Biocatalysts based on immobilized cells of microorganisms in the production of bioethanol and biobutanol

Abstract

In this work, we discuss the processes for the production of bioethanol and biobutanol, which are promising alternative fuels, using biocatalysts based on cells of various microorganisms immobilized in poly(vinyl alcohol) cryogel. Biocatalysts based on immobilized cells reliably allow ethanol production from a variety of industrial and agricultural wastes (wheat straw, beet and sugarcane bagasse, parchment, corn cobs, soybean processing waste) with a high degree of conversion of consumed substrates to the target product. Ethanol concentrations are appreciably higher in media with biocatalysts than in free cells of the same microorganisms. It is found that immobilized cells of filamentous fungi can convert a wider range of the sugars contained in processed media to ethanol than commonly used yeasts. It is shown that the immobilization of the genus Clostridium cells that produce butanol enables us to reliably change the ratio of solvents that accumulate in the medium during acetone-butanol-ethanol fermentation in the direction of a greater amount of butanol, thereby improving the process’s characteristics relative to present-day technologies based on free bacterial cells.