Cupriavidus sp. strain BIS7 is a Malaysian tropical soil bacterium that exhibits broad heavy-metal resistance [Co(II), Zn(II), Ni(II), Se(IV), Cu(II), chromate, Co(III), Fe(II), and Fe(III)]. It is particularly resistant to Fe(II), Fe(III), and Zn(II). Here we present the assembly and annotation of its genome.
Cupriavidus sp. USMAA1020 was isolated from Malaysian environment and able to synthesize poly(3-hydroxybutyrate-co-4-hydroxybutyrate), [P(3HB-co-4HB)] when grown on gamma-butyrolactone as the sole carbon source. The polyester was purified from freeze-dried cells and analyzed by nuclear magnetic resonance (NMR) spectroscopy. 1H and 13C NMR results confirmed the presence of 3HB and 4HB monomers. In a one-step cultivation process, P(3HB-co-4HB) accumulation by Cupriavidus sp. USMAA1020 was affected by carbon to nitrogen ratio (C/N). A two-step cultivation process accumulated P(3HB-co-4HB) copolyester with a higher 4HB fraction (53 mol%) in nitrogen-free mineral medium containing gamma-butyrolactone. The biosynthesis of P(3HB-co-4HB) was also achieved by using 4-hydroxybutyric acid and alkanediol as 1,4-butanediol. The composition of copolyesters varied from 32 to 51 mol% 4HB, depending on the carbon sources supplied. The copolyester produced by Cupriavidus sp. USMAA1020 has a random sequence distribution of 3-hydroxybutyrate (3HB) and 4-hydroxybutyrate (4HB) units when analyzed by nuclear magnetic resonance (NMR) spectroscopy. When gamma-butyrolactone was used as the sole carbon source, the 4HB fraction in copolyester increased from 25 to 60 mol% as the concentration of gamma-butyrolactone in the culture medium increased from 2.5 g/L to 20.0 g/L.
Copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] has been the center of attention in the bio-industrial fields, as it possesses superior mechanical properties compared to poly(3-hydroxybutyrate) [P(3HB)]. The usage of oleic acid and 1-pentanol was exploited as the carbon source for the production of P(3HB-co-3HV) copolymer by using a locally isolated strain Cupriavidus sp. USMAA2-4. In this study, the productivity of polyhydroxyalkanoate (PHA) was improved by varying the frequency of feeding in fed-batch culture. The highest productivity (0.48 g/L/h) that represents 200 % increment was obtained by feeding the carbon source and nitrogen source three times and also by considering the oxygen uptake rate (OUR) and oxygen transfer rate (OTR). A significantly higher P(3HB-co-3HV) concentration of 25.7 g/L and PHA content of 66 wt% were obtained. The 3-hydroxyvalerate (3HV) monomer composition obtained was 24 mol% with the growth of 13.3 g/L. The different frequency of feeding carried out has produced a blend copolymer and has broadened the monomer distribution. In addition, increase in number of granules was also observed as the frequency of feeding increases. In general, the most glaring increment in productivity offer advantage for industrial P(3HB-co-3HV) production, and it is crucial in developing cost-effective processes for commercialization.