Pseudomonas aeruginosa produced medium chain length poly(3-hydroxyalkanoates) (mcl-PHAs) when grown on substrates contg. very long chain fatty acids (VLCFA, C > 20). Looking for low cost carbon sources, we tested Brassica carinata oil (erucic acid content 35-48%) as an intact triglyceride contg. VLCFA. Oleic (C18:1), erucic (C22:1), and nervonic (C24:1) acids were also employed for mcl-PHA prodn. as model substrates. The polymers obtained were analyzed by GC of methanolyzed samples, GPC, 1H and 13C NMR, ESI MS of partially pyrolyzed samples, and DSC. The repeating units of such polymers were satd. and unsatd., with a higher content of the latter in the case of the PHA obtained from B. carinata oil. Statistical anal. of the ion intensity in the ESI mass spectra showed that the PHAs from pure fatty acids are random copolymers, while the PHA from B. carinata oil is either a pure polymer or a mixt. of polymers. Wt.-av. mol. wt. varied from ca. 56,000 g/mol for the PHA from B. carinata oil and oleic acid, to about 120,000 g/mol for those from erucic and nervonic acids. The PHAs from erucic and nervonic acids were partially cryst., with rubbery characteristics and a m.p. (Tm) of 50 °C, while the PHAs from oleic acid and from B. carinata oil afforded totally amorphous materials, with glass transition temps. (Tg) of -52 °C and -47°C, respectively.
Synthesis and characterization of poly(3-hydroxyalkanoates) from Brassica carinata oil with high content of erucic acid and from very long chain fatty acids
2011
Abstract
Pseudomonas aeruginosa produced medium chain length poly(3-hydroxyalkanoates) (mcl-PHAs) when grown on substrates contg. very long chain fatty acids (VLCFA, C > 20). Looking for low cost carbon sources, we tested Brassica carinata oil (erucic acid content 35-48%) as an intact triglyceride contg. VLCFA. Oleic (C18:1), erucic (C22:1), and nervonic (C24:1) acids were also employed for mcl-PHA prodn. as model substrates. The polymers obtained were analyzed by GC of methanolyzed samples, GPC, 1H and 13C NMR, ESI MS of partially pyrolyzed samples, and DSC. The repeating units of such polymers were satd. and unsatd., with a higher content of the latter in the case of the PHA obtained from B. carinata oil. Statistical anal. of the ion intensity in the ESI mass spectra showed that the PHAs from pure fatty acids are random copolymers, while the PHA from B. carinata oil is either a pure polymer or a mixt. of polymers. Wt.-av. mol. wt. varied from ca. 56,000 g/mol for the PHA from B. carinata oil and oleic acid, to about 120,000 g/mol for those from erucic and nervonic acids. The PHAs from erucic and nervonic acids were partially cryst., with rubbery characteristics and a m.p. (Tm) of 50 °C, while the PHAs from oleic acid and from B. carinata oil afforded totally amorphous materials, with glass transition temps. (Tg) of -52 °C and -47°C, respectively.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
