Molecular insight into cellulose degradation by the phototrophic green alga Scenedesmus.
María B. Velazqueza, María V. Busia, Diego F. Gomez-Casatia, Chitralekha Nag-Dasguptab* and Julieta Barchiesia*.
a Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Argentina.
b Research Cell, Lucknow, Amity University Uttar Pradesh, India.
Running title: Cellulose degradation by Scenedesmus.
Julieta Barchiesi*
Corresponding autor at: Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Suipacha 570, Rosario 2000, Argentina.
E-mail address :barchiesi@cefobi-conicet.gov.ar
Chitralekha Nag Dasgupta*
Co-corresponding autor at: Research Cell, Lucknow, Amity University Uttar Pradesh, Sector 125, Noida, 201313, India.
E-mail address : cndasgupta@lko.amity.edu
Abstract
Lignocellulose is the most abundant natural biopolymer on earth and a potential raw material for the production of fuels and chemicals. However, only some organisms such as bacteria and fungi produce the necessary enzymes to metabolize it. In this work we detected the presence of extracellular cellulases in the genome of five species ofScenedesmus . These microalgae grow in both, freshwater and saltwater regions as well as in soils, displaying highly flexible metabolic properties. The comparison of sequences of the different cellulases with hydrolytic enzymes from other organisms by means of multi-sequence alignments and phylogenetic trees showed that these enzymes belong to the families of glycosyl hydrolases 1, 5, 9 and 10. In addition, most of these presented a greater similarity of sequence with enzymes from invertebrates, fungi, bacteria and other microalgae than with cellulases from plants; and the 3D modeling data obtained showed that both the main structures of the modeled proteins and the main amino acid residues implicated in catalysis and substrate binding are well conserved in Scenedesmus enzymes.
We propose that these cellulase-producing phototrophic microorganisms could act as catalysts for the hydrolysis of cellulosic biomass fueled by sunlight.