However, the physiological limits of cellular production systems (pH, temperature, growth inhibition by a range of compounds) are a major obstacle to their cost-competitiveness. The bio-based production of commodities by fermentation is well-established. In response to concerns over the link between global warming and greenhouse gas emissions from these refineries, the production of platform chemicals from renewable resources has been identified as an attractive alternative to those derived from fossil fuels. In addition to fuels, petrochemical refineries produce a wide range of highly valuable platform chemicals, which are used in applications such as polymer, plastic, detergent, agrochemical and pharmaceutical production. The petrochemical industry continues to be an important player in the international economy. This 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. The highest GA production efficiency was 47 gGA/gGDH using free-state GDH.

After the 10th reuse cycle on MM-SBA-15, a 22% conversion yield was observed, generating 25 gGA/gGDH. Glucose in bread waste hydrolysate was converted to GA by free-state and immobilized GDH. After 5 cycles, GDH activity was at least 14% greater than the remaining activity on commercial supports. MM-SBA-15 showed significantly higher immobilization efficiency (> 98%) than the commercial supports. 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.

The K m and V max values for recombinant GDH were calculated as 0.87 mM and 5.91 U/mg, respectively. Sulfolobus solfataricus GDH was expressed in Escherichia coli. In this study, an engineered glucose dehydrogenase (GDH) was optimized for gluconic acid (GA) production. Contemporary approaches include the use of immobilized enzymes that can be harnessed to produce high-value chemicals from waste. 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. Used as starting materials for the manufacture of diverse products, their cheap availability and efficient sourcing are an industrial requirement. Platform chemicals are essential to industrial processes.

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