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Enzymatic extruded starch as a carbon source for the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) by Haloferax mediterranei

Paper ID Volume ID Publish Year Pages File Format Full-Text
36111 45121 2006 8 PDF Available
Title
Enzymatic extruded starch as a carbon source for the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) by Haloferax mediterranei
Abstract

The extremely halophilic Archaeon Haloferax mediterranei can accumulate polyhydroxyalkanoate (PHA) on a medium containing high salt concentration. The available carbon source for the cell growth and PHA production was the native cornstarch being treated by an enzymatic reactive extrusion process. The extrusion process was processed at a 25 mm single-screw extruder with α-amylase quantities at 1–5 g/100 g wet weight of cornstarch, screw speed at 39–78 rpm and temperatures controlled at 55 °C for zone 1, 65 °C for zone 2, 85 °C for zone 3 and 90 °C for the die. By using an extruded starch/yeast extract ratio (ES/YE ratio) of 1/1.7 g/g in the feeding medium to maintain starch and organic nitrogen concentrations during the pH-stat fed-batch fermentation, the PHA content could reach 50.8% (w/w) of dry cell. From the nuclear magnetic resonance (1H NMR) spectrum, the PHA was confirmed to be a poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) copolymer with a composition of 10.4 mol% of HV unit. The glass transition temperature of this copolymer was −1.2 °C as measured by a differential scanning calorimeter. On the same thermogram, two melting peaks were found at 129.1 and 144.0 °C, respectively; which were much lower than those of the polyhydroxybutyrate (PHB) homopolymer.

Keywords
Haloferax mediterranei; Enzymatic extrusion; Poly(3-hydroxybutyrate-co-3-hydroxyvalerate); Starch; Fed-batch culture; pH-stat
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Enzymatic extruded starch as a carbon source for the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) by Haloferax mediterranei
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Publisher
Database: Elsevier - ScienceDirect
Journal: Process Biochemistry - Volume 41, Issue 11, November 2006, Pages 2289–2296
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us