• Biotechnology and Bioprocess Engineering:BBE
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• 제8권3호
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• pp.205-209
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• 2003

Solubilization of domestic household waste through Steam explosion with Subsequent ethanol production by the microbial saccharifitation and fermentation of the exploded product was studied. The effects of steam explosion on the changes of the density, viscosity, pH, and amounts of extractive components in artificial household waste were determined. The composition of artificial waste used was similar to leftover waste discharged from a typical home in Japan. Consecutive microbial saccharification and fermentation, and simultaneous microbial saccharification and fermentation of the Steam-exploded product were attempted using Aspergillus awamori, Trichoderma viride, and Saccharomyces cerevisiae; the ethanol yields of each process were compared. The highest ethanol yield was obtained with simultaneous microbial saccharification and fermentation of exploded product at a steam pressure of 2 MPa and a steaming time of 3 min.

• Journal of Microbiology
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• 제42권4호
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• pp.267-277
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• 2004

Effects of elevated $CO_2$ on soil microorganisms are known to be mediated by various interactions with plants, for which such effects are relatively poorly documented. In this review, we summarize and syn­thesize results from studies assessing impacts of elevated $CO_2$ on soil ecosystems, focusing primarily on plants and a variety the of microbial processes. The processes considered include changes in microbial biomass of C and N, microbial number, respiration rates, organic matter decomposition, soil enzyme activities, microbial community composition, and functional groups of bacteria mediating trace gas emission such as methane and nitrous oxide. Elevated $CO_2$ in atmosphere may enhance certain micro­bial processes such as $CH_4$ emission from wetlands due to enhanced carbon supply from plants. How­ever, responses of extracellular enzyme activities and microbial community structure are still controversy, because interferences with other factors such as the types of plants, nutrient availabilitial in soil, soil types, analysis methods, and types of $CO_2$ fumigation systems are not fully understood.

• KSBB Journal
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• 제13권3호
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• pp.279-283
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• 1998

To investigate the feasibility of the microbial process for removal of heavy metals from the high solid content sludge, the effect of sludge concentration on the solubilization of heavy metals by an iron oxidizing bacterium Thiolbacillus ferrooxidans was examined. With increasing the sludge concentration, the removal efficiency of heavy metals and the oxidation rate of iron were inhibited. Especially, when the sludge concentration is over 5% (w/v), the activity of T. ferrooxidans was remarkably inhibited. This inhibition is considered to occur due to the dissolved inhibitory materials such as organic compounds, heavy metals, and others which were extracted from the sludge during incubation period. In conclusion, the microbial process by T. ferrooxidans is only effectively used in ranges of 1.3 to 4.0% (w/v) sludge concentration.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.326-329
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• 2003

When an electrokinetic process is applied to a HOC-contaminated soil, hybrid types combined with soil flushing, chemical oxidation, and bioremediation are generally used. Especially when the electrokinetic process is combined with bioremediation, the hybrid technology can solve several limits of bioremediation such as low microbial mobility, low soil temperature, and shortage of nutrients in subsurface circumstance. Because microbial surface is charged negatively, the microorganism moves from cathode to anode under electrical field. In this study, mixed culture mainly-consisted by Pseudomonas sp. was applied to remediate pentadecane-contaminated kaolinite with particle size less than 300${\mu}{\textrm}{m}$. This remediation system was named ‘electrokinetic bioaugmentation’ and consisted of model aquifer, electrode reservoirs, bioreactor, power supply, and pump. The mixed culture above 0.5 of optical density in bioreactor was supplied to two reservoirs and penetrated soil when the electric current was applied. To enhance the removal efficiency, the optimal medium composition, electric current, and voltage were investigated.

• Journal of Microbiology and Biotechnology
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• 제16권2호
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• pp.200-204
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• 2006

The enzymology of an activated sludge system for a petroleum wastewater purification process was investigated. Leucine-aminopeptidase (L-AMP), ${\beta}$-glucosidase (${\beta}-GLC$), and lipase (LIP) were selected for the study. It was found that more than 81.7% of enzymatic activity was associated with microbial cells in the activated sludge floc. The metabolic response of a mixed microbial population to increased phenol concentration showed that L-AMP activity increased in the activated sludge, whereas activities of ${\beta}-GLC$ and LIP decreased, due to the inhibitory effect of the phenol which varied from 100 mg/l to 500 mg/l.

• 한국식품과학회지
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• 제42권3호
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• pp.281-286
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• 2010

본 연구는 자동화된 상업용 배추김치 제조공정 중에서 원료와 공정별로 미생물의 변화를 조사하고자 수행하였다. 김치제조에 사용되는 여러가지 재료별로 미생물 분포를 조사한 결과, 마늘, 생강, 고추가루에서 많은 수의 호기성 박테리아, 젖산균, Leuconostoc, 그리고 효모가 검출되었으며, 이로써 위 부원료들이 김치에 존재하는 미생물들의 주요 공급원임을 알 수 있었다. 김치를 제조하는 공정 별로 미생물 변화를 모니터링 한 결과, 배추절임 공정에서 총 균수가 증가하였고 그 이후 세척공정에서는 단지 미생물수를 1 log CFU/g 줄이는데 그쳐 미생물 수 감소효과는 적은 것으로 판명되었다. 효모 또한 다양한 부재료와 최종 김치에서 검출되었다. 따라서, 김치 제품에 최종적으로 존재하는 미생물 수를 줄이고자 한다면 위의 원료 중에서는 위의 부재료에 대해, 그리고 제조공정에서는 절임에 사용되는 천일염과 절임탱크에 대해 적절한 살균대책이 강구되어야 하겠다. 또한 차염소산 살균 공정은 절임과 세척공정 사이에 위치해야만 가장 큰 효과를 기대할 수 있을 것으로 판단되었다. 또한 검출된 효모에 대한 저해 수단으로 적절한 저해제의 첨가도 고려되어야 하겠다. 본 연구의 결과는 공장김치의 HACCP 구축과 개선에 활용될 것으로 기대된다.

