Biochemical characterization of a catalase-peroxidase and its potential role in regulating H2O2 during enzymatic degradation of lignocellulose

Lignocellulosic biomass is one of the most underutilized resources today. It is composed of cellulose, hemicellulose and lignin and is available in abundance throughout the planet. This resource is considered one of the most promising renewable energy sources to replace fossil fuels, but due to the complexity of the structure of lignocellulose, few bother to utilize it. Lignin is a phenolic compound entangled in lignocellulose, and as there are few efficient ways of lignin degradation, most of it ends up getting burned as fuel in biorefineries. There are many known organisms that can degrade lignins, among them fungi and bacteria. One of these was discovered during an ongoing study and is called Giesbergia Hankyogi. This bacterium produces a KatG enzyme, GhKatG, a catalase-peroxidase capable of efficiently decompose H2O2 through both catalase and peroxidase activity. In this study the biochemical properties of this enzyme were explored, as was the effects it has on other known biomass degrading enzymes such as LPMOs and enzyme cocktails containing cellulases. The results show the enzyme thrives in relatively temperate temperatures, is pH dependent, and the catalytic activity is lost relatively quickly in these conditions. Experiments testing the effect of GhKatG in a reaction with other enzymes on several different cellulosic and lignocellulosic substrates show that GhKatG indeed influences the activity of these other enzymes