• Proceedings of the Korea Society of Environmental Biology Conference
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• 2004.12a
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• pp.105-105
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• 2004

• Korean Journal of Microbiology
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• v.28 no.3
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• pp.229-235
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• 1990

A rapid and sensitive method to detect the extracellular enzymatic activity of bacteria colonies grown on agar plates is described. Selective agar media supplemented with protein, starch, chitin, Tween-80, etc. are conventionally used to detect biochemical properties of bacteria. It has been experimentally demonstrated with bacteria pure cultures that fluorogenic Methylumbelliferyl (MUF)-substrates are excellent substrate analogues for normally occurring polymers. Based on MUF-substrate hydrolysis the new method provides reliable qualitative estimates of extracellular enzymatic properties of bacteria within minutes using pure cultures as well as agar p;ates prepared for colony counts. Extracellular enzyme activities of heterotrophic bacteria from freshwater ecosystems and marine sediment using this method are discussed.

• Asian-Australasian Journal of Animal Sciences
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• v.3 no.2
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• pp.115-120
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• 1990

Extracellular nuclease(s) in buffalo rumen fluid were purified from strained rumen fluid by a procedure involving Seitz filtration, acetone fractionation and gel filtration on Sephadex G-100. The enzyme resolved into two peaks exhibiting both DNase and RNase activities. The molecular weight of enzyme corresponding to peaks I and II were approximately 30,000 and 12,000 respectively. The properties of enzymes from the two peaks, however, were same. Optimum temperature for both DNase and RNase activities was at $50^{\circ}C$. Whereas DNase activity was stable upto $60^{\circ}C$, RNase activity was stable only up to $50^{\circ}C$. DNase activity recorded two pH optima, one at pH 5.5 and the other at pH 7.0. RNase activity recorded a broad pH optimum between pH 6.0-8.0. pH stability of the enzyme coincided with pH optima for both the activities. DNase activity was stimulated by $Mg^{2+}$ and $Mn^{2+}$ and inhibited by $Fe^{2+}$, $Zn^{2+}$, $Hg^{2+}$ and $Ag^+$. RNase activity was also stimulated by $Mg^{2+}$ and $Mn^{2+}$ and inhibited by $Cu^{2+}$, $Fe^{2+}$, $Zn^{2+}$, $Hg^{2+}$ and $Ag^+$. Reducing agents stimulated both the activities.

• Journal of Microbiology and Biotechnology
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• v.14 no.1
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• pp.178-181
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• 2004

A gene encoding an extracellular nuclease was cloned from Aeromonas hydrophila strain ATCC14715. The gene was overexpressed and the enzyme was purified by fusing to maltose binding protein. It was shown that the protein possessed DNase activity on both single-stranded and double-stranded DNAs. It exhibited both endo- and exonuclease activities. It was also shown that the protein had an RNase activity. Possible roles of this extracellular enzyme in the A. hydrophila life cycle are discussed.

• Journal of Forest and Environmental Science
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• v.24 no.1
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• pp.53-59
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• 2008

Extracellular enzyme activities of Fomitopsis palustris were determined by the particle sizes, culture periods and concentrations of wood particle substrate which was mixture of 4 domestic coniferous woods, such as Pinus densiflora, Larix leptolepsis, Pinus koraiensis, and Pinus rigida. The results showed that the culture conditions had an effect on the secretion of most of the extracellular enzymes from Fomitopsis palustris in the mixed wood particle substrate. :The optimal culture conditions for enzyme activities were 80~100 mesh in wood particle size, 7.5% in concentrations of wood substrate, and 4~8 weeks in culture period.

• BMB Reports
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• v.44 no.1
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• pp.40-45
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• 2011

Extracellular superoxide dismutase (EC-SOD) is an antioxidant enzyme that protects cells and tissues from extracellular damage by eliminating superoxide anion radicals produced during metabolism. Two different forms of EC-SOD exist, and their different enzyme activities are a result of different disulfide bond patterns. Although only two folding variants have been discovered so far, five folding variants are theoretically possible. Therefore, we constructed five different mutant EC-SOD expression vectors by substituting cysteine residues with serine residues and evaluated their expression levels and enzyme activities. The mutant EC-SODs were expressed at lower levels than that of wild-type EC-SOD, and all of the mutants exhibited inhibited extracellular secretion, except for C195S ECSOD. Finally, we demonstrated that co-expression of wild-type EC-SOD and any one of the mutant EC-SODs resulted in reduced secretion of wild-type EC-SOD. We speculate that mutant EC-SOD causes malfunctions in systems such as antioxidant systems and sensitizes tissues to ROS-mediated diseases.

