The cell wall acyl type was determined for representative strains from major taxonomic clusters within the genera Streptomyces and Streptoverticillium. Streptomycete strains contained between 2.5 and 7.5nmol of glycolic acid/mg of cells, confirming previous reports of the presence of an acetyl muramic acid. Streptoverticillium strains contained between 5.0 and 8.0nmol glycolic acid/mg of cells, indicating that they also have an acetyl rather than glycolyl muramic acid. The findings are discussed in the context of differences in lysozyme sensitivity between members of the two genera and in connection with the mechanism of lysozyme resistance in Streptoverticillum.
The amino acid requirements of Spiroplasma citri, S. floricola, S. melliform, SR-3, brevi and S. apis were determined in a chemically defined medium. Deletion of individual amino acids from an otherwise complete growth medium indicated that of the 20 amino acids tested, 14 were essential for good growth in S. citri, 10 in S. floricola, 10 in S. melliform, 10 in brevi, 7 in S. apis and 14 in SR-3. Asparagine, glutamic acid, glycine, leucine, proline, threonine and valine were essential for good growth for all spiroplasmas tested, but deletion of cysteine and serine had marginal or no significant effect on their growth. Requirements for other amino acids varied from nonessential to essential for growth. The specific growth rate of spiroplasmas was affected by the amino acid composition of the growth medium. For example, the specific growth rate of S. floricola in a medium deficient in threonine was 0.06×10-2 hr-1, however, the specific growth rate in medium containing 4.8×10-2M amino acid was 4.2×10-2 hr-1.
Two strains of asporogenous yeasts isolated from moss collected in Japan were found to represent a new species of the genus Candida. This species resembled Candida musae and Candida haemulonii in taxonomic criteria commonly employed and several chemotaxonomic criteria. However, it could be clearly distinguished from these two species in DNA-DNA hybridization experiments. This yeast was named Candida tsuchiyae Nakase et Suzuki in honor of Prof. Tsuchiya who contributed much to the progress of the serological classification of yeasts. A description of this species is given. Strain JCM 1638 was designated as the type of this species.
The β-D-xylosidase gene (xynB) from Bacillus subtilis PAP115 was cloned via the pBR325 vector in Escherichia coli. The resulting hybrid plasmid, named pRH300, contained a 4.6kbp EcoRI-bordered insert. A subcloning procedure, using the pUC8 plasmid, allowed the determination of the location of the xynB gene on a 3.18kbp fragment which was cloned into the pRH271 plasmid (a pBR325 vector harboring the xylanase gene (xynA) from B. subtilis PAP1115). The new vector, named pRH100, enabled E. coli to produce an intracellular xylanase and a cell-bound xylosidase.
The cellular carbohydrate composition of the whole cell hydrolysates, the DNA base composition, the ubiquinone systems, and the Diazonium Blue B (DBB) color test were examined in 108 strains of 61 species assigned to the genera Rhodosporidium, Leucosporidium, Rhodotorula, and to other basidiomycetous and ascomycetous yeasts. Taxonomic evaluations of these yeasts were made based upon the data presented. The yeasts were divided into two major groups based upon the presence of xylose in the cells. They had ubiquinone systems, Q-8, Q-9, or Q-10. All basidiomycetous yeasts gave the positive color reaction with DBB except two strains of Rhodotorula glutinis, whereas the ascomycetous ones were all negative. A good correlation was found between the groupings based upon the presence of xylose in the cells, DNA base composition, ubiquinone systems, assimilation of inositol, formation of starch-like compounds, and basidial forms in the Rhodosporidium, Leucosporidium, Cystofilobasidium, Filobasidium, and Filobasidiella. Further, species of the genera Rhodosporidium and Leucosporidium, including their anamorphs Rhodotorula and Candida, should be revised taxonomically on the basis of chemotaxonomy. The presence of xylose in the cells, even in small amounts, is significant taxonomically. The ratio of mannose to glucose is also an indicative index in some strains.
This paper describes the minimum length of the sequence required for the potato spindle tuber viroid (PSTV) cDNA cloned in plasmid or phage DNA vectors to be infective. To examine the infectivity, we cloned the BamHI fragments containing the full length of PSTV cDNA into the BamHI sites of pUC plasmids or double-stranded forms of M13mp phage DNA. When the BamHI monomeric unit was inserted into pUC8 or M13mp8 in a particular orientation, the 14 base pair sequence (GGATCCCCGGGGAA) of PSTV cDNA was directly duplicated at both of the insertion junctions. These recombinant DNAs were infectious to tomato plants at the same level as the recombinant containing a tandem dimer of cDNA. Insertion of the BamHI monomer into pUC12 or M13mp10 created the direct repetition of the 11 base pair sequence (GGATCCCCGGG) at both of the insertion junctions. Infectivities of both the pUC12 and the M13mp10 recombinants were tenfold lower than those of the pUC8 and the M13mp8 recombinants. On the other hand, when the plasmids or the phage DNAs carried the BamHI monomer in the opposite orientation so as to create the terminal repetition of the 7 base pair sequence (GGGATCC), the infectivity was scarcely detected. We also constructed a recombinant DNA having the AluI monomeric unit in either orientation, in which no terminal repetition was generated. This recombinant DNA showed no detectable infectivity. These results indicate that the cloned BamHI monomer having the direct repetition of the 14 base pair sequence at both the termini is able to express fully the infectivity, whereas the monomer having the shorter stretch of repetition shows only limited infectivity. Neither the sequences of vectors used nor the orientations of the cDNA sequence are crucial for infection by cloned cDNAs. Since the 14 nucleotide sequence is found in the middle of the regions which are conserved in many viroid sequences, this sequence is thought to be an essential site for viroid replication, probably a processing site of the oligomeric forms of viroid RNA found in infected plants.