초록
<P><B>Abstract</B></P><P><B>BACKGROUND</B></P><P>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, <I>Burkholderia cepacia</I> USM (JCM 15050) and <I>Cupriavidus necator</I> NSDG‐GG, an engineered strain of <I>Cupriavidus necator</I> H16, to evaluate their PHA production.</P><P><B>RESULTS</B></P><P>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). <I>B. cepacia</I> USM utilized the hydrolysate more efficiently compared with <I>C. necator</I> 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 <I>B. cepacia</I> 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 <I>B. cepacia</I> USM was able to metabolize phenolic compounds.</P><P><B>CONCLUSION</B></P><P>Through optimized alkali pretreatment and enzymatic hydrolysis, RH has the potential to be converted to PHA by <I>B. cepacia</I> USM, thus valorizing this agricultural by‐product. © 2016 Society of Chemical Industry</P>