The high lipid, protein and sugar content in agricultural waste streams are ideal for biochemical valorization into value added products. Innovative research on improving the stability and recovery of biocatalysts in extreme environments, typical of waste streams, is essential for their translation in bioprocessing. Here, we explore biocatalytic valorization of lactose in whey permeate to rare sugars. Rare sugars are monosaccharides with near-equivalent sweetness intensity as sucrose, but a fraction of the caloric density and minimal adverse health impacts. Present in very small amounts in nature, an opportunity remains to produce these natural sweeteners from agricultural ‘waste’ sugars such as lactose. Tagatose and allulose, are of particular interest as they have been granted GRAS status by the USDA. We successfully have bioengineered a recombinant fusion protein, lactase, that can effectively self-immobilize onto cellulose in less than 2 hours and confirmed that the addition of a carbohydrate binding module (CBM) does not alter the optimum reaction conditions of the native enzyme. The protecting effect of sugars on enzymes to improve their catalytic activity was studied. At 50 degrees Celsius, lactase was inactivated within 2 hours, whereas lactase in the same buffer supplemented with 40% (% w/w) trehalose, glucose and sucrose enabled retention of 91 %, 37 % and 79 % of the original enzyme activity, respectively, after 25 hours exposure, an important consideration for higher temperature bioprocessing. To optimize the recombinant enzyme’s performance, both rigid and flexible linkers between the enzyme and the CBM will be studied. Improving the stability of enzymes for the valorization of whey permeate waste streams into rare sugars will promote economic and environmental sustainability of global dairy processing. Innovative research to improve or supplement synthetic biology and biocatalyst is crucial in valorizing waste streams into value added products and in reducing the environmental burden of food manufacturing.

Biocatalytic approaches to valorization of food and agriculture waste streams

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.