Current Microbiology

Sekar, Vaithilingam

doi: 10.1007/BF01568694pmid: N/A

Mutants of two different isolates ofBacillus thuringiensis var.aizawai that are different from the parental strains in their plasmid profile were generated by plasmid curing experiments. Examination of these mutants by microscopy resulted in the identification of derivatives containing only the small crystal inclusions as well as those containing both the small and the large crystal inclusions. Acrystalliferous variants were also identified. Analysis of the plasmid profiles of these mutants along with the results from the bioassays seem to indicate that the spodopteran-active δ-endotoxin (i.e., small crystal inclusions) gene of theB. thuringiensis var.aizawai isolates used in this study is most likely located on the chromosome. The determinants of the large crystal inclusions (nontoxic toSpodopera exigua), however, appear to be located on either a plasmid (of 46 mega-Daltons in size) of one isolate or the chromosome of the other.

Dumora, Catherine; Lacoste, Anne-Marie; Cassaigne, André

doi: 10.1007/BF01568695pmid: N/A

Pseudomonas aeruginosa, grown in a medium containing O-phosphorylethanolamine as the sole source of phosphate and carbon, is able to take up this ester phosphate via two kinetically distinct systems with apparent Km values of 2.5 and 55 μM, respectively. An inducible O-phosphorylethanolamine-binding protein was purified to homogeneity from the shock fluid of the bacteria. It has an average molecular weight of 38 kda and an isoelectric point of 5.35. One mole of substrate was bound per mole of protein with a dissociation constant of 1.2 μM. This binding protein appears very specific since neither phosphate, phosphoserine, phosphocholine,sn-glycerol-3-phosphate, 2-aminoethylphosphonic acid, nor ethanolamine could inhibit the binding of O-phosphoryl-[2-14C]ethanolamine when measured by equilibrium dialysis.

Raschtchian, Ayoub; Abbott, Mark; Shaffer, Marilee

doi: 10.1007/BF01568696pmid: N/A

The DNA fragments coding for ribosomal RNA inCampylobacter jejuni have been cloned from a genomic library ofC. jejuni constructed inEscherichia coli. Clones carrying DNA Sequences for rRNA were identified by hybridization of 5′-end-labeled rRNA fromC. jejuni to colony blots of transformants from this gene library. Cloned DNA sequences homologous to each of 5S, 16S, and 23S rRNA were idenfified by hybridization of labeled plasmid DNA to Northern blots of rRNA. The gene coding for 23S rRNA was found to be located on a 5.5kb HindIII fragment, while the 5S and 16S rRNA genes were on HindIII fragments of 1.65 and 1.7 kb, respecitively. The DNA fragment containing the 16S rRNA gene was characterized by restriction endonuclease mapping, and the location of the 16S rRNA gene on this fragment was determined by hybridization of 5′-end-labeled rRNA to restriction fragments and also by DNA sequence determination. It appears that the major portion of the coding region for 16S rRNA is located on the 1.7-kb HindIII fragment, while a small portion is carried on an adjacent HindIII fragment of 7.5 kb. Cloned rRNA genes fromC. jejuni were used to study the organization of the rDNA inC. jejuni and other members of the genùsCampylobacter.

Wirsen, Carl; Jannasch, Holger; Wakeham, Stuart; Canuel, Elizabeth

doi: 10.1007/BF01568697pmid: N/A

In a psychrophilic and barophilic marine bacterial isolate of the genusAlteromonas, the ratio of total unsaturated versus saturated fatty acids in the membrane lipids increased when the organism was grown at increasing hydrostatic pressures and decreasing temperatures. This regulatory capacity, as well as the presence of relatively large amounts of 20:5 polyunsaturated fatty acid, appear to be functional in maintaining membrane fluidity within a range of pressures distinctly below and above the specific optimum and at typical deep sea temperatures.

McCowen, Sara; Sellers, Joseph; Phibbs, Paul

doi: 10.1007/BF01568698pmid: N/A

Glycerol kinase is induced in cells ofPseudomonas aeruginosa strain PAO when grown in the presence of glycerol or glycerol-3-phosphate. The enzyme was isolated from the soluble cytoplasmic fraction of cell extracts and purified 500-fold by ammonium sulfate precipitation and chromatography on columns of Sephadex G-25, DEAE-Sephadex, hydroxyapatite, and Sephadex G-200. A molecular weight of 120,000 was estimated by gel filtration of the catalytically active enzyme. In polyacrylamide gel electrophoresis the purified product contained one major band of Coomassie Blue staining material. The enzyme exhibited an apparent Km of 40 μM for glycerol and 23 μM for ATP. Of the nucleotide triphosphates tested, only ATP served as a phosphoryl group donor. Mg++ or Mn++ was required for activity, although a threefold greater concentration of Mn++ was required when Mn++ substituted for Mg++. In contrast to most other catabolic glycerol kinases in bacteria, the enzyme was not inhibited by fructose-1,6-diphosphate nor by other tested metabolites.

