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Godfried D. Vogels - One of the best experts on this subject based on the ideXlab platform.
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Bacteriolytic activities of the free-living soil amoebae,Acanthamoeba castellanii, Acanthamoeba polyphaga andHartmannella vermiformis
Antonie van Leeuwenhoek, 1995Co-Authors: Peter H.h. Weekers, Andreas M. W. Engelberts, Godfried D. VogelsAbstract:Bacteriolytic activities of axenically grown free-living soil amoebae Acanthamoeba castellanii, Acanthamoeba polyphaga and Hartmannella vermiformis towards various Gram-positive and Gram-negative bacteria were determined. A spectrophotometric assay revealed that the specific bacteriolytic activities of both Acanthamoeba species were higher as those of the three Hartmannella strains. Bacillus megaterium, Bacillus subtilis, Chromatium vinosum, Micrococcus luteus and Pseudomonas fluorescens were more easily lysed than the other bacteria tested. Agrobacterium tumefaciens, Klebsiella aerogenes and Serratia marcescens were hardly affected at all by the amoebal bacteriolytic activities. Among the Gram-negative bacteria we observed differences in lysis sensitivity while the Gram-positive bacteria tested were sensitive to lysis. Isoelectric focusing (IEF) gel-electrophoresis in the pH range 3–10 was performed to separate the bacteriolytic isoenzymes of amoebae. Bacteriolytic patterns were shown by using an activity assay in which lysis bands were formed in the agar/bacteria gel-overlay. The activity assay revealed remarkable differences in typical banding patterns for bacteriolytic activities among amoebae. Distinct differences between typical pI points of bacteriolytic activities in Acanthamoeba and Hartmannella were shown. Bacteriolytic activities of Hartmannella were more pronounced and observed in the isoelectric points (pI) range of 4.0–9.3 while for Acanthamoeba the range was pI 4.5–8.9.
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Bacteriolytic activities of the free-living soil amoebae, Acanthamoeba castellanii, Acanthamoeba polyphaga and Hartmannella vermiformis.
Antonie van Leeuwenhoek, 1995Co-Authors: Peter H.h. Weekers, Andreas M. W. Engelberts, Godfried D. VogelsAbstract:Bacteriolytic activities of axenically grown free-living soil amoebae Acanthamoeba castellanii, Acanthamoeba polyphaga and Hartmannella vermiformis towards various Gram-positive and Gram-negative bacteria were determined. A spectrophotometric assay revealed that the specific bacteriolytic activities of both Acanthamoeba species were higher as those of the three Hartmannella strains. Bacillus megaterium, Bacillus subtilis, Chromatium vinosum, Micrococcus luteus and Pseudomonas fluorescens were more easily lysed than the other bacteria tested. Agrobacterium tumefaciens, Klebsiella aerogenes and Serratia marcescens were hardly affected at all by the amoebal bacteriolytic activities. Among the Gram-negative bacteria we observed differences in lysis sensitivity while the Gram-positive bacteria tested were sensitive to lysis. Isoelectric focusing (IEF) gel-electrophoresis in the pH range 3-10 was performed to separate the bacteriolytic isoenzymes of amoebae. Bacteriolytic patterns were shown by using an activity assay in which lysis bands were formed in the agar/bacteria gel-overlay. The activity assay revealed remarkable differences in typical banding patterns for bacteriolytic activities among amoebae. Distinct differences between typical pI points of bacteriolytic activities in Acanthamoeba and Hartmannella were shown. Bacteriolytic activities of Hartmannella were more pronounced and observed in the isoelectric points (pI) range of 4.0-9.3 while for Acanthamoeba the range was pI 4.5-8.9.
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Axenic cultivation of the free-living amoebae, Acanthamoeba castellanii and Hartmannella vermiformis in a chemostat
Journal of Microbiological Methods, 1994Co-Authors: Peter H.h. Weekers, Godfried D. VogelsAbstract:Abstract A simple procedure for the axenic cultivation of the free-living soil amoebae Acanthamoeba castellanii and Hartmannella vermiformis in chemostats was developed. Amoebal cell numbers, optical density and protein concentrations were determined to quantitate amoebal cell growth, and respiration rates were determined to assure optimum growth conditions for the cultures. Dilution rates were gradually increased to obtain steady-state conditions with minimum generation times and maximum cell numbers of approximately 25 and 16 hours, and 2.5 and 3.2 × 10 6 cells per ml for A. castellanii and H. vermiformis , respectively.
