• 환경생물
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• 제40권4호
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• pp.442-454
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• 2022

A total of 31 bacterial strains were isolated from the Geum River basin in the Republic of Korea during our investigation of indigenous prokaryotic species. The isolated bacterial strains had high 16S rRNA gene sequence similarity (>98.7%) with those of validly published bacterial species, which have not been reported in Republic of Korea. The 31 bacterial strains were phylogenetically diverse and assigned to 4 phyla, 8 classes, 18 orders, 21 families, and 27 genera. At the genus level, the unreported species were affiliated with Kineococcus, Pedococcus, Rhodoluna, Salinibacterium, Rhodoluna, Arthrobacter, Williamsia, Nakamurella, Nocardioides of the class Actinobacteria, Patulibacter of the class Thermoleophilia, Pontibacter, Hymenobacter of the class Cytophagia, Flavobacterium of the class Flavobacteriia, Geomicrobium of the class Bacilli, Brevundimonas, Gellertiella, Rhizobium, Paracoccus, Taonella, Sphingomonas of the class Alphaproteobacteria, Burkholderia, Polaromonas, Hydrogenophaga, Chitinilyticum, Azospira, Zoogloea of the class Betaproteobacteria, and Pseudomonas of the class Gammaproteobacteria. The unreported bacterial species were further characterized by examining their morphological, cultural, physiological, and biochemical properties. The detailed descriptions of the 31 bacterial strains were provided.

• Journal of Species Research
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• 제12권spc2호
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• pp.54-59
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• 2023

To obtain unrecorded bacterial species from Korean islands, various samples were collected from the islands in 2022. After plating the samples on marine agar or Reasoner's 2A, and incubating aerobically, approximately 1,200 bacterial strains were isolated and identified using 16S rRNA gene sequences. A total of 10 strains showed ≥98.7% 16S rRNA gene sequence similarity with the bacterial species that were validly published but not reported in Korea. The unrecorded bacterial strains belong to three phyla, five classes, 10 orders, 10 families, and 10 genera, which are assigned to Sphingomonas, Falsirhodobacter and Asticcacaulis of the class Alphaproteobacteria; Colwellia and Halomonas of the class Gammaproteobacteria; Chitinophaga of the class Chitinophagia; Chryseobacterium of the class Flavobacteriia; Microlunatus, Zhihengliuella, and Streptomyces of the class Actinomycetia. The details of the unreported species including Gram reaction, colony and cell morphology, biochemical characteristics, and phylogenetic position are also provided in the description of the strains.

• Journal of Species Research
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• 제12권4호
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• pp.267-276
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• 2023

To obtain unrecorded bacterial species in Korea, various soils of coastal areas were collected from the Republic of Korea in 2022. After plating the samples on marine agar and incubating aerobically and anaerobically, approximately 1,700 bacterial strains were isolated and identified using 16S rRNA gene sequences. A total of 20 strains showed ≥98.7% 16S rRNA gene sequence similarity with validly published bacterial species but not reported in Korea, indicating they are unrecorded bacterial species in Korea. The unrecorded bacterial strains belonged to four phyla, six classes, 15 orders, 16 families, and 19 genera which were assigned to Blastomonas and Sphingomonas of the class Alphaproteobacteria; Pseudidiomarina, Kushneria, Salinicola, and Salinisphaera of the class Gammaproteobacteria; Evansella, Virgibacillus, and Paenibacillus of the class Bacilli; Cyclobacterium of the class Cytophagia; Pedobacter of the class Sphingobacteriia; and Demequina, Ornithinimicrobium, Blastococcus, Jatrophihabitans, Kineococcus, Glaciihabitans, Aeromicrobium and Streptomyces of the class Actinomycetes. The details of the 20 unreported species, including Gram reaction, morphology, biochemical characteristics, and phylogenetic position are also provided in the description of the strains.

• 환경생물
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• 제31권2호
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• pp.158-164
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• 2013

환경시료에서 마이크로시스틴 분해능을 나타낸 균주 1종을 분리하였고 16S rRNA gene sequence 분석 결과, Microbacterium sp.로 동정되어 Microbacterium sp. MA21로 명명하였다. R2A배지를 기본 배지로 하여 $50{\mu}g\;L^{-1}$ microcystin-LR을 첨가하여 $30^{\circ}C$, 12시간 동안 배양한 후 PPIA를 통해 microcystin이 80% 이상 분해되는 것을 확인하였다. Microcystin-LR의 분해를 HPLC 분석을 통해 재확인하였고, microcystin 분해산물로 추정되는 두 개의 peak를 확인하였다. 16S rRNA 염기서열을 이용한 계통분류 분석 결과, 본 연구에서 분리한 Microbacterium sp. MA21은 Alphaproteobacteria의 Sphingomonas 속에 속하지 않는 것은 물론 Actinobacteria에는 속하지만 기존에 보고되지 않은, 새로운 genus로 확인되었다.

