Research On Optimal Conditions For Biomass Degradation Of Ulva Prolifera And Ethanol Fermentation

Since2007, our country most coastal waters began to breakout greentide in Yellow Sea every year as temperatures rise. The main species isUlva prolifera. And the most serious regions are the Yellow Sea and theEast China Sea. There were more than one million tons of biomassaccumulation when Ulva prolifera outbreaks in2008. How to deal withthese Ulva prolifera is a troublesome problem. Burying and burningprocess would not only waste a lot of resources, but also pollute theenvironment. Use of certain methods for energy-oriented use algae cannot only solve the environment pollution, but also be an effective way toimprove the energy crisis. Energy utilization of the algae is an effectiveway which can solve the environmental pollution and improve the energycrisis.In this paper, the green tide dominator species Ulva prolifera duringgreen tide blooming along Shandong coasts were collected in2011. Ulvaprolifera contains abundant mineral elements. The determination of10common metal elements showed that the highest contents were K, Na,Mg and Ca elements. There were some heavy metals with a certainproportion in algae, such as Hg, Pb, and Cd. The two of third of U.prolifera blades was carbohydrate, which could be degraded into thereduced sugar with variance methods for alcohol fermentation. And thecellulose with higher proportions was the materials for degrading.In lab, the blades of Ulva prolifera were degraded with cellulases.The effects of substrate concentration, enzyme amount, time, temperature,pH and synergistic hemicellulase on the enzymatic reaction were studed.The optimal experimental conditions were:50g/L of substrateconcentration,150U/g of cellulase,150U/g of hemicellulase, pH5.2,50℃, time48h. Reducing sugar yield from algae powder was about59.08%,and reducing sugar yield from fresh algae was about6.14%in2days and7.86%in5days.For decreasing the cellulase cost, by using Congo red stainingmethod, eight larger lysis zone strains which had the ability ofcellulose-decomposing were obtained from rotted Ulva prolifera andGreen tide outbreak sea area. Cellulose enzyme activity characteristic andthe ability to decompose Ulva prolifera of each strain were studied andhigh cellulose enzyme activity strains were identified. Enzyme activity ofFPA and CMC in strain H3, H4, H6and Q1was higher than others, andCMC-Na as carbon source induced enzyme work best. Four strains wereidentified by morphological and molecular: H3strain belonged toBacillus sp., H4strain belonged to Burkholderia sp., Q1strain belongedto Stenotrophomonas sp., and H6strain was Penicillium oxalicum.H3strain was used for blades degradation. The optimal conditionsfor producing the enzyme degradation with H3were：1:15ratio ofmaterial to water,50℃, pH8.5, time5days, and the highest rate of totalreducing sugar was6.4%.In order to improve the yield of ethanol fermentation, the yeast1043and yeast32868were selected and used in the enzymatic reaction liquidfor synergistic fermentation. And the effects of different strains, inoculum,initial sugar concentration, fermentation time and other factors on thefermentation of ethanol were studied. The optimized scheme was10%inoculation quantity of yeast1043and press1:1to add yeast32868,3%initial sugar concentration, time3days,35℃, pH6.5, with the highestethanol yield of15.67%. We found that some nutrients have a certain rolein the fermentation. There was a obvious improvement of ethanolproduction when MgSO4(0.4g/L),(NH4)2·SO4(4g/L) and KH2PO4(1.5g/L)were added into the fermentation liquid, and the highest ethanol yield was18.67g/L.The technology for producting bio-ethanol by crude enzymes frommicrobial degradation of fresh Ulva prolifera was established. Thetechnology has the features of low cost, simple preparation, environment friendly and suitable for large-scale production. Overall, the study laid thetheoretical foundation for the bioethanol industrial production with Ulvaprolifera.