• Journal of Microbiology and Biotechnology
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• v.27 no.11
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• pp.1942-1951
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• 2017

Campylobacter jejuni and Campylobacter coli are important foodborne pathogenic bacteria, particularly in poultry meat. In this study, the presence of extracellular DNase activity was investigated for biofilm-deficient Campylobacter strains versus biofilm-forming Campylobacter strains isolated from chickens, to understand the relationship between extracellular DNase activity and biofilm formation. A biofilm-forming reference strain, C. jejuni NCTC11168, was co-incubated with biofilm non-forming strains isolated from raw chickens or their supernatants. The biofilm non-forming strains or supernatants significantly prohibited the biofilm formation of C. jejuni NCTC11168. In addition, the strains degraded pre-formed biofilms of C. jejuni NCTC11168. Degradation of C. jejuni NCTC11168 biofilm was confirmed after treatment with the supernatant of the biofilm non-forming strain 2-1 by confocal laser scanning microscopy. Quantitative analysis of the biofilm matrix revealed reduction of extracellular DNA (16%) and proteins (8.7%) after treatment. Whereas the biofilm-forming strains C. jejuni Y23-5 and C. coli 34-3 isolated from raw chickens and the C. jejuni NCTC11168 reference strain showed no extracellular DNase activity against their own genomic DNA, most biofilm non-forming strains tested, including C. jejuni 2-1, C. coli 34-1, and C. jejuni 63-1, exhibited obvious extracellular DNase activities against their own or 11168 genomic DNA, except for one biofilm non-former, C. jejuni 22-1. Our results suggest that extracellular DNase activity is a common feature suppressing biofilm formation among biofilm non-forming C. jejuni or C. coli strains of chicken origin.

• Microbiology and Biotechnology Letters
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• v.40 no.4
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• pp.348-355
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• 2012

In the present study, we investigated the overexpression and characterization of bovine pancreatic (bp)- DNase I in Saccharomyces cerevisiae and Pichia pastoris. The bp-DNase I gene was fused in frame with the GAL10 promoter, $MF{\alpha}$, and GAL7 terminator sequences, resulting in the plasmid, pGAL-$MF{\alpha}$-DNaseI (6.4 kb). Also, the bp-DNase I gene was fused in frame with the AOX1 promoter, $MF{\alpha}$, and AOX1 terminator sequences, resulting in the plasmid, pPEXI (8.8 kb). The recombinant plasmids, pGAL-$MF{\alpha}$-DNaseI and pPEXI were introduced into S. cerevisiae and P. pastoris host cells, respectively. When the transformed yeast cells were cultured at $30^{\circ}C$ for 48 h in galactose or methanol medium, bp-DNase I was overexpressed and the most of activity was found in the extracellular fraction. P. pastoris transformant activity showed 45.5 unit/mL in the culture medium at 48 h cultivation, whereas S. cerevisiae transformant revealed 37.7 unit/mL in the extracellular fraction at 48 h cultivation. The enzymatic characteristics, such as DNA cleavage and half life were investigated. Treatment of the recombinant DNase I from P. pastoris induced degradation of the calf thymus DNA within 1 minute, and this DNA degradation rate was higher than that of commercial bp-DNase I (SIGMA) and the recombinant DNase I from S. cerevisiae.

• 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.

• Proceedings of the Zoological Society Korea Conference
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• 1995.10b
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• pp.171.2-171
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• 1995

• Journal of Microbiology
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• v.42 no.1
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• pp.64-67
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• 2004

The pellets from a culture of Streptomyces coelicolor A3(2) that were submerged shaken were disintegrated into numerous hyphal fragments by DNase treatment. The pellets were increasingly dispersed by hyaluronidase treatment, and mycelial fragments were easily detached from the pellets. The submerged mycelium grew by forming complexes with calcium phosphate precipitates or kaolin, a soil particle. Therefore, the pellet formation of Streptomyces coelicolor A3(2) can be considered a biofilm formation, including the participation of adhesive extracellular polymers and the insoluble substrates.

• The Korean Journal of Ecology
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• v.18 no.1
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• pp.109-120
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• 1995

As the genetically modified microorganisms (GMMs) and their recombinant plasmid DNAs could be released into natural environments, their stabilities and impacts to indigenous microorganisls have become very importhant research subjects concerning with environmental and ecological aspects. In this study, the genetically modified E. coli CU103 and its recombinant pCU103 plasmid DNA, in which pcbCD genes involving in degradation of biphenyl and 4-chlorobiphenyl were cloned, were studied for their survival and stability in several different waters established under laboratory conditions. E. coli CU103 and its host E. coli XL1-Blue survived longer in sterile distilled water (SDW) and filtered autoclaved river water (FAW) than in filtered river water (FW). A lot of extracellular DNAs were released from E. coli CU103 by lytic action of phages in FW and the released DNAs were degraded by DNase dissolved in the water. Such effects of the factors in FW on stability of the recombinant pCU103 plasmid were also observed in the results of gel electrophoresis, quantitative analysis with bisbenzimide, and transformation assay. Therefore, the recombinant plasmids of pCU103 were found to be readily liberated from the genetically modified E. coli CU103 into waters by normal metabolic processes and lysis of cells. And the plasmid DNAs were quite stable in waters, but their stabilities could be affected by physicoKDICical and biological factors in non-sterile natural waters.

• Korean Journal of Veterinary Research
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• v.26 no.2
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• pp.251-257
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• 1986

Isolation of Staphylococcus hyicus subsp. hyicus from piglets suffering from exudative epidermitis and healthy pigs was performed, and some properties of the isolates were examined. Twentry-six litters of exudative epidermitis observed in the field were sucking piglets with ages ranging from 1 to 5 weeks and most (73.1%) of these cases occurred in piglets between 2 and 3 weeks of age. Staphylococcus hyicus subsp. hyicus was isolated front 192(38.9%) of 494 healthy pigs. The rate of isolation of these organism from healthy pigs was found to vary greatly among farms at an isolation rate of 33.3% to 45.5% and this organism was isolated more frequently front sucking piglets below the age of 8 weeks than adult pigs. All of the isolates originated from the diseased and healthy pigs were positive in heat-stable DNase, Tween 80 hydrolysis, gelatinase, protease, but negative in clumping factor and hemelysin on sheep blood agar. There was no difference related to origin in the production of extracellular active substances. Typical lesions of the classic exudative epidermitis were produced by inoculation of Staphylococcus hyicus subsp. hyicus isolated from the diseased and healthy pigs. The pathogenic potentials of isolates from healthy pigs were no different from that of the isolates obtained from diseased pigs.

• Microbiology and Biotechnology Letters
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• v.20 no.3
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• pp.243-248
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• 1992

In order to examine the viability depending on rehydration process and membrane injury of Nocardia mediterranei upon lyophilization, We labeled $3^H$-thymidine in deoxyribonucleic acid of N. mediterrranei to obtain information on the mechanisms of injury caused by lyophilization. Suspensions of rehydrated cells were incubated with added DNase in a buffer solution. Extracellular radioactivity levels appeared to be high in the rehydrated solutions after lyophilization than freezing-thawing. Thus, the membrane systems were injured by lyophilization, but not ovenvhelmed. These considerations were confirmed by electron microscopy. In effects of rehydration, the cell membrane was seriously damaged by strong atmospheric pressure as soon as the inner ampule was opened, but this was not the case without admitting air under vacuum. N. rnediterranei cells, with no additives, were lyophilized and reconstituted without admitting air, virtually about 84% of the cells were viable.