• 미생물학회지
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• 제52권2호
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• pp.212-219
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• 2016

식물 근권 토양으로부터 색소생성 균주 106균주를 수집하여 색소 생성능이 우수한 균주로부터 노란색(33개), 주황색(12개), 분홍색, 빨간색, 갈색 그리고 보라색 총 49개의 세균색소를 추출하였다. 식물병원균에 대한 항균활성능이 우수한 색소를 선발하기 위하여 고추점무늬병원균(Xanthomonas axonopodis), 흑마병원균(Xanthomonas campestris)과 딸기잿빛곰팡이병원균(Botrytis cinerea), 고추탄저병원균(Colletotrichum acutatum), 그리고 시들음병원균(Fusarium oxysporum)을 대상으로 항균활성 검정을 수행하였다. 색소생성 Chryseobacterium sp. RBR9 균주가 생산하는 노란색 색소와 Methylobacterium sp. RI13 균주가 생산하는 빨간색 색소는 X. axonopodis와 X. campestris에 항세균 활성을 나타내었다. 차나무 토양으로부터 분리된 Collimonas sp. DEC-B5가 생산하는 보라색 색소는 항세균 활성과 더불어 B. cinerea와 Colletotrichum acutatum에 항진균활성을 나타내었다. 특히, 보라색 색소는 최소저해 농도 $20{\mu}M$에서 B. cinerea를 65% 이상 생육 저해하였다. 항진균활성 보라색 색소를 HPLC 분석한 결과, violacein (91.6%)와 deoxyviolacein(8.4%)으로 동정되었다. 보라색 색소 violacein의 생산량은 SCB 배지에서 $43.2{\mu}M$이었고 D-mannitol 1.5%, yeast extract 0.2%를 첨가한 경우 $431.6{\mu}M$로 약 10배 높은 색소 생성량을 나타내었다. 본 연구에서 분리된 Collimonas sp. DEC-B5가 생산하는 violacein 색소는 딸기잿빛곰팡이병원균 방제제로 활용 가능성이 확인되었다.

• 생명과학회지
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• 제32권12호
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• pp.1005-1012
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• 2022

본 연구는 한라마 출생시와 이유기의 분변 미생물 조성과 다양성 차이에 대해 16S 앰플리콘시퀀싱 데이터 분석을 통해 수행하였다. 출생시에 Proteobacteria (35.7%)가, 이유기에는 Firmicutes (45.6%)가 문 수준에서 가장 우점하는 미생물로 확인되었다. 속 수준에서는 출생시에 Escherichia (19.7%), Clostridium (14.0%)가 우점종으로 관측되었으며, 이유기에는 Fibrobacter (6.6%)가 가장 높게 분포하고 있었다. 다양성(α-diversity) 분석 결과 이유기에 풍부도와 균등도 지표들이 통계적으로 유의한 수준에서 높게 나타났다. PCoA 분석을 수행한 결과 출생시와 이유기 미생물 군집 특성(β-diversity)은 속 수준과 종 수준에서 두개의 그룹으로 명확히 구분되었다. 미생물 분포에 대한 통계적 유의성 검증을 위해 세 가지 Jensen-Shannon, Bray-Curtis, Unifrac의 distance metric를 이용해 PERMANOVA 분석을 수행한 결과 통계적 유의성(q<0.001)을 보이며 조성 차이가 있었다. 출생시와 이유기 특성을 대표하는 미생물 마커 선발을 위해 LEfSe 분석을 수행하였다. 속 수준에서 출생시에 장내 질환을 유발할 가능성이 있는 Escherichia, Bacteroides, Clostridium, Methylobacterium 등이 우점하였으며, 이유기에는 섬유소 분해에 관여하는 Fibrobacter가 상대적으로 많이 분포하였다. 본 연구를 통해 승용마로 가치가 높은 한라마의 출생시와 이유기의 미생물 조성 및 다양성 차이에 대한 결과를 제시하였으며 성장단계별 질병예방 및 영양소 흡수에 관여하는 미생물 구명을 위한 기초자료로 활용될 수 있을 것으로 기대한다.