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Effects of Grazing by the Free-Living Soil Amoebae Acanthamoeba castellanii, Acanthamoeba polyphaga, and Hartmannella vermiformis on Various Bacteria.
Applied and environmental microbiology, 1993Co-Authors: Peter H.h. Weekers, Paul L. E. Bodelier, John P. H. Wijen, Godfried D. VogelsAbstract:Cultures of 10 different bacteria were used to serve as food sources for axenically grown Acanthamoeba castellanii, Acanthamoeba polyphaga, and Hartmannella vermiformis. The nonpigmented enterobacteriaceae Escherichia coli K-12 and Klebsiella aerogenes appeared to be excellent feed to all three amoebae. Hardly any growth or ammonium production was observed in tests with Chromatium vinosum and Serratia marcescens, which share the presence of pigmented compounds. Distinct differences in net ammonium production were detected and were correlated to the amoebal growth yield. In general, growth of amoebae and ammonium production increased in the order A. polyphaga, A. castellanii, and H. vermiformis.
Rolf Michel - One of the best experts on this subject based on the ideXlab platform.
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discrepancy between morphological and molecular biological characters in a strain of Hartmannella vermiformis page 1967 lobosea gymnamoebia
Protistology, 2002Co-Authors: Julia Walochnik, Rolf Michel, Horst AspockAbstract:Summary Hartmannella strain C3/8, isolated from the sediments of a water reservoir in Germany,has been affiliated to H. vermiformis as all lightmicroscopical characters of thetrophozoites as well as their ultrastructure and locomotion behavior correspondcompletely to the original isolates of H. vermiformis . However, in contrast to the typestrain of this species, the cysts of the strain C3/8 exhibit a regular spatial separation ofthe cyst wall into the endocyst and a wavy ectocyst. As cyst structure is considered tobe a stable taxonomic character among Gymnamoebia, we sequenced the 18S rRNAgene of this particular Hartmannella strain and compared it to four strains of H.vermiformis . It was shown that the sequence dissimilarity of the Hartmannella strainC3/8 to several strains of H. vermiformis is smaller than the sequence dissimilaritiesbetween different strains of the species with identical cyst morphology. Moreover, itwas shown that in the genus Hartmannella there seems to be no correlation betweenthe geographical origin of the strains and their relatedness. Altogether the results ofour study suggest the existence of polymorphism within the species
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evidence for bacteriophages within gram negative cocci obligate endoparasitic bacteria of naegleria sp
Acta Protozoologica, 2001Co-Authors: Rolf Michel, Karl-dieter Müller, Ernst N Schmid, Gerhild Gmeiner, Barbel HauroderAbstract:Gram-negative cocci observed as endocytobionts within the cytoplasm of a Naegleria strain isolated from a garden pond harboured small hexagonal particles of about 70 nm identified as bacteriophages called ”Neo-Ph/2”. These phages resembled the recently described phages; strain ”Neo-Ph/1” observed for the first time within the Chlamydia-like endocytobiont Neochlamydia Hartmannellae (Parachlamydiaceae) multiplying within Hartmannella vermiformis (Schmid et al. 2001). The possible reasons for this obvious similarity are object for discussion in this article.
