• 한국미생물·생명공학회지
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• 제48권4호
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• pp.515-524
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• 2020

With the increasing demand for enzymes in industrial applications there is a growing need to easily produce industrially important microbial enzymes. This study was carried out to screen the indigenous refinery bacterial isolates for their production of two industrially important enzymes i.e. lipase and protease. A total of 15 bacterial strains were isolated using Soil Extract Agar media from the oil-contaminated environment and one was shown to produce high quality lipase and protease enzymes. The culture conditions (culture duration, temperature, source of nitrogen, carbon, and pH) were optimized to produce the optimum amount of both the lipase (37.6 ± 0.2 Uml-1) and the protease (41 ± 0.4 Uml-1) from this isolate. Productivity of both enzymes was shown to be maximized at pH 7.5 in a medium containing yeast extract and peptone as nitrogen sources and sucrose and galactose as carbon sources when incubated at 35 ± 1℃ for 48 h. Bacterial strain SAB06 was identified as Bacillus licheniformis (MT250345) based on biochemical, morphological, and molecular characteristics. Further studies are required to evaluate and optimize the purification and characterization of these enzymes before they can be recommended for industrial or environmental applications.

• Journal of Microbiology and Biotechnology
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• 제33권10호
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• pp.1257-1267
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• 2023

Although rational genetic engineering is nowadays the favored method for microbial strain improvement, building up mutant libraries based on directed evolution for improvement is still in many cases the better option. In this regard, the demand for precise and efficient screening methods for mutants with high performance has stimulated the development of biosensor-based high-throughput screening strategies. Genetically encoded biosensors provide powerful tools to couple the desired phenotype to a detectable signal, such as fluorescence and growth rate. Herein, we review recent advances in engineering several classes of biosensors and their applications in directed evolution. Furthermore, we compare and discuss the screening advantages and limitations of two-component biosensors, transcription-factor-based biosensors, and RNA-based biosensors. Engineering these biosensors has focused mainly on modifying the expression level or structure of the biosensor components to optimize the dynamic range, specificity, and detection range. Finally, the applications of biosensors in the evolution of proteins, metabolic pathways, and genome-scale metabolic networks are described. This review provides potential guidance in the design of biosensors and their applications in improving the bioproduction of microbial cell factories through directed evolution.

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

• Journal of Microbiology and Biotechnology
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• 제20권3호
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• pp.602-608
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• 2010

An atrazine-degrading bacterium, strain KU001, was obtained from a sugarcane field at the Cane and Sugar Research and Development Center at the Kasetsart University, Kamphaeng Saen Campus, Thailand. Strain KU001 had a rod-to-coccus morphological cycle during growth. Biolog carbon source analysis indicated that the isolated bacterium was Arthrobacter histidinolovorans. Sequence analysis of the PCR product indicated that the 16S rRNA gene in strain KU001 was 99% identical to the same region in Arthrobacter sp. The atrazine degradation pathway in strain KU001 consisted of the catabolic genes trzN, atzB, and atzC. Strain KU001 was able to use atrazine as a sole nitrogen source for growth, and surprisingly, atrazine degradation was not inhibited in cells grown on ammonium, nitrate, or urea, as compared with cells cultivated on growth-limiting nitrogen sources. During the atrazine degradation process, the supplementation of nitrate completely inhibited atrazine degradation activity in strain KU001, whereas ammonium and urea had no effect on atrazine degradation activity. The addition of strain KU001 to sterile or nonsterile soils resulted in the disappearance of atrazine at a rate that was 4- to 5-fold more than that achieved by the indigenous microbial community. The addition of citrate to soils resulted in enhanced atrazine degradation, where 80% of atrazine disappeared within one day following nutrient supplementation.

• Journal of Microbiology and Biotechnology
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• 제27권6호
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• pp.1171-1179
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• 2017

Butanol is a promising alternative to ethanol and is desirable for use in transportation fuels and additives to gasoline and diesel fuels. Microbial production of butanol is challenging primarily because of its toxicity and low titer of production. Herein, we compared the transcriptome and phenome of wild-type Escherichia coli and its butanol-tolerant evolved strain to understand the global cellular physiology and metabolism responsible for butanol tolerance. When the ancestral butanol-sensitive E. coli was exposed to butanol, gene activities involved in respiratory mechanisms and oxidative stress were highly perturbed. Intriguingly, the evolved butanol-tolerant strain behaved similarly in both the absence and presence of butanol. Among the mutations occurring in the evolved strain, cis-regulatory mutations may be the cause of butanol tolerance. This study provides a foundation for the rational design of the metabolic and regulatory pathways for enhanced biofuel production.