• Journal of Microbiology and Biotechnology
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• 제17권1호
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• pp.96-103
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• 2007

Plant growth-promoting rhizobacteria (PGPR) have the potential to be used as microbial inoculants to reduce disease incidence and severity and to increase crop yield. Some of the PGPR have been reported to be able to enter plant tissues and establish endophytic populations. Here, we demonstrated an approach to screen bacterial endophytes that have the capacity to promote the growth of pepper seedlings and protect pepper plants against a bacterial pathogen. Initially, out of 150 bacterial isolates collected from healthy stems of peppers cultivated in the Chungcheong and Gyeongsang provinces of Korea, 23 putative endophytic isolates that were considered to be predominating and representative of each pepper sample were selected. By phenotypic characterization and partial 16S rDNA sequence analysis, the isolates were identified as species of Ochrobacterium, Pantoea, Pseudomonas, Sphingomonas, Janthinobacterium, Ralstonia, Arthrobacter, Clavibacter, Sporosarcina, Acidovorax, and Brevundimonas. Among them, two isolates, PS4 and PS27, were selected because they showed consistent colonizing capacity in pepper stems at the levels of $10^6-10^7CFU/g$ tissue, and were found to be most closely related to Pseudomonas rhodesiae and Pantoea ananatis, respectively, by additional analyses of their entire 16S rDNA sequences. Drenching application of the two strains on the pepper seedlings promoted significant growth of peppers, enhancing their root fresh weight by 73.9% and 41.5%, respectively. The two strains also elicited induced systemic resistance of plants against Xanthomonas axonopodis pv. vesicatoria.

• Journal of Microbiology and Biotechnology
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• 제21권2호
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• pp.115-123
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• 2011

To investigate the effects of pipe materials on biofilm accumulation and water quality, an annular reactor with the sample coupons of four pipe materials (steel, copper, stainless steel, and polyvinyl chloride) was operated under hydraulic conditions similar to a real plumbing system for 15 months. The bacterial concentrations were substantially increased in the steel and copper reactors with progression of corrosion, whereas those in stainless steel (STS) and polyvinyl chloride (PVC) reactors were affected mainly by water temperature. The heterotrophic plate count (HPC) of biofilms was about 100 times higher on steel pipe than other pipes throughout the experiment, with the STS pipe showing the lowest bacterial number at the end of the operation. Analysis of the 16S rDNA sequences of 176 cultivated isolates revealed that 66.5% was Proteobacteria and the others included unclassified bacteria, Actinobacteria, and Bacilli. Regardless of the pipe materials, Sphingomonas was the predominant species in all biofilms. PCR-DGGE analysis showed that steel pipe exhibited the highest bacterial diversity among the metallic pipes, and the DGGE profile of biofilm on PVC showed three additional bands not detected from the profiles of the metallic materials. Environmental scanning electron microscopy showed that corrosion level and biofilm accumulation were the least in the STS coupon. These results suggest that the STS pipe is the best material for plumbing systems in terms of the microbiological aspects of water quality.

• Journal of Microbiology and Biotechnology
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• 제28권2호
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• pp.227-235
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• 2018

Foodborne illness represents a major threat to public health and is frequently attributed to pathogenic microorganisms on fresh produce. Recurrent outbreaks often come from vegetables that are grown close to or within the ground. Therefore, the first step to understanding the public health risk of microorganisms on fresh vegetables is to identify and describe microbial communities. We investigated the phyllospheres on Chinese cabbage (Brassica rapa subsp. pekinensis, N = 54). 16S rRNA gene amplicon sequencing targeting the V5-V6 region of 16S rRNA genes was conducted by employing the Illumina MiSeq system. Sequence quality was assessed, and phylogenetic assessments were performed using the RDP classifier implemented in QIIME with a bootstrap cutoff of 80%. Principal coordinate analysis was performed using a weighted Fast UniFrac matrix. The average number of sequence reads generated per sample was 34,584. At the phylum level, bacterial communities were composed primarily of Proteobacteria and Bacteroidetes. The most abundant genera on Chinese cabbages were Chryseobacterium, Aurantimonadaceae_g, Sphingomonas, and Pseudomonas. Diverse potential pathogens, such as Pantoea, Erwinia, Klebsiella, Yersinia, Bacillus, Staphylococcus, Salmonella, and Clostridium were also detected from the samples. Although further epidemiological studies will be required to determine whether the detected potential pathogens are associated with foodborne illness, our results imply that a metagenomic approach can be used to detect pathogenic bacteria on fresh vegetables.

