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1.
Anne M. Berry Eric M. Glare David Hansman James C. Paton 《FEMS microbiology letters》1989,65(3):275-278
Twenty-four of 63 enteric Gram-negative organisms (38.1%) which were isolated from 35 apparently healthy Nigerian students were found to have low trimethoprim resistance (MIC less than 1000 mg/l). These isolates were also found to be resistant to several other antibiotics and trimethoprim resistance was found to be transferable from 15 (62.5%) of the trimethoprim resistant organisms into E. coli EC 1005. It is likely that the high percentage of trimethoprim resistance encountered in this study is related to the high rate of resistance transfer which was observed. 相似文献
2.
Plasmid curing in bacteria 总被引:5,自引:0,他引:5
J.T. Trevors 《FEMS microbiology letters》1986,32(3-4):149-157
3.
José Cansado Elisa Longo Dolores Agrelo Tomás G. Villa 《FEMS microbiology letters》1989,65(1-2):233-237
Acridine orange, an intercalating dye usually employed in the curing of bacterial plasmids, was tested for its ability to cure K1 and K2 killer strains (laboratory and wine strains). The results showed a high curing percentage of the killer character. This was demonstrated by the loss of M1 or M2 dsRNAs (responsible for toxin production and resistance to it) and because the meiotic products exhibited non-Mendelian segregation. The curing percentages varied, depending on the strain but not on the killer type, and showed similar efficiency as compared with other known curing agents. 相似文献
4.
5.
Jamal S. M. Sabir Ebtesam El-Bestawy 《World journal of microbiology & biotechnology》2009,25(4):545-552
Fourteen randomly clover indigenous nodulated Rhizobium strains were isolated from different locations in Saudi Arabia. They were identified as different strains of the genus Rhizobium leguminosarum biovar trifolii and characterized for their intrinsic antibiotic resistance against a range of antibiotics, nodulation capability and plasmid
profiles. Results revealed the presence of high molecular weight plasmids (megaplasmids) in all the selected strains. Based
on the ability for nodulation production, two weak strains (RtI1 and RtI2) and one efficient strain (RtA1) were selected for protoplast fusion and the numbers of nodules produced by the intra-specific protoplast fusion strains
were investigated. Results clearly confirmed the effective role of the protoplast fusion in enhancing both nodulation production
capacity of Rhizobium species and their range of antibiotic resistance. Protoplast fusion of the local Rhizobium species resulted in 1.93- to 5.67-fold increase in nodulation number compared to their parental strains, which was considered
an excellent result concerning agricultural practices, especially the formation of nitrogen-fixing root nodules on legume
crop plants. Protoplast fusion also produced fusants with a wide range of antibiotic resistance, another advantage added to
the new strains against environmental stresses. In conclusion, protoplast fusion proved its efficiency as a tool for constructing
a second generation of Rhizobia with much better characteristics for efficient applications in arid land. 相似文献
6.
Keyhani J Keyhani E Attar F Haddadi A 《Journal of industrial microbiology & biotechnology》2006,33(3):238-242
This research reports the sensitivity of a clinical isolate of Enterococcus faecalis to sodium N-lauroylsarcosinate (sarkosyl) and sodium dodecyl sulfate (SDS), as well as the efficiency of these detergents
in curing the strain. Compared to Escherichia coli, Enterococcus faecalis was very sensitive to both detergents, with minimum inhibitory concentrations (MIC) for the latter being 100 times lower
than for Escherichia coli. The clinical isolate of Enterococcus faecalis used in this study exhibited plasmid-borne resistance to kanamycin (MIC 2 mg/ml) and tetracycline (MIC 50 μg/ml); 3% curing
was observed after growth in the presence of sarkosyl but no curing was observed after growth in the presence of either SDS
or acridine orange. In contrast, 35% curing of plasmid-bearing Escherichia coli was observed after growth in the presence of either SDS or acridine orange, but none was observed after growth in the presence
of sarkosyl. 相似文献
7.