• Journal of Microbiology and Biotechnology
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• 제17권10호
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• pp.1645-1654
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• 2007

The total methylotrophic population associated with rice plants from different cultivars was enumerated at three different stages: vegetative, flowering, and harvesting. The bacterial population in the leaf, rhizosphere soil, endophytic in the stem and roots, and epiphytic in the florets and grains were determined from four rice cultivars, Il-mi, Nam-pyeoung, O-dae, and Dong-jin, sampled from three different field sites. The methylotrophic bacteria isolated on AMS media containing 0.5% methanol as the sole carbon source uniformly showed three distinct morphologies, which were recorded as separate groups and their distribution among the various samples was determined using the ecophysiological index. The growth stage at the time of sampling had a more significant effect on the methylotrophic population and their distribution than the field site or cultivar. A similar effect was also observed for the PPFMs, where their population in different plant parts increased from V10 to R4 and then decreased towards stage R9. A canonical discriminant analysis of the PPFM population from different parts of rice showed clear variations among the cultivars, sampled sites, and growth stages, although the variations were more prominent among the growth stages.

• KSBB Journal
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• 제30권2호
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• pp.69-76
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• 2015

The antibacterial activity of a antimicrobial (organic synthetic or organic natural material) on the bacteria (Bacillus megaterium, Arthrobacter oxydans, Micrococcus luteus, Methylobacterium aquaticum) detected in the automobiles showed 99.9% bacteria decrease rate within 30 min of being in contact with the tested bacteria culture. The MIC of the organic synthetic material based antimicrobials and the organic natural material based antimicrobial on the bacteria were 31~500 mg/mL and 8~250 mg/mL, respectively. The bacteria and biofilms were formed on the surface of aluminum after 5 ~8 days in the case of addition of the organic synthetic material based antimicrobial to the MIC values for the tested bacteria culture. On the other hand, there was no proliferation of bacteria and formation of biofilms on the surface of aluminum even after 30 days in the case of addition of the organic natural material based antimicrobial to the MIC values for the tested bacteria culture. As a result, the organic natural material based antimicrobial was confirmed to be more excellent effect of inhibition of bacterial proliferation and restraint of biofilms formation than the organic synthetic material based antimicrobial.

• The Plant Pathology Journal
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• 제24권1호
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• pp.74-79
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• 2008

This research was conducted to evaluate fungal and bacterial populations in unhulled and brown rice under indoor storage conditions, and to examine the relationship between microbial populations and environmental conditions such as temperature and relative humidity. The temperature and relative humidity of the storage room ranged from $22.6^{\circ}C\;to\;27.0^{\circ}C$ and 23.3% to 44.2%, respectively. Total fungal and bacterial populations remained relatively stable over the storage period. Predominant fungi included Aspergillus candidus, A. flavus, A. fumigatus, and Penicillium spp.; the predominant bacteria were Bacillus, Microbacterium, Sphingomonas, and Methylobacterium spp. Total fungi and bacteria were not significantly correlated with either unhulled (r=0.448, P=0.372) or brown (r=0.466, P=0.351) rice. In unhulled rice, total fungi showed positive correlations with total Aspergillus (r=0.994, P<0.001) and total Penicillium (r=0.906, P<0.05); A. flavus was positively correlated with total Aspergillus (r=0.913, P<0.05) and total fungi (r=0.868, P<0.05). In brown rice, Bacillus spp. was also positively correlated with total bacteria (r=0.998, P<0.001). Mean temperature was negatively correlated with A. candidus (r=-0.852, P<0.05) and total fungi (r=-0.961, P<0.01), and mean relative humidity was positively correlated with total Penicillium spp.(r=0.884, P<0.05) in brown rice. Hence these results could provide basic information on the fungal and bacterial populations in unhulled and brown rice stored under room conditions, and on the effect of environmental conditions on the populations of fungi and bacteria, especially Aspergillus and Penicillium spp.