McCowen, Sara; MacArthur, Linda; Gates, James

doi: 10.1007/BF01568699pmid: N/A

Lectins were extracted from whole fern grindings ofAzolla pinnata (AP) andAzolla filiculoides (AF) by precipitation with ammonium sulfate to 20% of saturation. At high pH both lectins dissociate into inactive subunits (5000 mol wt) which reassociate into active aggregates (>500,000 mol wt) following concentration by ammonium sulfate precipitation or freezing and thawing. Although amino sugars inhibited hemagglutinating activity of both AP and AF lectins,d-fructose was inhibitory only to the AP lectin hemagglutinating activity, andd-galactose was slightly inhibitory to the AP lectin but not to the AF lectin. Both lectins exhibited specificity for freshly extracted cyanobionts from homologous fern species: AP lectin agglutinated cyanobiont filaments from AP, but not from AF; AF lectin agglutinated cyanobiont filaments from AF, but not AP. Neither lectin reacted with cultured cyanobionts from either fern species. Hemagglutinating titers were likewise reduced by adsorption of these lectins to homologous cyanobiont cells. This report provides strong suggestive evidence for specificity in this N-fixing symbiosis between aquatic fern and cyanobacterium.

Bauld, John; Favinger, Jeffrey; Madigan, Michael; Gest, Howard

doi: 10.1007/BF01568700pmid: N/A

A representative of the purple sulfur bacteria was isolated from organic-rich intertidal sediments of Hamelin Pool, Shark Bay, Australia. The isolate, strain HPC, is nutritionally versatile, being capable of photoheterotrophic growth in the absence of reduced sulfur sources and of dark microaerophilic growth, either heterotrophically or lithotrophically. Vitamins are not required. Nine organic carbon substrates, including the C2−C5 fatty acids, support photoheterotrophic growth. The isolate is an obligate halophile capable of growth over a wide salinity range (0.5%–8.5% NaCl). On the basis of its morphology, physiology, pigmentation, and DNA base ratio, strain HPC is considered to be an obligately halophilic representative ofChromatium vinosum.

Mäkinen, Kauko; Syed, Salam; Mäkinen, Pirkko-Liisa; Loesche, Walter

doi: 10.1007/BF01568701pmid: N/A

Treponema denticola ATCC 35405, a human oral spirochete associated with periodontal disease, was shown to contain three enzymes (I, II, and III) with proline iminopeptidase activity. II and III were considered to be true iminopeptidases, whereas enzyme I was found to be a benzoylarginine peptidase with iminopeptidase activity. Enzyme III, the dominant proline iminopeptidase ofT. denticola in terms of its activity towardN-l-prolyl-2-naphthylamine, was considered to be a sulfhydryl peptidase: 0.167 μM p-chloromercuribenzoic acid totally inactivated the enzyme, and 1.0 mM dithiothreitol restored 92% of activity. The activity of this enzyme was not affected by metal chelators. Chemical modification of enzyme III suggests that tyrosyl (or histidyl) and carboxyl groups may be necessary for its activity. The hydrolysis ofN-l-prolyl-2-naphthylamine was found to be very characteristic ofT. denticola ATCC 35405; out of 24 differentN-l-aminoacyl-2-naphthylamines tested, only the proline derivative was hydrolyzed at a high rate. The substrate specificity of the enzymes discovered indicates that they may be important for the nutrition ofT. denticola. The iminopeptidase activity may be related to the pathogenicity of this organism in periodontal disease.

Robertson, Eugene; Reeves, Henry

doi: 10.1007/BF01568702pmid: N/A

Isocitrate lyase has been purified to homogeneity, as determined by SDS-polyacrylamide gel electrophoresis and subsequent silver staining, fromEscherichia coli D5H3G7. The enzyme was found to have a subunit molecular weight of 48,000 and a native molecular weight of 188,000 as determined by gel filtration chromatography. Thus, the enzyme appears to have tetrameric structure. The isoelectric point was determined to be 4.6, and the enzyme displayed a pH optimum at 7.3. The Km of isocitrate lyase forthreo-Ds-isocitrate was determined to be 8 μM. The purification procedure is highly reproducible and results in a 39% net yield of purified protein.