Biosynthesis Of Polyhydroxyalkanoate By Massilia Haematophila Umtkb-2 Using Optimized Culture Parameters And Its Polymer Characterization

Abstract

Polyhydroxyalkanoate (PHA) is a type of biodegradable polymer that is synthesized by some bacteria under limited nutrient and excess carbon source. The production of PHA by Massilia sp. remains mostly unexplored even though some previous studies had highlighted its ability to accumulate P(3HB). In this study, chemical and physical culture parameters were screened for P(3HB) and P(3HB-co-3HV) copolymer production by a local aquatic bacteria, Massilia haematophila UMTKB-2. This strain had shown proficiency in producing homopolymer, P(3HB), using glucose as a carbon source and urea as a nitrogen source. The potential of this bacteria to accumulate copolymer has never been reported. It was found that M. haematophila UMTKB-2 could produce 4.40 g/L of P(3HB-co-3HV) with 4 mol% 3-hydroxyvalerate (3HV) monomer using glucose and 1-pentanol as carbon source and precursor respectively. The P(3HB-co-3HV) production was enhanced through the optimization of fermentation parameters using the response surface methodology (RSM) in shake flasks. The production of P(3HB-co-3HV) by M. haematophila UMTKB-2 using optimal conditions (0.07 wt% of 1-pentanol concentration, 176 rpm of agitation rate, and 122h of incubation time), had yielded 5.0 g/L of P(3HB-co-3HV) with 7 mol% of 3HV monomer, were higher than the value obtained from un-optimized conditions (0.06 wt% of 1-pentanol concentration, 200 rpm of agitation rate, and 108 h of incubation time). In comparison with non-optimized conditions, a 14 % increment of copolymer concentration and two-fold increment of 3HV composition were observed.