Pretreatment of lignocellulosic biomass results in the formation of byproducts (furfural, hydroxymethylfurfural [HMF], vanillin, acetate etc.), which affect microbial growth and productivity. Furfural (0.02%), HMF (0.04%), and acetate (0.6%) showed positive effects on Ralstonia eutropha 5119 growth and polyhydroxyalkanoate (PHA) production, while vanillin exhibited negative effects. Response optimization and interaction studies between the variables glucose, ammonium chloride, furfural, HMF, and acetate using the response surface methodology resulted in maximum PHA production (2.1 g/L) at optimal variable values of 15.3 g/L, 0.43 g/L, 0.04 g/L, 0.05 g/L, and 2.34 g/L, respectively. Different lignocellulosic biomass hydrolysates (LBHs), including barley biomass hydrolysate (BBH), Miscanthus biomass hydrolysate (MBH), and pine biomass hydrolysate (PBH), were evaluated as potential carbon sources for R. eutropha 5119 and resulted in 1.8, 2.0, and 1.7 g/L PHA production, respectively. MBH proved the best carbon source, resulted in higher biomass (Yx/s, 0.31 g/g) and PHA (Yp/s, 0.14 g/g) yield.
The authors would like to acknowledge the KU Research Professor Program of Konkuk University, Seoul, South Korea. This study was supported by Research Program to solve social issues of the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (2017M3A9E4077234), National Research Foundation of Korea (NRF) (NRF- 2015M1A5A1037196 , NRF2016R1D1A1B03932301 , 2017R1D1A1B03030766 ). This work was also supported by Next-Generation BioGreen21 Program (SSAC, PJ01312801), Rural Development Administration. Consulting service from the Microbial Carbohydrate Resource Bank (MCRB, Seoul, Korea) was kindly appreciated. This work was also supported by Polar Academic Program (PAP, PE18900). Appendix A
