Combined polyhydroxyalkanoates (PHA) and 1, 3-propanediol production from crude glycerol: Selective conversion of volatile fatty acids into PHA by mixed microbial consortia. (1st June 2018) - Burniol-Figols, Anna
Abstract: Crude glycerol is an important by-product of the biodiesel industry, which can be converted into volatile fatty acids (VFA) and/or 1, 3-propanediol (1, 3-PDO) by fermentation. In this study, a selective conversion of VFA to polyhydroxyalkanoates (PHA) was attained while leaving 1, 3-PDO in the supernatant by means of mixed microbial consortia selection strategies. The process showed highly reproducible results in terms of PHA yield, 0.99 ± 0.07 Cmol PHA/Cmol S (0.84 g COD PHA/g COD S), PHA content (76 ± 3.1 g PHA/100 g TSS) and 1, 3-PDO recovery (99 ± 2.1%). The combined process had an ultimate yield from crude glycerol of 0.19 g COD PHA and 0.42 g COD 1, 3-PDO per g of input COD. The novel enrichment strategy applied for selectively transforming fermentation by-products into a high value product (PHA) demonstrates the significance of the enrichment process for targeting specific bio-transformations and could potentially prove valuable for other biotechnological applications as well. Graphical abstract: Highlights: Selective consumption of VFA over 1, 3-PDO was attained in mixed microbial cultures. VFA were converted to P(HB- co -HV) with a yield of 0.84 g COD PHA/g COD substrate. A high PHA production rate was achieved (0.41 g PHA.L −1 .h −1 ). 1, 3-PDO was completely recovered in the supernatant (99 ± 2.1%).