• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.28 no.1
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• pp.1-8
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• 2022

With the spread of COVID-19 worldwide, non-face-to-face services have grown rapidly, but at the same time, the problem of plastic waste is getting worse. Accordingly, eco-friendly policies such as carbon neutrality and sustainable circular economy are being promoted worldwide. Due to the high demand for eco-friendly products, the packaging industry is trying to develop eco-friendly packaging materials using PLA and PBAT and create new business models. On the other hand, Ulva australis occurs in large quantities in the southern seas of Korea and off the coast of Jeju Island, causing marine environmental problems. In this study, lactic acid was produced through dilute acid pretreatment, enzymatic saccharification, and fermentation processes to utilize Ulva australis as a new alternative energy raw material. In general, seaweeds vary in carbohydrate content and sugar composition depending on the species, harvest location, and time. Seaweed is mainly composed of polysaccharides such as cellulose, alginate, mannan, and xylan, but does not contain lignin. It is difficult to expect high extraction yield of the complex polysaccharide constituting Ulva australis with only one process. However, the fusion process of dilute acid and enzymatic saccharification presented in this study can extract most of the sugars contained in Ulva australis. Therefore, the fusion process is considered to be able to expect high lactic acid production yield when a commercial-scale production process is established.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.29 no.2
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• pp.95-102
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• 2023

Despite the easing of social distancing, demand for non-face-to-face services continues to rise. Recently, the EU is pursuing a comprehensive plastic use reduction by expanding the scope of plastic use regulations for packaging plastics according to the New Cyclical Economy Action Plan(NCEAP). In response to this trend, the packaging industry is moving away from conventional non-degradable/petroleum-based plastics and conducting research on packaging materials using biodegradable plastics such as PLA(Poly Lactic Acid), PBAT(Poly Butylene Adipate-co-butylene Terephthalate). On the other hand, ginkgo leaves occur in large quantities in Korea and act as a cause of slip accidents and flooding. In this study, a method to utilize ginkgo biloba leaf as a new alternative biomass resource was proposed by producing lactic acid through pretreatment, enzymatic saccharification, and fermentation processes. For the efficiency of lactic acid production, a comparative analysis of lignin content from before and after browning was performed. In addition, the degree of glucan extraction was evaluated by applying a pretreatment method using three catalysts: hot water, sulfuric acid, and sodium hydroxide. It is difficult to expect high production of lactic acid with single process. Therefore, an integrated process operation using both the pretreated hydrolyzate and the residual solid enzymatic saccharification solution must necessarily be applied.

• Journal of Microbiology and Biotechnology
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• v.23 no.11
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• pp.1577-1585
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• 2013

Bioethanol production from lignocellulose is considered as a sustainable biofuel supply. However, the low cellulose hydrolysis efficiency limits the cellulosic ethanol production. The cellulase is strongly inhibited by the major end product cellobiose, which can be relieved by the addition of ${\beta}$-glucosidase. In this study, three ${\beta}$-glucosidases from different organisms were respectively expressed in Saccharomyces cerevisiae and the ${\beta}$-glucosidase from Saccharomycopsis fibuligera showed the best activity (5.2 U/ml). The recombinant strain with S. fibuligera ${\beta}$-glucosidase could metabolize cellobiose with a specific growth rate similar to the control strain in glucose. This recombinant strain showed higher hydrolysis efficiency in the cellulose simultaneous saccharification and fermentation, when using the Trichoderma reesei cellulase, which is short of the ${\beta}$-glucosidase activity. The final ethanol concentration was 110% (using Avicel) and 89% (using acid-pretreated corncob) higher than the control strain. These results demonstrated the effect of ${\beta}$-glucosidase secretion in the recombinant S. cerevisiae for enhancing cellulosic ethanol conversion.

• Korean Chemical Engineering Research
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• v.53 no.4
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• pp.468-471
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• 2015

Microalgae have the advantages of being able to utilize the solar energy and culturing at a low cost. In particular, microalgae have a great potential in the production of biodiesel due to the high lipid content. Lipids produced from microalgae are converted to fatty acid methyl ester (FAME) by trans-esterification reaction and FAME is called a biodiesel in general. In addition, microalgae can also be utilized as a substrate for ethanol fermentation after saccharification reaction. In this study, three types of microalgae (Nanochloris, Dunaliella tertiolecta, Tetraselmis) were cultured and their lipid contents were compared. In addition, the effects of lighting period on the growth rate and lipid content were studied. Finally, the amounts of glucose produced from each saccharified microalgae were investigated. As a result, we demonstrated that D. tertiolecta has 43.6% higher lipid content and 22% higher glucose conversion than two others.

