| 1. |
- Ast, Jennifer C, et al.
(författare)
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Phylogenetic analysis of the lux operon distinguishes two evolutionarily distinct clades of Photobacterium leiognathi.
- 2004
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Ingår i: Archives of Microbiology. - : Springer Science and Business Media LLC. - 0302-8933 .- 1432-072X. ; 181:5, s. 352-61
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Tidskriftsartikel (refereegranskat)abstract
- The luminous marine bacterium Photobacterium mandapamensis was synonymized several years ago with Photobacterium leiognathi based on a high degree of phenotypic and genetic similarity. To test the possibility that P. leiognathi as now formulated, however, actually contains two distinct bacterial groups reflecting the earlier identification of P. mandapamensis and P. leiognathi as separate species, we compared P. leiognathi strains isolated from light-organ symbiosis with leiognathid fishes (i.e., ATCC 25521(T), ATCC 25587, lequu.1.1 and lleuc.1.1) with strains from seawater originally described as P. mandapamensis and later synonymized as P. leiognathi (i.e., ATCC 27561(T) and ATCC 33981) and certain strains initially identified as P. leiognathi (i.e., PL-721, PL-741, 554). Analysis of the 16S rRNA and gyrB genes did not resolve distinct clades, affirming a close relationship among these strains. However, strains ATCC 27561(T), ATCC 33981, PL-721, PL-741 and 554 were found to bear a luxF gene in the lux operon ( luxABFE), whereas ATCC 25521(T), ATCC 25587, lequu.1.1 and lleuc.1.1 lack this gene ( luxABE). Phylogenetic analysis of the luxAB(F)E region confirmed this distinction. Furthermore, ATCC 27561(T), ATCC 33981, PL-721, PL-741 and 554 all produced a higher level of luminescence on high-salt medium, as previously described for PL-721, whereas ATCC 25521(T), ATCC 25587, lequu.1.1 and lleuc.1.1 all produced a higher level of luminescence on low-salt medium, a characteristic of P. leiognathi from leiognathid fish light organs. These results demonstrate that P. leiognathi contains two evolutionarily and phenotypically distinct clades, P. leiognathi subsp. leiognathi (strains ATCC 25521(T), ATCC 25587, lequu.1.1 and lleuc.1.1), and P. leiognathi subsp. mandapamensis (strains ATCC 27561(T), ATCC 33981, PL-721, PL-741 and 554).
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| 2. |
- Barker-Astrom, K., et al.
(författare)
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Chlorosis during nitrogen starvation is altered by carbon dioxide and temperature status and is mediated by the ClpP1 protease in Synechococcus elongatus
- 2005
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Ingår i: Archives of Microbiology. - : Springer Science and Business Media LLC. - 0302-8933 .- 1432-072X. ; 183:1, s. 66-69
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Tidskriftsartikel (refereegranskat)abstract
- The interactive effects of inorganic carbon status, temperature and light on chlorosis induced by nitrogen deficiency, and the roles of Clp proteases in this process were investigated. In wild-type cultures grown in high or ambient CO2, following transfer to media lacking combined nitrogen, phycocyanin per cell dropped primarily through dilution of the pigment through cell division, and also suffered variable degrees of net degradation. When grown at high CO2 (5%), chlorophyll (Chl) suffered net degradation to a greater extent than phycocyanin. In marked contrast, growth at ambient CO2 resulted in Chl per cell dropping through dilution. Conditions that drove net Chl degradation in the wild-type resulted in little or no net Chl degradation in a clpPI inactivation mutant, with Chl content dropping largely through growth dilution in the mutant. The chlorotic response of a clpPII inactivation strain was nearly the same as that of wild-type, although phycocyanin degradation may have been slightly accelerated in the former.
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| 3. |
- Braune, Wolfram, et al.
(författare)
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Phototactic responses in Haematococcus lacustris and its modification by light intensity and the carotenoid biosynthesis inhibitor Norflurazon
- 1990
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Ingår i: Archives of Microbiology. - 0302-8933 .- 1432-072X. ; 154, s. 448-452
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Tidskriftsartikel (refereegranskat)abstract
- At fluence rates below 45 W· m-2 cells of the flagellate stage of Haematococcus lacustris react only positively phototactically with a rather high degree of orientation (indicated by r values up to 0.66 with the Rayleigh test). The directedness of orientation decreases with decreasing irradiance. The degree of directedness of the phototactic response depends on the intensity of preirradiation: Low light intensity applied after strong light application results in a dark reaction (low r values), low light given after darkness stimulates a rather high degree of directedness of positive phototaxis. Weak blue light (=483 nm; 0.4 W · m-2) stimulates positive phototactic response, whereas comparable red light (=658 nm; 0.5 W · m-2) does not. Cells which were grown in a medium containing 10-4 M Norflurazon (effective in inhibition of carotenoid biosynthesis) although maintaining motility completely lose the ability to react positively phototactically. The possible role of carotenoids in the phototactic orientation is discussed.
