A γ-polyglutamate (γ-PGA)-producing Bacillus strain was isolated from "kinema" in Nepal and found to harbor a plasmid species. The hybridized region on the kinema plasmid, pNKH, with the γ-PGA production- stimulating factor (PSF) gene (psf) on "natto" plasmid pUH1, which is responsible for γ-PGA production in Bacillus subtilis (natto), was identified, and the nucleotide sequence was determined. Only one possible open reading frame (ORF) was found which was 1, 281 bp in length. The ORF could potentially encode a polypeptide consisting of 427 amino acids with a molecular weight of 50, 251. The polypeptide was found to be 7 residues longer than that of pUH1 PSF. The percent match of the amino acid sequence between pNKH ORF and pUH1 PSF was 92%. These results suggest that the plasmid pNKH of kinema Bacillus might be responsible for γ-PGA production in kinema fermentation.
Plasmid pCINod1 carrying attP of a lysogenic rhizobiophage and the nod genes was constructed. Inoculation of a conjugation mixture of Escherichiacoli harbouring pCINod1 and a nodulation-defective Rhizobiumleguminosarum biovar trifolii strain resulted in formation of root nodules on white clover. Rhizobium transconjugant strain CNH1 isolated from these nodules had integrated pCINod1 into its chromosome. The light and electron microscopic observation of the nodulation process revealed that the nod genes on the chromosome of strain CNH1 were completely functional.
Fine structure of an oligotrophic bacterium, Agromonas oligotrophica, was studied by electron microscopic observation of thin-sectioned cells. Cells grown in 0.01% (w/v) each of peptone and meat extract (1/100PM) showed the following three remarkable features: (1) Cytoplasm is divided into several compartments which are surrounded by cytoplasmic membrane. (2) Several electron-dense cores are visible in each cell which are stained by DAPI (4, 6-diamidino-2-phenylindole). (3) The organism divides not by the usual septum formation but by irregular budding and/or elongation and pinching off. The process is independent of the cytoplasmic compartmentalization. Cells grown in 1/100PM supplemented with 0.4% (w/v) NaCl or those grown in medium including 0.1% (w/v) each of peptone and meat extract (1/10PM) are characterized by abnormal morphological features; deformed cell shape, incomplete development of cytoplasmic membrane, incomplete compartmentalization of cytoplasm and the hollow space between the outer layer and cytoplasmic membrane. The abnormal morphological appearance may relate to the halo and organo sensitivities of this organism.
Phylogenetic relationships between two species from the genera Saccharomyces (S. cerevisiae, S. kluyveri) and Kluyveromyces (K. aestuarii, K. marxianus), a plant parasitic dimorphic yeast (Nematospora coryli), and two phytopathogenic filamentous fungi (Ashbya gossypii, Eremotheciumashbyi) were investigated by comparing partial nucleotide sequences of ribosomal DNA (rDNA). The three types of sequenced regions evolve with different speed and allow the analysis at distinct taxonomic levels: conserved regions (18S rDNA, small ribosomal subunit), variable regions (25S rDNA, large ribosomal subunit), and highly variable regions ITS1 and ITS2 (internal transcribed spacers). Segments homologous to positions 619 to 1035 and 1205 to 1617 of the 18S rDNA and positions 470 to 890 and 1535 to 1984 of the 25S rDNA of S. cerevisiae were sequenced. The maximal resolving power of rDNA sequence analysis is provided by including the rapidly evolving ITS1 and ITS2 regions. In the phylogenetic sequence analysis of all regions by the genera Kluyveromyces and Saccharomyces cluster together with two filamentous pathogens on cotton, A. gossypii and E. ashby, as well as the plant pathogenic yeast N. coryli. The molecular evidence from ribosomal sequences suggests that morphology and ornamentation of ascospores, the persistence of ascus walls as well as mycelium formation should not be used as differentiating characters in yeast taxonomy, especially in family delimitation. Our sequence data support the inclusion of plant pathogenic, predominantly filamentous genera like Ashbya or Eremothecium or dimorphic genera like Nematospora with falcate ascospores within a new family of the Saccharomycetaceae. Similarly, the saprophytic genus Kluyveromyces with reniform ascospores and deliquescent ascus walls unequivocally belongs to the family of Saccharomycetaceae.
Three isolates of spherical thermoacidophilic archaebacteria (strains TA-1, TA-2 and N-8) were obtained from acidic hot springs at Hakone and Noboribetsu in Japan. We have studied the isolates using electron microscopy, Gram staining, sensitivity to lysozyme, growth conditions, lipid compositions, SDS-PAGE patterns of whole-cell proteins, DNA base composition and partial 16S rRNA sequences. These characteristics of the isolates were compared with those of the type strains, Sulfolobusacidocaldarius, Sulfolobus solfataricus, Acidianus brierleyi, Acidianus infernus, Metallosphaera sedula and Desulfurolobus ambivalens. Comparative studies indicated that the isolate TA-1 was novel species of either Sulfolobus or Acidianus, the isolate TA-2 belonged to the genus Metallosphaera, and the isolate N-8 belonged to the same species of S. acidocaldarius isolated from Yellowstone.
An open reading frame (ORF469) was found near the attP core site of the actinophage R4 which encoded a 469-amino acid polypeptide. A gene disruption experiment suggested that the ORF469 gene was essential for site-specific excision of the prophage R4 genome from its host chromosome. The predicted amino acid sequence of the protein showed a similarity to a resolvase of Tn2501 and SpoIVCA of Bacillus subtilis.
Assuming that cells grow exponentially in length, the cycle of cells in chemostat cultures was analyzed parametrically by the age-size method (James, T. W. et al., Exp. Cell Res., 94, 267-276, 1975), which fitted well to the raw data of the length distribution. For simulation, we used the cell length and coefficient of variation at division from empirical data. The cell length and coefficient of variation at birth, the specific growth rate in extension, and the proportion of growing cells were estimated for simulation. We found that the stop-grow point of a cycle depended on the culture conditions: cells grown at D=0.247h-1 in the chemostat culture had the stop-grow point at 0.72 of the cycle, similar to cells growing exponentially in the batch culture. Cells grown at D=0.126h-1 and D= 0.062h-1 in the chemostat cultures had the stop-grow points at 0.85 and 0.97 of the cycles, respectively. There was a sub-population of non- growing cells estimated.