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Verrucomicrobium spinosum gen. nov., sp. nov.: a Fimbriated Prosthecate Bacterium
System. Appl. Microbiol. 10,54-56 (1987)
Verrucomicrobium spinosum gen. nov., sp. nov.: a Fimbriated Prosthecate Bacterium HEINZ SCHLESNER Institut rur Allgemeine Mikrobiologie, 2300 Kiel, Federal Republic of Germany Received February 26, 1987
Summary Six new isolates of prosthecate bacteria which morphologically resemble Prosthecomicrobium spp. are described as Verrucomicrobium spinosum. Their most striking morphological characteristic is the possession of bundles of fimbriae which originate from the tips of the prosthecae. Fimbriated strains of prosthecomicrobia or ancalomicrobia have not yet been reported. These heterotrophic Verrucomicrobium strains utilise only a limited spectrum of carbon sources, i. e. mainly hexoses and their derivatives. The G+C content of their DNA is 57.9 - 59.3 mol% and thus more than 5 mol% lower than the range defined for the genus Prosthecomicrobium.
Key words: Verrucomicrobium spinosum - Verrucomicrobium - Prosthecate bacteria - Prosthecomicrobium - Ancalomicrobium - Phylogeny of prosthecate bacteria
Introduction Heterotrophic bacteria with multiple appendages (prosthecobacteria) have been grouped with the genera Prosthecomicrobium, Ancalomicrobium and Stella. The genera are mainly defined by morphological criteria such as shape, number, length, and location of prosthecae. The members of the genus Prosthecomicrobium exhibit 10 to 30 prosthecae per cell, which extend in all directions from the cell surface. They are typically shorter than 2 [lm and conical in shape (Staley, 1984). Ancalomicrobium adetum, the only species of its genus, has normally less than eight prosthecae which are tube-like and about 3 [lm long (Staley, 1968). Cells of Stella are flat, six-pronged stars with prosthecae less than 0.5 [lm long (Vasilyeva, 1985). This morphology is typical for oligotrophic growth conditions, while higher nutrient concentrations result in nearly spherical cells. No differentiation of the tips of the prosthecae has been observed. Six strains of new prosthecate bacteria from Lake Vollstedter See (Holstein, Germany) were found to be unusually fimbriated. The tips of their prosthecae carry bundles of filaments that originate from a small area there. The characteristics of these new isolates are described in this paper.
Materials and Methods Media and most of the test procedures have been described elsewhere (Schlesner, 1986). Enrichment procedure. Samples of surface water (surface to ca. 5 cm depth) from Lake Vollstedter See (Holstein, Germany) were taken aseptically. After two weeks of storage in the laboratory at room temperature (20-23 QC), Erlenmeyer flasks were inoculated with one ml sample. The flasks contained 50 ml of enrichment medium and a sediment of CaC0 3 • The enrichment medium contained (per liter); N-acetylglucosamin, 1.0 g; Hutner's basal salts (Cohen-Bazire et aI., 1957),20 ml; vitamin solution (Staley, 1968),10 ml. The pH was adjusted to 9.7. After autoclaving and cooling, a solution of NaH2 P0 4 X H 2 0 was added aseptically to give a concentration of 0.65 mmolJl. The enrichment cultures were incubated at room temperature (20-23 QC). Subsequent microscopic checks indicated an increase in prosthecate bacteria. After three weeks, streakS were made on agar solidified medium M 13 (Schlesner, 1986), and the colonies were examined microscopically. The production of phosphatase was tested according to Holding and Coliee, 1971. m-Diaminopimelic acid was identified using the method of Rhuland et aI., 1955.
Verrucomicrobium spinosum gen. nov ., sp. nov .
