Can microbes compete with cows for sustainable protein production - A feasibility study on high quality protein

Abstract

An increasing population and their increased demand for high-protein diets will require dramatic changes in the food industry, as limited resources and environmental issues will make animal derived foods and proteins, gradually more unsustainable to produce. To explore alternatives to animal derived proteins, an economic model was built around the genome-scale metabolic network of E. coli to study the feasibility of recombinant protein production as a food source. Using a novel model, we predicted which microbial production strategies are optimal for economic return, by capturing the tradeoff between the market prices of substrates, product output and the efficiency of microbial production. A case study with the food protein, Bovine Alpha Lactalbumin was made to evaluate the upstream economic feasibilities. Simulations with different substrate profiles at maximum productivity were used to explore the feasibility of recombinant Bovine Alpha Lactalbumin production coupled with market prices of utilized materials. We found that recombinant protein production could be a feasible food source and an alternative to traditional sources.

Figure 1. Simulation of economic productivity.

The plot depictures α-La fermentations at maximized productivity with yield per substrate, substrate compositions and economic return based on the substrate price per hour on the X, Y and Z axis respectively. The global maximum represents a fermentation, which converts the initial substrate into α-La worth 21.8 times the value of the starting material. The fermentation is simulated to take 11 hours and require the substrate to compose of 5% soybean and 95% sugar.

Figure 2. Simulation of economic yield.

The plot depictures α-La fermentations at maximized productivity with yield per substrate, substrate compositions and economic return based on the substrate price on the X, Y and Z axis respectively. The global maximum represents a fermentation, which converts the initial substrate into α-La worth 52 times the value of the starting material. The fermentation is simulated to take 300 hours and require the substrate to compose of 100% sugar.

Figure 3. Total fermentation time.

The plot depictures α-La fermentations at maximized productivity with yield per substrate, substrate compositions and time on the X, Y and Z axis respectively. The simulations vary greatly in total time, from a few hours to almost two weeks. Simulations with high yield per substrate do in general take longer. The rapid decline along the 60% yield (g/g) simulations seen in Figs 2 and 3 is a result of the cell growth and recombinant protein production being unable to maintain suitable productivity for prolonged fermentations.