Conversion of rice husks to polyhydroxyalkanoates (PHA) via a three-step process : optimized alkaline pretreatment, enzymatic hydrolysis, and biosynthesis by Burkholderia cepacia USM (JCM 15050)
(2017) In Journal of Chemical Technology and Biotechnology 92(1). p.100-108- Abstract
BACKGROUND: Rice husks (RH) are agricultural residues with abundant storage of cellulose and hemicellulose, making them a potential feedstock for polyhydroxyalkanoate (PHA) production. In this study, optimization of pretreatment with alkali under various conditions was performed before enzymatic hydrolysis using Celluclast 1.5 L (EC 3.2.1.4) and Novozyme 188 (EC 3.2.1.21). The hydrolysate was fed to two strains, Burkholderia cepacia USM (JCM 15050) and Cupriavidus necator NSDG-GG, an engineered strain of Cupriavidus necator H16, to evaluate their PHA production. RESULTS: Pretreatment of RH using 1.0 mol L−1 potassium hydroxide (KOH) at high temperature and pressure (HTP) (121 °C, 0.1 MPa) gave maximum sugar yield of up to 87%... (More)
BACKGROUND: Rice husks (RH) are agricultural residues with abundant storage of cellulose and hemicellulose, making them a potential feedstock for polyhydroxyalkanoate (PHA) production. In this study, optimization of pretreatment with alkali under various conditions was performed before enzymatic hydrolysis using Celluclast 1.5 L (EC 3.2.1.4) and Novozyme 188 (EC 3.2.1.21). The hydrolysate was fed to two strains, Burkholderia cepacia USM (JCM 15050) and Cupriavidus necator NSDG-GG, an engineered strain of Cupriavidus necator H16, to evaluate their PHA production. RESULTS: Pretreatment of RH using 1.0 mol L−1 potassium hydroxide (KOH) at high temperature and pressure (HTP) (121 °C, 0.1 MPa) gave maximum sugar yield of up to 87% (per total carbohydrate content) after optimized enzymatic hydrolysis, whereby the undiluted hydrolysate contained approximately 20 g L−1 total reducing sugars (TRS). B. cepacia USM utilized the hydrolysate more efficiently compared with C. necator NSDG-GG, with a maximum cell dry weight (CDW) of 4.9 g L−1 and 40 wt% PHA at shake-flask scale. The CDW and PHA content of B. cepacia USM cultivated in a 5 L fermentor were 7.8 g L−1 and 50%, respectively. The decrease in total phenolics at the end of fermentation suggested that B. cepacia USM was able to metabolize phenolic compounds. CONCLUSION: Through optimized alkali pretreatment and enzymatic hydrolysis, RH has the potential to be converted to PHA by B. cepacia USM, thus valorizing this agricultural by-product.
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- author
- Heng, King Sern ; Hatti-Kaul, Rajni LU ; Adam, Farook ; Fukui, Toshiaki and Sudesh, Kumar
- organization
- publishing date
- 2017-01-01
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- alkali pretreatment, Burkholderia cepacia, polyhydroxyalkanoate, rice husks
- in
- Journal of Chemical Technology and Biotechnology
- volume
- 92
- issue
- 1
- pages
- 9 pages
- publisher
- Wiley-Blackwell
- external identifiers
-
- scopus:84999766525
- wos:000389443600012
- ISSN
- 0268-2575
- DOI
- 10.1002/jctb.4993
- language
- English
- LU publication?
- yes
- id
- cd6c2a98-28de-4870-841a-945a53f7e479
- date added to LUP
- 2017-03-21 15:28:04
- date last changed
- 2024-07-07 14:52:12
@article{cd6c2a98-28de-4870-841a-945a53f7e479, abstract = {{<p>BACKGROUND: Rice husks (RH) are agricultural residues with abundant storage of cellulose and hemicellulose, making them a potential feedstock for polyhydroxyalkanoate (PHA) production. In this study, optimization of pretreatment with alkali under various conditions was performed before enzymatic hydrolysis using Celluclast 1.5 L (EC 3.2.1.4) and Novozyme 188 (EC 3.2.1.21). The hydrolysate was fed to two strains, Burkholderia cepacia USM (JCM 15050) and Cupriavidus necator NSDG-GG, an engineered strain of Cupriavidus necator H16, to evaluate their PHA production. RESULTS: Pretreatment of RH using 1.0 mol L<sup>−1</sup> potassium hydroxide (KOH) at high temperature and pressure (HTP) (121 °C, 0.1 MPa) gave maximum sugar yield of up to 87% (per total carbohydrate content) after optimized enzymatic hydrolysis, whereby the undiluted hydrolysate contained approximately 20 g L<sup>−1</sup> total reducing sugars (TRS). B. cepacia USM utilized the hydrolysate more efficiently compared with C. necator NSDG-GG, with a maximum cell dry weight (CDW) of 4.9 g L<sup>−1</sup> and 40 wt% PHA at shake-flask scale. The CDW and PHA content of B. cepacia USM cultivated in a 5 L fermentor were 7.8 g L<sup>−1</sup> and 50%, respectively. The decrease in total phenolics at the end of fermentation suggested that B. cepacia USM was able to metabolize phenolic compounds. CONCLUSION: Through optimized alkali pretreatment and enzymatic hydrolysis, RH has the potential to be converted to PHA by B. cepacia USM, thus valorizing this agricultural by-product.</p>}}, author = {{Heng, King Sern and Hatti-Kaul, Rajni and Adam, Farook and Fukui, Toshiaki and Sudesh, Kumar}}, issn = {{0268-2575}}, keywords = {{alkali pretreatment; Burkholderia cepacia; polyhydroxyalkanoate; rice husks}}, language = {{eng}}, month = {{01}}, number = {{1}}, pages = {{100--108}}, publisher = {{Wiley-Blackwell}}, series = {{Journal of Chemical Technology and Biotechnology}}, title = {{Conversion of rice husks to polyhydroxyalkanoates (PHA) via a three-step process : optimized alkaline pretreatment, enzymatic hydrolysis, and biosynthesis by Burkholderia cepacia USM (JCM 15050)}}, url = {{http://dx.doi.org/10.1002/jctb.4993}}, doi = {{10.1002/jctb.4993}}, volume = {{92}}, year = {{2017}}, }