• Environmental Engineering Research
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• 제20권2호
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• pp.141-148
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• 2015

The presence of phenols in treated palm oil mill effluent (POME) is an environmental concern due to their phytotoxicity and antimicrobial activity. In this study, phenol-degrading bacteria, Methylobacterium sp. NP3 and Acinetobacter sp. PK1 were immobilized on oil palm empty fruit bunches (EFBs) for removal of phenols in the treated POME. The bacterial exopolysaccharides (EPS) were responsible for cell adhesion to the EFBs during the immobilization process. These immobilized bacteria could effectively remove up to 5,000 mg/L phenol in a carbon free mineral medium (CFMM) with a greater degradation efficiency and rate than that with suspended bacteria. To increase the efficiency of the immobilized bacteria, three approaches, namely activation, acclimation, and combined activation and acclimation were applied. The most convenient and efficient strategy was found when the immobilized bacteria were activated in a CFMM containing phenol for 24 h before biotreatment of the treated POME. These activated immobilized bacteria were able to remove about 63.4% of 33 mg/L phenols in the treated POME, while non-activated and/or acclimated immobilized bacteria could degrade only 35.0%. The activated immobilized bacteria could be effectively reused for at least ten application cycles and stored for 4 weeks at $4^{\circ}C$ with the similar activities. In addition, the utilization of the abundant EFBs gives value-added to the palm oil mill wastes and is environmentally friendly thus making it is attractive for practical application.

• Molecules and Cells
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• 제20권3호
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• pp.392-400
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• 2005

The genes encoding the DNA gyrase A (GyrA) and B subunits (GyrB) of Methylovorus sp. strain SS1 were cloned and sequenced. gyrA and gyrB coded for proteins of 846 and 799 amino acids with calculated molecular weights of 94,328 and 88,714, respectively, and complemented Escherichia coli gyrA and gyrB temperature sensitive (ts) mutants. To analyze the role of type II topoisomerases in the intrinsic quinolone resistance of methylotrophic bacteria, the sequences of the quinolone resistance-determining regions (QRDRs) in the A subunit of DNA gyrase and the C subunit (ParC) of topoisomerase IV (Topo IV) of Methylovorus sp. strain SS1, Methylobacterium extorquens AM1 NCIB 9133, Methylobacillus sp, strain SK1 DSM 8269, and Methylophilus methylotrophus NCIB 10515 were determined. The deduced amino acid sequences of the QRDRs of the ParCs in the four methylotrophic bacteria were identical to that of E. coli ParC. The sequences of the QRDR in GyrA were also identical to those in E. coli GyrA except for the amino acids at positions 83, 87, or 95. The $Ser^{83}$ to Thr substitution in Methylovorus sp. strain SS1, and the $Ser^{83}$ to Leu and $Asp^{87}$ to Asn substitutions in the three other methylotrophs, agreed well with the minimal inhibitory concentrations of quinolones in the four bacteria, suggesting that these residues play a role in the intrinsic susceptibility of methylotrophic bacteria to quinolones.

• Journal of Microbiology
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• 제40권2호
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• pp.109-118
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• 2002

The present work is aimed at providing additional new pure cultures of oxalate utilizing bacteria and its preliminary characterization for further work in the field of oxalate-metabolism and taxonomic studies. The taxonomy of 14 mesophilic, aerobic oxalotrophic bacteria isolated by an enrichment culture technique from soils rhizosphers, and the juice of the petiole/stem tissue of plants was investigated. Isolates were characterized with 95 morphological, biochemical and physiological tests. Cellular lipid components and carotenoids of isolates were also studied as an aid to taxonomic characterization. All isolates were Gram-negative, oxidase and catalase positive and no growth factors were required. In addition to oxalates, some of the strains grow on methanol and/or formate. The taxonomic similarities among isolates, reference strains or previously reported oxalotrophic bacteria were analysed by using the Simple Matching (S/ sub SM/) and Jaccard (S$\_$J/) Coefficients. Clustering was performed by using the unweighted pair group method with arithmetic averages (UPGMA) algorithm. The oxalotrophic strains formed five major and two single-member clusters at the 70-86% similarity level. Based on the numerical taxonomy, isolates were separated into three phenotypic groups. Pink-pigmented strains belonged to Methylobacterium extorquens, yellow-pigmented strains were most similar to Pseudomonas sp. YOx and Xanthobacter autorophicus, and heterogeneous non-pigmented strains were closely related to genera Azospirillum, Ancylobacter, Burkholderia and Pseudomonas. New strains belonged to the genera Pseudomonas, Azospirillum and Ancylobacter that differ taxonomically from other known oxalate oxidizers were obtained. Numerical analysis indicated that some strains of the yellow-pigmented and nonpigmented clusters might represent new species.

