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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Korean Journal of Microbiology
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Journal DOI :
The Microbiological Society of Korea
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Volume & Issues
Volume 49, Issue 4 - Dec 2013
Volume 49, Issue 3 - Sep 2013
Volume 49, Issue 2 - Jun 2013
Volume 49, Issue 1 - Mar 2013
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PD-1 Expression in LPS-Induced Raw264.7 Cells Is Regulated via Co-activation of Transcription Factor NF-κB and IRF-1
Choi, Eun-Kyoung ; Lee, Soo-Woon ; Lee, Soo-Woong ;
The Korean Journal of Microbiology, volume 49, issue 4, 2013, Pages 301~308
DOI : 10.7845/kjm.2013.3082
Programmed Death-1 (PD-1) is one of the important immune-inhibitory molecules which was expressed in T cells, B cells, NKT cells, and macrophages activated by various immune activating factors. Lipopolysaccharide (LPS), the major component of the outer membrane of Gram-negative bacteria, is one of the crucial immunogens for PD-1 expression. However, there are only a few reports on the expression mechanisms of PD-1 in innate immune cells. In this study, we investigate the expression mechanisms of PD-1 in LPS-stimulated Raw264.7 cell lines by RT-PCR, Western Blot, flow cytometry as well as ChIP assay and co-immunoprecipitation. When Raw264.7 cells were stimulated with LPS, PD-1 expression was greatly up-regulated via PI3K and p38 signaling. Primary macrophages isolated from LPS-injected mice were also shown the increased expression of PD-1. In promoter assay, NF-
and IRF-1 binding regions in mouse PD-1 promoter are important for PD-1 expression. We also found that the co-activation of NF-
and IRF-1 is indispensable for the maximum PD-1 expression. These results indicate that the modulation of PD-1 expressed in innate immune cells could be a crucial for the disease therapy such as LPS-induced mouse sepsis model.
Biochemical Characterization of Heterologously Expressed Chitinase 1 (Chi1) from an Inky Cap, Coprinellus congregatus
Yoo, Yeeun ; Choi, Hyoung T. ;
The Korean Journal of Microbiology, volume 49, issue 4, 2013, Pages 309~312
DOI : 10.7845/kjm.2013.3081
Fungal cell walls consist of various glucans and chitin. Fungi produce chitinases for their growth and development. The inky cap, Coprinellus congregatus, produces at least two different chitinases during its life cycle. Chitinase 1 (chi1) is expresses throughout its life cycle while chitinase 2 (chi2) is expressed at the mushroom autolysing phase. The cloned cDNA of chi1 is successfully expressed as a fusion protein with c-myc in Pichia pastoris, and purified by the affinity chromatography. The optimum pH and temperature of Chi1 was pH 8.0 and
, respectively when 4-nitrophenyl N,N',N"-triacetyl-
-D-chitotrioside was used as the substrate. The
for the substrate was 0.780 mM and 0.10 OD
, respectively. The addition of purified Chi1 resulted in total growth inhibition against several plant pathogenic fungi such as Alternaria alternata, Fusarium graminearum and Trichoderma harzianum at the concentration of 60
Comparison of Biofilm Formed on Stainless Steel and Copper Pipe Through the Each Process of Water Treatment Plant
Kim, Geun-Su ; Min, Byung-Dae ; Park, Su-Jeong ; Oh, Jung-Hwan ; Cho, Ik-Hwan ; Jang, Seok-Jea ; Kim, Ji-Hae ; Park, Sang-Min ; Park, Ju-Hyun ; Chung, Hyen-Mi ; Ahn, Tae-Young ; Jheong, Weonhwa ;
The Korean Journal of Microbiology, volume 49, issue 4, 2013, Pages 313~320
DOI : 10.7845/kjm.2013.3083
Biofilm formed on stainless and copper in water treatment plant was investigated for sixteen weeks. Biofilm reactor was specially designed for this study. It was similar to that of a real distribution pipe. Raw water, coagulated, settled, filtered and treated water were used in this study. The average number of heterotrophic bacteria counts was
, 1 CFU/ml, respectively. Density of biofilm bacteria formed on stainless and copper pipes in raw, coagulated and settled water increased above
within second weeks while more biofilm bacteria counts were found on the stainless pipe than on the copper pipe. In case of filtered water (free residue chlorine 0.44 mg/L), there was no significant difference in the number of biofilm bacteria on both pipes and biofilm bacteria below
were detected on both pipe materials after fifth weeks. Biofilm bacteria were not detected on both pipe materials in treated water (free residue chlorine 0.88 mg/L). According to the results of DGGE analysis, Sphingomonadacae was a dominant species of biofilm bacteria formed on the stainless pipe while the copper pipe had Bradyrhizobiaceae and Sphingomonadaceae as dominant bands. In case of filtered water, a few bands (similar to Propionibacterium sp., Sphingomonas sp., Escherichia sp., and etc.) that have 16S rRNA sequences were detected in biofilm bacteria formed on both pipes after fifth weeks. Stainless pipe had higher species richness and diversity than the copper pipe.
