Biosynthesis of PHB tercopolymer by Bacillus cereus UW85.
OBJECTIVE
The study was attempted to determine the ability of a Gram-positive Bacillus cereus UW85 strain to biosynthesize poly (3-hydroxybutyrate) copolymers when epsilon-caprolactone, or epsilon-caprolactone and glucose, were used as carbon sources.


RESULTS
Bacillus cereus was grown for 24 h under nitrogen-limited conditions in a mineral salts medium. Growth was monitored by measurement of turbidity. Glucose level was determined by the colorimetric anthrone


METHODS
The epsilon-caprolactone concentration was determined by gas chromatography. The bacterial biopolymers were extracted with chloroform in a Soxhlet extractor and then characterized by nuclear magnetic resonance and gel permeation chromatography. When epsilon-caprolactone was used as a carbon substrate, the bacterial strain produced tercopolymer with 3-hydroxybutyrate, 3-hydroxyvalerate and 6-hydroxyhexanoate units. However, when caprolactone and glucose were supplied together, only homopolymer of poly (3-hydroxybutyrate) was produced.


CONCLUSIONS
All tercopolymers isolated from B. cereus UW85 cells were obtained with yields up to 9% (w/w) and low number-average molecular weight compared with the homopolymer PHB.


CONCLUSIONS
Bacillus cereus UW85 produced tercopolymer with a low molecular weight from one substrate (epsilon-caprolactone) used as a carbon source. The results are significant for the potential future application of Bacillus biopolymers to bioplastics production.
Labuzek
S
S
Department of Biochemistry, Faculty of Biology and Environmental Protection, University of Silesia, Katowice, Poland.
Radecka
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I
D001409:Bacillus cereus / Q000378:metabolism*; D002208:Caproates / Q000378:metabolism; D003470:Culture Media; D005947:Glucose / Q000378:metabolism; D006885:Hydroxybutyrates / Q000302:isolation & purification / Q000378:metabolism*; D007783:Lactones / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D011091:Polyesters / Q000302:isolation & purification / Q000378:metabolism*; D000094122:Polyhydroxybutyrates
D002208:Caproates; D003470:Culture Media; D005947:Glucose; D006885:Hydroxybutyrates; D007783:Lactones; D011091:Polyesters; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates; C121056:caprolactone