iBB

Agro-industrial residues rich in pectin are generated in high amounts worldwide from the sugar industry or the industrial processing of fruits and vegetables. A recent paper by BSRG-iBB researchers, published in the Journal of Fungi (special issue “Yeast Biorefineries” (edited by Isabel Sá-Correia and Naseem Gaur), describes the optimization of the performance of Rhodotorula strains envisaging the use of the major carbon sources present in Sugar Beet Pulp (SBP) hydrolysates. SBP valorization through the production of lipids and carotenoids by the oleaginous red yeasts examined, supported by complete catabolism of the major carbon sources present, looks promising for industrial implementation. The work was conducted by the PhD student of the IST PhD Programme in Biotechnology and Biosciences Luís C. Martins (FCT_DP AEM programme fellowship) under the supervision of Isabel Sá-Correia. This work was developed in the context of the ERA-NET-Industrial Biotechnology-2 project, “YEASTPEC-Engineering of the yeast Saccharomyces cerevisiae for bioconversion of pectin-containing agro-industrial side-streams”.

Pectin-rich agro-industrial residues generated worldwide from the industrial processing of fruits and vegetables,are feedstocks with potential for sustainable biorefineries. Although the most important yeast cell factory platform is Saccharomyces cerevisiae, this species cannot naturally catabolise the main sugars present in pectin-rich agro-industrial hydrolysates, in particular D-galacturonic acid and L-arabinose. However, there are non-conventional yeasts considered advantageous alternatives whenever they can express highly interesting metabolic pathways, natively assimilate a wider range of carbon sources or exhibit higher tolerance to relevant bioprocess-related stresses. For this reason, the interest in nonconventional yeasts is gaining momentum. A review published in Applied Microbiology and Biotechnology discusses major challenges and progress on the isolation, selection, sugar catabolism, metabolic engineering and use of nonconventional yeasts and S. cerevisiae-derived strains for the bioconversion of pectin-rich residue hydrolysates  Examples of value-added products synthesised by different yeasts using pectin-rich residues are also reviewed. The first author of this paper is the PhD student of the FCT Doctoral Program in Applied and Environmental Microbiology Luís C. Martins advised by Prof. Isabel Sá-Correia from iBB-BSRG.

Methanol is a promising feedstock for metabolically competent yeast strains-based biorefineries. However, methanol toxicity can limit the productivity of these bioprocesses. For this reason, the identification of genes whose expression is required for maximum methanol tolerance is important for mechanistic insights and rational genomic manipulation to obtain more robust methylotrophic yeast strains. The chemogenomic analysis performed in this new BSRG-iBB study provided new valuable information on genes and potential regulatory networks involved in overcoming methanol toxicity in the model yeast Saccharomyces cerevisiae. The article was just published in the Journal of Fungi and belongs to the Special Issue “Yeast Biorefineries” (edited by Isabel Sá-Correia and Naseem A. Gaur). The article has as co-authors the PhD students of the IST Biotechnology and Biosciences PhD Programme ( FCT_DP Applied and Environmental Microbiology) Marta N. Mota (first  author) and Luís C. Martins, under Prof. Isabel Sá-Correia’s supervision. The gathered knowledge is an important starting point for the improvement of methanol tolerance in yeasts capable of catabolizing and copying with methanol concentrations present in promising bioeconomy feedstocks, including industrial residues.