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.
