Production of poly-β-hydroxybutyrate on lactic acid by Alcaligenes eutrophus H16 in a 3-l bioreactor

Susan Linko*, Hanna Vaheri, J. Seppälä

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    30 Citations (Scopus)

    Abstract

    Poly-β-hydroxybutyrate (PHB) was produced by Alcaligenes eutrophus H16 in a 2-l working volume Biostat® MD bioreactor in both batch and fed-batch mode, using lactic acid as the sole carbon source during the production phase. For the batch and 2-stage fed-batch fermentations, the organism was first precultivated on a fructose-based, nutrient-rich medium for 24 h, followed by another 24 h on medium in which fructose was omitted and ammonium sulfate supplied as the nitrogen source. In fed-batch fermentations, the dissolved oxygen level was automatically controlled at about 3 to 4.5%. In batch fermentation with 20 g l-1 of lactic acid as the carbon source and about 9 g (d.m.) of initial cell concentration in the production phase, the maximum PHB concentration obtained in 25 h was 5.8 g l-1, corresponding to 62% of cell dry matter. In 2-stage fed-batch fermentations with the same initial cell concentration and with a total of 20 g l-1 of lactic acid, the maximum PHB concentration increased to 7.5 g l-1, 81% of the dry biomass. In a l-stage fed-batch fermentation with both the growth and production phases carried out in the bioreactor, the maximum PHB concentration could be increased to 8.4 g l-1, 70% of dry biomass. In this case the total PHB production time was decreased by about 24 h as compared with the 2-stage batch and fed-batch processes. The polymer accumulation could be conveniently monitored by the consumption of acid as the PHB was synthesized.

    Original languageEnglish
    Pages (from-to)401-406
    Number of pages6
    JournalEnzyme and Microbial Technology
    Volume15
    Issue number5
    DOIs
    Publication statusPublished - 1993
    MoE publication typeA1 Journal article-refereed

    Keywords

    • Alcaligenes eutrophus
    • biodegradable polyester
    • biopolymer
    • fermentation
    • PHB
    • Poly-β-hydroxybutyric acid

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