Simultaneous saccharification and fermentation of wheat bran flour into ethanol using coculture of amylotic Aspergillus niger and thermotolerant Kluyveromyces marxianus

Abstract

Studies on simultaneous saccharification and fermentation (SSF) of wheat bran flour, a grain milling residue as the substrate using coculture method were carried out with strains of starch digesting Aspergillus niger and nonstarch digesting and sugar fermenting Kluyveromyces marxianus in batch fermentation. Experiments based on central composite design (CCD) were conducted to maximize the glucose yield and to study the effects of substrate concentration, pH, temperature, and enzyme concentration on percentage conversion of wheat bran flour starch to glucose by treatment with fungal α-amylase and the above parameters were optimized using response surface methodology (RSM). The optimum values of substrate concentration, pH, temperature, and enzyme concentration were found to be 200 g/L, 5.5, 65°C and 7.5 IU, respectively, in the starch saccharification step. The effects of pH, temperature and substrate concentration on ethanol concentration, biomass and reducing sugar concentration were also investigated. The optimum temperature and pH were found to be 30°C and 5.5, respectively. The wheat bran flour solution equivalent to 6% (w/V) initial starch concentration gave the highest ethanol concentration of 23.1 g/L after 48 h of fermentation at optimum conditions of pH and temperature. The growth kinetics was modeled using Monod model and Logistic model and product formation kinetics using Leudeking-Piret model. Simultaneous saccharificiation and fermentation of liquefied wheat bran starch to bioethanol was studied using coculture of amylolytic fungus A. niger and nonamylolytic sugar fermenting K. marxianus.

Keywords

simultaneous saccharification and fermentation (SSF) / starch / coculture fermentation / statistical experimental design / bioethanol / Monod model

References

[1] Roble N D, Ogbonna J C, Tanaka H. A novel circulating loop bioreactor with cell immobilized in loofa (Luffa cylindrical) sponge for the bioconversion of raw cassava starch to ethanol. Appl Microbiol Biotechnol, 2002, 60: 671-678

[2] Sree N K, Sridhar M, Suresh K, Banat I M, Rao L V. High alcohol production by repeated batch fermentation using an immobilized osmotolerant Saccharomyces cerevesiae. J Ind Microbiol, 2000, 24: 222-226

[3] Neves M A D, Kimura T, Shimizu N. Production of alcohol by simultaneous saccharification and fermentation of low grade wheat flour. Brazilian Arch Biol Technol, 2006, 49: 481-190

[4] Lee J H, Pagan R J, Rogers P L. Continuous simultaneous saccharification and fermentation of starch using Zymmomonas mobilis. Biotechnol Bioeng, 1983, 25: 659-669

[5] Tanaka H, Kurosawa H, Murakama H. Ethanol production from starch by a co-immobilized mixed culture system of Aspergillus awamoriand Zymmomonas mobilis. Biotechnol Bioeng, 1986, 28: 1761-1768

[6] Verma G, Nigam P, Singh D, Chaudhary K. Bioconversion of starch to ethanol in a single step process by coculture of amylolytic yeasts and Saccharomyces cerevisiae. Bioresour Technol, 2000, 72: 261-266

[7] Nigam P, Singh D. Enzyme and microbial systems involved in starch processing. Enzy Microbial Technol, 1995, 17: 770-778

[8] Nakamura Y, Kobayashi F, Ohnaga M, Swada T. Alcohol fermentation of starch by genetic recombinant yeast having glucoamylase activity. Biotechnol Bioeng, 1997, 53: 21-25

[9] Ratnam B V V, Narasimha Rao M, Damodara Rao M, Subba Rao S, Ayyanna C. Optimization of fermentation conditions for production of ethanol from sago starch using response surface methodology. J Microbiol Biotechnol, 2003, 19: 523-526

[10] Ratnam Bandaru V V, Subba Rao S, Raomendu D, Narasima Rao M, Chityala A. Optimization of fermentation condition for the production of ethanol from sago starch by co-immobilized amyloglucosidase and cells of Zymomonas mobilisusing response surface methodology. Enzym Microbiol Technol, 2006, 38: 209-214

[11] Sunitha I, Subba Rao M V, Ayyanna C. Optimization of medium components and fermentation conditions for production of L-glutamic acid by co-immobilized whole cells of Micrococcus glutanicusand Pseudomonas reptilivora. Bioproces Eng, 1998, 18: 353-359

[12] Ramon F, Dlia M L, Pingaud H, Riba J P. Kinetic study and mathematical modeling of the growth of Saccharomyces cerevisiae522D in presence of K2 killer protein. J Chem Technol Biotechnol, 1997, 68: 195-201

[13] Reynders M B, Rawling D E, Harrison S T L. Studies on the growth, modeling and pigment production by the yeast Phaffia rhodozymaduring fed batch cultivation. Biotechnol Lett, 1996, 18: 649-654

[14] Balusu R, Paduru R R, Kuravi S K, Seenayya G, Reddy G. Optimization of critical medium components using response surface methodology for ethanol production from cellulosic biomass by Clostridium thermocellumSS19. Proc Biochem, 2005, 40: 3025-3030

[15] Miller G L. Estimation of reducing sugar by dinitrosalicylic acid method. Anal Chem, 1972, 31: 426-428

[16] Bailey J E, ed. Kinetics of substrate utilization, product formation and biomass production in cell cultures. In: Biochemical Engineering Fundamentals, 3rd edition. New York: McGraw Hill Book Company, 1986

[17] Aiba S, ed. Biochemical Engineering: Comprehensive text on fermentation of batch kinetics. In: Biochemical Engineering, 2nd edition. New York: Academic Press Inc, 1973

RIGHTS & PERMISSIONS

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg