Characterization of New Bacterial Copolyesters Containing 3-Hydroxyoxoalkanoates and Acetoxy-3-hydroxyalkanoates (original) (raw)
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Applied and Environmental Microbiology, 1988
Pseudomonas oleovorans grows on C 6 to C 12 n -alkanes and 1-alkenes. These substrates are oxidized to the corresponding fatty acids, which are oxidized further via the β-oxidation pathway, yielding shorter fatty acids which have lost one or more C 2 units. P. oleovorans normally utilizes β-oxidation pathway intermediates for growth, but in this paper we show that the intermediate 3-hydroxy fatty acids can also be polymerized to intracellular poly-( R )-3-hydroxyalkanoates (PHAs) when the medium contains limiting amounts of essential elements, such as nitrogen. The monomer composition of these polyesters is a reflection of the substrates used for growth of P. oleovorans . The largest monomer found in PHAs always contained as many C atoms as did the n -alkane used as a substrate. Monomers which were shorter by one or more C 2 units were also observed. Thus, for C-even substrates, only C-even monomers were found, the smallest being ( R )-3-hydroxyhexanoate. For C-odd substrates, only ...
Polymer Testing, 2010
Medium chain length polyhydroxyalkanoates (mcl-PHA) have been produced by fed-batch cultivation of Pseudomonas oleovorans. Using octanoic acid as the sole carbon substrate, a copolymer of 3-hydroxyoctanoate and 3-hydroxyhexanoate monomer units was accumulated up to 38 wt. % of cell mass. Mcl-PHA based nanocomposites have then been prepared using Cloisite 15A as nanofiller and characterized. Wide angle X-ray diffraction and rheological analysis of the nanocomposites highlighted their morphologies, which can be considered as well-intercalated structures. The thermal characteristics of mcl-PHA are not significantly affected by the nanofiller incorporation. On the contrary, the storage moduli of nanocomposites are greatly enhanced with increasing clay fraction due to the degree of dispersion of the nanoplatelets in the polymer matrix.
Studies on polyhydroxyalkanoates biosynthesis by some Pseudomonas spp. strains
Medium-chain-length polyhydroxyalkanoates (mcl-PHAs) are naturally produced by bacteria and accumulates in cytoplasm in the form of granules, in particular culture broth conditions. PHAs are biodegradable, biocompatible and have useful mechanical properties that recommend them for divers applications in various fields. In order to obtain mcl-PHAs of microbial origin we used two Pseudomonas spp. strains, namely Pseudomonas putida ICCF 391 and Pseudomonas fluorescens ICCF 392. Researches have focused the ability of these two strains to use structurally related or not related substrates, to obtain biopolymers with controlled composition, and growth the amount of PHAs in reproducible conditions. Moreover, bioprocess conditions for mcl-PHAs biosynthesis, fermentation broth processing, and polymers composition-were reproducible. As the results achieved with the two strains were similar, researches continued with Pseudomonas fluorescens strain, which is less studied regarding the potential of PHA biosynthesis. Were carried out (co) polymer films containing more than 85% PHO, as determined by GC-FID.
Reactive and Functional Polymers, 2008
The biosynthesis of poly-(3-hydroxyalkanoates) (PHAs) by Pseudomonas guezennei using glucose and/or fatty acids with chain-length from 3 to 18 carbon atoms as carbon sources was investigated. Glucose, acetate, pyruvate, propionate, valerate, hexanoate, heptanoate, octanoate, decanoate, and oleic acid were supplemented in the mineral medium as the sole carbon source or as a mixture for PHAs accumulation. Chemical composition of the resulting PHAs was analysed by coupled gas chromatography mass spectroscopy (GCMS), Fourier Transform Infrared Spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). PHAs contained up to 10 different types of 3hydroxyalkanoic acid units, including saturated 3-hydroxyacids from C4 to C14, and unsaturated monomers as 3-hydroxydodecenoate (3HDde) and 3-hydroxytetradecenoate (3HTde). 3-Hydroxydecanaote (3HD) and 3-hydroxyoctanaote (3HO) were incorporated preferentially except during cultivation on heptanoic acid, when P. guezennei synthesized PHAs with a higher concentration of 3-hydroxyheptanoate (3HHp). Thermal analysis indicated semi-crystalline polymers with melting temperatures (Tm) ranging from 42 and 51 °C, fusion enthalpy (ΔHm) comprised between 4 and 22 J/g, and glass transition temperatures (Tg) from −41 to −50 °C. Crystallinity index (CI) as deduced from FTIR spectra showed values comprised between 0.32 and 0.37. Molecular weights as determined by gel permeation chromatography (GPC-MALLS) ranged from 64 200 to 390 000 g/mol.
Journal of Industrial Microbiology and Biotechnology, 2019
Extreme environments are a unique source of microorganisms encoding metabolic capacities that remain largely unexplored. In this work, we isolated two Antarctic bacterial strains able to produce poly(3-hydroxyalkanoates) (PHAs), which were classified after 16S rRNA analysis as Pseudomonas sp. MPC5 and MPC6. The MPC6 strain presented nearly the same specific growth rate whether subjected to a temperature of 4 °C 0.18 (1/h) or 30 °C 0.2 (1/h) on glycerol. Both Pseudomonas strains produced high levels of PHAs and exopolysaccharides from glycerol at 4 °C and 30 °C in batch cultures, an attribute that has not been previously described for bacteria of this genus. The MPC5 strain produced the distinctive medium-chain-length-PHA whereas Pseudomonas sp. MPC6 synthesized a novel polyoxoester composed of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate-co-3-hydroxyoctanoate-co-3-hydroxydecanoate-co-3-hydroxydodecanoate). Batch bioreactor production of PHAs in MPC6 resulted in a titer of 2.6 (g/L) ...
