• Journal of Microbiology and Biotechnology
• /
• 제28권1호
• /
• pp.95-104
• /
• 2018

Biosurfactants or microbial surfactants are surface-active biomolecules that are produced by a variety of microorganisms. Biodegradability and low toxicity have led to the intensification of scientific studies on a wide range of industrial applications for biosurfactants in the field of environmental bioremediation as well as the petroleum industry and enhanced oil recovery. However, the major issues in biosurfactant production are high production cost and low yield. Improving the bioindustrial production processes relies on many strategies, such as the use of cheap raw materials, the optimization of medium-culture conditions, and selecting hyperproducing strains. The present work aims to obtain a mutant with higher biosurfactant production through applying mutagenesis on Bacillus subtilis SPB1 using a combination of UV irradiation and nitrous acid treatment. Following mutagenesis and screening on blood agar and subsequent formation of halos, the mutated strains were examined for emulsifying activity of their culture broth. A mutant designated B. subtilis M2 was selected as it produced biosurfactant at twice higher concentration than the parent strain. The potential of this biosurfactant for industrial uses was shown by studying its stability to environmental stresses such as pH and temperature and its applicability in the oil recovery process. It was practically stable at high temperature and at a wide range of pH, and it recovered above 90% of motor oil adsorbed to a sand sample.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2000년도 춘계학술발표대회
• /
• pp.470-473
• /
• 2000

Indole은 미생물에 강한 독성을 가지고 있으므로 indole의 생물학적 전환이 어려우므로 단지 소수의 미생물들이 Indole이나 그것의 연관물질들로부터 Indigo와 Indirubin을 생산하는데 응용되어 왔다. 본 연구실에서 분리된 Pseudomonas savastanoi BCNU 106은 toluene에 강한 내성을 가졌으며 P. savastanoi BCNU 106의 Indole 내성 정도는 p-xylene이나 toluene이 배지 부피의 20% 로 첨가되었을 때 160 mg/ml로 매우 높은 내성 정도를 나타내었다. Indole (100 mg/ml) 과 p-xylene (0.2 ml/ml)을 포함한 two-phase culture system에서 자란 P. savastanoi BCNU 106은 indole로부터 푸른색 indigo나 보라색 indirubin의 미생물학적 전환을 보여주었다. indigo와 indirubin의 생산은 P. savastanoi BCNU 106가 적절한 농도의 유기용매가 중층된 two-phase system에서 자랐을 경우에만 형성되었다. 그러므로 본 연구는, 분리된 indole 내성 세균이 유기용매하에서 indirubin과 같은 산업적 가치를 가진 유용물질을 생산하는데 응용될 수 있을 것으로 사료된다.

• Toxicological Research
• /
• 제28권2호
• /
• pp.103-106
• /
• 2012

The effect of continuous humidifier use on the bioaerosol concentration in an indoor environment was investigated. An ultrasonic humidifier was operated for 10 hr per day for 15 days in an apartment room. During this time period, viable bioaerosol samples were taken using a single-stage Andersen sampler containing culture media plates for bacteria and fungi. The culture plates were then incubated at room temperature for 2~7 days depending on the media. The counts for the air sample plates were corrected for multiple impactions using the positive hole conversion method and are reported as the colony forming units per cubic meter of air (CFU/$m^3$). While the bacterial concentration measured using the tryptic soy agar (TSA) did not show any significant change during the first 3 days, the concentration increased from the $6^{th}$ day (6979 CFU/$m^3$) and reached a maximum on the $9^{th}$ day (46431 CFU/$m^3$). The concentration then decreased to 2470 CFU/$m^3$ on the $12^{th}$ day, at which point the fungal concentration increased rapidly to 14424~16038 CFU/$m^3$. Also, while the fungal concentration showed a significant change until the $9^{th}$ day of humidifier use, fungal growth was observed on the wallpaper and increased rapidly from the $12^{th}$ day. However, the bacterial concentration increased rapidly after the fungi were removed by remediation. The major fungal species identified in the samples were Penicillium representing 34%, Aspergillus representing 31%, Cladosporium representing 24%, and Alternaria representing 1%. The results also indicated that a relative humidity over 80% was easily achieved with continuous humidifier use. Yet, maintaining a high humidity in a room can cause a rapid outbreak of microbial growth.

• Applied Biological Chemistry
• /
• 제46권1호
• /
• pp.1-6
• /
• 2003

본 연구는 폐수 중의 질소 제거를 위한 생물학적 처리용 미생물 개발을 위한 목적으로 질소의 산화 능력이 뛰어난 균주를 분리하였다. 분리된 세균 중에서 질소 산화능과 생육 속도가 뛰어난 CH-N 균주를 선별하였으며, 생리, 생화학적 특성 조사에 의해 Bacillus sp로 추정되어 Bacillus sp. CH-N이라 명명하였다. 분리 균주는 0.5% glucose가 포함된 초기 pH가 7,0인 암모니아 및 아질산성 질소 함유 배지에서 30시간 배양 후 각각 85%와 90%의 암모니아성과 아질산성 질소의 감소율을 나타내었다. 폐수 및 생활하수에 분리 균주를 이용한 결과, 수질 속의 암모니아성 질소가 단시간에 크게 감소시키는 효과를 확인하였다. 균주를 고정시킨 담체의 질소산화 효과를 시험하고자 Bacillus sp. CH-N을 고정시킨 세라믹 담체를 이용한 결과, 배양 2일 후에는 암모니아성 질소가 전부 제거되었다.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제6권4호
• /
• pp.301-305
• /
• 2001

The co-expression of the arg U gene in a double-vector expression system of recombi-nant Escherichia coli BL22(DE3)[pET-IEN2a+pAC-argU] significantly enhanced the production level of reconminant human interferon -$\alpha$2a(rhIFN-$\alpha$2a) in high cell density cultures, compared to a recombinant E. coli culture containing only the single expression vector, pET-IEN2a. The dry cell mass concentration increased to almost 100 g/L, and more than 4 g/L of rhIFN-$\alpha$2a was accumu-lated in the culture broth. Evidently, the synthesis of rhIFN-$\alpha$2a was strongly dependent on the pre-induction growtih rate and more efficient at a higher specific growth rate. The additional sup-ply of tRN $A^{Arg(AGG/AGA)}$ enhanced the expression level of the rhIFN-$\alpha$2a gene in the early stage of the post-induction phase, yet thereafter the specific production rate of rhIFN-$\alpha$2a rapidly de-creased due to severe segregational instability of plasmid vector pET-IEN2a. It would appear that the plasmid instability with only occurred to pET-IEN2a in the double vector system, was re-lated to the effect of translational stress due to the over expression of rhIFN-$\alpha$2a.

• Journal of Microbiology and Biotechnology
• /
• 제7권4호
• /
• pp.267-271
• /
• 1997

We developed a dermal equivalent (DE) which was engineered using human dermal fibroblasts and a matrix of collagen gel. The in vitro construction of the DE was accomplished by casting a porcine collagen type I solution plus concentrated medium with isolated and cultured fibroblasts. These constructs were attached to culture dishes or left floating in culture medium. Contraction of attached gels results in decreased gel thickness without a change in gel diameter, and contraction of floating gels results in decreased gel thickness and diameter. After contraction, there was no increase in cell number in floating gels, but cells in attached gels began to increase after about 4 days of the lag phase in cell growth curve. At this lag phase, addition of fibroblast growth factor (FGF) at a concentration of $0.1{\mu}$/ml promoted cell proliferation in the attached collagen gels, but no effect in floating gels. These results indicate that the method of contraction had an influence on the extracellular matrix (ECM) organization, and this influenced not only cell growth but also fibroblast responsiveness to FGF. This suggests that attached collagen gel is more suitable as a dermal equivalent than the floating gel. And the final contracted area of attached gel is much larger than that of the floating gel since floating gel is contracted in all directions but attached gel is contracted only vertically.

• 한국미생물·생명공학회지
• /
• 제10권2호
• /
• pp.87-93
• /
• 1982

Mucor plumbeus FRI 0007 균주의 배양조건에 따른 균체생산량 및 지방질의 생산량을 검토한 결과 온도는 37$^{\circ}C$, pH3.5에서 정치배양 하는 것이 최적조건이며, 25일간 배양했을때 균체량은 2.39g/50$m\ell$, 지방질의 함량은 50.73% 이었다. 균체량과 지방질의 함량은 온도가 증가할수록, pH가 낮을수록 증가하였으나 진탕배양의 경우 균체량은 감소하나 지방질의 함량은 증가되었다. 트리-글리세리드의 함량은 pH가 낮을때, 그리고 진탕배양을 했을때 그 함량이 높았다. 지방산의 조성은 온도, 질소원와 종류 및 진탕에 의한 영향을 받았으며 온도가 낮을때 그리고 진탕을 했을때 포화도가 낮았다. 지방질을 구성하고 있는 모노-글리세리드와 디-글리세리드는 팔미트산과 올레산으로 트리-글리세리드는 주로 팔미트산, 올레산 및 리놀레산으로 결합되어 있으며 포화도는 모노-글리세리드가 가장 높았다.

• 한국미생물·생명공학회지
• /
• 제44권1호
• /
• pp.34-39
• /
• 2016

전국에서 수집한 누룩으로부터 50점의 S. cerevisiae 균주를 분리하고 18S rRNA 유전자 영역 중 ITS 단편의 염기서열 분석을 통하여 동정하였다. 누룩에서 분리한 S. cerevisiae 균주 중 MBYK45로 명명된 균주는 대조구 균주 및 누룩에서 분리한 다른 균주들에 비해 맥아당을 이용한 균체성장 및 에탄올 생산성이 우수하였다. MBYK45 균주는 맥아당 농도 20%, 배지 pH 6.0, 배양온도 $35^{\circ}C$ 조건에서 에탄올 생산성이 $3.79{\pm}0.14g^{-1}l^{-1}h^{-1}$로 가장 우수하였고 $110.80{\pm}0.81g/l$ 에탄올을 생산하였다. 본 연구를 통하여 맥아를 원료로 하는 전통주 제조에 적합한 것으로 사료되는 S. cerevisiae MBYK45 균주를 누룩으로부터 분리하였으며 균체성장 및 에탄올 생산을 위한 최적 배양조건을 설정하였다.

• Journal of Microbiology and Biotechnology
• /
• 제19권3호
• /
• pp.314-322
• /
• 2009

Four different bacterial colonies were isolated from an old stock of an entomopathogenic nematode, Steinernema monticolum. They all showed entomopathogenicity to final instar larvae of beet armyworm, Spodoptera exigua, by hemocoelic injection. However, they varied in colony form, susceptibility to antibiotics, and postmortem change of the infected host insects. Biolog microbial identification and 16S rDNA sequence analyses indicate that these are four different species classified into different bacterial genera. Owing to high entomopathogenicity and a cadaver color of infected insect host, Serratia sp. was selected as a main symbiotic bacterial species and analyzed for its pathogenicity. Although no virulence of Serratia sp. was detected at oral administration, the bacteria gave significant synergistic pathogenicity to fifth instar S. exigua when it was treated along with a spore-forming entomopathogenic bacterium, Bacillus thuringiensis. The synergistic effect was explained by an immunosuppressive effect of Serratia sp. by its high cytotoxic effect on hemocytes of S. exigua, because Serratia sp. caused septicemia of S. exigua when the bacterial cells were injected into S. exigua hemocoel. The cytotoxic factor(s) was present in the culture medium because the sterilized culture broth possessed high potency in the cytotoxicity, which was specific to granular cells and plasmatocytes, two main immune-associated hemocytes in insects.

• 한국미생물·생명공학회지
• /
• 제4권3호
• /
• pp.105-110
• /
• 1976

곰팡이를 이용하여 섬유소분해효소를 생산할 목적으로 전국각처에서 수집한 102종의 시료로부터 총 221주의 곰팡이를 분리하였다. 이들 분리균주의 섬유소분해능을 여과 지붕괴법 ？ 액화법 및 cup method로서 1차 36균주를 선별하였고 1차 선별된 균주를 탄소원을 변경하여 배양한뒤 활성을 추정하여 2차로 15균주를 선별하였다. 15균주를 개선된 배지에서 배양한뒤 $C_1$, $C_{x}$ 및 filter paper-activity을 측정하여 최종적으로 $C_1$및 $C_{x}$ -Cellulase의 활성이 강한 균주인 Aspergillus sp. strain No. AS-9, Penicillium sp. strain No. KI-1-2 Trichoderma sp. strain No. KI-7-2, KI-7-5, 및 KI-4-IB을 선별하였다. 이상 최종적으로 선별된 균주중의 strain No. KI-4-1-1B 조효소액으로 ammonia 처리볏짚을 당화시킬 때 24시간 작용으로 26%가 당화되었다.