• 환경생물
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• 제36권2호
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• pp.190-198
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• 2018

The petroleum industry is an important part of the world economy. However, the massive exposure of petroleum in nature is a major cause of environmental pollution. Therefore, the microbial mediated biodegradation of petroleum residues is an emerging scientific approach used to resolve these problem. Through the screening of diesel contaminated soil we isolated a rapid phenanthrene and a diesel degrading bacterium identified as Enterobacter cancerogenus DA1 strain through 16S rRNA gene sequence analysis. The strain was registered in NCBI with an accession number MG270576. The optimal growth condition of the DA1 strain was determined at pH 8 and $35^{\circ}C$, and the highest degradation rate of the diesel was achieved at this condition. At the optimal condition, growth of the strain on the medium containing 0.05% phenanthrene and 0.1% of diesel-fuel was highest at 45 h and 60 h respectively after the incubation period. Biofilm formation was found significantly higher at $35^{\circ}C$ as compared to $30^{\circ}C$ and $40^{\circ}C$. Likewise, the lipase activity was found significantly higher at 48 h after the incubation compared to 24 h and 72 h. These results suggest that the Enterobacter cancerogenus DA1 could be an efficient candidate, for application through ecofriendly scientific approach, for the biodegradation of petroleum products like diesel.

• Journal of Life Science
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• 제11권1호
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• pp.11-13
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• 2001

Several culture conditions affecting cellulose production by a newly isolated Acetobacter sp. A9 were examined by cultivating cells under shaking cultures. The inoculum size in the range of 1-10% (v/v) did not influence cellulose production. Maximum cellulose production was obtained with 200 rpm of agitation speed. The cells grown in the 75 ml of medium in a 250-ml conical flask produced the highest level of cellulose. The strain was able to produce cellulose at 25-3$0^{\circ}C$ with a maximum at 3$0^{\circ}C$. Cellulose production occurred at pH 4.5-7.5 with a maximum at pH6.5.

• Journal of Microbiology and Biotechnology
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• 제10권2호
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• pp.187-194
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• 2000

An actinomycetes strain, T-2, which produces transglutaminase (EC 2.3.2.13), was isolated from soil and identified as belonging to the Actinomadura sp., based on taxonomc studies. The conditions for the transglutaminase production and its enzymatic properties were investigated. The optimum components for the transglutaminase production were 2% glucose, 1% polypeptone and soytone, and 0.1% MnCl2. The optimum pH and temperature of the enzyme reaction were pH 8.0 and $45^{\circ}C$, respectively. The enzyme was stable within the pH range of 5.0-9.0 and $30^{\circ}C-45^{\circ}C$. The novel enzyme required no calcium ions for its activity. This enzyme polymerized various proteins such as casien, soy protein, hemoglobin, egg white, gelatin, and soybean milk.

• Journal of Ginseng Research
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• 제8권1호
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• pp.1-7
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• 1984

In order to confirm the antimutagenicity of ginseng extracts, mutagenicity of ginseng and several medicinal herbs of which extracts were used as drinks, was examined through the method of Ames test. The obtained results were as follows. 1. Strong mutagenicities for Salmonella tyhimurium TA98, TA100, TA1535 were observed in all sample herbs Paenonia aalbiflora, Rehmannia glutinosa, Astragalus membranaceus, Angelica acutiloba, Cnidium officinale, Laurus nobilis and Panax ginseng without S-9 mix metabolic activation. 2. In the case of S-9 mix metabolic activation, even in a low concentraction, the extracts of Angelica autilobu, Cnidium officinale and Paenonla albtilora showed also a high mutagenicities for the strain TA98 and TA1535. 3. Even in high concentration of ginseng extracts, mutagenicity was almost neglectable through the metabolic activation of S-9 mix, compared with other extracts of medicinal herbs.

• 한국균학회지
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• 제3권2호
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• pp.25-29
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• 1975

우리나라 담자균류 12균주 중 톱밥의 lignin을 잘 분해하는 균주 Pleurotus ostreatus 1주를 선발할 수 있었다. 이 균주는 톱밥에 20%의 미강을 첨가하고 보통배지에 첨가되는 무기염을 첨가하면 $30^{\circ}C$에서 30일이면 lignin의 49%를 분해할 수 있었고 다시 무기 N을 단백질로 전환시킬 수도 있으며 여기서 단백질 증가율은 26%였다.