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| 4. |
- Dubey, Mukesh, et al.
(författare)
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Investigating the compatibility of the biocontrol agent Clonostachys rosea IK726 with prodigiosin-producing Serratia rubidaea S55 and phenazine-producing Pseudomonas chlororaphis ToZa7
- 2016
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Ingår i: Archives of Microbiology. - : Springer Science and Business Media LLC. - 0302-8933 .- 1432-072X. ; 198, s. 369-377
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Tidskriftsartikel (refereegranskat)abstract
- This study was carried out to assess the compatibility of the biocontrol fungus Clonostachys rosea IK726 with the phenazine-producing Pseudomonas chlororaphis ToZa7 or with the prodigiosin-producing Serratia rubidaea S55 against Fusarium oxysporum f. sp. radicis-lycopersici. The pathogen was inhibited by both strains in vitro, whereas C. rosea displayed high tolerance to S. rubidaea but not to P. chlororaphis. We hypothesized that this could be attributed to the ATP-binding cassette (ABC) proteins. The results of the reverse transcription quantitative PCR showed an induction of seven genes (abcB1, abcB20, abcB26, abcC12, abcC12, abcG8 and abcG25) from subfamilies B, C and G. In planta experiments showed a significant reduction in foot and root rot on tomato plants inoculated with C. rosea and P. chlororaphis. This study demonstrates the potential for combining different biocontrol agents and suggests an involvement of ABC transporters in secondary metabolite tolerance in C. rosea.
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| 5. |
- Ekelund, Nils, 1956-
(författare)
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Effects of calcium channel blockers and DCMU on motility and the photophobic response of Gyrodinium dorsum
- 1989
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Ingår i: Archives of Microbiology. - 0302-8933 .- 1432-072X. ; 151, s. 187-190
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Tidskriftsartikel (refereegranskat)abstract
- The effects of the calcium channel blockers, verapamil, diltiazem and lanthanum ions and the Ca2+ dependency on motility as well as the photophobic response (stop-response) of Gyrodinium dorsum were studied. At Ca2+ concentrations below 10-3 M, motility was inhibited. La3+ inhibits the stop-response, in contrast to verapamil and diltiazem. The only calcium channel blocker that increased the amount of non-motile cells was verapamil. The results indicate that motility are Ca2+ dependent and that the stop-responses of G. dorsum could be affected by extracellular Ca2+. Effects of the photosythesis inhibitor (DCMU) on the stop-response was also determined. With background light of different wavelength (614, 658 and 686 nm) the stop-response increased. DCMU inhibited this effect of background light. Negative results with the monoclonal antibody Pea-25 directed to phytochrome and the results with DCMU, indicate that the stop-response of G. dorsum is coupled to photosynthesis rather than to a phytochrome-like pigment. Oxygen evolution, but not cell movement, was completely inhibited by 10-6 M DCMU.
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| 6. |
- Ferreira, Daniela, et al.
(författare)
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Transcription and regulation of the hydrogenase(s) accessory genes, hypFCDEAB, in the cyanobacterium Lyngbya majuscula CCAP 1446/4
- 2007
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Ingår i: Archives of Microbiology. - : Springer Science and Business Media LLC. - 0302-8933 .- 1432-072X. ; 188:6, s. 609-617
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Tidskriftsartikel (refereegranskat)abstract
- Lyngbya majuscula CCAP 1446/4 is a filamentous cyanobacterium possessing both an uptake and a bi-directional hydrogenase. The presence of a single copy of the hyp operon in the cyanobacterial genomes suggests that these accessory genes might be responsible for the maturation of both hydrogenases. We investigated the concomitant transcription of hypFCDEAB with the hydrogenases structural genes-hup and hox. RT-PCRs performed with L. majuscula cells grown under different physiological conditions showed a substantial decrease in the relative amount of hupL transcript under non-N-2-fixing conditions. In contrast, no significant differences were observed for the transcript levels of hypFCDEAB in all conditions tested, while minor fluctuations could be discerned for hoxH. Previously, it was demonstrated that the transcriptional regulators NtcA and LexA interact with the promoter regions of hup and hox, respectively, and that putative binding sites for both proteins are present in the hyp promoter of L. majuscula. Therefore, a putative involvement of NtcA and LexA in the regulation of the hyp transcription was investigated. Electrophoretic mobility shift assays resulted in NtcA or LexA-bound retarded fragments, suggesting the involvement of these proteins in the transcriptional regulation of hypFCDEAB.
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| 7. |
- Gustafsson, Mattias, et al.
