Evaluation of unrefined glycerine pitch as an efficient renewable carbon resource for the biosynthesis of novel yellow-pigmented P(3HB-co-4HB) copolymer towards green technology

Discharging the unrefined glycerine, a by-product from biodiesel production is the simplistic solution adopted for its management which has led to its price reduction in the market worldwide and created serious environmental impact. Therefore, we have explored the application of unrefined glycerine pitch as direct fermentative substrate in the biosynthesis of novel yellow-pigmented poly(3-hydroxybutyrate-co-4-hydroxybutyrate) P(3HB-co-4HB)] copolymer by Cupriavidus sp. USMAHM13 through onestage cultivation. Utilization of glycerine pitch (10 g/L) together with 1,4-butanediol (5 g/L) had resulted in the highest achievement of 2.91 g/L of P(3HB-co-40%4HB) copolymer which was naturally dyed with the yellow pigment through the co-extraction process. Enhancement of 4HB monomer accumulation was also attained through the addition of ammonium acetate as nitrogen source. It was revealed that utilization of recovered crude glycerine from glycerine pitch was more preferred compared to the other recovered components. Utilization of glycerine pitch in the biosynthesis of P(3HB-co-4HB) copolymer would not only contribute to the efficient waste management but also would promote the development of cost-efficiency microbial fermentation.