• Journal of Microbiology and Biotechnology
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• 제29권9호
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• pp.1424-1433
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• 2019

DDT is a hydrophobic organic pollutant, which can be bio-accumulated in nature and have adverse consequences on the physical condition of humans and animals. This study investigated the relationship between the white-rot fungus Pleurotus eryngii and biosurfactant-producing bacterium Ralstonia pickettii associated with the degradation of DDT. The effects of R. pickettii on fungal development were examined using in vitro confrontation assay on a potato dextrose agar (PDA) medium. R. pickettii culture was added to the P. eryngii culture at 1, 3, 5, 7, and 10 ml ($1ml{\approx}1.44{\times}10^{13}CFU$). After 7 d incubation, about 43% of the initial DDT ($12.5{\mu}M$) was degraded by the P. eryngii culture only. The augmentation of 7 ml of R. pickettii culture revealed a more highly optimized synergism with DDT degradation being approximately 78% and the ratio of optimization 1.06. According to the confrontational assay, R. pickettii promoted the growth of P. eryngii towards the bacterial colony, with no direct contact between the bacterial cells and mycelium (0.71 cm/day). DDD (1,1-dichloro-2,2-bis(4-chlorophenyl) ethane), DDE (1,1-dichloro-2,2-bis(4-chlorophenyl) ethylene), and DDMU (1-chloro-2,2-bis(4-chlorophenyl) ethylene) were identified as metabolic products, indicating that the R. pickettii could enhance the DDT biodegradation by P. eryngii.

• Journal of Microbiology and Biotechnology
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• 제30권2호
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• pp.244-247
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• 2020

We have expressed extracellular poly(3-hydroxybutyrate) (PHB) depolymerase of Ralstonia pickettii T1 on the Escherichia coli surface using Pseudomonas OprF protein as a fusion partner by C-terminal deletion-fusion strategy. Surface display of depolymerase was confirmed by flow cytometry, immunofluorescence microscopy and whole cell hydrolase activity. For the application, depolymerase was used as an immobilized catalyst of enantioselective hydrolysis reaction for the first time. After 48 h, (R)-methyl mandelate was completely hydrolyzed, and (S)-mandelic acid was produced with over 99% enantiomeric excess. Our findings suggest that surface displayed depolymerase on E. coli can be used as an enantioselective biocatalyst.

• 대한환경공학회지
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• 제35권7호
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• pp.503-508
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• 2013

본 연구의 목적은 가축사체 매몰지 토양의 침출수 오염에 따른 병원성 미생물에 의한 잠재적 위해성을 평가하기 위하여 미생물 군집을 조사하는 것이다. 경기도 지역에 위치한 가축사체 매몰지 세 군데(A, B, C) 토양을 대상으로 DNA를 추출하여, 16S rRNA 염기서열을 분석을 통해 미생물 군집을 조사하였다. 연구결과를 문(phylum)별로 구분해보면, A 토양은 전체 토양미생물이 Proteobacteria (100%) 1개의 문으로 동정되었으며, B 토양은 Actinobacteria (66.4%) > Proteobacteria (31.1%) > Bacteriodetes (2.1%) > Acidobacteria (0.3%) 순으로, C 토양은 Actinobacteria (63.1%) > Proteobacteria (36.9%) 순으로 분포하였다. 속(genus)별로 구분해보면, A 토양에서는 Pseudomonas가 98% 비율로 나타났고，B와 C 토양의 경우 Arthrobacter이 각각 68, 61%로 우점하였다. 세 군데(A, B, C) 토양 미생물 군집의 종 다양성을 Shannon 지수에 근거하여 분석한 결과, B 토양(3.45)과 C 토양(3.43)은 유사한 수준이었으나, A 토양(2.37)은 가장 낮게 계산되었다. 또한, 분석결과 Salmonella, Campylobacter 그리고 Clostridium perfringens과 같은 병원균도 발견되지 않았으나, 세균혈증을 일으키는 Ralstonia pickettii가 높은 농도로 관찰되었다. 본 연구에 사용된 가축 매몰지 토양은 침출수에 의한 미생물학적 오염도가 낮은 것으로 판단되지만, 가축매몰에 따른 병원성 미생물에 의한 토양의 잠재적 위해성을 평가하기 위하여 지속적인 모니터링이 필요하다.

• 미생물학회지
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• 제40권4호
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• pp.313-319
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• 2004

울산석유화학공단과 인접한 지역(선암)및 농촌지역(대암)의 산림토양에서 내산성 종속영양세균 및 나프탈렌분해세균의 분포와 특성을 조사하였다. 토양 pH의 평균은 선암과 대암에서 각각 3.8과 4.6으로 측정되었다. 종속영양세균과 나프탈렌분해세균을 최확수치(MPN)법으로 계수하였으며, 선암의 경우 pH 7.0과 pH 4.0에서 생장하는 종속영양세균 수의 중앙간은 각각 $5.3{\times}10^7\;3.3{\times}10^7$ MPN/dried Soil g이었고, 나프탈렌분해세균 수의 중앙간은 pH 7.0과 4.0에서 각각 $5.6{\times}10^4$ 와 $4.0{\times}10^5$ MPN/dried soil g이었다. 대암에서 측정한 종속영양세균수의 중앙간은 두 pH 모두 선암에서보다 많았으나 나프탈렌분해세균의 농도는 선암이 대암보다 높았다. MPN시험관과 농화배양으로부터 17개의 나프탈렌분해세균을 분리하였으며, 이들은 Sphingomonas paucimobilis, Brevundimonas vesicularis, Burkholderia cepacia, Ralstonia pickettii, Pseudomonas fluorescens, Chryseomonas luteola 등으로 동정되었다. 분리한 17개 균주 중 6개는, 최소배지에서의 나프탈렌분해 활성이 PH 7.0에 비해 PH 4.0에서 더 높았으나 영양배지에 접종하였을 때의 생장정도는 pH 4.0이 pH 7.0보다 더 크지 않았다. 배지의 pH가 분리한 세균의 세포막 지방산 조성을 변화시켜 나프탈렌분해 활성에 영향을 주는 것으로 생각된다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제17권6호
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• pp.23-32
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• 2012