(författare)
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Fatty-acid-displaced transcriptional repressor, a conserved regulator of cytochrome P450 102 transcription in Bacillus species
- 2001
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Ingår i: Archives of Microbiology. - : Springer Science and Business Media LLC. - 0302-8933 .- 1432-072X. ; 176:6, s. 459-464
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Tidskriftsartikel (refereegranskat)abstract
- Bacillus subtilis strain 168 encodes two flavocytochromes P450, Cyp102A2 and Cyp102A3. The cyp102A3 gene is preceded by, and organized in an operon with, a gene for a transcriptional regulator, encoded by fatR. The paralogous gene, cyp102A2, is most likely transcribed as a mono-cistronic message. We show that fatR encodes a protein that binds to an operator sequence that is present upstream of its own reading frame, thereby repressing the expression of the fatR-cyp102A3 operon. Unsaturated fatty acids and phytanic acid have the capacity to interact with FatR and to abrogate its binding to the operator sequence.
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| 8. |
- Hagemann, Martin, et al.
(författare)
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Detection of a phage genome carrying a zonula occludens like toxin gene (zot) in clinical isolates of Stenotrophomonas maltophilia.
- 2006
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Ingår i: Archives of Microbiology. - : Springer Science and Business Media LLC. - 0302-8933 .- 1432-072X. ; 185:6
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Tidskriftsartikel (refereegranskat)abstract
- During a study of the genetic diversity of Stenotrophomonas strains, we found an autonomous replicating DNA molecule in chromosomal DNA preparations of the clinical Stenotrophomonas maltophilia strain c5. The entire sequence of 6,907 bp of the isolated DNA molecule was determined, which was called phiSMA9. Seven ORFs, which code for proteins with considerable similarity to proteins in databases, were identified in the DNA sequence. The largest ORF shows high sequence similarities to the pI protein of the filamentous phage phiLf, which was later shown to be identical to toxin Zot of Vibrio cholerae. Beside the Zot-like protein, six other proteins with similarities to known phage proteins such as a phage replication protein RstA and phage absorption or coat protein are encoded on phiSMA9, which indicate that this circular DNA molecule represents the replicative form of a linear phage genome. A PCR-based screening showed that only five from the totally investigated 47 Stenotrophomonas strains of clinical and environmental origin harbor these genes. Altogether, we describe the first genome of a phage for the nosocomial pathogen Stenotrophomonas, which contains a Zot toxin like gene and might be regarded as the first Stenotrophomonas virulence factor.
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| 9. |
- Hambraeus, Gustav, et al.
(författare)
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Escherichia coli RNase E and RNase G cleave a Bacillus subtilis transcript at the same site in a structure-dependent manner
- 2004
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Ingår i: Archives of Microbiology. - : Springer Science and Business Media LLC. - 0302-8933 .- 1432-072X. ; 181:2, s. 137-143
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Tidskriftsartikel (refereegranskat)abstract
- The decay of Bacillus subtilis aprE leader-lacZ mRNA was examined in Escherichia coli wild-type and in mutants deficient in RNase E, RNase G, or both. Two versions of the mRNA were studied: the wild-type mRNA, which has a stem-loop at the 5' end, and a mutant mRNA, with a single-stranded 5' end. The half-life of both transcripts was determined by RNase E, the half-life of the mutant transcript being one-third of that of the wild-type transcript. RNase G cleaved both transcripts at a site within an AU-rich sequence in the stem-loop region, but cleavage was much more efficient when the stem-loop was destabilized. RNase E cleaved at the same site, but less efficiently and only in the mutant transcript.
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| 10. |
- Karlsson, Anna, 1969-, et al.
(författare)
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CO2-dependent fermentation of phenol to acetate, butyrate and benzoate by an anaerobic, pasteurised culture
- 2000
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Ingår i: Archives of Microbiology. - : Springer Science and Business Media LLC. - 0302-8933 .- 1432-072X. ; 173:5-6, s. 398-402
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Tidskriftsartikel (refereegranskat)abstract
- Fermentative degradation of phenol was studied using a non-methanogenic, pasteurised enrichment culture containing two morphologically different bacteria. Phenol was fermented to benzoate, acetate and butyrate and their relative occurrence depended on the concentration of hydrogen. Proportionately more benzoate was formed with high initial levels of H2. The influence of P(H2) on the fermentation pattern was studied both in dense cell suspensions and in growing cultures by addition of hydrogen. An increase in growth yield (OD578 was observed, compared to controls, as a consequence of phenol degradation, however, the increase was less in H2-amended treatments, in which most of the phenol ended up as benzoate. The degradation of phenol in the dense cell suspension experiments was dependent on CO2. Benzoate was not degraded when added as a substrate to the growing culture. This is, to our knowledge, the first report concerning the fermentative degradation of phenol to nonaromatic products.
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