• Molecules and Cells
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• 제23권3호
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• pp.370-378
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• 2007

A superoxide dismutase was purified 62-fold in seven steps to homogeneity from Methylobacillus sp. strain SK1, an obligate methanol-oxidizing bacterium, with a yield of 9.6%. The final specific activity was 4,831 units per milligram protein as determined by an assay based on a 50% decrease in the rate of cytochrome c reduction. The molecular weight of the native enzyme was estimated to be 44,000. Sodium dodecyl sulfate gel electrophoresis revealed two identical subunits of molecular weight 23,100. The isoelectric point of the purified enzyme was found to be 4.4. Maximum activity of the enzyme was measured at pH 8. The enzyme was stable at pH range from 6 to 8 and at high temperature. The enzyme showed an absorption peak at 280 nm with a shoulder at 292 nm. Hydrogen peroxide and sodium azide, but not sodium cyanide, was found to inhibit the purified enzyme. The enzyme activity in cell-free extracts prepared from cells grown in manganese-rich medium, however, was not inhibited by hydrogen peroxide but inhibited by sodium azide. The activity in cell extracts from cells grown in iron-rich medium was found to be highly sensitive to hydrogen peroxide and sodium azide. One mol of native enzyme was found to contain 1.1 g-atom of iron and 0.7 g-atom of manganese. The N-terminal amino acid sequence of the purified enzyme was Ala-Tyr-Thr-Leu-Pro-Pro-Leu-Asn-Tyr-Ala-Tyr. The superoxide dismutase of Methylobacillus sp. strain SK1 was found to have antigenic sites identical to those of Methylobacillus glycogenes enzyme. The enzyme, however, shared no antigenic sites with Mycobacterium sp. strain JC1, Methylovorus sp. strain SS1, Methylobacterium sp. strain SY1, and Methylosinus trichosproium enzymes.

• Journal of Species Research
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• 제8권3호
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• pp.249-258
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• 2019

Owing to a distinct environmental regime and anthropogenic effects, freshwater bacterial communities of urban streams are considered to be different from those of large freshwater lakes and rivers. To obtain unrecorded, freshwater bacterial species in Korea, water and sediment samples were collected from various urban streams of the Han River watershed in 2018. After plating the freshwater samples on R2A agar, approximately 1000 bacterial strains were isolated from the samples as single colonies and identified using 16S rRNA gene sequence analyses. A total of 26 strains, with >98.7% 16S rRNA gene sequence similarity with validly published bacterial species but not reported in Korea, were determined to be unrecorded bacterial species in Korea. The unrecorded bacterial strains were phylogenetically diverse and belonged to four phyla, six classes, 12 orders, 16 families, and 21 genera. At the generic level, the unreported species were assigned to Nocardioides, Streptomyces, Microbacterium, Kitasatospora, Herbiconiux, Corynebacterium, and Microbacterium of the class Actinobacteria; Paenibacillus and Bacillus of the class Bacilli; Caulobacter, Methylobacterium, Novosphingobium, and Porphyrobacter of the class Alphaproteobacteria; Aquabacterium, Comamonas, Hydrogenophaga, Laribacter, Rivicola, Polynucleobacter, and Vogesella of the class Betaproteobacteria; Arcobacter of the class Epsilonproteobacteria; and Flavobacterium of the class Flavobacteriia. The details of the 26 unreported species, including Gram reaction, colony and cell morphology, biochemical properties, and phylogenetic position are also provided in the strain descriptions.