• Korean Journal of Veterinary Research
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• v.33 no.1
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• pp.61-69
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• 1993

In order to search for new antibiotics from anaerobic bacteria, a large number of samples from domestic soil were collected and processed by apropriate methods. A potential strain, Streptococcus sp. An-21-1, was found to produce antimicrobial compounds. The Results were as follows; 1. During fermentation, the bacteria grew rapidly up to 20hr, thereafter entered the death phase. The optimal temperature and pH for the bacterial growth were $37^{\circ}C$ and pH 7.0, respectively. 2. Antibiotics were purified from culture broth by solvent extraction, silica gel column chromatography and Sepadex L.H 20 column. 3. Physicochemical properties of Ap-1 and Ap-2 were similar ; Their melting points were between $234-237^{\circ}C$. Color reactions of ninhydrin, 2,7-dichlorofluorescein, 4-dimethylaminobenzaldehyde, Dragendroffs reagent and 20% $H_2SO_4$, were positive. Therefore, we assumed that these antibiotics have amine group, immine group, alkaloid, and lipid components. These were stable to heat. UV spectrophotometry showed two peaks at 210 nm and 260 nm. From above results, we assumed these antibiotics are belong to the peptide antibiotic family.

• Journal of Hydrogen and New Energy
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• v.26 no.5
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• pp.409-415
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• 2015

This study was performed to optimize the integrated anaerobic digestion (AD) and microbial electrolysis cells (MECs) for the enhanced hydrogen production. The optimum operational conditions of integrated AD and MECs were obtained using response surface methodology. The optimum substrate concentration and operational pH were 10 g/L and 6.8, respectively. In the confirm test, 1.43 mol $H_2/mol$ hexose was achieved, which was 2.5 times higher than only AD. After 40 to 60 hour at seeding, the volatile fatty acids (VFAs) in reactor of AD were not changed. However the VFAs of reactor of AD-MECs were reduced by 61.3% (acetate: 76.4%, butyrate: 50.0%, lactate: 55.0%).

• Journal of Hydrogen and New Energy
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• v.27 no.5
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• pp.533-539
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• 2016

This study was performed to evaluate the characteristics of start-up of anaerobic digestion from food waste with different inoculum ratios. The hydrogen yield was similar with different inoculum ratios. The hydrogen production rate increased with increasing inoculum ratio. But the specific hydrogen production rate decreased with increasing inoculum ratio. Total volatile fatty acids composition analysis showed that butyrate and acetate were the prevalent products in all reactors, followed by lactate and propionate. The acetate was most prevalent product in reactors at $X_0/S_0=0.080$ and 0.159. But in reactors at $X_0/S_0=0.239$ and 0.318, butyrate accounted for greater than 50% of the total volatile fatty acids.

• KSBB Journal
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• v.16 no.4
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• pp.403-408
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• 2001

Distillation condensate generated from downstream processing of microbial alcohol fermentation imposes a serious burden to biological wastewater treatment or anaerobic digestion due to its high contents of SS (suspended solids) and TN (total nitrogen), A pilot scale microfiltration of the stillage condensate with a stainless steel SCEPTER membrane of 0.1 ${\mu}$m pore size was carried out to remove SS which was mostly composed of microbial cell residue. A stable permeate flux was achieved when the decanter effluent containing 0.7% of SS was filtered under the conditions of X10 VCR (volume concentration ratio), 2.5 bar of TMP (transmembrane pressure), and 60$^{\circ}C$. When stillage condensate with 2.6% SS was treated directly with microfiltration, VCR below X3 was recommended for a long duration of filtration. The permeate and retentate obtained from microfiltration were recycled to make-up medium of fermentation. Adding permeate or retentate up to 30% of fermentation volume showed no distinguished undesirable influence during the course of alcohol fermentation. Although only slight improvements in the final amount of CO$_2$ evolution and alcohol content were observed, fermentation rate increased so that the required time to reach 450 L/ton of CO$_2$ evolution was shortened to 72% of that with normal media.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.2
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• pp.118-127
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• 2007

This study investigated the effect of varying TS concentration levels using supernatant of food waste. The experiment was performed at varying TS concentration levels ranging from 5% to 10% by a $35^{\circ}C$-mesophilic digestion reactor, dual digestion system with acid and methane fermenters combined. As a result, removal efficiency and stabilization were observed at TS concentration of 7~8%, But the removal efficiency notably decreased at 8% or higher TS level. At a stabilized phase of the reactor, more than $0.3m^3/kg{\cdot}vs$ gas was produced, with phenomena such as salt accumulation and increase of pH level being unnoticed. These results indicate that the increase of anaerobic digestion of food waste supernatant TS content has an effect on reaction and that it is necessary to control and operate concentration within 8%, given that the effect is stronger at 8% or higher.

• Korean Journal of Microbiology
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• v.52 no.2
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• pp.183-191
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• 2016

Marine bacteria have represented unique physiologies and products which are not discovered from terrestrial organisms. There has been great interest to utilize and develop marine bacteria in many industrial sectors. Recently, we isolated and characterized anaerobic bacteria from various marine environments in Korea to search organic acids fermenting strains. From our enrichment performed under anaerobic condition, 65 strains were isolated and identified by the 16S rRNA gene sequence analysis. Among them, eleven strains were selected for phylogenetical and biochemical analysis. All tested strains were affiliated with Class Clostridia except one with Class Bacteroidia. Most of strains produce acetate (6 strains) with butyrate (2 strains) and/or formate (4 strains). Strain MCWD5 transformed 40% of glucose to extracellular polymeric substances. These results indicate that many novel anaerobic microorganisms which have great potential in commercial application are distributed in the marine environments of Korean Peninsula.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.1
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• pp.65-72
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• 2001