• Korean Journal of Microbiology
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• v.28 no.3
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• pp.199-203
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• 1990

To study distribution of bacterial flora and their biochemical characteristics in the Antarctic soilecosystem, these experiments were performed during the austral summer(Feb., 1989) on the King George Island, Antarctica. The numbers of heterotrophic bacterial colonies and extracellular enzyme actibities were estimated from the Antarctic terrestrial soils which were sampled from 17 different locations near Sejong station (Korea) and Teniente Jubany station (Argentina) on the King George Island. The numbers of heterotrophic bacterial colonies were extremely variable with sampling sites and incubation temperatures. Arithmetric average numbers were $2.5\times 10^{4}$, $2.7\times 10^{7}$ , $6.9\times 10^{5}$ CFU/$cm^{3}$ soil at the incubation temperature of $37^{\circ}C$, $25^{\circ}C$ and $4^{\circ}C$, respectively. The activities of extracellular $\alpha$-glucosidase, $\beta$-glucosidase and N-acetyl-$\beta$-glucosaminidase were shown as similar mean percentage in the colonies obtained at different temperatures. Mean value of protease activities, however, was remarkably higher (92%) in the colonies grown at $4^{\circ}C$,.

• Journal of Microbiology and Biotechnology
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• v.20 no.7
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• pp.1101-1106
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• 2010

Pulsed electric field (PEF) of 1Hz, 1.5 kV, and 1ms increased the activities of catalase and inulinase over the whole range of applied Se concentrations compared with the non-treated cultures. A significant effect of selenium concentration (in the range of 5-14 ${\mu}g/ml$) on both intra- and extracellular enzyme activities was noted. At a Se concentration of 10 ${\mu}g/ml$, the activities of intra- and extracellular inulinases and extracellular catalase in the PEF-treated cultures reached the maximum of 71 U/g d.m., 46 U/g d.m., and approx. 8 U/ml, respectively. The maximum activity of intracellular catalase of approx. 6 U/ml (with and without PEF) was recorded at 5 ${\mu}g$ Se/ml. Further increasing of selenium concentration caused a decrease in the activity of the enzymes.

• Ecology and Resilient Infrastructure
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• v.2 no.3
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• pp.247-254
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• 2015

Changes in land-use type can affect soil and water properties in stream ecosystems. This study examined the effects of different land-use types on biogeochemical properties and microbial activities of a stream. We collected water and sediment samples in a stream at three different sites surrounded by varying land-use types; a forest, a radish field and a rice paddy. Nitrogen contents, such as nitrate, nitrite and total nitrogen in the stream water body, showed significant differences among the sampling sites. The highest nitrogen values were recorded at the site surrounded by cropland, as fertilizer runoff impacted the stream. Soil organic matter content in the sediment showed significant differences among sites, with the highest content exhibited at the forest mouth site. These differences might be due to the organic matter in surrounding terrestrial ecosystems. Microbial activities determined by extracellular enzyme activities showed similar values throughout all sites in the water body; however, the activities in the sediments exhibited the highest values near the forest site and mirrored the soil organic matter content values. From these results, we conclude that different land-use types are important factors affecting water and sediment properties in stream ecosystems.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.1 s.109
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• pp.38-46
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• 2005

This study was focused on the optimum culture condition in CMCase, FPase and xylanase activities of two fungal strains that secret extracellular enzymes for using enzymatic deinking agent to old newsprint. The results of this study were as follows. When Fusarium pallidoroseum was grown on the medium, containing of rice bran+xylan $2.0\%,\;peptone\;0.6\%,\;KH_2PO_4\;0.075\%\;and\;MnSO_4\;0.06\%\;with\;pH\;9.0,\;at\;29^{\circ}C$ for 6 days, the quantitative degree of extracellular enzyme production was the highest. Optimum culture condition for Aspergillus niger was pH 5.0, $27^{\circ}C$ incubating temperature and 7 days incubation period on liquid medium, containing of CMC+xylan $2.5\%,\;yeast\;extract\;0.4\%,\;K_3PO_4\;0.05\%\;and\;CaCl_2+FeSO_4\;0.08\%$. Aspergillus niger was fairly higher FPase and xylanase activities than Trichoderma reesei ATCC 28217.