Protein Engineering And Functional Genomics Approaches To Alleviate P And N Pollution As A Result Of Animal Agriculture

Abstract

Animal agriculture may be a significant source of P and N pollution. In order to maximize animal growth, diets are often supplemented with inorganic P, depleting a nonrenewable resource. Furthermore, towards the same end, animal diets are often supplemented with a rich source of protein, generally soybean meal. This competes with human consumption of soy. The biotechnological application of phytase to supplement animal diets reduces manure P pollution and can completely replace the use of nonrenewable inorganic P. We attempted to increase the stability of Escherichia coli AppA2 phytase through de novo disulfide bond engineering to withstand the heat of feed pelleting. Though unsuccessful in our goal, we discovered disulfide bonds affect protein kinetics and other characteristics through not only modulation of stability, but also atom motility and position. We also explored potential additional benefits of phytase. Knowing AppA2 to possess a nucleotide binding site, we explored whether phytase could degrade DNA. Our studies failed to indicate substantial nuclease activity of phytase. Finally, towards the goal of alleviating animal agriculture N pollution in the form of poultry feathers and competition for human food sources, we studied the degradation of feather keratin by Streptomyces fradiae k11. By combining a functional genomics approach of draft genome sequencing and shotgun proteomics, comparative microbiological studies and mechanism driven experiments, we laid a new groundwork for continued research aimed at converting feather waste into a valuable protein resource. 3