Four newly isolated bacteria from soil were used to manufacture microbial inoculum to compost food waste. The bacteria, GM103, V25, V31, and V35, were identified as Bacillus licheniformis, B. subtilis, B. stearothermophilius, and B, subtilis, respectively. The bacterial strains were efficient to degrade protein and starch and also able to inhibit the growth of plant pathogenic fungus Rhizopus stronifer. The GM103 showed distinct capability in degrading starch, but grow only aerobically. The other three bacterial strains. V25, V31, and V35, could grow both aerobically as well as anaerobically, in 10%(w/v) salt, at $50^{\circ}C$, and had good viability and survival rate in soil. These characteristics of the bacterial strains are very adquate in Korean food composting containing high concentration of salt, especially at home. By mixing the 4 bacterial culture broth with molasses, beet pulp, zeolite, The bacterial inoculum for food waste composting-BIOTOP-CLEAN-was made. The performance of food waste composting by the BIOTOP-CLEAN was compared with that by control(not treated) and HS(other demestic company's inoculum product for food waste composting). The maximum temperature of the food waste during the composting with the BIOTOP-CLEAN was $50^{\circ}C$, while those of the control and HS were $30^{\circ}C$ and $35^{\circ}C$, respectively. The BIOTOP-CLEAN gave the good smell and showed dark brown color, while the control gave bad smell and HS gave less bad smell. These indicates that the food waste composting by the BIOTOP-CLEAN had been well accomplished. The culture broth of V25, V31, V35 were sparyed to the plants of tomato, chinese cabbage, raddish, red pepper every month and the spraying the culture broth to these plant significantly improved the production yield of the crops, due to the control effect of the bacterial strains against the plant pathogens.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.1
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• pp.54-61
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• 2007

The influences of pH were investigated for anaerobic hydrogen gas production under the constant pH condition ranged from pH 3 to 10. Carbon dioxide and hydrogen gas were main components of the gas but methane was not detected in the produced gas when sucrose was added in enrichment medium. When the modified Gompartz equation was applied for the statistical analysis of experimental data, a hydrogen production potential and maximum gas production rate at pH 5 were 1,182 mL and 112.46 mL/g dry wt biomass/hr. The hydrogen conversion ratio was 22.56%. The butyrate/acetate ratios at pH 5 and pH 6 are 1.63 and 0.38. Higher butyrate/acetate ratio produced more hydrogen gas generation. The Haldane equation model was used to find the optimum pH and fitted well with the experimental data$(r^2=0.98)$. The optimum pH and specific hydrogen production were 5.5 and 119.61 mL/g VSS/h.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.5
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• pp.341-345
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• 2009

Continuous dry anaerobic digestion of organic solid wastes (30% TS, Total Solids) comprised of food waste and paper was performed under mesophilic condition. During the operation, hydraulic retention time (HRT) was decreased as follows: 150 d, 100 d, 60 d, and 40 d, which corresponded to the solid loading rate of 2.0, 3.0, 5.0, and 7.5 kg TS/$m^3$/d, respectively. Volumetric biogas production rate ($m^3$/$m^3$/d) increased as HRT decreased, and the highest biogas production rate of 3.49${\pm}$0.31 $m^3$/$m^3$/d was achieved at 40 d of HRT. At this HRT, high volatile solids (VS) reduction of 76% was maintained, and methane production yield of 0.25 $m^3$/kg $TS_{added}$ was achieved, indicating 67.4% conversion of organic solid waste to bioenergy. The highest biogas production yield of 0.52 $m^3$/kg $TS_{added}$ was achieved at 100 d of HRT, but it did not change much with respect to HRT. For the ease feed pumping, some amount of digester sludge was recycled and mixed with fresh feed to decrease the solid content. Recirculation volume of 5Q was found to be the optimal in this experimental condition. Specific methanogenic activity (SMA) of microorganisms at mesophilic-dry condition was 2.66, 1.94, and 1.20 mL $CH_4$/g VS/d using acetate, butyrate, and propionate as a substrate, respectively.

• Korean Journal of Food Science and Technology
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• v.29 no.2
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• pp.343-347
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• 1997

Effect of culture conditions on the fermentation of wheat flour solution by mixed lactic acid bacteria of Lactobacillus brevis, L. fermentum and L. plantarum was investigated. The optimum temperature for the fermentation of wheat flour solution was $35^{\circ}C$ because pH decreased the lowest value and TTA (total titrable acidity) increased the highest value at this temperature. In aerobic condition, fermentor was purged with air at 1.0 vvm and was purged with nitrogen gas at 1.0 vvm in anaerobic condition. The decrease of pH and the increase of TTA in aerobic condition were higher than those in anaerobic condition. In aerobic condition, the optimum condition of oxygen supply was found to be oxygen transfer rate coefficient of $60\;hr^{-1}$ which corresponded to agitation speed of 250 rpm in a 5 L fermentor. Repeated fed-batch cultures were performed using pH-stat in order to increase the productivity of fermented wheat flour. With increasing the repeated fraction of culture volume, mean cycle time increased but maximum operation time decreased. However, the volume of produced broth per culture volume per time and total volume of produced broth per culture volume were maximum at the repeated fraction of culture volume of 20%. In a repeated fed-batch fermentation of wheat flour solution using mixed lactic acid bacteria, the culture condition was optimum at temerature of $35^{\circ}C$, aeration rate of 1.0 vvm, oxygen transfer rate coefficient of $60\;hr^{-1}$, and repeated fraction of culture volume of 20%.