Combined Chlorite-Monochloramine Application for Controlling Nitrifying and Heterotrophic Bacteria in Drinking Water Distribution System
Park, Se-Keun ; Kim, Yeong-Kwan ; Choi, Sung-Chan ;
The Korean Journal of Microbiology, volume 49, issue 4, 2013, Pages 321~327
DOI : 10.7845/kjm.2013.3068
In the present work, the reactors that harbor bacterial biofilms including ammonia-oxidizing bacteria (AOB) and heterotrophic bacteria were treated with a continuous dose of chlorite (
) either with or without monochloramine at
. Both chlorite alone and combined chlorite-monochloramine applications effectively reduced biofilm and bulk AOB levels to near or below the detection limit (
and 0.2 MPN/ml). The combined chlorite-monochloramine application exhibited greater AOB inactivation than chlorite alone. Unlike AOB, heterotrophic plate count (HPC) was unaffected by chlorite alone. In contrast to chlorite-only application, a combination of chlorite and monochloramine resulted in a significant reduction in HPC levels with log reductions of 3.1 and 3.0 for biofilm and bulk water, respectively. The results demonstrate that the combined chlorite-monochloramine application can provide an effective treatment for the inhibition of AOB and heterotrophic bacteria in a drinking water distribution system.
Phylogenetic Analysis of Bacterial Populations in a Tomato Rhizosphere Soil Treated with Chicken Feather Protein Hydrolysate
Kim, Se-Jong ; Han, Song-Ih ; Whang, Kyung-Sook ;
The Korean Journal of Microbiology, volume 49, issue 4, 2013, Pages 328~335
DOI : 10.7845/kjm.2013.3067
As a result of conducting a cultural experiment of tomato using chicken feather protein hydrolysate (CPH) which was mass produced by keratin protein degrading bacterium Chryseobacterium sp. FBF-7 (KACC 91463P), we found that the stem and the root of tomato showed significant improvement in growth. For the purpose of phylogenic interpretation, a comparison was drawn between the effect of CPH, a treated CPH and untreated, on the changes of bacterial populations by 454 pyrosequencing based on 16S rRNA gene sequences. Tomato rhizosphere soil untreated with CPH (NCPH) showed 6.54 Shannon index from 3,281 sequence reads, and the rhizosphere soil treated with CPH (TCPH) showed 6.33 Shannon index from 2,167 sequence reads, displaying that it does not affect the diversity. Bacterial populations were composed of 19 phyla in the rhizosphere soil, and the phylum Proteobacteria occupied 40% of total bacterial populations. Bradyrhizobium, Agromonas, Nitrobacter, and Afipia (BANA group) which belong to Bradyrhizobiaceae were abundant and commonly detected in both the treated and untreated soils, suggesting the dominance of bacterial group in rhizosphere soil. The results obtained showed that CPH treatment does not affect the indigenous bacterial populations present in the rhizosphere soil.