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Development of 18S rRNA-targeted Oligonucleotide Probes for Specific Detection of Hartmannella and Naegleria in Legionella – positive Environmental Samples
Systematic and applied microbiology, 2001Co-Authors: Dorothee Grimm, Karl-heinz Schleifer, Rolf Michel, Wolfgang Ludwig, Bettina C. Brandt, Jörg Hacker, Michael SteinertAbstract:Aquatic protozoa are natural hosts of the human pathogen Legionella pneumophila. The fluorescence labeled 16S rRNA-targeted oligonucleotide probe LEGPNE1 has recently been shown to specifically detect extracellular legionellae as well as intracellular legionellae parasitizing protozoa. In this study we designed oligonucleotide probes which are complementary to distinct regions of the 18S rRNA of the Legionella host organisms of the genera Hartmannella and Naegleria. The specificity of the probes, HART498 and NAEG1088, was tested by in situ hybridization of various laboratory reference strains. In order to evaluate the fluorescent probes for environmental studies three selected Legionella-positive cold water habitats were examined for the presence of these protozoa. Traditional culture methods followed by morphological identification revealed an almost consistent presence of Naegleria spp. in cold water habitats. Other protozoa species including Acanthamoeba spp., Echinamoeba spp., Hartmannella spp., Platyamoeba placida, Saccamoeba spp., Thecamoeba quadrilineata, and Vexillifera spp. were found sporadically. Concomitant analysis of the pH, conductivity and temperature of the water samples revealed no preference of Legionella or the respective protozoa for certain environmental conditions. The specificity of the newly designed 18S rRNA probes demonstrates that they are valuable and rapid tools for the identification of culturable environmental protozoa.
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development of 18s rrna targeted oligonucleotide probes for specific detection of Hartmannella and naegleria in legionella positive environmental samples
Systematic and Applied Microbiology, 2001Co-Authors: Dorothee Grimm, Karl-heinz Schleifer, Rolf Michel, Wolfgang Ludwig, Bettina C. Brandt, Jörg Hacker, Michael SteinertAbstract:Aquatic protozoa are natural hosts of the human pathogen Legionella pneumophila. The fluorescence labeled 16S rRNA-targeted oligonucleotide probe LEGPNE1 has recently been shown to specifically detect extracellular legionellae as well as intracellular legionellae parasitizing protozoa. In this study we designed oligonucleotide probes which are complementary to distinct regions of the 18S rRNA of the Legionella host organisms of the genera Hartmannella and Naegleria. The specificity of the probes, HART498 and NAEG1088, was tested by in situ hybridization of various laboratory reference strains. In order to evaluate the fluorescent probes for environmental studies three selected Legionella-positive cold water habitats were examined for the presence of these protozoa. Traditional culture methods followed by morphological identification revealed an almost consistent presence of Naegleria spp. in cold water habitats. Other protozoa species including Acanthamoeba spp., Echinamoeba spp., Hartmannella spp., Platyamoeba placida, Saccamoeba spp., Thecamoeba quadrilineata, and Vexillifera spp. were found sporadically. Concomitant analysis of the pH, conductivity and temperature of the water samples revealed no preference of Legionella or the respective protozoa for certain environmental conditions. The specificity of the newly designed 18S rRNA probes demonstrates that they are valuable and rapid tools for the identification of culturable environmental protozoa.
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Neochlamydia Hartmannellae gen. nov., sp. nov. (Parachlamydiaceae), an endoparasite of the amoeba Hartmannella vermiformis
Microbiology, 2000Co-Authors: Matthias Horn, Karl-dieter Müller, Thomas R. Fritsche, Karl-heinz Schleifer, Michael Wagner, Ernst N Schmid, Rolf MichelAbstract:Free-living amoebae are increasingly being recognized to serve as vehicles of dispersal for various bacterial human pathogens and as hosts for a variety of obligate bacterial endocytobionts. Several Chlamydia-like Acanthamoeba endocytobionts constituting the recently proposed family Parachlamydiaceae are of special interest as potential human pathogens. In this study coccoid bacterial endocytobionts of a Hartmannella vermiformis isolate were analysed. Infection of H. vermiformis with these bacteria resulted in prevention of cyst formation and subsequent host-cell lysis. Transfection experiments demonstrated that the parasites were not capable of propagating within other closely related free-living amoebae but were able to infect the distantly related species Dictyostelium discoideum. Electron microscopy of the parasites revealed typical morphological characteristics of the Chlamydiales, including the existence of a Chlamydia-like life-cycle, but indicated that these endocytobionts, in contrast to Chlamydia species, do not reside within a vacuole. Comparative 16S rRNA sequence analysis showed that the endocytobiont of H. vermiformis, classified as Neochlamydia Hartmannellae gen. nov., sp. nov., is affiliated to the family Parachlamydiaceae. Confocal laser scanning microscopy in combination with fluorescence in situ hybridization using rRNA-targeted oligonucleotide probes confirmed the intracellular localization of the parasites and demonstrated the absence of other bacterial species within the Hartmannella host. These findings extend our knowledge of the phylogenetic diversity of the Parachlamydiaceae and demonstrate for the first time that these endocytobionts can naturally develop within amoebae of the genus Hartmannella.
