• Journal of Food Hygiene and Safety
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• v.18 no.3
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• pp.101-106
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• 2003

The aim of this study is to develop a label-free immunosensor for microbial detection and to evaluate its applicability to Pseudomonas aeruginosa detection in various food samples. The antibodies used were a polyclonal antiserum from rabbit (polyvalent type) and a monoclonal antibody raised against the flagella of P. aeruginosa. Antibody immobilization was done by a thiolated antibody chemisorption onto one gold electrode of a piezoelectric quartz crystal with a thiol-cleavable, heterobifunctional cross-linker, sulfosuccinimidyl 6-[3-(2-pyridyldithio)propionamido]hexanoate. To the Stomacher-treated samples from various raw and processed foods under cold storage, comprising sirloin, cod and pettitoes, spiking and enrichment culture were done to prepare the model samples, followed by the measurements of the frequency shifts after sample injections. The frequency shifts obtained by the sample matrices themselves were in the range of 52~89 Hz. The injections of the spiked samples caused the frequency shifts of 108~200 Hz, whereas the enriched samples decreased the steady-state resonant frequencies by 162~222 Hz. All sample measurements including baseline stabilization, sample injection and acquisition of the steady-state response were accomplished within 30 min.

• The Korean Journal of Food And Nutrition
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• v.25 no.2
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• pp.233-238
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• 2012

Diarrheal diseases constitute one of the major causes of morbidity and mortality in infants and young children globally. One of the main microorganisms causing diarrheal diseases is Campylobacter jejuni. For treatment of these diseases, Portulaca oleracea has been widely used as a folk remedy for a long time. This study was performed to investigate the antimicrobial activity of P. oleracea against gastroenteritis pathogens including C. jejuni. P. oleracea was extracted with petroleum ether, chloroform, ethylacetate, methanol, and hot water. The antimicrobial activity of the P. oleracea extracts was determined using the paper disc method, minimum inhibitory concentration, and the liquid culture method. The 10 $mg/m{\ell}$ ethylacetate extract showed the strongest antimicrobial activity against Salmonella typhimurium, Salmonella enteriditis, and Shigella spp.. The hot water extract from P. oleracea showed the highest anti-microbial activity against C. jejuni at 10~20 $mg/m{\ell}$. The hot water extract of P. oleracea retarded the growth of C. jejuni for 36 hr at $42^{\circ}C$.

• Journal of Life Science
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• v.21 no.3
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• pp.444-450
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• 2011

Perchlorate ($ClO_4^-$) is a contaminant found in surface water and soil/ground water. Autotrophic perchlorate-reducing bacteria (PRB) use hydrogen gas ($H_2$) as an electron donor to remove perchlorate. Since iron corrosion can produce $H_2$, feasibility of autotrophic perchlorate-removal using zero-valent iron (ZVI) was examined in this study using activated sludge that is easily available from a wastewater treatment plant. Batch test showed that activated sludge microorganisms could successfully degrade perchlorate in the presence of ZVI. The perchlorate biodegradation was confirmed by molar yield of $Cl^-$ as perchlorate was degraded. Scanning electron microscope revealed that rod-shaped microorganisms on the surface of iron particles used for the autotrophic perchlorate-removal, suggesting that iron particles could serve as supporting media for the formation of biofilm as well. DGGE analyses revealed that microbial profile of the inoculum (activated sludge) was different from that of biofilm sample obtained from the ZVI-added enrichment culture used for $ClO_4^-$-degradation. A major band of the biofilm sample was most closely related to the class Clostridia.

• The Korean Journal of Mycology
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• v.35 no.2
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• pp.96-100
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• 2007

In order to select ${\gamma}-Linolenic$ acid (GLA)-producing fungi, a total of forty-four strains of 4 genera such as Phytophthora, Pythium, Mucor and Rhizopus were obtained from Koran Agricultural Culture Collection (KACC) and then analysed by using GC-FID and GC-MS. GLA was detected on 39 fungal strains, and the highest rate of GLA was found as 24.8% of total fatty acids on Mucor hiemalis f. sp. hiemalis KACC 40264. Total GLA content of Zygomycota was comparatively high - Mucor (14.2%) and Rhizopus (14.3%), whereas that of Oomycetes was low - Phytophthora (3.3%) and Pythium (3.0%). Moreover, total fatty acids of the Zygomycota fungi such as Mucor (15.4 mg/100 ml) and Rhizopus (7.1 mg/100 ml) were higher compared with the Oomycetes such as Phytophthora (2.6 mg/100 ml) and Pythium (4.5 mg/100 ml). Thus, two genera such as Mucor and Rhizopus have higher potential as an useful microbial resource. The total fatty acid content varies even within the strains of the same genus e.g. Mucor. M. blumbeus KACC 40935 showed the highest values on productivity (18.2%) of GLA and total fatty acid contents (50.8 mg/100 ml liquid medium).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.4
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• pp.305-311
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• 1993

