• Journal of Microbiology and Biotechnology
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• v.26 no.7
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• pp.1259-1266
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• 2016

Bioethanol was produced from Kappaphycus alvarezii seaweed biomass using separate hydrolysis and fermentation (SHF). Pretreatment was evaluated for 60 min at 121℃ using 12% (w/v) biomass slurry with 364 mM H₂SO₄. Enzymatic saccharification was then carried out at 45℃ for 48 h using Celluclast 1.5 L. Ethanol fermentation with 12% (w/v) K. alvarezii hydrolyzate was performed using the yeasts Saccharomyces cerevisiae KCTC1126, Kluyveromyces marxianus KCTC7150, and Candida lusitaniae ATCC42720 with or without prior adaptation to high concentrations of galactose. When non-adapted S. cerevisiae, K. marxianus, and C. lusitaniae were used, 11.5 g/l, 6.7 g/l, and 6.0 g/l of ethanol were produced, respectively. When adapted S. cerevisiae, K. marxianus, and C. lusitaniae were used, 15.8 g/l, 11.6 g/l, and 13.4 g/l of ethanol were obtained, respectively. The highest ethanol concentration was 15.8 g/l, with Y_EtOH = 0.43 and Y_T% = 84.3%, which was obtained using adapted S. cerevisiae.

• Journal of Microbiology and Biotechnology
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• v.2 no.3
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• pp.197-203
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• 1992

Studies of the pretreatment of chitin and its subsequent hydrolysis by Aspergillus carneus chitinase are reported. Ball milling was found to be the most effective way among the pretreatment methods tested. Data are presented describing the effect of enzyme and substrate concentrations on the rate and extent of the hydrolysis process. It was found that the successive addition of enzyme improved the saccharification yield. Significant product inhibition of the chitinase was observed when N-acetylglucosamine concentration was 3.6％ or higher. Adsorption of enzymes to the substrate occurred during a 24 hr hydrolysis period. An initial rapid and extensive adsorption occurred, followed by gradual desorption which increased during the time of reaction. Intermediate removal of the hydrolyzate and continuation of the hydrolysis by adsorbed enzyme on the residual chitin was also investigated. A total of 75.4 g/l reducing sugars, corresponding to 69.2％ saccharificaton yield (as N-acetylglucosamine) was obtained. In addition an increase in the amount of recoverable enzymes was observed under these conditions. Evidence presented here suggests that the technique, whereby the free enzymes in the recovered hydrolyzate are re-adsorbed onto the new substrate, may provide a means of recirculating the dissolved enzymes.

• Journal of Forest and Environmental Science
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• v.36 no.1
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• pp.62-66
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• 2020

Ethanol fermentation of the enzymatic hydrolysates from the products pretreated using 1-ethyl-3-methyl-imidazolium acetate ([EMIM]Ac) and its co-solvents with dimethylformamide (DMF) was conducted using Saccharomyces cerevisiae (D452-2). The optical density change due to the yeast cell growth, the consumption amount of monosugars (glucose, xylose), the concentration of acetate, and ethanol production yield were investigated. The co-solvent system lowered inhibition of the growth of the cells. The highest concentration of glucose (7.8 g/L) and xylose (3.6 g/L) was obtained from the enzymatic hydrolysates of the pretreated product by pure [EMIM]Ac. The initial concentration of both monosugars in the enzymatic hydrolysates was decreased with increasing fermentation time. Ethanol of Approximately 3 g/L was produced from the enzymatic hydrolysates by pure [EMIM]Ac and co-solvent with less than 50% DMF.

• Microbiology and Biotechnology Letters
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• v.17 no.4
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• pp.349-357
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• 1989

Uncooked starch can be effectively saccharified in an enzyme reaction system containing attrition-milling media. To develope the high efficiency bioattritor, an agitated bead type bioreactor was constructed, and its effectiveness was evaluated. The optimal operation condition of bioattritor was found to be 300 g glass bead/L, 200 rpm, standard type impeller for 220 g/L of uncooked corn starch. The torque under the various operational conditions were also measured. The interrelation-ship between energy consumption for agitation of attrition-milling media and enhanced extent of saccharification of uncooked starch was evaluated, Power consumption was measured to be around 1.53 watt/L under the optimal operation condition. The attrition coupled enzyme reaction system is identified to tie a very excellent energy saying process for saccharification of uncooked starch, and seems to have a bright prospect of industrial application.