Peter H.h. Weekers - One of the best experts on this subject based on the ideXlab platform.
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Differences in isoenzyme patterns of axenically and monoxenically grown Acanthamoeba and Hartmannella
Antonie van Leeuwenhoek, 1997Co-Authors: Peter H.h. Weekers, Johan F. De JonckheereAbstract:Axenically and monoxenically grown Acanthamoeba castellanii, Acanthamoeba polyphaga and different isolates of Hartmannella vermiformis strains were examined by polyacrylamide isoelectric focusing in the pH range 3–10. Isoenzyme patterns of acid phosphatase (AP), propionyl esterase (PE), malate dehydrogenase (MDH), alcohol dehydrogenase (ADH), glucose phosphate isomerase (GPI) and phosphoglucomutase (PGM) were compared. Zymograms were used to reveal differences in typical isoenzyme patterns between axenically and monoxenically grown amoebae and to compare axenically grown A. castellanii, A. polyphaga and H. vermiformis. Comparison of zymograms for AP, PE and MDH between axenically grown Acanthamoeba and Hartmannella strains revealed different isoenzyme patterns. Acanthamoeba showed strong bands for ADH and extremely weak bands for GPI and PGM, while Hartmannella lacked ADH but possessed bands for GPI and PGM.\par Comparison of zymograms from axenically and monoxenically grown amoebae revealed a lower intensity and even lack of typical isoenzyme bands in lysates from monoxenic cultures. The observed changes in typical isoenzyme patterns induced by the bacterial substrate can influence the correct isoenzymatic typing of different strains in clinical and phylogenetic studies.
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Bacteriolytic activities of the free-living soil amoebae,Acanthamoeba castellanii, Acanthamoeba polyphaga andHartmannella vermiformis
Antonie van Leeuwenhoek, 1995Co-Authors: Peter H.h. Weekers, Andreas M. W. Engelberts, Godfried D. VogelsAbstract:Bacteriolytic activities of axenically grown free-living soil amoebae Acanthamoeba castellanii, Acanthamoeba polyphaga and Hartmannella vermiformis towards various Gram-positive and Gram-negative bacteria were determined. A spectrophotometric assay revealed that the specific bacteriolytic activities of both Acanthamoeba species were higher as those of the three Hartmannella strains. Bacillus megaterium, Bacillus subtilis, Chromatium vinosum, Micrococcus luteus and Pseudomonas fluorescens were more easily lysed than the other bacteria tested. Agrobacterium tumefaciens, Klebsiella aerogenes and Serratia marcescens were hardly affected at all by the amoebal bacteriolytic activities. Among the Gram-negative bacteria we observed differences in lysis sensitivity while the Gram-positive bacteria tested were sensitive to lysis. Isoelectric focusing (IEF) gel-electrophoresis in the pH range 3–10 was performed to separate the bacteriolytic isoenzymes of amoebae. Bacteriolytic patterns were shown by using an activity assay in which lysis bands were formed in the agar/bacteria gel-overlay. The activity assay revealed remarkable differences in typical banding patterns for bacteriolytic activities among amoebae. Distinct differences between typical pI points of bacteriolytic activities in Acanthamoeba and Hartmannella were shown. Bacteriolytic activities of Hartmannella were more pronounced and observed in the isoelectric points (pI) range of 4.0–9.3 while for Acanthamoeba the range was pI 4.5–8.9.