Results and Discussion In September 1982, samples were taken from the surface of Lake Vollstedter See, a small eutrophic lake in Holstein, Germany. As the pH of the lake water was 9.5, the enrichment medium was adjusted to a pH-value of 9.7. Six strains of prosthecate bacteria could be isolated from these enrichment cultures. They were very similar in most reactions tested, but they differed significantly from other described prosthecobacteria, in morphological and physiological characteristics as well as on the molecular level. The Gram-negative cells measured 0.8-1.0 X 1.0-3.8 [.tm and had numerous prosthecae, which resembled warts, with a conical shape and up to 0.5 [.tm long (Fig. 1a). Occasionally, longer tube-like prosthecae (2 [.tm or more) were observed (Fig. 1b). Fimbriae, varying in number and length, originated from the tips of these prosthecae. Morphologically similar bacteria have been observed in enrichment cultures with surface water of Lake Plugsee (Holstein, Germany) to which a vitamin solution (Staley, 1968) was added (P. Hirsch, Kiel, pets. com.), but pure cultures of prosthecobacteria with fimbriae have not yet been reported, and electronmicroscopic studies with over 30 strains of Prosthecomicrobium-like bacteria have never shown such fimbriae-bearing cells. Therefore, the possession of fimbriae appears to be of taxonomic significance.
a
55
The strains were mesophilic, eurytherm with a maximum growth temperature of 34°C. The strains were stenohaline; they grew in M 13 without artificial sea water (ASW, Lyman and Fleming, 1940) or without added NaCl, but also in M 13 prepared with 12.5%, 25% or 50% ASW. There was no growth with 75% ASW. 1% NaCI was tolerated, but 1.5% were lethal. Best growth was recorded in M 13 prepared with 25% ASW. Tests for carbon source utilization gave similar results for all strains. Only a limited number of substrates were used as sole carbon or energy sources. These substrates were mainly hexoses and their di- or trisaccharides, as well as derivatives of glucose. C1 - or C2-compounds were not utilized, neither were fatty acids or amino acids. A similar restricted carbon spectrum was found in the genus Stella (Schlesner, 1983; Vasilyeva, 1985). These bacteria utilize only very few organic acids and amino acids. In contrast, strains of Ancalomicrobium adetum or Prosthecomicrobium spp. have a much broader substrate spectrum; they grow with sugars, sugar alcohols, fatty acids, and amino acids (Staley, 1984). The DNA base composition does not allow a differentiation of Prosthecomicrobium (65 - 70 mol% G+C; Staley, 1984), from Ancalomicrobium (70.4 - 71.4 mol % G+C; Staley and Mandel, 1973), or Stella (69.3 - 73.5 mol % G+C; Vasilyeva, 1985). The G+C content of the
b 1pm
tp
~
Fig. la, b. Verrucomicrobium spinosum. Numerous fimbriae (fi) are excreted from the tips of wart-like prosthecae (wp ). Long, tubelike prosthecae (tp) are also fimbri ated. Negatively stained with phosphotungstic acid.
56
H. Schlesner
new isolates, however, is more than 5% below the ranges mentioned above and this difference could indicate a new genus (Owen and Pitcher, 1985). These arguments are supported by the determination of the phylogenetic position of one of the new isolates (strain IFAM 1439) and other prosthecobacteria by means of 16S rRNA oligonucleotide sequencing. Four strains of Stella spp. (including S. humosa; Fischer et aI., 1985), four strains of Prosthecomicrobium spp. (including P. pneumaticum and P. enhydrum; Fischer, 1986) and Ancalomicrobium adetum (E. Stackebrandt, Kiel, pers. com.) were identified as members of the alpha subdivision of photosynthetic bacteria and their non-phototrophic relatives. However, strain IFAM 1439 did not fit into any of the groups of the phylogenetic tree of eubacteria and thus takes an isolated position (Albrecht et al., 1987). The creation of a new genus is warrented to harbour the new isolates. Because of their wartlike protrusions with terminal, rigid fimbriae that give the organism a thorny appearance, the genus name Verrucomicrobium is proposed with V. spinosum as the type species. Description of Verrucomicrobium gen. nov. Ver.ru'.co.mi.cro'.bi.um L. fern. n. verruca - wart; Gr. adj. micros - small; Gr. n. bios -life; M. L. neutr. n. Verrucomicrobium - warty microbe. Unicellular, Gram-negative bacteria with numerous fimbriated prosthecae extending in all directions from the cell surface. Heterotrophic, aerobic, facultatively anaerobic. DNA base composition 57.9 - 59.3 mol% G+C (one species). Type species: Verrucomicrobium spinosum.
