Microbial synthesis of poly(3-hydroxyalkanoates) by Pseudomonas aeruginosa from fatty acids: identification of higher monomer units and structural characterization.
Pseudomonas aeruginosa ATCC 27853 accumulated poly(3-hydroxyalkanoates) (PHAs) after growth on saturated fatty acids with an odd number of carbon atoms. No nutrient limitation was required to induce PHA synthesis, although better yields were obtained when the medium was magnesium deprived. A comparative study was carried out between PHAs obtained from C-odd and those from C-even carbon sources. Repeating units identification was performed by gas chromatography (GC) and capillary liquid chromatography-electrospray mass spectrometry (LC-ESI MS) of methanolyzed samples. When C-odd n-alkanoic acids from nonanoic to pentadecanoic were used the lowest hydroxyalkanoate unit found was 3-hydroxyvalerate and the highest 3-hydroxypentadecanoate, whereas when C-even acids from octanoic to eicosanoic were used these were 3-hydroxycaproate and 3-hydroxyeicosanoate, respectively. Weight average molecular weights were in the range 187 000-596 000. DSC traces showed Tm and DeltaHm which varied from 43 to 58 degrees C and from 5.9 to 24.8 J/g, with the PHAs generated from C-odd carbon sources having lower values. ESI MS of partially pyrolyzed samples allowed the identification of oligomers up to heptamers, and statistical analysis of the ions intensity in the mass spectra showed that these PHAs are random copolyesters.
Barbuzzi
Tony
T
Dipartimento di Scienze Chimiche, Università di Catania, Viale A. Doria 6, 95125 Catania, Italy, Istituto di Chimica e Tecnologia dei Polimeri, Consiglio Nazionale delle Ricerche, Viale A. Doria 6, 95125 Catania, Italy.
Giuffrida
Mario
M
Impallomeni
Giuseppe
G
Carnazza
Santina
S
Ferreri
Annamaria
A
Guglielmino
Salvatore P P
SP
Ballistreri
Alberto
A
D002152:Calorimetry, Differential Scanning; D002849:Chromatography, Gas; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism*; D006880:Hydroxy Acids / Q000378:metabolism; D008274:Magnesium / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D010421:Pentanoic Acids / Q000737:chemistry; D011091:Polyesters / Q000737:chemistry* / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization; D013696:Temperature; D013816:Thermodynamics
D005227:Fatty Acids; D006880:Hydroxy Acids; D010421:Pentanoic Acids; D011091:Polyesters; C013056:beta-hydroxyvaleric acid; D008274:Magnesium