Microbial Diversity of the Trichloroethylene Contaminated Groundwater Treatment System and Characterization of Pseudomonas sp. DHC8
Nam, Ji-Hyun ; Shin, Ji-Hye ; Kwon, Kiwook ; Bae, Wookeun ; Lee, Dong-Hun ;
The Korean Journal of Microbiology, volume 49, issue 4, 2013, Pages 336~342
DOI : 10.7845/kjm.2013.3065
Trichloroethylene (TCE) is a widely used substance in commercial and industrial applications, yet it must be removed from the contaminated soil and groundwater environment due to its toxic and carcinogenic nature. We investigated bacterial community structure, dominant bacterial strain, and removal efficiency in a TCE contaminated groundwater treatment system using immobilized carrier. The microbial diversity was determined by the nucleotide sequences of 16S rRNA gene library. The major bacterial population of the contaminated groundwater treatment system was belonging to BTEX degradation bacteria. The bacterial community consisted mainly of one genus of Pseudomonas (Pseudomonas putida group). The domination of Pseudomonas putida group may be caused by high concentration of toluene and TCE. Furthermore, we isolated a toluene and TCE degrading bacterium, named Pseudomonas sp. DHC8, from the immobilized carrier in bioreactor which was designed to remove TCE from the contaminated ground water. Based on the results of morphological and physiological characteristics, and 16S rRNA gene sequence analysis, strain DHC8 was identified as a member of Pseudomonas putida group. When TCE (0.83 mg/L) and toluene (60.61 mg/L) were degraded by this strain, removal efficiencies were 72.3% and 100% for 12.5 h, respectively. Toluene removal rate was 2.89
-DCW/h and TCE removal rate was 0.02
-DCW/h. These findings will be helpful for maintaining maximum TCE removal efficiency of a reactor for bioremediation of TCE.
The Study on the Effect of Efficient Microorganism for Early Stabilization of the Burial Sites
Kim, Hyun-Sook ; Park, Sujung ; Jheong, Weonhwa ; Srinivasan, Sathiyaraj ; Lee, Sang-Seob ;
The Korean Journal of Microbiology, volume 49, issue 4, 2013, Pages 343~352
DOI : 10.7845/kjm.2013.3043
In this study, we have evaluated the effect of efficient microorganisms on odor-removal efficiency and early stabilization of the burial sites. We have developed an efficient microorganism designated as 'KEM' which have the ability to degrade organic compounds and remove odor effectively. Other efficient microorganisms already used on site, such as EM and Bacillus sp., were also compared. We preceded these experiment using lab-scale reactors under three conditions (control, only media and only body) and comparing the effect of with or without the application of tree efficient microorganisms separately. Analysis was focused on eight components (ammonia, TMA,
, methyl mercaptan, dimethyl sulfide, dimethyl disulfide,
), and as a result, efficient microorganisms were shown efficiency in the removal of ammonia and methyl mercaptan. The applied KEM decayed up to 71.2% of the buried meat. We were unable to observe significant differences in microbial communities between efficient microorganisms-treated and non-treated reactors due to the large presence of microorganisms in both soil and carcasses. However, it was possible to observe the effect on odor control and decay rate through the application of efficient microorganisms.
Efficient Clean-up of Oil Spilled Shorelines Using the Compressed Air Jet System and Concomitant Microbial Community Analysis
Chang, Jae-Soo ; Kim, Kyung Hee ; Lee, Jae Shik ; Ekpeghere, Kalu I. ; Koh, Sung-Cheol ;
The Korean Journal of Microbiology, volume 49, issue 4, 2013, Pages 353~359
DOI : 10.7845/kjm.2013.3087
The objectives of this study were to investigate effectiveness of the Compressed Air Jet (CAJ) System for cleaning up shorelines contaminated with crude oils and to examine effects of the system on total petroleum hydrocarbon (TPH) removal and microbial community changes before and after remediation of the oil-contaminated shorelines. These data will lead to better understanding of optimized remediation process. About 66% of TPH reduction was observed when the contaminated site was treated with the CAJ System 2, 3, 4, and 5 times. This treatment system was more efficient than the seawater pumping system under similar treatment conditions (by 40%). By the way, little oil degrader communities were observed despite a potential function of the air jet system to stimulate aerobic oil degraders. The apparent low population density of the oil degraders might be as a result of low concentration of TPH as a carbon source and limiting nutrients such as nitrogen and phosphorus. It was proposed that the CAJ System would contribute significantly to removal of residual oils on the shorelines in combination with addition of these limiting nutrients.
Quantitative Microbial Risk Assessment on Legionella Infection in Children Playing in Interactive Fountains
Lee, In-Sup ; Zo, Young-Gun ;
The Korean Journal of Microbiology, volume 49, issue 4, 2013, Pages 360~368
DOI : 10.7845/kjm.2013.3086
Recently interactive water fountains are gaining popularity in making public facilities in South Korea. The total number of interactive fountains is rapidly growing at the rate of >50% annually. In this study, we performed quantitative microbial risk assessment to estimate infection risks in children by Legionella spp. while playing in interactive fountains. The exposure dose for a given concentration of Legionella in water was calculated using water-aerosol partition rate of Legionella, exposure duration, inhalation rate, and deposit rate of aerosols in the lungs following inhalation. The dose was converted to infection risk by using the dose-response function developed for L. pneumophila. High weight and/or old children, i.e., 12-year children, running around in fountains were the highest risk group by showing >0.05 infection probability for fountain waters containing
CFU/L Legionella. The result supported the current guideline by Korea Centers for Disease Control and Prevention, which permits use of water with <
CFU/L Legionella cells for all purposes. However, the results still warrant further evaluation of the guideline to accommodate risks for children because the dose-response relationship in the model was developed for healthy adults. Further risk assessment studies need to be conducted by employing dose-response model for children who generally carries weaker immune system than adults.