目的:比较纳米瓷充填材料和复合树脂充填乳牙V类洞边缘微渗漏的影响以及固化效率的差异。方法:第一部分为微渗漏实验,选取滞留拔除的上颌乳前牙20颗,唇侧制备V类洞,随机分为A、B两组,分别用Composan LCM和Filtek~(TM) Z350充填,亚甲基蓝染色处理,24 h后使用体式显微镜观察,测量染料渗入深度为微渗漏值,每组各选2个样本扫描电镜观察充填体与牙体组织间粘结情况。第二部分为显微硬度实验,分别用两种充填材料制作模块各9个,记为A、B两组,材料模块光固化24 h后使用显微硬度仪检测充填材料的固化效率。结果:Composan LCM组微渗漏值明显低于Filtek~(TM)Z350组(P0.05);扫描电镜下观察Filtek~(TM) Z350组充填材料与牙体组织间可见裂缝,界面参差不齐,有不连续的小断裂,Composan LCM组界面连续均匀,未见明显裂缝;两组充填材料的固化效率无显著差异(P0.05)。结论:纳米瓷充填材料和复合树脂均可用于乳牙龋洞充填,使用纳米瓷充填材料可减少微渗漏。 相似文献
8.
Shigella dysenteriae type 1, isolated locally, was found to contain six plasmids and these could be eliminated using SDS. A 70-kb plasmid was necessary to maintain the normal cell-wall morphology. Synthesis of nine major membrane proteins (90 to 40 kDa) was severely impaired in all-plasmid cured strains. Electron microscopy revealed a prominent separation between the outer and inner membranes of the cured strains, indicating that plasmid loss led to defects in the cell envelope. The growth rates of the strains having only the 70-kb plasmid and the plasmidless strain were 3- to 30-fold less than in the wild type strain.The authors are with the National Institute of Cholera and Enteric Diseases, P-33, C.I.T. Road, Scheme XM, Beliaghata, Calcutta-700 010, India 相似文献
9.
Microsporidia are a highly successful and ecologically diverse group of parasites, and thus represent interesting model systems for research on host-parasite interactions. However, such research often requires the ability to cure hosts of infections, a difficult task, given the short lifespan of most invertebrates and the efficient vertical transmission of some parasites. To our knowledge, few treatments are available to cure microsporidiosis in invertebrate hosts, and protocols have not yet been developed to inhibit vertical transmission and thereby cure host lines. We present a protocol for inhibiting vertical transmission of the microsporidian parasite Octosporea bayeri in the freshwater crustacean Daphnia magna. We used 100 mg/L Fumidil B dissolved in the culture medium of the host. This technique allowed Daphnia to survive and reproduce and inhibited vertical transmission of the parasite. The method presented here may be of general interest for other aquatic host-parasite systems involving microsporidia. 相似文献
10.
Jan Kostal Miloslav Suchanek Hana Klierova Katerina Demnerova Blanka Kralova Dani L. McBeth 《International biodeterioration & biodegradation》1998,42(4):4111
Pseudomonas C12B is able to degrade alkyl sulfates, alkylbenzene sulfonates, and linear alkanes and alkenes. Mitomycin C curing experiments and conjugation experiments demonstrated that the ability to utilize n-alkanes (C9–C12) and n-alkenes (C10 and C12) of medium chain length was plasmid-encoded. The plasmid was designated pDEC. Its size was estimated at several hundreds kb according to mobility in agarose gels. The plasmid did not confer resistance to the antibiotics tested. Analysis of alkylsulfatases P1 and P2 in original and cured strains confirmed that both enzymes are encoded by the chromosome. The ability of Pseudomonas C12B to utilize alkylbenzene sulfonates also appears to be encoded by the chromosome. pDEC could be transferred only to cured derivatives of Pseudomonas C12B, but not to strains of P. aeruginosa, P. putida, or Acinetobacter sp. Cured derivatives of Pseudomonas C12B could not serve as hosts for the broad host range plasmid CAM–OCT. The enzyme system encoded by the putative dec genes present on plasmid pDEC differs from the system coded by the alk genes of plasmid OCT in the size range of hydrocarbons preferentially used. 相似文献