OPTIMIZATION OF SIMULTANEOUS SACCHARIFICATION AND FERMENTATION CONDITIONS WITH AMPHIPATHIC LIGNIN DERIVATIVE AS AN ACCELERATOR

摘要

An aim of this study is to optimize fed-batch type of simultaneous saccharification and fermentation(SSF)conditions for softwood unbleached kraft pulp as a substrate with amphipathic lignin derivatives(A-LDs)as a cellulase-aid agent.Firstly,the process was tested in 100-mL buffered solutions with gentle shaking at A-LD charges of 2.5,3.0 and 5.0 g/L.The highest bioethanol yield was obtained at an A-LD charge of 3.0 g/L.To improve agitation of the media,the process was secondly attempted using a 3-L jar fermenter equipped with a powerful mechanical stirrer.Among four stirring programs tested without A-LDs,a stirring program,comprised of 40-rpm stirring in the pre-hydrolysis process,20-rpm stirring for the first 3 days of SSF and 40-rpm stirring for 5 min every hour,gave the highest bioethanol concentration of 64.5 g/L.When A-LDs were added to the medium under the same stirring conditions,the concentration was reached 81.0 g/L.Thus,bioethanol concentration in the fed-batch SSF was significantly improved by 1.7 times by the optimization of the SSF conditions in the presence of A-LDs.