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Bacteriolytic activities of the free-living soil amoebae, Acanthamoeba castellanii, Acanthamoeba polyphaga and Hartmannella vermiformis.
Antonie van Leeuwenhoek, 1995Co-Authors: Peter H.h. Weekers, Andreas M. W. Engelberts, Godfried D. VogelsAbstract:Bacteriolytic activities of axenically grown free-living soil amoebae Acanthamoeba castellanii, Acanthamoeba polyphaga and Hartmannella vermiformis towards various Gram-positive and Gram-negative bacteria were determined. A spectrophotometric assay revealed that the specific bacteriolytic activities of both Acanthamoeba species were higher as those of the three Hartmannella strains. Bacillus megaterium, Bacillus subtilis, Chromatium vinosum, Micrococcus luteus and Pseudomonas fluorescens were more easily lysed than the other bacteria tested. Agrobacterium tumefaciens, Klebsiella aerogenes and Serratia marcescens were hardly affected at all by the amoebal bacteriolytic activities. Among the Gram-negative bacteria we observed differences in lysis sensitivity while the Gram-positive bacteria tested were sensitive to lysis. Isoelectric focusing (IEF) gel-electrophoresis in the pH range 3-10 was performed to separate the bacteriolytic isoenzymes of amoebae. Bacteriolytic patterns were shown by using an activity assay in which lysis bands were formed in the agar/bacteria gel-overlay. The activity assay revealed remarkable differences in typical banding patterns for bacteriolytic activities among amoebae. Distinct differences between typical pI points of bacteriolytic activities in Acanthamoeba and Hartmannella were shown. Bacteriolytic activities of Hartmannella were more pronounced and observed in the isoelectric points (pI) range of 4.0-9.3 while for Acanthamoeba the range was pI 4.5-8.9.
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Axenic cultivation of the free-living amoebae, Acanthamoeba castellanii and Hartmannella vermiformis in a chemostat
Journal of Microbiological Methods, 1994Co-Authors: Peter H.h. Weekers, Godfried D. VogelsAbstract:Abstract A simple procedure for the axenic cultivation of the free-living soil amoebae Acanthamoeba castellanii and Hartmannella vermiformis in chemostats was developed. Amoebal cell numbers, optical density and protein concentrations were determined to quantitate amoebal cell growth, and respiration rates were determined to assure optimum growth conditions for the cultures. Dilution rates were gradually increased to obtain steady-state conditions with minimum generation times and maximum cell numbers of approximately 25 and 16 hours, and 2.5 and 3.2 × 10 6 cells per ml for A. castellanii and H. vermiformis , respectively.
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Effects of Grazing by the Free-Living Soil Amoebae Acanthamoeba castellanii, Acanthamoeba polyphaga, and Hartmannella vermiformis on Various Bacteria.
Applied and environmental microbiology, 1993Co-Authors: Peter H.h. Weekers, Paul L. E. Bodelier, John P. H. Wijen, Godfried D. VogelsAbstract:Cultures of 10 different bacteria were used to serve as food sources for axenically grown Acanthamoeba castellanii, Acanthamoeba polyphaga, and Hartmannella vermiformis. The nonpigmented enterobacteriaceae Escherichia coli K-12 and Klebsiella aerogenes appeared to be excellent feed to all three amoebae. Hardly any growth or ammonium production was observed in tests with Chromatium vinosum and Serratia marcescens, which share the presence of pigmented compounds. Distinct differences in net ammonium production were detected and were correlated to the amoebal growth yield. In general, growth of amoebae and ammonium production increased in the order A. polyphaga, A. castellanii, and H. vermiformis.
Michael Steinert - One of the best experts on this subject based on the ideXlab platform.