Conversion of Ginsenoside Rb1 and Taxonomical Characterization of Stenotrophomonas sp. 4KR4 from Ginseng Rhizosphere Soil
Jeon, In-Hwa ; Cho, Geon-Yeong ; Han, Song-Ih ; Yoo, Sun Kyun ; Whang, Kyung-Sook ;
The Korean Journal of Microbiology, volume 49, issue 4, 2013, Pages 369~376
DOI : 10.7845/kjm.2013.3085
We isolated the
-glucosidase producing bacteria (BGB) in ginseng root system (rhizosphere soil, rhizoplane, inside of root). Phylogenetic analysis of the 28 BGB based on the 16S rRNA gene sequences, BGB from rhizosphere soil belong to genus Stenotrophomonas (3 strains), Bacillus (1 strain), and Pseudoxanthomonas (1 strain). BGB isolates from rhizoplane were Stenotrophomonas (16 strains), Streptomyces (1 strain) and Microbacterium (1 strain). BGB from inside of root were categorized into Stenotrophomonas (3 strains) and Lysobacter (2 strains). Especially, Stenotrophomonas comprised the largest portion (approximately 90%) of total isolates and Stenotrophomonas was a dominant group of the
-glucosidase producing bacteria. We selected strain 4KR4, which had high
-glucosidase activity (108.17 unit), could transform ginsenoside Rb1 into Rd, Rg3, and Rh2 ginsenosides. In determining its relationship on the basis of 16S rRNA sequence, 4KR4 strain was most closely related to Stenotrophomonas rhizophila e-
(AJ293463) (99.62%). Therefore, on the basis of these polyphasic taxonomic evidence, the ginsenoside Rb1 converting bacteria 4KR4 was identified as Stenotrophomonas sp. 4KR4 (=KACC 17635).
Bacterial Diversity of the South Pacific Sponge, Dactylospongia metachromia Based on DGGE Fingerprinting
Jeong, In-Hye ; Park, Jin-Sook ;
The Korean Journal of Microbiology, volume 49, issue 4, 2013, Pages 377~382
DOI : 10.7845/kjm.2013.3090
The bacterial community structures of the marine sponge, Dactylospongia metachromia, collected from Chuuk of Micronesia on February 2012, were analyzed by denaturing gradient gel electrophoresis (DGGE). The DGGE fingerprints of two individuals of D. metachromia, CH607 and CH840 showed the same band patterns. The sequences derived from DGGE bands revealed 93~100% similarities with known bacterial species in the public database and high similarity with uncultured bacterial clones. The bacterial community structures of both D. metachromia sponges (CH607, CH840) were composed of 6 phyla, 8 classes: Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Acidobacteria, Actinobacteria, Chloroflexi, Cyanobacteria, Spirochaetes. DGGE fingerprint - based phylogenetic analysis revealed that the bacterial community profiles were identical in two individuals of the same sponge species collected from the same geographical location.
Characterization of Phylogenetic Incongruence among Protein Coding Genes of Vibrio Strains Pathogenic to Humans
Zo, Young-Gun ;
The Korean Journal of Microbiology, volume 49, issue 4, 2013, Pages 383~390
DOI : 10.7845/kjm.2013.3091
Lateral gene transfer (LGT) of genes from other bacteria into Vibrio cholerae is expectable because of the pronounced natural competence of the bacterium. In this study, quantitative aspects of LGT among the three species of Vibrio pathogenic to humans were characterized. Genome sequences of V. cholerae N16961, V. parahaemolyticus RIMD2210633, V. vulnificus CMCP6, and Escherichia coli K12 substrain MG1655 were analyzed to determine orthologous quartets of protein coding genes present in all four genomes. Phylogenetic analyses on the quartets were conducted to resolve vertical versus lateral patterns of gene polymorphisms based on congruence versus incongruence of phylogenetic trees. About 70% of the quartets could be resolved as either cohesive topology (75%) or LGT tree topologies (25%). The amount of LGT genes in Vibrio spp. appeared to be abnormally high for a genus and comparable to those of families. Patched distributions of LGT from different donors were observed on a chromosome. In the small chromosome of V. cholerae, physical linkages among LGT loci spanned half the length of the chromosome. Either accumulative selection for the donor alleles in LGT or presence of large-scale LGT events was hypothesized. These findings warrant further studies on the nature of donor-specificity of LGT alleles and its influence on evolution of Vibrio virulence to humans.
