Co-production of polyhydroxyalkanoates and carotenoids through bioconversion of glycerol by Paracoccus sp strain LL1

Polyhydroxyalkanoates (PHA) have emerged as a potential alternative to synthetic plastics, although its large-scale production is limited by the expenditure incurred in feed materials. Co-production of various valuable bioproducts along with PHA has been proposed to alleviate the overall production cost. Here, high-yield co-production of PHA and carotenoids was achieved in single step fermentation by Paracoccus sp. LL1. The halophilic bacterial strain could metabolize a wide range of substrates including methanol, lactose, galactose, glycerol, fructose, mannitol, etc. Under batch fermentation using mineral media supplemented with 2% glycerol, Paracoccus sp. LL1 synthesized 3.77 g L-1 PHA with concomitant production of 3.6 mg L-1 of carotenoids after 96 h. An enhancement of 2.2-folds in total dry cell weight (DCW) was achieved through cell retention culture of Paracoccus sp. LL1, resulting in a maximum DCW (24.2 g L-1) containing PHA (39.3%, ww(-1)) with concomitant enhancement in the production of total carotenoids. Paracoccus sp. LL1 could convert glycerol into carotenoids and PHA to a level of 7.14 mg L-1 and 9.52 g L-1, respectively. It is the first report showing value addition in PHA production process through co-production of high value carotenoids by Paracoccus sp. using glycerol as substrate. (C) 2017 Elsevier B.V. All rights reserved.