Description of Verrucomicrobium spinosum sp. nov. spi. no'.sum L. fem. n. spina - spine; M. L. adj. spinosum - spiny. Cells measure 0.8 - 1.0 x 1.0 - 3.8 [tm. They have numerous conical prosthecae of about 0.5 [tm in length, which give the cells a warty appearance. Fimbriae extrude from the tips of these prosthecae. The cells are nonmotile. Colonies are light yellow. Growth is optimal between 26 and 33°C,the maximum growth temperature is 34°C. Vitamins are not required. The organism is stenohaline; 50% artificial sea water or 1 % NaCI are tolerated. Sugars are fermented without gas formation. Nitrate is not reduced under anaerobic conditions. Carbon sources utilised are: maltose, mannose, melibiose, melizitose, rhamnose, raffinose, trehalose, cellobiose, fructose, galactose, glucose, lactose, xylose, saccharose, N-acetylglucosamine, glucuronate, amygdalin, salicin, esculin, and glycerol. Carbon sources not utilised are: D-arabinose, L-arabinose, sorbose, inulin, lyxose, fucose, ribose, methanol, ethanol, mannitol, sorbitol, inositol, acetate, adipate, butyrate, caproate, 2-oxoglutarate, pyruvate, succinate, valerate, formate, ~-hydroxybutyrate, lactate, malate, propionate, aspartate, aspartic acid, glutamine, glutamic acid, histidine, proline, serine, and threonine. The following carbohydrates (0.2%) could be utilised fermentatively (acid, but no gas formation): glucose, lactose, saccharose, mal-
tose, mannose, melibiose, rhamnose, trehalose, cellobiose, fructose, galactose, xylose, and N-acetylglucosamin. Ammonia, nitrate, urea, and N-acetylglucosamine are used as a nitrogen source. Gelatin and starch are hydrolized, casein and Tween-80 are not. Catalase, cytochromoxidase, phosphatase, and urease are produced, H 2S and NH3 are not produced. Cell wall contains m-diaminopimelic acid. DNA base composition: 58.6 ± 0.2 mol% G+C (Tm) for strains IFAM 1439T • Habitat: Surface water of an eutrophic lake (Vollstedter See, Holstein, Germany). Type strain: IFAM 1439 (= DSM 4136) Acknowledgements. The technical assistance of Helga Marxsen is gratefully acknowledged. This work was supported by a grant from the Deutsche Forschungsgemeinschaft.
