A closed-loop biorefinery approach for polyhydroxybutyrate (PHB) production using sugars from carob pods as the sole raw material and downstream processing using the co-product lignin

• Published in: Bioresource technology 2020-07, Vol.307, p.123247-123247, Article 123247
• Main Authors: Manikandan, N. Arul, Pakshirajan, Kannan, Pugazhenthi, G.
• Format: Article
• Language: English
• Subjects: Biorefinery; Carob pods; Cupriavidus necator; Galactans; Hydroxybutyrates; Lignin; Mannans; Plant Gums; Polyesters; Polyhydroxybutyrate; Sugars; Taguchi experimental design
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2020.123247

[Display omitted] •A novel closed-loop biorefinery approach was developed for PHB production.•R. eutropha outperformed the B. megaterium with maximum PHB concentration.•PHB yield and purity more than 90% was achieved for both the PHB producers.•Prepared PHB demonstrated its advantage in food packaging applications. A novel closed-loop biorefinery model using carob pods as the feed material was developed for PHB production. The carob pods were delignified, and as the second step, sugars present in the delignified carob pods were extracted using water. Ralstonia eutropha and Bacillus megaterium were cultivated on the carob pod extract and its performance was evaluated using Taguchi experimental design. R. eutropha outperformed the B. megaterium in terms of its capability to grow at a maximum initial sugar concentration of 40 g L−1 with a maximum PHB production of 12.2 g L−1. Finally, the concentrated lignin from the first step was diluted with different proportion of chloroform to extract PHB from the bacterial biomass. The PHB yield and purity obtained were more than 90% respectively using either R. eutropha or B. megaterium. Properties of the PHB produced in this study were examined to establish its application potential.