Influence of synthetic carbon grade on the metabolic flux of polyhydroxyalkanoate monomeric constitution synthesized by Bacillus cereus AAR-1

Carbon substrate is a pivotal factor influencing polyhydroxyalkanoate (PHA) properties of varied industrial importance. Three synthetic sucrose samples with varying manufacturing purity levels were selected as carbon substrates to synthesize diverse PHAs using a wild-type Bacillus cereus AAR-1. Comparative monomeric analyses of the extracted biopolymers revealed Poly (3-hydroxytetradecanoate) (P3HTD), Poly(3-hydroxybutyrate-co-2-hydroxytetradecanoate) [P(3HB-co-2HTD)], and Poly(3-hydroxybutyrate) (P3HB) with carbon elemental contents that ranged from 39 to 53 % and no nitrogen detected. The decomposition temperature of [P(3HB-co-2HTD)] was 279 °C, indicating higher thermal stability than the individual monomeric units. Notably, the homopolymer P3HTD exhibited an increased melting temperature of 172.4 °C and a reduced crystallinity percentage (X_c % = 20.7 %), crucial properties for bioplastics and medical sector applications. All the biopolymers displayed a low specific heat capacity ranging between 0.03 and 0.05 J/g°C, suitable for applications such as thermal storage materials and temperature-regulating textiles. The results suggest that different carbon purity grades influenced homopolymer accumulated in Bacillus cereus AAR-1.