Title : Susceptibility of cellulose from various types of biomass after microwave-assisted hydrotropic pretreatment to enzymatic hydrolysis
Abstract:
Plant biomass is a cheap and renewable source of carbon which might be used as a substrate in biosynthesis processes. The effective use of lignocellulosic biomass depends on the efficient delignification of the biomass, which largely increases the susceptibility of cellulose to enzymatic hydrolysis. The study was aimed at evaluating the influence the effectiveness of microwave-assisted hydrotropic pretreatment of pine chips, beech chips and wheat straw, taking into account changeable process conditions with sodium cumene sulfonate (NaCS) on the susceptibility of cellulose to enzymatic hydrolysis. The concentration of glucose obtained as a result of enzymatic hydrolysis of cellulose is strongly correlated with biomass extractives. A higher concentration of glucose as a result of enzymatic hydrolysis was achieved from the raw material marked by a high level of loss of biomass components and a high content of cellulose in the biomass, which is related to the already discussed effect of the absence of cellulose extraction during microwave-assisted hydrotropic pretreatment. Obtaining the highest concentration of glucose as a result of hydrolysis of a given type of biomass subjected to microwave-assisted hydrotropic pretreatment has always been conditioned by the use of 40% w/v NaCS at 117 PSI for 60 minutes. As a result of enzymatic hydrolysis of non-wood (wheat straw) and hardwood (beech chips) biomass, a high concentration of glucose was achieved at, respectively, 463.27±11.25 mg/g of biomass and 327.70±22.15 mg/g of biomass. The highest resistance to enzymatic hydrolysis involving cellulases was determined for pine chip (softwood) biomass, which yielded a maximum glucose concentration at 50.77±0.75 mg/g of biomass. The processed wheat straw and beech chip biomass obtained as a result of microwave-assisted hydrotropic pretreatment was marked by the highest cellulose content and a high susceptibility to enzymatic hydrolysis (effect of a high level of delignification), which speaks for the use of these raw materials as a source of carbon in microbiological biosynthesis processes. From among the analysed sources of biomass, the lowest susceptibility to enzymatic hydrolysis of cellulose was recorded for pine chips, which is related to the lower level of delignification obtained. The obtained biomass after microwave-assisted hydrotropic pretreatment is a potential source of carbon that can be used in microbiological biosynthesis processes.