This study was conducted to monitor microbial species dynamics within the aquifer due to long term operation of geothermal heat pump system. The species were identified by molecular biological methods of 16S rDNA. Groundwater sample was collected from both open (S region) and closed geothermal recovery system (J region) along with the control. J measured and control as well as S measured found Ralstonia pickettii as dominant species at year 2010. In contrast, Rhodoferax ferrireducens was dominantly observed for the control of S. In 2011, Sediminibacterium sp. was universely identified as the dominant species regardless of the monitoring places and type of sample, i.e., measured or control. The difference in the dynamics between the measured and the control was not critically observed, but annual variation was more strikingly found. It reveals that possible environmental changes (e.g. ORP and DO) due to the operation of geothermal heat recovery system in aquifer could be more exceedingly preceded to differentiate annual variation of microbial species rather than positional differences.

• 한국치위생학회지
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• 제18권5호
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• pp.843-852
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• 2018

Objectives: The study aimed to isolate the abundant bacteria in dental caries in children and to investigate the bacterial species involved in addition to those that have been previously reported. Methods: The specimens were collected from the supragingival plaques of each dental caries area, pit and fissure caries, deep dentinal caries, smooth surface caries, and dental caries, and from healthy subjects in the control group. Bacteria were cultured from these specimens, DNA was extracted from the isolated bacteria, and the 16S rRNA gene sequences were analyzed and identified. Results: Based on the results of the 16S rRNA gene sequence analysis for the 90 strains of dominant bacteria from the 45 specimens, 5, 7, 8, 7, and 13 species were identified from the supragingival plaques from healthy teeth, pit and fissure caries, deep dentinal caries, smooth surface caries, and dental caries, respectively. In healthy teeth, Actinomyces naeslundii dominated. Corynebacterium durum, Ralstonia pickettii, and Streptococcus intermedius showed equal distribution. The dominant bacterial species in dental caries, S. sanguinis, showed the greatest difference in prevalence in pit and fissure caries. In deep dentinal caries, S. mutans and Lactobacillus rhamnosus were dominant; in smooth surface caries, S. mutans and S. sanguinis were dominant; and in the supragingival plaques of dental caries, S. sanguinis and S. mutans were dominant. Conclusions: The bacterial species isolated from dental caries encompassed four phyla, eight genera, and 22 species. In addition, the SS1-2 strain, belonging to the genus Neisseria, was identified as a new species from among the isolated strains.

• Journal of Microbiology and Biotechnology
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• 제32권10호
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• pp.1292-1298
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• 2022

Soil autotrophic bacterial communities play a significant role in the soil carbon (C) cycle in paddy fields, but little is known about how rhizosphere soil microorganisms respond to different long-term (35 years) fertilization practices under double rice cropping ecosystems in southern China. Here, we investigated the variation characteristics of rhizosphere soil RubisCO gene cbbL in the double rice ecosystems of in southern China where such fertilization practices are used. For this experiment we set up the following fertilizer regime: without any fertilizer input as a control (CK), inorganic fertilizer (MF), straw returning (RF), and organic and inorganic fertilizer (OM). We found that abundances of cbbL, 16S rRNA genes and RubisCO activity in rhizosphere soil with OM, RF and MF treatments were significantly higher than that of CK treatment. The abundances of cbbL and 16S rRNA genes in rhizosphere soil with OM treatment were 5.46 and 3.64 times higher than that of CK treatment, respectively. Rhizosphere soil RubisCO activity with OM and RF treatments increased by 50.56 and 45.22%, compared to CK treatment. Shannon and Chao1 indices for rhizosphere soil cbbL libraries with RF and OM treatments increased by 44.28, 28.56, 29.60, and 23.13% compared to CK treatment. Rhizosphere soil cbbL sequences with MF, RF and OM treatments mainly belonged to Variovorax paradoxus, uncultured proteobacterium, Ralstonia pickettii, Thermononospora curvata, and Azoarcus sp.KH33C. Meanwhile, cbbL-carrying bacterial composition was obviously influenced by soil bulk density, rhizosphere soil dissolved organic C, soil organic C, and microbial biomass C contents. Fertilizer practices were the principal factor influencing rhizosphere soil cbbL-carrying bacterial communities. These results showed that rhizosphere soil autotrophic bacterial communities were significantly changed under conditions of different long-term fertilization practices Therefore, increasing rhizosphere soil autotrophic bacteria community with crop residue and organic manure practices was found to be beneficial for management of double rice ecosystems in southern China.