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Development of 18S rRNA-targeted Oligonucleotide Probes for Specific Detection of Hartmannella and Naegleria in Legionella – positive Environmental Samples
Systematic and applied microbiology, 2001Co-Authors: Dorothee Grimm, Karl-heinz Schleifer, Rolf Michel, Wolfgang Ludwig, Bettina C. Brandt, Jörg Hacker, Michael SteinertAbstract:Aquatic protozoa are natural hosts of the human pathogen Legionella pneumophila. The fluorescence labeled 16S rRNA-targeted oligonucleotide probe LEGPNE1 has recently been shown to specifically detect extracellular legionellae as well as intracellular legionellae parasitizing protozoa. In this study we designed oligonucleotide probes which are complementary to distinct regions of the 18S rRNA of the Legionella host organisms of the genera Hartmannella and Naegleria. The specificity of the probes, HART498 and NAEG1088, was tested by in situ hybridization of various laboratory reference strains. In order to evaluate the fluorescent probes for environmental studies three selected Legionella-positive cold water habitats were examined for the presence of these protozoa. Traditional culture methods followed by morphological identification revealed an almost consistent presence of Naegleria spp. in cold water habitats. Other protozoa species including Acanthamoeba spp., Echinamoeba spp., Hartmannella spp., Platyamoeba placida, Saccamoeba spp., Thecamoeba quadrilineata, and Vexillifera spp. were found sporadically. Concomitant analysis of the pH, conductivity and temperature of the water samples revealed no preference of Legionella or the respective protozoa for certain environmental conditions. The specificity of the newly designed 18S rRNA probes demonstrates that they are valuable and rapid tools for the identification of culturable environmental protozoa.
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development of 18s rrna targeted oligonucleotide probes for specific detection of Hartmannella and naegleria in legionella positive environmental samples
Systematic and Applied Microbiology, 2001Co-Authors: Dorothee Grimm, Karl-heinz Schleifer, Rolf Michel, Wolfgang Ludwig, Bettina C. Brandt, Jörg Hacker, Michael SteinertAbstract:Aquatic protozoa are natural hosts of the human pathogen Legionella pneumophila. The fluorescence labeled 16S rRNA-targeted oligonucleotide probe LEGPNE1 has recently been shown to specifically detect extracellular legionellae as well as intracellular legionellae parasitizing protozoa. In this study we designed oligonucleotide probes which are complementary to distinct regions of the 18S rRNA of the Legionella host organisms of the genera Hartmannella and Naegleria. The specificity of the probes, HART498 and NAEG1088, was tested by in situ hybridization of various laboratory reference strains. In order to evaluate the fluorescent probes for environmental studies three selected Legionella-positive cold water habitats were examined for the presence of these protozoa. Traditional culture methods followed by morphological identification revealed an almost consistent presence of Naegleria spp. in cold water habitats. Other protozoa species including Acanthamoeba spp., Echinamoeba spp., Hartmannella spp., Platyamoeba placida, Saccamoeba spp., Thecamoeba quadrilineata, and Vexillifera spp. were found sporadically. Concomitant analysis of the pH, conductivity and temperature of the water samples revealed no preference of Legionella or the respective protozoa for certain environmental conditions. The specificity of the newly designed 18S rRNA probes demonstrates that they are valuable and rapid tools for the identification of culturable environmental protozoa.
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The Lly protein protects Legionella pneumophila from light but does not directly influence its intracellular survival in Hartmannella vermiformis.
Applied and environmental microbiology, 1995Co-Authors: Michael Steinert, H Engelhard, M Flügel, E Wintermeyer, Jörg HackerAbstract:The lly locus (legiolysin) mediates the browning of the culture medium of Legionella pneumophila in the late stationary growth phase, presumably as a result of synthesis of homogentisic acid. Mutagenesis of the lly gene of the L. pneumophila Philadelphia I derivative JR32 did not affect intracellular replication in the natural host Hartmannella vermiformis. The Lly-negative mutant, however, showed a markedly decreased resistance to ordinary light. The cloned lly gene conferred an increased resistance to light in recombinant L. pneumophila and Escherichia coli K-12, indicating a contribution of the Lly protein to ecological adaptation of Legionella species.
Jörg Hacker - One of the best experts on this subject based on the ideXlab platform.