Enhanced Antioxidant Effect of Black Soybean by Cheonggukjang with Potential Probiotic Bacillus subtilis CSY191
Hwang, Chung Eun ; Seo, Weon Taek ; Cho, Kye Man ;
The Korean Journal of Microbiology, volume 49, issue 4, 2013, Pages 391~397
DOI : 10.7845/kjm.2013.3070
-glycosidase activity, total phenolic and isoflavone contents, and antioxidant activities during the fermentation of Korean black soybeans (Seoritae and Seomoktae) fermented food cheonggukjang by the potential probiotic Bacillus subtilis CSY191 were investigated. The levels of total phenolic and isoflavone-malonylglycoside and -aglycone contents increased, while 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging activity and ferric reducing/antioxidant power (FRAP) increased, but the isoflavone-glycoside contents decreased after cheonggukjang fermentation. The content of antioxidant compounds, including isoflavone-aglycones and -malonylglycosides, was increased by fermenting-processing, whereas the content of isoflavone-glycosides was decreased in the fermented soybeans. In particular, the Seoritae soybean fermented at 3
for 48 h displayed the highest antioxidant activities, compared to those of the Seomoktae soybean and the fermented. The highest levels of daidzein, glycitein, and genistein were present at concentrations of 253.0
, and 114.1
after 48 h of Seoritae soybean fermentation. From those results, we suggest that the high antioxidant activity of cheonggukjang of black soybeans might be related to the markedly higher levels of total phenolic and isoflavone-aglycone and -malonylglycoside contents achieved during fermentation.
Biocontrol of Red Pepper Using Mixed Culture of Antagonistic Bacterium and Phosphate Solubilizing Yeast
Lee, Gun Woong ; Min, Byung-Dae ; Park, Sujeong ; Jheong, Weonhwa ; Go, Eun Byeul ; Lee, Kui-Jae ; Chae, Jong-Chan ;
The Korean Journal of Microbiology, volume 49, issue 4, 2013, Pages 398~402
DOI : 10.7845/kjm.2013.3078
This study was to investigate beneficial effects of microbial mixture on red pepper which was capable of promoting plant growth by solubilizing insoluble phosphate as well as protecting plants from pathogenic attack. Saccharomyces sp. L13 was isolated for phosphate solubilizing activity on aluminium phosphate, tricalcium phosphate, calcium hydrophosphate, and magnesium hydrophosphate. On the other hand, Bacillus sp. L32 was isolated for antagonistic activity against Phytophthora capsisi and Colletotrichum gloeosporioides, causing Phytophthora blight and Anthracnose disease in pepper, respectively. The strain L32 exhibited antagonistic activities both under dual culture assays and detached leaves assays. The each strain under the condition of mixed cultivation exhibited the same growth rates as one under pure cultivation. In greenhouse study, the mixed culture showed the both effect of plant growth promotion and reduction of disease symptom development against P. capsisi and C. gloeosporioides providing a potential as effective microbial agent for plant husbandry.
