (GA) production. Sulfolobus solfataricus GDH was expressed in Escherichia coli. The Km and Vmax values for recombinant GDH were calculated as 0.87 mM and 5.91 U/mg, respectively. Recombinant GDH was immobilized on a hierarchically porous silica support (MM-SBA-15) and its activity was compared with GDH immobilized on three commercially available supports. MM-SBA-15 showed significantly higher immobilization efficiency (> 98%) than the commercial supports. After 5 cycles, GDH activity was at least 14% greater than the remaining activity on commercial supports. Glucose in bread waste hydrolysate was converted to GA by free-state and immobilized GDH. After the 10th reuse cycle on MM-SBA-15, a 22% conversion yield was observed, generating 25 gGA/gGDH. The highest GA production efficiency was 47 gGA/gGDH using free-state GDH.ConclusionsThis study demonstrates the feasibility of enzymatically converting BWH to GA: immobilizing GDH on MM-SBA-15 renders the enzyme more stable and permits its multiple reuse.
Highlights
Platform chemicals are essential to industrial processes
Proteincontaining fractions were analysed by bicinchoninic acid assay (BCA), pooled and subjected to size exclusion chromatography (Fig. 1b)
The peak obtained indicated that glucose dehydrogenase (GDH) was 99.83% of the total sample and that the multiple-banding on the a GDH 43kDa b
Summary
Used as starting materials for the manufacture of diverse products, their cheap availability and efficient sourcing are an industrial requirement. Petrochemical refineries produce a wide range of highly valuable platform chemicals, which are. Platform chemicals are essential to industrial processes. Used as crude materials for the manufacture of diverse products, their cheap availability and efficient sourcing is a focus for modern companies [9]. The majority of platform chemicals are derived from non-renewable petroleum feedstocks. GA production via microbial fermentation processes are FDA approved and various organisms have been shown to produce this acid. Aspergillus niger and Gluconobacter oxydans, which are highly selective and efficient, have been widely used for GA production [12], but are limited to producing GA at non-toxic levels
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