A Rhizoctonia solani strain, RI-64, carrying DNA plasmids grew slowly, was weakly pathogenic, produced oxalic acid and was unable to form sclerotia on agar media. But 5 of 205 isolates regenerated from protoplasts of RI-64 grew rapidly and formed sclerotia, yet they carried plasmids and produced a small amount of oxalic acid. Sclerotia were formed in media containing pyruvate or glycerol, but were repressed in media containing large amounts of glucose. Growth and sclerotium formation were repressed in media adjusted to low pH and in media containing oxalic acid. These results suggest that slow growth and inability to form sclerotia in strain RI-64 result from low pH in the media around mycelia, caused by the production of oxalic acid.
A description and illustrations are provided of a new species, Rhodosporidium kratochvilovae, to accommodate two self-sporulating strains with the Q-10 ubiquinone system formerly identified as Rhodosporidium toruloides. This proposal is principally based on the life cycle, electrophoretic comparison of enzymes, cellular carbohydrate composition, ubiquinone system, DNA base composition, and DNA-DNA homology. Some chemotaxonomic data also endorse the inclusion of two strains of Rhodotorula glutinis in the new teleomorph-species.
Bacterial flora of rhizosphere of the rice plant was examined to determine the relationship of nitrogen-fixing bacteria to rice plants. Of 7, 344 bacterial strains from the rhizosphere, 1, 005 strains (13.7%) reduced acetylene. Representative 74 strains with acetylene reduction activity were selected for identification. All of these strains were gram negative, aerobic or facultatively anaerobic, and most had ubiquinone (Q-10) and cellular fatty acid composition, mainly with straight-chain fatty acids. Twenty-two strains were assigned to the following known species: Azospirillum brasilense Tarrand, Krieg and Döbereiner (1 strain), Azospirillum lipoferum Tarrand, Krieg and Döbereiner (1 strain), Enterobacter cloacae (Jordon) Hormaeche and Edwards (4 strains), Erwinia herbicola (Löhnis) Dye (2 strains), Klebsiella oxytoca (Flugge) Lautrop (6 strains), and Xanthobacterautotrophicus (Baumgarten, Reh and Schlegel) Wiegel, Wilke, Baumgarten, Opitz and Schlegel (8 strains). Fifty-two strains could not be assigned to any known species.
The presence of pyrophosphatidic acid (pyro-PA) was investigated in the lipid extracts of yeasts (241 strains belonging to 167 species of 43 genera). Pyro-PA can be clearly separated from other polar lipids by two-dimensional thin layer chromatography, and it can be distinguished from other phospholipids by its specific staining (purple blue) with Dittmer reagent. Pyro-PA was found exclusively in basidiomycetous species (127 strains belonging to 78 species of 14 genera). In contrast, no detectable amount of pyro-PA was found in the cellular lipids of ascomycetous species (114 strains belonging to 89 species of 31 genera). These results demonstrate that the determination of the presence of pyro-PA in the cellular lipids is useful in distinguishing ascomycetous from basidiomycetous yeasts.
Some properties of the LIV-III transport system, a common factor in the entry of branched-chain amino acids in Salmonella typhimurium, have been studied using a double mutant, KA266 (livA brnQ), which is defective in transport via either the LIV-I or LIV-II system. The LIV-III system operates with a low affinity (Km: >15μM) for L-isoleucine, L-leucine, and L-valine. Isoleucine transport via the LIV-III system is inhibited competitively by leucine or valine, but non-competitively by L-cysteine. Uptake of branched-chain amino acids into cells is partially repressed when the bacteria are grown in the presence of 2mM glycyl-L-leucine or more. In the wild type, transport activity of the LIV-III system for isoleucine and leucine is not detected. The LIV-II system appears to show a low affinity for valine similar to the LIV-III system, hence the combined activity of these systems is expressed as the activity of the LIV-III system. The defect in transport via the LIV-II system leads to a great reduction in the transport of valine in the LIV-III system.
Rapid and simple dot hybridization was designed and developed for the identification of Legionella species. DNAs from 18 type strains of Legionella species were quantitatively spotted on nitrocellulose filters and kept in a desiccation chamber. When an organism was suspected of belonging to the Genus Legionella, the DNA of the isolate was quickly extracted from a single colony, or 1ml of the bacterial suspension that matched the turbidity of the No. 2 McFarland standard. The DNA was labeled with photobiotin within 15min and a dot hybridization experiment was carried out between the labeled DNA of the unknown organism and the reference DNAs of 18 type strains of Legionella species. Hybridization was stopped within 4hr. Hybridized spots were visualized with alkaline-phosphatase color detection method. The reaction for the color detection was stopped within 30min and the color intensity of the hybridized spots was measured with a color graphic analyzer to determine the strongest spot. Among about 500 environmental strains identified as legionellae at the genus level, 20 strains were serologically unidentified. They were hippurate-positive legionellae but did not react to any antisera of hippurate-positive Legionella species. These strains were finally identified as L. pneumophila by our simplified colorimetric dot-hybridization method.
A taxonomic study below the generic or at the specific level was made of electrophoretic patterns of seven enzymes in 23 strains of Mrakia, Cystofilobasidium, Leucosporidium, and Rhodosporidium species. The seven enzymes were glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, isocitrate dehydrogenase, malate dehydrogenase, hexokinase, phosphoglucomutase, and fumarase. Seven species, M. frigida, M. gelida, C. bisporidii, C. capitatum, L. antarcticum, L. scottii, and R. infirmominiatum, constituted clusters separate from one another: their similarity values were all 0 or 14%. The three strains of L. antarcticum had quite different enzyme patterns (s=0%). The two Q9-equipped strains of L. scottii were linked to each other with a similarity value of 57%. The Q10-equipped strain of L. scottii showed dissimilar enzyme patterns to the two Q9-equipped strains mentioned above (s=14%). The calculated similarity value was 71% between the two strains of C. bisporidii. Among the three strains of R. infirmominiatum examined, the type strain was linked to the remaining two strains (s=43%). The similarity value was 86% between the two strains of R. infirmominiatum. All of the strains of M. frigida and M. nivalis examined had similarity values of 71% or more. The same similarity values were obtained among the examined strains of M. gelida and M. stokesii (s=71% or more). These results are discussed from the taxonomic point of view.