Microbiological, Physicochemical, and Antioxidant Properties of Plain Yogurt and Soy Yogurt
Lim, Sung-Mee ;
The Korean Journal of Microbiology, volume 49, issue 4, 2013, Pages 403~414
DOI : 10.7845/kjm.2013.3074
This study evaluated the physicochemical and microbiological characteristics and antioxidant properties of yogurt samples fermented with lactic acid bacteria (LAB) obtained from pickled cabbage. API 50 CHL systems and 16S rRNA nucleotide sequence analyses revealed that the isolates were Lactobacillus casei PC05 and L. acidophilus PC16. Cell counts, titratable acidity, and viscosity of the yogurt samples fermented with L. acidophilus PC16 were significantly higher than those of the samples fermented with L. casei PC05 (P<0.05). The detected cell counts and physicochemical properties were significantly lower in plain yogurt than in soy yogurt (P<0.05). Yogurt samples fermented with L. acidophilus PC16 exhibited higher antioxidant activity, measured as ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and chelate ferrous ions, than those fermented with L. casei PC05. However, the ability to scavenge superoxide anions and superoxide dismutase (SOD) activity were significantly (P<0.05) higher in yogurt samples fermented with L. casei PC05 compared to those in samples fermented with L. acidophilus PC16. The antioxidant activity of soy yogurt was significantly (P<0.05) higher than that of plain yogurt. The antioxidant activity of the tested strains resulted in lipid peroxidation inhibition (in vitro), which may be related to the elimination of free radicals, chelating ability, and reducing power. There were no significant differences in the physicochemical properties and antioxidant activities of the yogurt samples during cold storage.
Toward The Fecal Microbiome Project
Unno, Tatsuya ;
The Korean Journal of Microbiology, volume 49, issue 4, 2013, Pages 415~418
DOI : 10.7845/kjm.2013.3080
Since the development of the next generation sequencing (NGS) technology, 16S rRNA gene sequencing has become a major tool for microbial community analysis. Recently, human microbiome project (HMP) has been completed to identify microbes associated with human health and diseases. HMP achieved characterization of several diseases caused by bacteria, especially the ones in human gut. While human intestinal bacteria have been well characterized, little have been studied about other animal intestinal bacteria. In this study, we surveyed diversity of livestock animal fecal microbiota and discuss importance of studying fecal microbiota. Here, we report the initiation of the fecal microbiome project in South Korea.
Isolation and Characterization of Double Deletion Mutants of nsdD and veA or nsdC, the Genes Positive Regulating Sexual Development of Aspergillus nidulans
Kim, Lee-Han ; Kim, Ha-Eun ; Han, Dong-Min ;
The Korean Journal of Microbiology, volume 49, issue 4, 2013, Pages 419~423
DOI : 10.7845/kjm.2013.3088
Three genes, nsdD, nsdC, and veA are known to be necessary for positive regulating sexual development of Aspergillus nidulans. Since the mutants of those genes hardly form fruiting bodies in heterokaryons constructed by cross between two of them, it is difficult to isolate double mutants. In this work, double mutants of
were isolated using the characteristic of the nsdD deletion mutant that it could develop mature cleistothecia in hypoxic and low temperature culture condition. According to the phenotypes of double mutants, the nsdD gene controls the apical growth independently with veA or nsdC. Deletion of veA or nsdC was epistatic to nsdD deletion for pigment production. Conidia formation in submerged culture with lactose as sole carbon source was observed in
double mutant implicating it to be unique phenotype of nsdC deletion.
Meta-Analysis of Risk Factors for Contamination of Environmental Waters by Legionella
Zo, Young-Gun ;
The Korean Journal of Microbiology, volume 49, issue 4, 2013, Pages 424~428
DOI : 10.7845/kjm.2013.3089
To identify risk factors for Legionella contamination, water quality variables routinely measured in examination of natural and city waters were meta-analyzed for significance of correlation to Legionella incidences. For evaluation of abundance of Escherichia coli as a risk factor, which is currently used as an indicator of Legionella contamination in an official guideline in Korea, odds ratio (OR) of above-cutoff total coliform counts for Legionella presence/absence was used as the effect size in the meta-analysis. The OR was estimated as 1.05 (0.36-3.12, 95% CI), and the probability of having identical odds reached 0.92. Also, ORs from individual studies showed significant heterogeneity (P=0.008), which contributed to 63% of total variance of the ORs. In the case of heterotrophic plate count (HPC), the OR for Legionella presence/absence was 2.72 (2.04-3.63) with highly significant deviation from identical odds (P<0.0001). ORs from different studies were seemingly homogeneous (
=12.7, P=0.12). Turbidity and concentrations of chlorine, iron ion and cupper ion were other routine variables that could be considered as risk factors. However, statistical measures from different studies were not uniform enough to develop an appropriate effect size while the number of studies reporting the variables was also small (3-5). In conclusion, HPC appeared to be appropriate as indicator of Legionella contamination, rather than fecal bacteria contamination. HPC may imply abundance of habitats (amoebas and biofilms) of Legionella in water. This result warrants further studies for standardizing protocols and cutoff values to infer Legionella risks from HPC.