Marine organisms were investigated to identify the marine actinomycetes that produced noble bioactive compounds. Microorganism counts range from $2.1{\times}10^3\;to\;1.2{\times}10\;CFU/g$ of marine organisms. Actinomycetes constituted 0.01 to $0.5\%$ of culturable microbial community. We identified the marine actinomycetes that produced novel bioactive compounds. During the course of screening for bioactives from the marine microorganisms, we found that the strain in sponge had antimicrobial activities. From the morphological, cultural and various physiological characteristics, this strain was identified for Actinomycetes No. 101. The optimal compositions of culture medium for Actinomycetes No. 101 were starch 30g/l as carbon source, casamino acid 10g/l as nitrogen source. The optimal pH of medium and fermentation temperature were $6.5{\sim}7.0$ and $30^{\circ}C$, respectively. Fermentation has been conducted in the marine broth at $30^{\circ}C$ for 72 hour. The yield of fermentation got about 3g as dry weight(per liter of broth). The distribution of antimicrobial activity of Actinomycetes No. 101 was screened by paper disc. The extract of cultured cell and broth inhibited the growth of Staphylococcus aureus and Bacillus subtilis, but the inhibition action was week against yeast and mold.

• Journal of Life Science
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• v.23 no.5
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• pp.676-681
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• 2013

Perchlorate (${ClO_4}^-$) is an emerging contaminant found in surface water and soil/groundwater. Microbial removal of perchlorate is the method of choice since perchlorate-reducing bacteria (PRB) can reduce perchlorate to harmless end-products. A previous study [3] showed experimental evidence of autotrophic perchlorate removal using elemental sulfur granules and activated sludge. The granular sulfur is a relatively inexpensive electron donor, and activated sludge is easily available from a wastewater treatment plant. A batch test was performed in this study to further investigate the effect of various environmental parameters on the perchlorate degradation by sludge microorganisms when elemental sulfur was used as electron donor. Results of the batch test suggest optimum conditions for autotrophic perchlorate degradation by sludge microorganisms. The results also show that sulfur-oxidizing PRB enriched from activated sludge removed perchlorate better than activated sludge. Taken together, this study suggests that autotrophic perchlorate removal using elemental sulfur and activated sludge can be improved by employing optimized environmental conditions and enrichment culture.

• Microbiology and Biotechnology Letters
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• v.39 no.3
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• pp.245-251
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• 2011

[ ${\alpha}$ ]Galactosidase was purified from a culture filtrate of Mortierella sp. by CM-sephadex C-50, and subsequent Sephadex G-100 column chromatography. The final preparation thus obtained showed a single band on SDS-polyacrylamide gel electrophoresis. The molecular weight was determined to be 56 kDa. $Gal^3Man^4$ ($6^3$-mono-O-${\alpha}$-D-galactopyranosyl-4-O-${\beta}$-D-mannotetraose), $Gal^{2,3}Man_5$ ($6^{2,3}$-di-O-${\alpha}$-D-galactopyranosyl-4-O-${\beta}$-D-mannopentaose), $Gal_2Man_3$ ($6^2$-mono-O-${\alpha}$-D-galactopyranosyl-4-O-${\beta}$-D-mannotriose), $Gal^2Man_6$ ($6^2$-mono-O-${\alpha}$-D-galactopyranosyl-4-O-${\beta}$-D-mannohexaose) and $Gal^2Man_5$ ($6^2$-mono-O-${\alpha}$-D-galactopyranosyl-4-O-${\beta}$-D-mannopentaose), prepared from 3 types of microbial ${\beta}$-mannnanase, were used as substrates. $Gal^3Man_4$ and $Gal^2Man_3$ had a stubbed ${\alpha}$-galactosyl residue on the $2^{nd}$ and $3^{rd}$ mannose from the reducing end of mannotetraose and mannotriose, thus ${\alpha}$-galactosidase showed a preference for stubbed ${\alpha}$-galactosyl residue. ${\alpha}$-Galactosidase hydrolyzed $Gal^3Man_4$ more rapidly than $Gal^2Man_3$. However, ${\alpha}$-galactosidase hardly acted on $Gal^{2,3}Man_5$, $Gal^2Man_6$ or $Gal^2Man_5$. The enzyme hydrolyzed melibiose to galactose and glucose, raffinose to galactose and sucrose, and also stachyose to galactose and raffinose.

