Valorizing waste liquor from dilute acid pretreatment of lignocellulosic biomass by Bacillus megaterium B-10

Dilute acid pretreatment liquor (DAPL) of lignocellulose contains abundant waste sugar resource for further upgrade. But the inhibitors, produced from sugar dehydrogenation, impedes the waste sugar valorization. In this study, an efficient biostrategy was developed to upgrade the waste sugar in DAPL. The concentration of sugar and phenolics in DAPL reached 19.61 g/L and 0.57 g/L, respectively, after pretreatment of rice straw with 0.5 % (v/v) sulfuric acid for 40 min at 121 degrees C. Bacillus megaterium B-10 could tolerate the furfural toxicity products in DAPL and convert the waste sugar into high-valuable products, polyhydroxyalkanoate (PHA). This polymer was characterized by GC-MS and H-1-NMR, and the as-synthesized PHA was identified as poly-3-hydroxybutyrate (PHB), a typical PHA. A demonstrated yield of PHB (1.496 g/L) was achieved, which accounted for 32.56 % of dry cell weight. Moreover, characterizations of PHB demonstrated that the biosynthetic PHB exhibited favorable thermoplastic properties. This bioconversion of B-10 provides an efficient strategy not only for waste pollution treatment, but also for lignocellulose valorization.

Automated summary

An efficient biostrategy was developed to upgrade waste sugar in Dilute Acid Pretreatment Liquor (DAPL) of lignocellulose, using Bacillus megaterium B-10 to convert the waste sugar into high-valuable polyhydroxyalkanoate (PHA). The concentration of sugar and phenolics in DAPL can reach certain levels after pretreating rice straw, and a demonstrated yield of poly-3-hydroxybutyrate (PHB) was achieved through this bioconversion.