Enzymatic hydrolysis of highly concentrated substrates obtained from Miscanthus giganteus

This work is the first to study the enzymatic hydrolysis of four types of substrates obtained from Miscanthus giganteus of the KAMIS variety of Russian breeding. The study was conducting using the authors’ methodology based on a chemical pretreatment of substrates at atmospheric pressure with HNO 3 and NaOH dilute solutions. A one-stage pretreatment of Miscanthus giganteus allows the polysaccharide content to be increased up to 90.4–90.8%, compared to 98.3–99.4% following a two-stage treatment. The experimental results of enzymatic hydrolysis of the four obtained substrates in the range of initial concentrations from 30 to 120 g/l are approximated using fractal kinetics approaches. An increase in the initial substrate concentrations in the specified range leads to an increase in the initial hydrolysis rate by 2.8–3.3 times and a decrease in the yield of reducing sugars by 12.4–13.1%. All four pretreatment types turned out to be extremely effective for Miscanthus giganteus, ensuring an increase in the reactivity to enzymatic hydrolysis by 34–36 times compared to the starting raw material. Lowered yields of reducing sugars are observed during enzymatic hydrolysis of the alkaline delignification product of Miscanthus giganteus, which is associated with the resistance of Miscanthus giganteus to treatment with sodium hydroxide. An increase in the initial concentration of substrates from 60 to 90 g/l does not lead to a significant decrease in the yield of reducing sugars. Therefore, enzymatic hydrolysis of highly concentrated substrates can be successfully used to produce biofuels and biochemicals.