17-03: Optimal enzyme mixtures for total hydrolysis of pretreated materials

Targets to decrease greenhouse gas emissions and dependency of fossil fuels, amongst others, have increased the interest for sustainable production of liquid biofuels and chemicals in the industrialised world. Plant biomass is the major readily available renewable source to substitute oil as raw material. Feasible utilization of carbohydrate components of biomass by the sugar route requires efficient processing methods for its pretreatment and hydrolysis at an acceptable cost. One of the major cost factors related to processing is the enzyme cost, determined to large extent by the high enzyme dosage required.

Since total hydrolysis of lignocellulosic biomass requires a multitude of different enzyme activities the mixture optimization is a challenging task. In addition, the availability of well characterized individual components of enzyme system may be limited. In this work we discuss the optimization of the enzyme mixtures in order to minimize the enzyme dosage for total hydrolysis of various and structurally different substrates, giving detailed information about the used methods and using purified enzymes or monocomponent enzyme mixtures.

The composition of mixtures of Trichoderma reesei enzymes and mixtures of thermostable enzymes were optimized for maximal hydrolysis efficiency in laboratory scale on different woody, straw and sugar cane bagasse substrates. Selection of the enzyme system, choice of the substrate in terms of source and pretreatment method and the hydrolysis conditions were the factors with largest effect on the optimal composition of the mixtures.