Synthesis of short-/medium-chain-length poly(hydroxyalkanoate) blends by mixed culture fermentation of glycerol.
Glycerol was used as a substrate in the bio-production of poly(hydroxyalkanoates) (PHAs) in an effort to establish an alternative outlet for glycerol and produce value-added products. Pseudomonas oleovorans NRRL B-14682 and Pseudomonas corrugata 388 grew and synthesized poly(3-hydroxybutyrate) (P3HB) and medium-chain-length PHA (mcl-PHA) consisting primarily of 3-hydroxydecanoic acid (C(10:0); 44 +/- 2 mol %) and 3-hydroxydodecenoic acid (C(12:1); 31 +/- 2 mol %), respectively, from glycerol at concentrations up to 5% (v/v). Cellular productivity maximized at 40% for P. oleovorans in 5% (v/v) glycerol and 20% for P. corrugata in 2% (v/v) glycerol after 72 h. Increasing the glycerol media concentration from 1% to 5% (v/v) caused a 61% and 72% reduction in the molar mass (M(n)) of the P3HB and mcl-PHA polymers, respectively. Proton-NMR analysis of the glycerol-derived P3HB revealed that the M(n) decrease was the result of esterification of glycerol onto the polymer in a chain terminating position. However, no evidence of glycerol-based chain termination was present in the mcl-PHA. The growth patterns of P. oleovorans and P. corrugata on glycerol permitted their use as mixed cultures to produce natural blends of P3HB and mcl-PHA. By incorporating a staggered inoculation pattern and varying the duration of the fermentations, P3HB/mcl-PHA ratios were achieved that varied from 34:66 to 96:4.
Ashby
Richard D
RD
Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA. rashby@errc.ars.usda.gov
Solaiman
Daniel K Y
DK
Foglia
Thomas A
TA
D000473:Alkanes / Q000138:chemical synthesis*; D003470:Culture Media; D005285:Fermentation; D008401:Gas Chromatography-Mass Spectrometry; D005990:Glycerol / Q000737:chemistry / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D011108:Polymers / Q000138:chemical synthesis*; D011549:Pseudomonas / Q000378:metabolism
D000473:Alkanes; D003470:Culture Media; D011108:Polymers; D005990:Glycerol