References Albrecht, W., Fischer, A., Smida, J., Stackebrandt, E.: Verrucomicrobium spinosum, a eubacterium representing an ancient line of descent. System. App!. Microbio!. (in press) Cohen-Bazire, G., Sistrom, W. R., Stanier, R. Y.: Kinetic studies of pigment synthesis by non-sulphur purple bacteria. J. Cell. Compo Physio!. 49, 25-68 (1957) Fischer, A., Roggentin, T., Schlesner, H., Stackebrandt, E.: 16S ribosomal RNA oligonucleotide cataloguing and the phylogenetic position of Stella humosa. System. App!. Microbio!' 6, 43-47 (1985) Fischer, A.: Phylogenetische Untersuchungen an 24 Stammen knospender und prosthekater Bakterien. Ph.D. Thesis, Technische Universitat, Munchen/FRG (1986) Holding, A. J., Collee, J. G.: Routine biochemical tests. In: Norris, J. R., Ribbons, D. W. (eds.), Methods in Microbiology, vo!' 6A. London-New York, Academic Press 1971 Lyman, J., Fleming, R. H.: Composition of sea water.]. Marine Res. (Sears Found.) 3,134-146 (1940) Owen, R. J., Pitcher, D.: Current methods for estimating DNA base composition and levels of DNA-DNA hybridisation. In: Goodfellow, M., Minnikin, D. E. (eds.), Chemical methods in bacterial systematics. London-New York-San Francisco, Academic Press 1985 Rhuland, L. E., Work, E., Denman, R. F., Hoare, D. S.: The behaviour of the isomers of a, E-diaminopimelic acid on paper chromatograms. ]. Am. Chern. Soc. 77, 4844-4846 (1955) Schlesner, H.: Isolierung und Beschreibung knospender und prosthekater Bakterien aus der Kieler Forde. Ph.D. Thesis, Christian-Albrechts-Universitat, Kiel FRG (1983) Schlesner, H.: Pirella marina sp. nov., a budding, peptidoglycanless bacterium from brackish water. System. App!. Microbio!. 8, 177-180 (1986) Staley, J. T.: Prosthecomicrobium and Ancalomicrobium: new prosthecate freshwater bacteria. ]. Bact. 95, 1921-1942 (1968) Staley, J. T., Mandel, M.: Deoxyribonuleic acid base composition of Prosthecomicrobium and Ancalomicrobium strains. Int. J. System Bact. 23, 271-273 (1973) Staley, J. T.: Prosthecomicrobium hirschii, a new species in a redefined genus. Int. J. System. Bact. 34, 304-308 (1984) Vasilyeva, L. V.: Stella, a new genus of soil prosthecobacteria, with proposals for Stella humosa sp. nov. and Stella vacuo/ata sp. nov. Int. J. System Bact. 35, 518-521 (1985)
Dr. Heinz Schlesner, Institut fur Allgemeine Mikrobiologie, Olshausenstr. 40, D-2300 Kiel
Verrucomicrobium spinosum gen. nov., sp. nov.: a Fimbriated Prosthecate Bacterium HEINZ SCHLESNER Institut rur Allgemeine Mikrobiologie, 2300 Kiel, Federal Republic of Germany Received February 26, 1987
Summary Six new isolates of prosthecate bacteria which morphologically resemble Prosthecomicrobium spp. are described as Verrucomicrobium spinosum. Their most striking morphological characteristic is the possession of bundles of fimbriae which originate from the tips of the prosthecae. Fimbriated strains of prosthecomicrobia or ancalomicrobia have not yet been reported. These heterotrophic Verrucomicrobium strains utilise only a limited spectrum of carbon sources, i. e. mainly hexoses and their derivatives. The G+C content of their DNA is 57.9 - 59.3 mol% and thus more than 5 mol% lower than the range defined for the genus Prosthecomicrobium.
Key words: Verrucomicrobium spinosum - Verrucomicrobium - Prosthecate bacteria - Prosthecomicrobium - Ancalomicrobium - Phylogeny of prosthecate bacteria
Introduction Heterotrophic bacteria with multiple appendages (prosthecobacteria) have been grouped with the genera Prosthecomicrobium, Ancalomicrobium and Stella. The genera are mainly defined by morphological criteria such as shape, number, length, and location of prosthecae. The members of the genus Prosthecomicrobium exhibit 10 to 30 prosthecae per cell, which extend in all directions from the cell surface. They are typically shorter than 2 [lm and conical in shape (Staley, 1984). Ancalomicrobium adetum, the only species of its genus, has normally less than eight prosthecae which are tube-like and about 3 [lm long (Staley, 1968). Cells of Stella are flat, six-pronged stars with prosthecae less than 0.5 [lm long (Vasilyeva, 1985). This morphology is typical for oligotrophic growth conditions, while higher nutrient concentrations result in nearly spherical cells. No differentiation of the tips of the prosthecae has been observed. Six strains of new prosthecate bacteria from Lake Vollstedter See (Holstein, Germany) were found to be unusually fimbriated. The tips of their prosthecae carry bundles of filaments that originate from a small area there. The characteristics of these new isolates are described in this paper.