Polymers, 2020
Aneurinibacillus sp. H1 is a promising, moderately thermophilic, novel Gram-positive bacterium capable of the biosynthesis of polyhydroxyalkanoates (PHA) with tunable monomer composition. In particular, the strain is able to synthesize copolymers of 3-hydroxybutyrate (3HB), 4-hydroxybutyrate (4HB) and 3-hydroxyvalerate (3HV) with remarkably high 4HB and 3HV fractions. In this study we performed an in-depth material analysis of PHA polymers produced by Aneurinibacillus sp. H1 in order to describe how the monomer composition affects fundamental structural and physicochemical parameters of the materials in the form of solvent-casted films. Results of infrared spectroscopy, X-ray diffractometry and thermal analysis clearly show that controlling the monomer composition enables optimization of PHA crystallinity both qualitatively (the type of the crystalline lattice) and quantitatively (the overall degree of crystallinity). Furthermore, resistance of the films against thermal and/or enzym...
Rapid Communications in Mass Spectrometry, 1992
Two different samples of copolyesters produced by Pseudomonas oleouorans when grown either on nonanoic acid alone or on an equimolar mixture of nonanoic and octanoic acids were evaluated for sequence distribution by controlled methanolysis to their oligomers, separation of the oligomers by HPLC, and analysis of the fractions so obtained by fast atom bombardment mass spectrometry (FAB-MS). The copolyesters contained primarily 0-hydroxyheptanoate and 0-hydroxynonanoate units, which showed no observable differences in their l H and *3C NMR spectra with changes in composition, so those analyses could not be applied. The observed oligomer composition and that calculated on the basis of Bernoullian statistics for sequence distributions in random copolymers of the compositions studied were in good agreement.
International Journal of Biological Macromolecules, 2001
In this study, we investigated the ability of Pseudomonas aeruginosa ATCC 27853 to grow and synthesize poly(3-hydroxyalkanoates) (PHAs) from saturated fatty acids with an even number of carbon atoms, from eight to 22, and from oleic acid. In a non-limiting medium, all carbon sources but docosanoic acid supported cell growth and PHA production, with eicosanoic acid giving the highest yield. In magnesium-limiting conditions, higher yields were obtained from sources with up to 16 carbon atoms. Composition was estimated by gas chromatography of methanolyzed samples and 13 C nuclear magnetic resonance. The 3-hydroxyalkanoate units extended from hexanoate to tetradecanoate or tetradecenoate, with octanoate and decanoate as the predominant components. Weight average molecular weights ranged from 78 000 to 316 000. Fast atom bombardment mass spectrometry of partially pyrolyzed samples, coupled to statistical analysis, showed that these PHAs are random copolymers.
We synthesized poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3-HB-co-3-HV)] copolymer having different contents of 3- hydroxyvalerate (3-HV) units (16.04, 16.3, 24.95, 25.62, and 16.52 mol % 3-HV) with different yields of polyhydroxyalkanoates (PHAs) by feeding with different cooking oils and with Alkaliphilus oremlandii OhILAs strain. The PHA production efficiency of the Alkaiphilus strain was compared with that of the control strain, Bacillus cereus. The synthesis of each PHA biopolymer was performed with different toxic spent oils as the sole carbon source in an oil-in-water-based microemulsion medium. We observed that the productivity of the poly(3- hydroxybutyrate) [P(3-HB)] copolymer from the Alkaliphilus strain was higher than those of the PHAs isolated from B. cereus and the Escherichia coli XL1B strain. The synthesized PHA copolymers were characterized by 1H-NMR and Fourier transform infrared (FTIR) spectroscopy. In the 1H-NMR spectra, a doublet resonance peak at 1.253 ppm of the/ methyl protons of the 3-hydroxybutyrate (3-HB) side group and one at 0.894 ppm due to the methyl protons of the 3-HV side group indicated the presence of 3-HB and 3-HV units in the copolymer. The chemical shift values at 1.25 and 2.2 ppm, due to the resonance absorption peaks of the methyl protons and methylene protons, confirmed the synthesis of the P(3-HB) homopolymer. From the FTIR spectra, a strong C@O stretching frequency in the range of 1745–1727 cm21, together with strong CAO stretching bands near 1200 cm21 and a strong band near 3400 cm21, confirmed the synthesis of P(3-HB-co-3-HV) and P(3-HB). Thus, waste cooking oil as a substrate provided an alternate route for the formation of P(3-HB-co-3- HV) and P(3-HB) by Alkaliphilus and E. coli strains, respectively
Applied and Environmental Microbiology, 2000
Pseudomonas oleovorans ATCC 29347 was grown in chemostat culture at different dilution rates with mineral media varying in their ratios of octanoate to ammonia (C 0 /N 0 ratio). At all dilution rates tested, three distinct growth regimes were observed: (i) carbon limitation with NH 4 ؉ in excess at low C 0 /N 0 ratios, (ii) purely nitrogen-limited growth conditions at high C 0 /N 0 ratios with residual octanoate in the culture supernatant, and (iii) an intermediate zone of dual-nutrient-limited growth conditions where both the concentration of octanoate and that of ammonia were very low. The dual-nutrient-limited growth zone shifted to higher C 0 /N 0 ratios with decreasing dilution rates, and the extension of the dual-nutrient-limited growth zone was inversely proportional to the growth rate.