Unraveling the role of the Burkholderia sacchari xyl operon in the regulation of xylose catabolism and enabling other bacterial platforms to consume xylose

Abstract

Burkholderia sacchari is a bacterium capable of producing polyhydroxyalkanoates (PHA) from xylose as a carbon source. PHA are thermoplastic, biodegradable and biocompatible materials that are an environmentally correct alternative to petrochemical plastics. Xylose is one of the sugars present in the sugarcane bagasse that constitutes an agro-industrial residue that has not yet been efficiently used by ethanological yeasts that ferment glucose well but not xylose. Producing PHA from xylose by B sacchari represents an excellent example of insertion of new bioproducts into biorefineries, such as sugar and alcohol plants, functioning in a sustainable manner and using renewable raw material for agriculture. Previous studies of xylose catabolism and the sequencing of the genome of this bacterium indicate the possibility of improving its growth rate at this carbon source. This work intends to understand the role of the xyl operon of B. sacchari in the regulation of xylose catabolism, as well as its functioning. In order to do this, it is necessary to analyze the in silico genomic sequence of this operon in order to verify its structure (intergenic regions, initiation codons, promoter sequences, terminators, regulatory binding sites, etc.) and the expected functioning of its genes in xylose catabolism. The role of xylR encoding a putative regulator will be evaluated by its cloning and expression in a larger number of copies in B sacchari and Pseudomonas, the latter being unable to grow in xylose. In addition, it should investigate xylose catabolism genes in the newly sequenced Pseudomonas genome using as reference protein sequences from different enzymes related to xylose catabolism. Recombinants will be evaluated for improvements in xylose consumption and PHA production.