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Development of 18S rRNA-targeted Oligonucleotide Probes for Specific Detection of Hartmannella and Naegleria in Legionella – positive Environmental Samples
Systematic and applied microbiology, 2001Co-Authors: Dorothee Grimm, Karl-heinz Schleifer, Rolf Michel, Wolfgang Ludwig, Bettina C. Brandt, Jörg Hacker, Michael SteinertAbstract:Aquatic protozoa are natural hosts of the human pathogen Legionella pneumophila. The fluorescence labeled 16S rRNA-targeted oligonucleotide probe LEGPNE1 has recently been shown to specifically detect extracellular legionellae as well as intracellular legionellae parasitizing protozoa. In this study we designed oligonucleotide probes which are complementary to distinct regions of the 18S rRNA of the Legionella host organisms of the genera Hartmannella and Naegleria. The specificity of the probes, HART498 and NAEG1088, was tested by in situ hybridization of various laboratory reference strains. In order to evaluate the fluorescent probes for environmental studies three selected Legionella-positive cold water habitats were examined for the presence of these protozoa. Traditional culture methods followed by morphological identification revealed an almost consistent presence of Naegleria spp. in cold water habitats. Other protozoa species including Acanthamoeba spp., Echinamoeba spp., Hartmannella spp., Platyamoeba placida, Saccamoeba spp., Thecamoeba quadrilineata, and Vexillifera spp. were found sporadically. Concomitant analysis of the pH, conductivity and temperature of the water samples revealed no preference of Legionella or the respective protozoa for certain environmental conditions. The specificity of the newly designed 18S rRNA probes demonstrates that they are valuable and rapid tools for the identification of culturable environmental protozoa.
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development of 18s rrna targeted oligonucleotide probes for specific detection of Hartmannella and naegleria in legionella positive environmental samples
Systematic and Applied Microbiology, 2001Co-Authors: Dorothee Grimm, Karl-heinz Schleifer, Rolf Michel, Wolfgang Ludwig, Bettina C. Brandt, Jörg Hacker, Michael SteinertAbstract:Aquatic protozoa are natural hosts of the human pathogen Legionella pneumophila. The fluorescence labeled 16S rRNA-targeted oligonucleotide probe LEGPNE1 has recently been shown to specifically detect extracellular legionellae as well as intracellular legionellae parasitizing protozoa. In this study we designed oligonucleotide probes which are complementary to distinct regions of the 18S rRNA of the Legionella host organisms of the genera Hartmannella and Naegleria. The specificity of the probes, HART498 and NAEG1088, was tested by in situ hybridization of various laboratory reference strains. In order to evaluate the fluorescent probes for environmental studies three selected Legionella-positive cold water habitats were examined for the presence of these protozoa. Traditional culture methods followed by morphological identification revealed an almost consistent presence of Naegleria spp. in cold water habitats. Other protozoa species including Acanthamoeba spp., Echinamoeba spp., Hartmannella spp., Platyamoeba placida, Saccamoeba spp., Thecamoeba quadrilineata, and Vexillifera spp. were found sporadically. Concomitant analysis of the pH, conductivity and temperature of the water samples revealed no preference of Legionella or the respective protozoa for certain environmental conditions. The specificity of the newly designed 18S rRNA probes demonstrates that they are valuable and rapid tools for the identification of culturable environmental protozoa.
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The Lly protein protects Legionella pneumophila from light but does not directly influence its intracellular survival in Hartmannella vermiformis.
Applied and environmental microbiology, 1995Co-Authors: Michael Steinert, H Engelhard, M Flügel, E Wintermeyer, Jörg HackerAbstract:The lly locus (legiolysin) mediates the browning of the culture medium of Legionella pneumophila in the late stationary growth phase, presumably as a result of synthesis of homogentisic acid. Mutagenesis of the lly gene of the L. pneumophila Philadelphia I derivative JR32 did not affect intracellular replication in the natural host Hartmannella vermiformis. The Lly-negative mutant, however, showed a markedly decreased resistance to ordinary light. The cloned lly gene conferred an increased resistance to light in recombinant L. pneumophila and Escherichia coli K-12, indicating a contribution of the Lly protein to ecological adaptation of Legionella species.