• KSBB Journal
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• v.4 no.3
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• pp.215-220
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• 1989

To develop an attrition coupled enzyme reactor with high efficiency-low energy consumption for saccharification of insoluble biomass, a 5L horizontal paddle type bioreactor was constructed and its performance was evaluated. The optimal condition for saccharification of 50g $\alpha$ -cellulose/L was found to be 200rpm with 500g of 3mm glass bead. Especially, the horizontal paddle type bloreactor was very effective for saccharification of high concentration of insoluble cellulose, in which around 72% of $\alpha$ -cellulose was saccharified for 75g $\alpha$ -cellulose/L, and even up to 70% for 100g of $\alpha$ -cellulose/L after 24hours. Under the optimal condition, the power consumption was measured to be around 1.7watth/g. Horizontal paddle type bioreactor seems to have an appropriated structural feature for industrial scale operation and to be an effective and energy saving attrition coupled enzyme reactor.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.1
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• pp.26-31
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• 2006

The saccharogenic liquid (SFW) obtained by the enzymatic saccharification of food wastes was used as a medium for production of bacterial cellulose (BC). The enzymatic saccharification of food wastes was carried out by the cultivation supernatant of Trichoderma harziaum FJ1 culture. Acetobacter xylinum KJ1 was employed for the BC production culture. The physical properties, such as polymerization, crystallinity, Young's modulus, and tensile strength, of BCs produced by three culture methods: the static cultures using HS (Hestrin-Schramm) as a reference medium (A) or the SFW medium (B), the shaking culture (C) or the air circulation culture (D) using the SFW medium, were investigated. The degrees of polymerization of BCs produced under the different culture conditions (A-D) showed 11000, 9500, 8500, and 9200, respectively. Young's modulus was 4.15, 5.0, 4.0, and 4.6 GPa, respectively. Tensile strength was 124, 200, 80, and 184 MPa, respectively. All of the BC had a form of cellulose I representing pure cellulose. In the case of the shaking culture, the degree of crystallinity was 51.2%, the lowest degree. Under the other culturing conditions, the trend should remain in the range of 89.7-84%. Overall, the physical properties of BC produced from SFW were similar to those of BC from HS medium, a commercial complex medium, and BC production by the air circulation culture mode brought more favorable results in terms of the physical properties and its ease of scale-up. Therefore, it is expected that a new BC production method, like air circulation culture using SFW, would contribute greatly to BC-related manufacturing.

• KSBB Journal
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• v.11 no.6
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• pp.712-717
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• 1996

Cellulase was modified with synthetic copolymers of polyoxyethylene derivative and maleic acid anhydride. The saccharification characteristics and enzymatic reaction kinetic mechanism of modified and native cellulases were observed. In modification reaction of cellulase, degree of modification(DM) increased, as mass ratio of copolymers to enzyme increased. Maximum DM was 55% at mass ratio of 4 and remained activity was 75%. In saccharification experiment modified enzyme had maintained higher stability than native enzyme over all the reaction and the final conversion yield of modified enzyme was greater than that of native enzyme. Numerical simulation based on the reaction mechanism considering enzymatic deactivation was performed. Modified enzyme had kept higher free enzyme concentration over all the reaction than that of native enzyme. Comparing calculation values with experimental data, calculation values were in accordance with experimental data.