• Journal of Ecology and Environment
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• 제34권4호
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• pp.401-410
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• 2011

We assayed the effects of simulated acid rain on the mass loss, $CO_2$ evolution, dehydrogenase activity, and microbial biomass-C of decomposing Sorbus alnifolia leaf litter at the microcosm. The dilute sulfuric acid solution composed the simulated acid rain, and the microcosm decomposition experiment was performed at 23$^{\circ}C$ and 40% humidity. During the early decomposition stage, decomposition rate of S. alnifolia leaf litter, and microbial biomass, $CO_2$ evolution and dehydrogenase activity were inhibited at a lower pH; however, during the late decomposition stage, these characteristics were not affected by pH level. The fungal component of the microbial community was conspicuous at lower pH levels and at the late decomposition stage. Conversely, the bacterial community was most evident during the initial decomposition phase and was especially dominant at higher pH levels. These changes in microbial community structure resulting from changes in microcosm acidity suggest that pH is an important aspect in the maintenance of the decomposition process. Litter decomposition exhibited a positive, linear relationship with both microbial respiration and microbial biomass. Fungal biomass exhibited a significant, positive relationship with $CO_2$ evolution from the decaying litter. Acid rain had a significant effect on microbial biomass and microbial community structure according to acid tolerance of each microbial species. Fungal biomass and decomposition activities were not only more important at a low pH than at a high pH but also fungal activity, such as $CO_2$ evolution, was closely related with litter decomposition rate.

• Environmental Engineering Research
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• 제11권4호
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• pp.173-180
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• 2006

Autotrophic nitrogen removal and its microbial community from a laboratory scale upflow anaerobic sludge bed reactor were characterized with dynamic behavior of nitrogen removal and sequencing result of molecular technique (DNA extraction, PCR and amplification of 16S rDNA), respectively. In the experiment treating inorganic wastewater, the anaerobic granular sludge from a full-scale UASB reactor treating industrial wastewater was inoculated as seed biomass. The operating results revealed that an addition of hydroxylamine would result in lithoautotrophic ammonium oxidation to nitrite/nitrate, and also hydrazine would play an important role for the success of sustainable nitrogen removal process. Total N and ammonium removal of 48% and 92% was observed, corresponding to nitrogen conversion of 0.023 g N/L-d. The reddish brown-colored granular sludge with a diameter of $1{\sim}2\;mm$ was observed at the lower part of sludge bed. The microbial characterization suggests that an anoxic ammonium oxidizer and an anoxic denitrifying autotrophic nitrifier contribute mainly to the nitrogen removal in the reactor. The results revealed the feasibility on development of high performance lithoautotrophic nitrogen removal process with its microbial granulation.

• 한국축산시설환경학회지
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• 제11권2호
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• pp.125-134
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• 2005

본 연구는 남은 음식물에 수분흡수제 또는 영양 보충제로 유기성 부산물인 제과부산물, 밀기울, 맥강, 육계분 등을 혼합한 후 rotary drum 방식의 반건식 살균처리 및 호기적 숙성 과정 별 혼합사료 내의 미생물 분포 및 사료단백질 pepsin 소화율과 in vitro 영양소 소화율을 측정하여 실제 동물 급여 시의 효능을 사전 예측하고자 실시하였다. 살균 처리 공정($80^{\circ}C$에서 30분간)은 전반적으로 균수를 감소시키는 경향과 곰팡이를 사멸시키는 효과가 있었으며(P<0.05), 연이은 숙성 과정은 살균과정에서 감소된 lactic acid bacteria를 증식시키는 효과가 있었다(P<0.05). 열처리 살균 공정은 혼합사료 단백질의 pepsin 소화율을 감소시켰다(P<0.05). 사료원료 건물 및 유기물의 in vitro 소화율은 제과부산물>밀기울>남은 음식물=맥강 순으로 높았다. 상기한 연구 결과는 반건식 남은 음식물 혼합사료의 동물 급여시 중요한 기초 자료로 활용될 것이다.

• Journal of Microbiology and Biotechnology
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• 제24권2호
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• pp.270-279
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• 2014

Microbial community shifts, associated with performance data, were investigated in an anaerobic batch digester treating high-solid food waste under mesophilic conditions using, a combination of molecular techniques and chemical analysis methods. The batch process was successfully operated with an organic removal efficiency of 44.5% associated with a biogas yield of 0.82 L/g $VS_{removal}$. Microbial community structures were examined by denaturing gel gradient electrophoresis. Clostridium and Symbiobacterium organisms were suggested to be mainly responsible for the organic matter catabolism in hydrolysis and acidogenesis reactions. The dynamics of archaeal and methanogenic populations were monitored using real-time PCR targeting 16S rRNA genes. Methanosarcina was the predominant methanogen, suggesting that the methanogenesis took place mainly via an aceticlastic pathway. Hydrogenotrophic methanogens were also supported in high-solid anaerobic digestion of food waste through syntrophism with syntrophic bacterium. Microbial community shifts showed good agreement with the performance parameters in anaerobic digestion, implying the possibility of diagnosing a high-solid anaerobic digestion process by monitoring microbial community shifts. On the other hand, the batch results could be relevant to the start-up period of a continuous system and could also provide useful information to set up a continuous operation.