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Appl. Environ. Microbiol., 01 1995, 34-39, Vol 61, No. 1
SK Hahn, YK Chang and SY Lee
We studied recovery of poly(3-hydroxybutyric acid) (PHB) from Alcaligenes
eutrophus and a recombinant Escherichia coli strain harboring the A.
eutrophus poly(3-hydroxyalkanoic acid) biosynthesis genes. The amount of
PHB degraded to a lower-molecular-weight compound in A. eutrophus during
the recovery process was significant when sodium hypochlorite was used, but
the amount degraded in the recombinant E. coli strain was negligible.
However, there was no difference between the two microorganisms in the
patterns of molecular weight change when PHB was recovered by using
dispersions of a sodium hypochlorite solution and chloroform. To understand
these findings, we examined purified PHB and lyophilized cells containing
PHB by using a differential scanning calorimeter, a thermogravimetric
analyzer, and nuclear magnetic resonance. The results of our analysis of
lyophilized whole cells containing PHB with the differential scanning
calorimeter suggested that the PHB granules in the recombinant E. coli
strain were crystalline, while most of the PHB in A. eutrophus was in a
mobile amorphous state. The stability of the native PHB in the recombinant
E. coli strain during sodium hypochlorite treatment seemed to be due to its
crystalline morphology. In addition, as determined by the thermogravimetric
analyzer study, lyophilized cell powder of the recombinant E. coli strain
containing PHB exhibited greater thermal stability than purified PHB
obtained by chloroform extraction. The PHB preparations extracted from the
two microorganisms had identical polymer properties.
Copyright © 1995, American Society for Microbiology
Recovery and characterization of poly(3-hydroxybutyric acid) synthesized in Alcaligenes eutrophus and recombinant Escherichia coli
BioProcess Engineering Research Center, Korea Advanced Institute of Science and Technology, Taejon.
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