Materials and Methods Media and most of the test procedures have been described elsewhere (Schlesner, 1986). Enrichment procedure. Samples of surface water (surface to ca. 5 cm depth) from Lake Vollstedter See (Holstein, Germany) were taken aseptically. After two weeks of storage in the laboratory at room temperature (20-23 QC), Erlenmeyer flasks were inoculated with one ml sample. The flasks contained 50 ml of enrichment medium and a sediment of CaC0 3 • The enrichment medium contained (per liter); N-acetylglucosamin, 1.0 g; Hutner's basal salts (Cohen-Bazire et aI., 1957),20 ml; vitamin solution (Staley, 1968),10 ml. The pH was adjusted to 9.7. After autoclaving and cooling, a solution of NaH2 P0 4 X H 2 0 was added aseptically to give a concentration of 0.65 mmolJl. The enrichment cultures were incubated at room temperature (20-23 QC). Subsequent microscopic checks indicated an increase in prosthecate bacteria. After three weeks, streakS were made on agar solidified medium M 13 (Schlesner, 1986), and the colonies were examined microscopically. The production of phosphatase was tested according to Holding and Coliee, 1971. m-Diaminopimelic acid was identified using the method of Rhuland et aI., 1955.
Verrucomicrobium spinosum gen. nov ., sp. nov .
Results and Discussion In September 1982, samples were taken from the surface of Lake Vollstedter See, a small eutrophic lake in Holstein, Germany. As the pH of the lake water was 9.5, the enrichment medium was adjusted to a pH-value of 9.7. Six strains of prosthecate bacteria could be isolated from these enrichment cultures. They were very similar in most reactions tested, but they differed significantly from other described prosthecobacteria, in morphological and physiological characteristics as well as on the molecular level. The Gram-negative cells measured 0.8-1.0 X 1.0-3.8 [.tm and had numerous prosthecae, which resembled warts, with a conical shape and up to 0.5 [.tm long (Fig. 1a). Occasionally, longer tube-like prosthecae (2 [.tm or more) were observed (Fig. 1b). Fimbriae, varying in number and length, originated from the tips of these prosthecae. Morphologically similar bacteria have been observed in enrichment cultures with surface water of Lake Plugsee (Holstein, Germany) to which a vitamin solution (Staley, 1968) was added (P. Hirsch, Kiel, pets. com.), but pure cultures of prosthecobacteria with fimbriae have not yet been reported, and electronmicroscopic studies with over 30 strains of Prosthecomicrobium-like bacteria have never shown such fimbriae-bearing cells. Therefore, the possession of fimbriae appears to be of taxonomic significance.
a
55
The strains were mesophilic, eurytherm with a maximum growth temperature of 34°C. The strains were stenohaline; they grew in M 13 without artificial sea water (ASW, Lyman and Fleming, 1940) or without added NaCl, but also in M 13 prepared with 12.5%, 25% or 50% ASW. There was no growth with 75% ASW. 1% NaCI was tolerated, but 1.5% were lethal. Best growth was recorded in M 13 prepared with 25% ASW. Tests for carbon source utilization gave similar results for all strains. Only a limited number of substrates were used as sole carbon or energy sources. These substrates were mainly hexoses and their di- or trisaccharides, as well as derivatives of glucose. C1 - or C2-compounds were not utilized, neither were fatty acids or amino acids. A similar restricted carbon spectrum was found in the genus Stella (Schlesner, 1983; Vasilyeva, 1985). These bacteria utilize only very few organic acids and amino acids. In contrast, strains of Ancalomicrobium adetum or Prosthecomicrobium spp. have a much broader substrate spectrum; they grow with sugars, sugar alcohols, fatty acids, and amino acids (Staley, 1984). The DNA base composition does not allow a differentiation of Prosthecomicrobium (65 - 70 mol% G+C; Staley, 1984), from Ancalomicrobium (70.4 - 71.4 mol % G+C; Staley and Mandel, 1973), or Stella (69.3 - 73.5 mol % G+C; Vasilyeva, 1985). The G+C content of the
b 1pm
tp
~
Fig. la, b. Verrucomicrobium spinosum. Numerous fimbriae (fi) are excreted from the tips of wart-like prosthecae (wp ). Long, tubelike prosthecae (tp) are also fimbri ated. Negatively stained with phosphotungstic acid.
