Biotechnological application of non-conventional yeasts for xylose valorization

Abstract

Demands for clean and sustainable processes and products that are environmentally friendly are challenging biotechnologists to develop new strategies to produce fuels and chemicals. As the petroleum demands rise together with the concern of climatic and environmental changes, there is an increasing interest for renewable energy. Sugars present in the lignocellulosic biomass can be used as raw material in biotechnological processes employing yeasts as catalysts. Several known yeasts such as Saccharomyces cerevisiae assimilate glucose but lack the efficiency to consume xylose. Due to industrial interest, there has been an increasing effort to discover and construct new xylose-assimilating yeast strains. In this sense, due to the diversity and metabolic potential, several non-conventional yeasts species were isolated, identified, and physiologically and genetically characterized in the last years. The current review sought to summarize the main characteristics as well as the biotechnological applications of non-conventional yeasts for xylose utilization. First, it will present and discuss the data about non-conventional yeasts that naturally and efficiently assimilate xylose as Scheffersomyces, Meyerozyma, Candida, Spathaspora, and Kluyveromyces. Then the yeasts Komagataella, Yarrowia, and Ogataea that do not assimilate xylose or poorly assimilate xylose justifying genetic manipulation to increase xylose utilization will also be presented. In each case, basic information about yeast taxonomy, morphology, and physiology will be presented, and the clearest biotechnological application will be introduced.