Bioengineering of poly(β-hydroxyalkanoates) for advanced material applications: incorporation of cyano and nitrophenoxy side chain substituents

Abstract

Novel functional poly(P-hydroxyalkanoates), PHAs, with hyperpolarizable side groups were prepared. Pseudomonas oleovorans ATCC 29347 and Pseudomonas putida KT 2442 were selected as biocatalysts. These organisms were first grown on citrate (40 mM) before polymer formation was studied in a second stage. The carbon sources in second-stage cultivations were mixtures (total of 15 mM) of octanoate (OA) with either 7.5 or 10 mMpara-cyanophenoxyhexanoate (CPH), para-cyanophenoxyvalerate (CPV), para-cyanophenoxybutyrate (CPB), or para-nitrophenoxyhexanoate (NPH). For both organisms, only small deviations in the number of colony-forming units per millilitre were observed when second-stage cultivations containing only 15 rnM octanoate were compared with those using mixtures of OA with either CPB, CPV, CPH, or NPH. PHA volumetric yields as a function of organism, carbon source mixture, and culture time are reported. The percent incorporations of substituted phenoxy side groups in the polymer products were determined by 'H NMR spectroscopy. Pseudomonasputida formed PHAs with up to 24.2% 3-hydroxy-6-(para-cyanophenoxy)hexanoate side groups when 5 mM OA and 10 mM CPH were used. A dramatic decrease in the percent incorporation of para-cyanophenoxy (CP) by P . putida was observed when the relatively shorter CP-substituted n-alkanoate chain CPV and CPB cosubstrates were used. Use of NPH in place of CPH had deleterious effects on both polymer formation and percent incorporation of substituted phenoxy side groups in P. putida. Pseudomonas oleovorans formed PHAs with only up to -2% CP side chains when a combination of OA and CPH was used and little to no CP side groups when a combination of OA and CPV or CPB was used. Substitution of NPH in place of CPH led to a modest increase (up to -5%) in substituted phenoxy side groups. Thus, a new route to first-generation chiral polymer structures for nonlinear optical applications was demonstrated.

A process for the recovery of poly(hydroxyalkanoates) from Pseudomonads Part 1: Solubilization

“…Therefore, these experiments were done using PHA-free cells. These were obtained either by culturing the PHA-negative mutant P. putida GPp104 [24] or by growing P. oleovorans on citric acid, which does not induce PHA accumulation [25]. Similar results were observed for both strains when subjected to the treatments listed in Table 1.…”

Microbiological Degradation of Polymeric Materials

“…Furthermore, a copolyester consisting of 3-hydroxybutyrate and 3-hydroxyvalerate, poly(3HB-co-3HV) can be synthesized in cells of Alcaligenes eutrophus [172]. Both long side-chain and novel side-chain polymers have been synthesized by the addition of appropriate substrates in the culture medium and with different bacterial strains [173][174][175]. The copolymers range from thermoplastics to elastomers.…”

Biosynthesis and Biodegradability of Copolythioesters from 3,3′‐Thiodipropionic Acid and Plant Oils by Cupriviadus necator

“…[1] Poly (3-hydroxybutyrate) [poly(3HB)] and its copolymers have been attracting great interest because of their unique properties, i.e., biodegradability, co-crystallization, and diverse mechanical properties that range from rigid to elastic, and are being considered for applications in industry, medicine, and other areas. [2] The incorporation of a variety of functional groups as side-chains, including halogens, [3] alkenyl, [4] phenyl, [5][6][7] cyano, [8] and branched alkyl groups [5] is of interest, because such a modification of the component unit may afford new microbial macromolecules. Recently, copolythioesters with a sulfur atom were isolated from Pseudomonas putida by using 11-thiophenoxyl undecanoic acid in expectation of producing potentially unique physical properties.…”