Biosynthesis and properties of P(3HB‐co‐3HV‐co‐3H4MV) produced by using the wild‐type strain Cupriavidus eutrophus B‐10646

Abstract

BACKGROUND Polyhydroxyalkanoates (PHA) containing 3‐hydroxy‐4‐methylvalerate (3H4MV) have better processing properties than other PHA types and were not prone to ageing. The main challenge in the production of these polymers is to simultaneously achieve high cell biomass, high polymer content, and high molar fraction of 3H4MV. The aim of this study was to investigate the production of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate‐co‐3‐hydroxy‐4‐methylvalerate) [P(3HB‐co‐3 HV‐co‐3H4MV)] by Cupriavidus eutrophus B‐10646, synthesize polymers with different contents of 3H4MV and investigate their properties. RESULTS It was shown that 4‐methylvalerate (4MV, the precursor substrate) concentration in the culture medium must not be higher than 1 g L−1, and that 4MV must be carefully dosed, with at least 10–12 h intervals between supplementations. A series of polymers with molar fractions of 3H4MV between 2.7 and 11.3 mol% was synthesized. Degrees of crystallinity, molecular weight characteristics, and thermal properties of the polymers have been investigated as dependent on proportions of monomers. CONCLUSION The content of 3H4MV depends on the concentration of 4MV and conditions of carbon nutrition. The molar fraction of 3H4MV had a strong effect on the crystalline to amorphous region ratio. PHA containing 3H4MV specimens synthesized in this study had a degree of crystallinity of below 50%, which remained unchanged for 2.5 years. © 2018 Society of Chemical Industry

Biosynthesis and Properties of a P(3HB-co-3HV-co-4HV) Produced by Cupriavidus necator B-10646

“…A similar mode of fractional dosing of various precursor substrates was developed earlier and, in combination with a controlled fermentation time of bacteria after additives added to the culture, was successfully implemented earlier [ 52 , 56 , 62 , 63 ]. This made it possible to synthesize a wide range of two-, three-, and four-component copolymers with different sets and ratios of 3- and 4-hydroxybutyrate, 3-hydroxyvalerate, and 3-hydroxyhexanoate monomers, the content of which varied from units to 50 mol.% or more, as well as copolymers of complex composition—poly(3-hydroxybutyrate- co -3-hydroxyvalerate- co -3-hydroxy-4-methylvalerate) [P(3HB- co -3HV- co -3H4MV)] [ 64 ].…”

Biosynthesis and Properties of Sulfur-Containing Polyhydroxyalkanoates (PHAs) Produced by Wild-Type Strain Cupriavidus necator B-10646

“…Modes of fractional and controlled supply of substrates-precursors of target monomers to a bacterial culture make it possible to avoid the effect of inhibition of bacteria. Moreover, regulated sampling at a certain time after the supply of precursors to a culture that is in a phase with a maximum rate of polymer synthesis and a minimum rate of endogenous biodegradation of PHA, as a rule, makes it possible to achieve a higher content of various monomers in the composition of the polymer chain [ 13 , 42 , 46 , 49 , 50 , 51 ].…”

Biodegradable Polyhydroxyalkanoates with a Different Set of Valerate Monomers: Chemical Structure and Physicochemical Properties

“…Previously, a series of P(3HB- co -3HV- co -3H4MV) polymers were synthesized by the C. necator B-10646 wild-type strain [ 51 ]. In the present work, samples with 3H4MV monomers content of 5.3 and 10.9 mol.% were obtained and studied at different contents of 3HV monomers, respectively, 23.4 and 8.6 mol.% ( Table 1 ).…”

“…The properties of the polymers changed not only by the set of monomers but also by their ratio (Table 1). * data from the first heating, ** the sample was synthesized earlier [50], *** the sample was synthesized earlier [51].…”

“… * data from the first heating, ** the sample was synthesized earlier [ 50 ], *** the sample was synthesized earlier [ 51 ]. …”