56
H. Schlesner
new isolates, however, is more than 5% below the ranges mentioned above and this difference could indicate a new genus (Owen and Pitcher, 1985). These arguments are supported by the determination of the phylogenetic position of one of the new isolates (strain IFAM 1439) and other prosthecobacteria by means of 16S rRNA oligonucleotide sequencing. Four strains of Stella spp. (including S. humosa; Fischer et aI., 1985), four strains of Prosthecomicrobium spp. (including P. pneumaticum and P. enhydrum; Fischer, 1986) and Ancalomicrobium adetum (E. Stackebrandt, Kiel, pers. com.) were identified as members of the alpha subdivision of photosynthetic bacteria and their non-phototrophic relatives. However, strain IFAM 1439 did not fit into any of the groups of the phylogenetic tree of eubacteria and thus takes an isolated position (Albrecht et al., 1987). The creation of a new genus is warrented to harbour the new isolates. Because of their wartlike protrusions with terminal, rigid fimbriae that give the organism a thorny appearance, the genus name Verrucomicrobium is proposed with V. spinosum as the type species. Description of Verrucomicrobium gen. nov. Ver.ru'.co.mi.cro'.bi.um L. fern. n. verruca - wart; Gr. adj. micros - small; Gr. n. bios -life; M. L. neutr. n. Verrucomicrobium - warty microbe. Unicellular, Gram-negative bacteria with numerous fimbriated prosthecae extending in all directions from the cell surface. Heterotrophic, aerobic, facultatively anaerobic. DNA base composition 57.9 - 59.3 mol% G+C (one species). Type species: Verrucomicrobium spinosum.
Description of Verrucomicrobium spinosum sp. nov. spi. no'.sum L. fem. n. spina - spine; M. L. adj. spinosum - spiny. Cells measure 0.8 - 1.0 x 1.0 - 3.8 [tm. They have numerous conical prosthecae of about 0.5 [tm in length, which give the cells a warty appearance. Fimbriae extrude from the tips of these prosthecae. The cells are nonmotile. Colonies are light yellow. Growth is optimal between 26 and 33°C,the maximum growth temperature is 34°C. Vitamins are not required. The organism is stenohaline; 50% artificial sea water or 1 % NaCI are tolerated. Sugars are fermented without gas formation. Nitrate is not reduced under anaerobic conditions. Carbon sources utilised are: maltose, mannose, melibiose, melizitose, rhamnose, raffinose, trehalose, cellobiose, fructose, galactose, glucose, lactose, xylose, saccharose, N-acetylglucosamine, glucuronate, amygdalin, salicin, esculin, and glycerol. Carbon sources not utilised are: D-arabinose, L-arabinose, sorbose, inulin, lyxose, fucose, ribose, methanol, ethanol, mannitol, sorbitol, inositol, acetate, adipate, butyrate, caproate, 2-oxoglutarate, pyruvate, succinate, valerate, formate, ~-hydroxybutyrate, lactate, malate, propionate, aspartate, aspartic acid, glutamine, glutamic acid, histidine, proline, serine, and threonine. The following carbohydrates (0.2%) could be utilised fermentatively (acid, but no gas formation): glucose, lactose, saccharose, mal-
tose, mannose, melibiose, rhamnose, trehalose, cellobiose, fructose, galactose, xylose, and N-acetylglucosamin. Ammonia, nitrate, urea, and N-acetylglucosamine are used as a nitrogen source. Gelatin and starch are hydrolized, casein and Tween-80 are not. Catalase, cytochromoxidase, phosphatase, and urease are produced, H 2S and NH3 are not produced. Cell wall contains m-diaminopimelic acid. DNA base composition: 58.6 ± 0.2 mol% G+C (Tm) for strains IFAM 1439T • Habitat: Surface water of an eutrophic lake (Vollstedter See, Holstein, Germany). Type strain: IFAM 1439 (= DSM 4136) Acknowledgements. The technical assistance of Helga Marxsen is gratefully acknowledged. This work was supported by a grant from the Deutsche Forschungsgemeinschaft.