• Journal of Microbiology and Biotechnology
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• 제19권2호
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• pp.113-120
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• 2009

Twenty-seven fenitrothion-degrading bacteria were isolated from different soils, and their genetic and phenotypic characteristics were investigated. Analysis of the 16S rDNA sequence showed that the isolates were related to members of the genera Burkholderia, Pseudomonas, Sphingomonas, Cupriavidus, Corynebacterium, and Arthrobacter. Among the 27 isolates, 12 different chromosomal DNA fingerprinting patterns were obtained by polymerase chain reaction(PCR) amplification of repetitive extra genic palindromic(REP) sequences. The isolates were able to utilize fenitrothion as a sole source of carbon and energy, producing 3-methyl-4-nitrophenol as the intermediate metabolite during the complete degradation of fenitrothion. Twenty-two of 27 isolates were able to degrade parathion, methyl-parathion, and p-nitrophenol but only strain BS2 could degrade EPN(O-ethyl-O-p-nitrophenyl phenylphosphorothioate) as a sole source of carbon and energy for growth. Eighteen of the 27 isolates had plasmids. When analyzed with PCR amplification and dot-blotting hybridization using various specific primers targeted to the organophosphorus pesticide hydrolase genes of the previously reported isolates, none of the isolates showed positive signals, suggesting that the corresponding genes of our isolates had no significant sequence homology with those of the previously isolated organophosphate pesticide-degrading bacteria.

• 한국환경보건학회지
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• 제28권3호
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• pp.9-18
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• 2002

This study was to observe the occurrence of heterotrophic bacteria in terms of free chlorine residuals in two different water distribution systems belong to both K and Y water treatment plant. The data analyzed in this study showed that in distribution systems(DS), the free chlorine residuals were decreased from 0.10 to 0.56 ㎎/1 for K, and 0.51 and 0.78 ㎎/l for Y The decay of free chlorine were clearly higher in both March and August than those in January. The HPC in DS were ranged from 0 to 40 CFU/ml for K,0 to 270 CFU/ml for Y, on R2A medium. In particular, Its level was relatively high at consumers' ground storage tanks, taps and point-of-end area of Y, The predominant genera found in the distribution systems were Acinetobacter, Sphingomonas (branch of Pseudomonas), Microroccus, Bacillus, Staphylococcus. The diversity of heterotrophic bacteria was increased in the end-point area. Most of them were either encapsulated cells or cocci of gram-positve. In conclusion, the point-of-end area in distribution systems showed that the longer flow distance from WTP the greater diversity and higher level of heterotrophic bacteria due to the significant decay of free chlorine residuals.

• KSBB Journal
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• 제32권2호
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• pp.133-139
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• 2017

Rheum palmatum has traditionally been used as a preventive agent and medication against fever and infection. The aim of this study was to isolate and characterize an antibacterial substance from R. palmatum that is effective against bacterial vaginosis. A methanol extract from R. palmatum showed antibacterial activity against Lactobacillus vaginalis KC TC 3515, Chryseobacterium gleum KCTC 2904, and Sphingomonas paucimobilis KCTC 2834, which cause bacterial vaginosis. After extraction and pH control of the methanol extract from R. palmatum, we found that acidic and alkaline extracts did not show antibacterial activity. A neutral extract (50 mg/mL) displayed an inhibitory zone of 18 mm on a nutrient agar plate with C. gleum KCTC 2904. Fractions No. 11 and 12 among 41 fractions obtained by silica gel column chromatography produced inhibitory zones of 10 mm on nutrient agar plates with C. gleum KCTC 2904. $R_f0.15$ and $R_f0.17$ spots produced by TLC of fraction No. 11 showed antibacterial activity against C. gleum KCTC 2904. Isolation and purification of the peak at a retention time (Rt) of 9.427 min was achieved by HPLC of $R_f0.29spots$. The peak at Rt 9.427 min showed antibacterial activity against C. gleum KCTC 2904.