Complete utilization of the major carbon sources present in sugar beet pulp hydrolysates by the oleaginous red yeasts rhodotorula toruloides and r. Mucilaginosa

Luís C. Martins, Margarida Palma, Angel Angelov, Elke Nevoigt, Wolfgang Liebl, Isabel Sá-Correia*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    21 Scopus citations

    Abstract

    Agro-industrial residues are low-cost carbon sources (C-sources) for microbial growth and production of value-added bioproducts. Among the agro-industrial residues available, those rich in pectin are generated in high amounts worldwide from the sugar industry or the industrial processing of fruits and vegetables. Sugar beet pulp (SBP) hydrolysates contain predominantly the neu-tral sugars D-glucose, L-arabinose and D-galactose, and the acidic sugar D-galacturonic acid. Acetic acid is also present at significant concentrations since the D-galacturonic acid residues are acety-lated. In this study, we have examined and optimized the performance of a Rhodotorula mucilaginosa strain, isolated from SBP and identified at the molecular level during this work. This study was extended to another oleaginous red yeast species, R. toruloides, envisaging the full utilization of the C-sources from SBP hydrolysate (at pH 5.0). The dual role of acetic acid as a carbon and energy source and as a growth and metabolism inhibitor was examined. Acetic acid prevented the catabo-lism of D-galacturonic acid and L-arabinose after the complete use of the other C-sources. However, D-glucose and acetic acid were simultaneously and efficiently metabolized, followed by D-galactose. SBP hydrolysate supplementation with amino acids was crucial to allow D-galacturonic acid and L-arabinose catabolism. SBP valorization through the production of lipids and carotenoids by Rhodotorula strains, supported by complete catabolism of the major C-sources present, looks promising for industrial implementation.

    Original languageEnglish (US)
    Article number215
    JournalJournal of Fungi
    Volume7
    Issue number3
    DOIs
    StatePublished - Mar 2021

    Keywords

    • Acetic acid
    • D-Galacturonic acid
    • L-Arabinose
    • Non-conventional yeasts
    • Oleaginous yeasts Rhodotorula toruloides
    • Pectin-rich residues
    • Rhodotorula mucilaginosa
    • Sugar beet pulp

    ASJC Scopus subject areas

    • Ecology, Evolution, Behavior and Systematics
    • Plant Science
    • Microbiology (medical)

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