• KSBB Journal
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• v.10 no.3
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• pp.304-316
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• 1995

For fuel alcohol production, enzymatic liquefaction and saccharification of tapioca starch by ${\alpha}$-amylase and glucoamylase were studied. The thermophilic ${\alpha}$-amylase Termamyl produced from Bacillus licheniformis gave a better liquefaction than the relalively low temperature enzyme BAN from B. subtilis. Oplimal temperature and pH with Termamyl were $90∼95^{\circ}C$ and 5.8, respectively. Minimal amount of Termamyl 240uc for a satisfactory liquefaction for a two-hour reaction was about 0.0125% (v/w) with respect to the mass of tapioca used. For saccharification experiments two enzymes, Novo AMG and Do-I1 enzymes were compared. The enzymatic activity of each enzyme was a little different depending on the substrate used and the latter was found to have a significant amount of ${\alpha}$-amylase activity. With Novo AMG optimal temperature was about $58^{\circ}C$ The pH optimum was 4.3 with maltose, however, with tapioca, no difference was observed between pH 4.3 and 5.7 which is a natural, unadjusted pH of liquefied tapioca. For 85% of completion of saccharification, it was necessary to use 0.0625% (v/w) of Novo AMG 400L for tapioca and to run the reaction for more than 10 hr, Packed volume of solid particles in tapioca slurry remained at around 30% during liquefaction and saccharification. This indicates that the removal of the solid particle before fermentation is not economically feasible at all, even though the solid particles make it very difficult to operate the bioreactor in a continuous mode with cell-recycle.

• Journal of Microbiology and Biotechnology
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• v.28 no.10
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• pp.1671-1682
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• 2018

Alginate lyases (endo and exo-lyases) are required for the degradation of alginate into its constituting monomers. Efficient bioethanol production and extraction of bioactives from brown algae requires intensive use of these enzymes. Nonetheless, there are few commercial alginate lyase preparations, and their costs make them unsuitable for large scale experiments. A recombinant expression protocol has been developed in this study for producing seven endo-lyases and three exo-lyases as soluble and highly active preparations. Saccharification of alginate using 21 different endo/exo-lyase combinations shows that there is complementary enzymatic activity between some of the endo/exo pairs. This is probably due to favorable matching of their substrate biases for the different glycosidic bonds in the alginate molecule. Therefore, selection of enzymes for the best saccharification results for a given biomass should be based on screens comprising both types of lyases. Additionally, different incubation temperatures, enzyme load ratios, and enzyme loading strategies were assessed using the best four enzyme combinations for treating Macrocystis pyrifera biomass. It was shown that $30^{\circ}C$ with a 1:3 endo/exo loading ratio was suitable for all four combinations. Moreover, simultaneous loading of endo-and exo-lyases at the beginning of the reaction allowed maximum alginate saccharification in half the time than when the exo-lyases were added sequentially.

• Journal of Microbiology and Biotechnology
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• v.21 no.7
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• pp.703-710
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• 2011

Enzymatic saccharification of corn stover using Phanerochaete chrysosporium and Gloeophyllum trabeum and subsequent fermentation of the saccharification products to ethanol by Saccharomyces cerevisiae and Escherichia coli K011 were achieved. Prior to simultaneous saccharification and fermentation (SSF) for ethanol production, solid-state fermentation was performed for four days on ground corn stover using either P. chrysosporium or G. trabeum to induce in situ cellulase production. During SSF with S. cerevisiae or E. coli, ethanol production was the highest on day 4 for all samples. For corn stover treated with P. chrysosporium, the conversion to ethanol was 2.29 g/100 g corn stover with S. cerevisiae as the fermenting organism, whereas for the sample inoculated with E. coli K011, the ethanol production was 4.14 g/100 g corn stover. Corn stover treated with G. trabeum showed a conversion 1.90 and 4.79 g/100 g corn stover with S. cerevisiae and E. coli K011 as the fermenting organisms, respectively. Other fermentation co-products, such as acetic acid and lactic acid, were also monitored. Acetic acid production ranged between 0.45 and 0.78 g/100 g corn stover, while no lactic acid production was detected throughout the 5 days of SSF. The results of our experiment suggest that it is possible to perform SSF of corn stover using P. chrysosporium, G. trabeum, S. cerevisiae and E. coli K011 for the production of fuel ethanol.