Microbial Synthesis of Poly(β-hydroxyalkanoates) Containing Fluorinated Side-Chain Substituents

Abstract

The preparation of novel fluorinated poly(β-hydroxyalkanoates), PHAs, was carried out using Pseudomonas oleovorans (ATCC 29347) and Pseudomonas putida (KT 2442) as biocatalysts. These organisms were first grown on 40 mM sodium citrate prior to studying polymer formation in the second stage using 1:1 molar mixtures of nonanoic acid (NA) and fluorinated acid cosubstrates. The following fluoro acids were synthesized and used in this study: 6,6,6-trifluorohexanoic acid (TFHxA), 6,6,7,7,8,8,8-heptafluorooctanoic acid (HpFOA), 6,6,7,7,8,8,9,9,9-nonafluorononanoic acid (NFNA), and 6,6,7,7,8,8,9,9,10,10,11,11,11-tridecafluoroundecanoic acid (TDFUDA). In general, the use of NA/fluoro acid cosubstrate mixtures instead of only NA in second-stage cultivations resulted in little to no cellular toxicity as measured by values of colony-forming units per milliliter. The mol percent incorporations of fluorinated side chains was determined by 1H and 19F NMR spectroscopies, and peak assignments were made using two-dimensional reverse-detected heteronuclear multiplet quantum correlation (HMQC) as well as 1H−H correlation spectroscopy (COSY). P. putida formed PHA after a 3-day second-stage cultivation time with 17.3 mol % fluorinated side chains using NA/NFNA as cosubstrates. For shorter second-stage cultivation times (1 day) where product yields were relatively higher, 0.3 g/L of product was formed that contained 6.4 mol % fluoroalkanoate side groups using P. oleovorans as the biocatalyst and NA/HpFOA as cosubstrates. The incorporation of 12.4 mol % fluoroalkanoate repeat units resulted in products which showed melting at higher temperatures (55−80 °C), crystallized at faster rates from the melt, and had higher heats of fusion. Investigation of the surface free energy of products by surface contact angle measurements showed only a modest increase from 87 to 94° for PHAs containing 0 and 17.3 mol % fluorinated side chains.

Engineering Native and Synthetic Pathways in Pseudomonas putida for the Production of Tailored Polyhydroxyalkanoates

“…The incorporation of fluoroalkanoate repeat units resulted in polymeric materials with T m s of 55–80 °C that crystallize at faster rates compared to their nonfluorinated counterparts. [ 129 ]…”

Epoxidation of Bacterial Polyesters with Unsaturated Side Chains. I. Production and Epoxidation of Polyesters from 10-Undecenoic Acid

“…In this manner the production of PHAs with various functional groups such as olefin, [1][2][3][4] halogen (chloride, 5 fluoride, 6,7 and bromide 8 ), and cyano 8 groups has been achieved. The presence of functional groups in the PHAs provides sites for chemical modification and can affect the physical properties of polymers such as their hydrophobicity and solubility.…”

Characterization of a Novel Subgroup of Extracellular Medium-Chain-Length Polyhydroxyalkanoate Depolymerases from Actinobacteria

“…Several mcl PHA-degrading bacterial strains were isolated in our laboratory from natural environmental samples (soil, sludge, and water) taken at different places on the Leioa campus of the University of the Basque Country, Vizcaya, Spain. Serial dilutions of the homogenized samples were spread on P(3HO)-mineral agar plates consisting of P(3HO) latex-covered petri plates with mineral medium such as M9 medium (45) and E medium (24). The plates were incubated for 2 to 3 days at 30°C.…”