Preliminary Study Of Reaction Conditions About Bioethanol Production From Laminaria Japonica

The aim of this study is to research the transformation from Laminaria japonica Polysaccharide tofuel ethanol. A marine bacterium that includes L. japonica polysaccharide-degrading enzymes was isolatedfrom marine environment, applying hydrolysis pretreatment before ethanol fermentation with L. japonica.Then, Studied the optimization hydrolysis conditions, fed-batch fermentation and so on. The maincontents are as follows:A bacterial strain, L206, which could degrade seaweed polysaccharides was isolated from the rottenbrown algae. The morphologic, biochemical and physiological characteristics and16S rRNA gene wereanalyzed to identify the taxonomic position of strain L206. Then the activity of seaweed polysaccharidedegrading enzyme was measured by DNS. The results showed that the bacterial strain was a Gram-negativeshort bacillus. Its logarithmic growth phase was3h~21h, with NaCl concentration range from0%to3%(w/v) for suitable growth. Phylogenetic analysis based on16S rRNA gene sequence comparisons indicatedthat the strain L206was Agarivorans albus. The comprehensive enzyme activity reached maximum levelafter strain L206was induced for72h by the powder of L. japonica, amylase present the highest enzymaticactivity (28.17U/mL), and followed by xylanase (23.83U/mL).L. japonica was hydrolyzed by acid, commercial enzyme, L. japonica polysaccharide-degradingenzymes step by step, and be produced ethanol through fermentation after hydrolyzate. L. japonica powderwas sequentially hydrolyzed by0.4N HCl,3%cellulase,0.3%amylase, and crude PS digestion enzymesfrom isolate L206, prior to fermentation. Bio-ethanol fermentation was using S.cereviseae BCRC21686,BCRC21687, and BCRC22220(4%v/v each) for7days. The results showed that the maximum ethanolconcentration up to1.1%(v/v)(3d), and the maximum yield of ethanol is17.56g/100g.There were further improvement to acid hydrolysis process, using0.1N citric acid,0.1N oxalic acid,0.4N hydrochloric acid,0.6N sulfuric acid to hydrolysis L.japonica. Then L. japonica hydrolyzate wassequentially hydrolyzed by3%cellulase,0.3%amylase, and crude PS digestion enzymes from isolate L206,prior to fermentation. The fermentate bacteria was insteaded of salt-tolerance yeast that is S.cerevisiaeBCRC21824(12%) for7days. The results showed that the maximum ethanol yield of0.1N oxalic acidhydrolysis process (25.56g/100g) is slightly higher than0.4N hydrochloric acid process (24.59g/100g),When the fermentation to day4.L. japonica was sequentially hydrolyzed by0.1N oxalic acid,3%cellulase,0.3%amylase, and crudePS digestion enzymes from isolate L206, prior to fermentation. The fermentate bacteria was insteaded ofsalt-tolerance yeast that is S.cerevisiae BCRC21824(24%) for3days, then added to50mL L. japonicahydrolyzate each day from day4to8. The results showed that the maximum ethanol concentration was1.61%(8d), and the maximum ethanol yield up to25.74g/100g(8d).