Role of non-genetically modified or native pentose fermenting microorganisms in establishing viable lignocellulosic biorefineries in the Brazilian context.

Brazil can play a pivotal role in the development of a circular bioeconomy as the country ranks among the top five major agricultural countries in the world producing a foreseeable lignocellulosic biomass from crops, such as sugarcane, soybean, corn, rice, coffee, and eucalyptus. Considering that pentose sugars (C5 sugars) represent 20%-35% of the amount of lignocellulosic biomass components, these sugars have a great potential in the development of carbon neutral economy. From the biomass conversion economic point of view, the conversion of hemicellulose into renewable products with a satisfactory yield is the most needed. However, the biochemical conversion of pentose sugars is challenging due to the scarcity of native pentose sugars fermenting microorganisms. While recent advances in metabolic engineering have been effective in developing a strong molecular chassis for efficient pentose sugars conversion, the yields, productivities, and stability of the genetically modified organisms (GMOs) are major limiting factors for industrial-scale applications. Native lignocellulosic sugars fermenting microorganisms are competent, robust, and inhibitor-tolerant but their lower productivities continue to be a big concern. This article explains the inherent characteristics of native pentose fermenting microorganisms in establishing viable lignocellulosic biorefineries in the Brazilian context, with a special focus on their isolation from Brazilian biodiversity, along with the evaluation of nongenetic engineering techniques to improve strains for biorefinery application.