• Microbiology and Biotechnology Letters
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• v.38 no.3
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• pp.335-339
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• 2010

A diesel-degrading bacterium, Gordonia sp. SD8, was isolated from soil contaminated with petroleum, and its diesel degradation was characterized in a soil as well as a liquid culture system. SD8 could grow in the mineral salt medium supplemented with diesel as a sole carbon and energy source. The maximum specific growth rate ($0.67{\pm}0.05\;d^{-1}$) and diesel degradation rate ($1,727{\pm}145$ mg-TPH $L^{-1}\;d^{-1}$) of SD8 showed at 20,000 mg-TPH $L^{-1}$ and $30^{\circ}C$, and then this bacterium could degrade high strength of diesel of 40,000 mg-TPH $L^{-1}$. The residual diesel concentration in the inoculated soil with SD8 was 3,724 mg-TPH kg-dry $soil^{-1}$ after 17 days, whereas the diesel concentration in the non-inoculated soil was $8,150{\pm}755$ mg-TPH kg-dry $soil^{-1}$. These results indicate that Gordonia sp. SD8 can serve as a promising microbial resource for the bioremediaion of contaminated soil with petroleum hydrocarbons including diesel.

• Korean Journal of Food Science and Technology
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• v.37 no.2
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• pp.194-198
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• 2005

Growth curves of Listeria monocytogenes in modified surimi-based imitation crab (MIC) broth were obtained by measuring cell concentration in MIC broth at different culture conditions [initial cell numbers, $1.0{\times}10^{2},\;1.0{\times}10^{3}\;and\;1.0{\times}10^{4}$, colony forming unit (CFU)/mL; temperature, 15, 20, 25, 37, and $40^{\circ}C$] and applied to Gompertz model to determine microbial growth indicators, maximum specific growth rate constant (k), lag time (LT), and generation time (GT). Maximum specific growth rate of L. monocytogenes increased rapidly with increasing temperature and reached maximum at $37^{\circ}C$, whereas LT and GT decreased with increasing temperature and reached minimum at $37^{\circ}C$. Initial cell number had no effect on k, LT, and GT (p > 0.05). Polynomial and square root models were developed to express combined effects of temperature and initial cell number using Gauss-Newton Algorism. Relative coefficients of experimental k and predicted k of polynomial and square root models were 0.92 and 0.95, respectively, based on response surface model. Results indicate L. monocytogenes growth was mainly affected by temperature and square root model was more effective than polynomial model for growth prediction.

• Korean Journal of Food Science and Technology
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• v.36 no.2
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• pp.349-354
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• 2004

Predictive growth model of Vibrio parahaemolyticus in modified surimi-based imitation crab broth was investigated. Growth curves of V. parahaemolyticus were obtained by measuring cell concentration in culture broth under different conditions ($Initial\;cell\;level,\;1{\times}10^{2},\;1{\times}10^{3},\;and\;1{\times}10^{4}\;colony\;forming\;unit\;(CFU)/mL$; temperature, 15, 25 37, and $40^{\circ}C$; pH 6, 7, and 8) and applying them to Gompertz model. Microbial growth indicators, maximum specific growth rate (k), lag time (LT), and generation time (GT), were calculated from Gompertz model. Maximum specific growth rate (k) of V. parahaemolyticus increased with increasing temperature, reaching maximum rate at $37^{\circ}C$. LT and GT were also the shortest at $37^{\circ}C$. pH and initial cell number did not influence k, LT, and GT values significantly (p>0.05). Polynomial model, $k=a{\cdot}\exp(-0.5{\cdot}((T-T_{max}/b)^{2}+((pH-pH_{max)/c^{2}))$, and square root model, ${\sqrt{k}\;0.06(T-9.55)[1-\exp(0.07(T-49.98))]$, were developed to express combination effects of temperature and pH under each initial cell number using Gauss-Newton Algorism of Sigma plot 7.0 (SPSS Inc.). Relative coefficients between experimental k and k Predicted by polynomial model were 0.966, 0.979, and 0.965, respectively, at initial cell numbers of $1{\times}10^{2},\;1{\times}10^{3},\;and\;1{\times}10^{4}CFU/mL$, while that between experimental k and k Predicted by square root model was 0.977. Results revealed growth of V. parahaemolyticus was mainly affected by temperature, and square root model showing effect of temperature was more credible than polynomial model for prediction of V. parahaemolyticus growth.