• Journal of Microbiology and Biotechnology
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• v.28 no.12
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• pp.2036-2045
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• 2018

An endo-${\beta}$-1,4-glucanase gene, cel5L, was cloned using the shot-gun method from Bacillus sp.. The gene, which contained a predicted signal peptide, encoded a protein of 496 amino acid residues, and the molecular mass of the mature Cel5L was estimated to be 51.8 kDa. Cel5L contained a catalytic domain of glycoside hydrolase (GH) family 5 and a carbohydrate-binding module family 3 (CBM_3). Chromatography using HiTrap Q and CHT-II resulted in the isolation of two truncated forms corresponding to 50 (Cel5L-p50) and 35 kDa (Cel5L-p35, CBM_3-deleted form). Both enzymes were optimally active at pH 4.5 and $55^{\circ}C$, but had different half-lives of 4.0 and 22.8 min, respectively, at $70^{\circ}C$. The relative activities of Cel5L-p50 and Cel5L-p35 for barley ${\beta}$-glucan were 377.0 and 246.7%, respectively, compared to those for carboxymethyl-cellulose. The affinity and hydrolysis rate of pNPC by Cel5L-p35 were 1.7 and 3.3 times higher, respectively, than those by Cel5L-p50. Additions of each to a commercial enzyme set increased saccharification of pretreated rice straw powder by 17.5 and 21.0%, respectively. These results suggest CBM_3 is significantly contributing to thermostability, and to affinity and substrate specificity for small substrates, and that these two enzymes could be used as additives to enhance enzymatic saccharification.

• Journal of Microbiology and Biotechnology
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• v.32 no.1
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• pp.117-125
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• 2022

Until recently, four types of cellobiose-fermenting Saccharomyces cerevisiae strains have been developed by introduction of a cellobiose metabolic pathway based on either intracellular β-glucosidase (GH1-1) or cellobiose phosphorylase (CBP), along with either an energy-consuming active cellodextrin transporter (CDT-1) or a non-energy-consuming passive cellodextrin facilitator (CDT-2). In this study, the ethanol production performance of two cellobiose-fermenting S. cerevisiae strains expressing mutant CDT-2 (N306I) with GH1-1 or CBP were compared with two cellobiose-fermenting S. cerevisiae strains expressing mutant CDT-1 (F213L) with GH1-1 or CBP in the simultaneous saccharification and fermentation (SSF) of cellulose under various conditions. It was found that, regardless of the SSF conditions, the phosphorolytic cellobiose-fermenting S. cerevisiae expressing mutant CDT-2 with CBP showed the best ethanol production among the four strains. In addition, during SSF contaminated by lactic acid bacteria, the phosphorolytic cellobiose-fermenting S. cerevisiae expressing mutant CDT-2 with CBP showed the highest ethanol production and the lowest lactate formation compared with those of other strains, such as the hydrolytic cellobiose-fermenting S. cerevisiae expressing mutant CDT-1 with GH1-1, and the glucose-fermenting S. cerevisiae with extracellular β-glucosidase. These results suggest that the cellobiose-fermenting yeast strain exhibiting low energy consumption can enhance the efficiency of the SSF of cellulosic biomass.

• KSBB Journal
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• v.4 no.2
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• pp.99-103
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• 1989

The kinetics of secondary hydrolysis of hemicellulose prehydrolyzate by a solid superacid, Nafion, was investigated. The maximum attainable xylose yields determined from continuous column reactor operation were about 90%. Nafion was found to be a stable hydrolytic catalyst provided that the feed solution was free of cationic substances.

• 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.

• Korean journal of food and cookery science
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• v.12 no.1
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• pp.60-73
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• 1996

This study was undertaken to investigate the effect of cereals on the physicochemical and sensory characteristics of Noti. Noti is one of Korean traditional pan-fried glutinous cereal cakes. Noti made from the steamed glutinous rice flour, glutinous Chinese millet flour, glutinous millet flour or glutinous Indian millet flour is saccharified with malt, and then pan-fried. Noti also has sweet taste without sugar added. In addition, Noti has elastic characteristic, high calorie and good flavor. Long storage makes it better taste. In this case, Noti was made from the steamed glutinous rice flour. By the sensory evaluation, color, flavor and moistness were unfavorable according to the storage. Consistency was not strongly increased when comparing with the common rice cake depending upon the storage. The texture tended to increase by storage period. Optimum conditions of the safe storage and overall acceptability were to add 15% malt and keep 6hr saccharification time at 60$^{\circ}C$. During the period of storage for 90 days, reducing sugar content was similar, moisture content was low and maintained, and the acid value was not increased abruptly. The hardness was not increased rapidly and fungal growth was considerably low. Cohesiveness and elasticity were increased during storage.

• Korean journal of food and cookery science
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• v.27 no.5
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• pp.577-587
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• 2011

In this study, lotus leaf was added to a Takju (Korean milky rice wine) preparation to evaluate its effects on physicochemical and fermentation properties. For rapid saccharification Takju was stored at 25$^{\circ}C$ for 2 days and then temperature was switched to 18$^{\circ}C$ to mature the wine for 21 days. From the start of fermentation to 2-days, the pH of Takju decreased rapidly and acidity increased. Maltose, a byproduct of starch saccharification, increased for 2 days then rapidly decreased. Glucose fluctuated for 7 days and of the 21-days fermentation. The ethanol production rate was highest during the first 7 days, then slowed. Total viable yeast and lactic acid bacterial counts increased rapidly for 2 days and then decreased gradually thereafter. Leuconostoc spp. grew rapidly for 1 day and sharply disappeared with decreasing pH. DPPH radical scavenging activity was significantly higher for Takju prepared with lotus leaf than without. The overall acceptance of Takju tended to increase when it was prepared with lotus leaf.