References Albrecht, W., Fischer, A., Smida, J., Stackebrandt, E.: Verrucomicrobium spinosum, a eubacterium representing an ancient line of descent. System. App!. Microbio!. (in press) Cohen-Bazire, G., Sistrom, W. R., Stanier, R. Y.: Kinetic studies of pigment synthesis by non-sulphur purple bacteria. J. Cell. Compo Physio!. 49, 25-68 (1957) Fischer, A., Roggentin, T., Schlesner, H., Stackebrandt, E.: 16S ribosomal RNA oligonucleotide cataloguing and the phylogenetic position of Stella humosa. System. App!. Microbio!' 6, 43-47 (1985) Fischer, A.: Phylogenetische Untersuchungen an 24 Stammen knospender und prosthekater Bakterien. Ph.D. Thesis, Technische Universitat, Munchen/FRG (1986) Holding, A. J., Collee, J. G.: Routine biochemical tests. In: Norris, J. R., Ribbons, D. W. (eds.), Methods in Microbiology, vo!' 6A. London-New York, Academic Press 1971 Lyman, J., Fleming, R. H.: Composition of sea water.]. Marine Res. (Sears Found.) 3,134-146 (1940) Owen, R. J., Pitcher, D.: Current methods for estimating DNA base composition and levels of DNA-DNA hybridisation. In: Goodfellow, M., Minnikin, D. E. (eds.), Chemical methods in bacterial systematics. London-New York-San Francisco, Academic Press 1985 Rhuland, L. E., Work, E., Denman, R. F., Hoare, D. S.: The behaviour of the isomers of a, E-diaminopimelic acid on paper chromatograms. ]. Am. Chern. Soc. 77, 4844-4846 (1955) Schlesner, H.: Isolierung und Beschreibung knospender und prosthekater Bakterien aus der Kieler Forde. Ph.D. Thesis, Christian-Albrechts-Universitat, Kiel FRG (1983) Schlesner, H.: Pirella marina sp. nov., a budding, peptidoglycanless bacterium from brackish water. System. App!. Microbio!. 8, 177-180 (1986) Staley, J. T.: Prosthecomicrobium and Ancalomicrobium: new prosthecate freshwater bacteria. ]. Bact. 95, 1921-1942 (1968) Staley, J. T., Mandel, M.: Deoxyribonuleic acid base composition of Prosthecomicrobium and Ancalomicrobium strains. Int. J. System Bact. 23, 271-273 (1973) Staley, J. T.: Prosthecomicrobium hirschii, a new species in a redefined genus. Int. J. System. Bact. 34, 304-308 (1984) Vasilyeva, L. V.: Stella, a new genus of soil prosthecobacteria, with proposals for Stella humosa sp. nov. and Stella vacuo/ata sp. nov. Int. J. System Bact. 35, 518-521 (1985)
Dr. Heinz Schlesner, Institut fur Allgemeine Mikrobiologie, Olshausenstr. 40, D-2300 Kiel