The role of Thiobacillus thiooxidans was investigated in the enhancement of pyrite oxidation by the mixtures of Thiobacillus ferrooxidans and T. thiooxidans. The oxidation of pyrite by T. ferrooxidans was remarkably enhanced by the addition of dead cell suspensions and cell-free extracts of both chemolithotrophic thiobacilli and heterotrophic bacteria. The same promoting effect on the bacterial pyrite oxidation was recognized with various substances such as protein, nucleic acid, yeast extract, peptone, and also surface-active agent. These results indicate that the enhancement of bacterial pyrite oxidation by the intact cells of T. thiooxidans is attributed at least partly to the organic substances excreted from T. thiooxidans cells into the pyrite medium, and that cellular organic substances have a physico-chemical effect on a direct interaction between iron-oxidizing bacteria and solid particles.
Chlamydospore formation in hyphae of Fusarium oxysporum f. sp. raphani was studied as a function of time. Hyphal suspensions were aseptically incubated in a salt solution supplemented with 0.01% glucose at 26-28° and examined by light microscopy. We counted both typical chlamydospores and chlamydospore-like bodies (CL bodies) in hyphae across the 0.3mm diameter of a microscope field. When arranged in a frequency distribution, the experimental data suggest that typical chlamydospores and CL bodies were formed in hyphae by chance. The formation of both bodies was characterized as a first order reaction. The number of CL bodies exceeded those of typical chlamydospores in all experiments. The optimal pH for the formation of both bodies was between 6.5 and 7.0. Autolysis of hyphae was observed after 8 or 9 days incubation. Apparently CL bodies are not precursors of chlamydospores. We recognize three distinct stages in the behavior of hyphae in carbon deficient media: 1. Hyphae continue to grow and chlamydospores and CL bodies are not formed in the first 3 days of incubation. 2. Chlamydospores and CL bodies are formed at constant rates but hyphae do not grow appreciably. 3. Hyphae begin to autolyse and coincidently the formation of chlamydospores and CL bodies ceases. Chlamydospore formation is considered to occur in a limited period under starved condition.
It was studied whether and in what manner various solid-liquid interface affect the metabolic activities of Escherichia coli. Solid materials tested were 5 kinds of organic polymers, 4 kinds of clay minerals and 3 kinds of mineral oxides. Rates of glucose uptake and oxygen consumption by the organism were determined with and without addition of each material. Three of the materials, styrene-divinylbenzene copolymer (SDB), polytetrafluoroethylene (TFE) and pyrophyllite significantly increased the respiratory activity and simultaneously decreased the rate of glucose uptake. Other materials showed weak or no effects. When SDB and TFE were removed from the cell suspension, their effects on the respiration and glucose uptake disappeared immediately. Thus it was apparent that these effects were reversible. The ratio of glucose metabolized by respiration was inversely proportional to the rate of glucose uptake. This relation is discussed in connection with the interface effect on the organism as a living system.
Forty-five isolates of the shiitake mushroom, Lentinus edodes, were partitioned into 24 genotypic classes based on isozyme variability at 11 marker loci. A conservative calculation indicates that over 200, 000 genotypic classes of L. edodes could now be recognized and authenticated based on this genetic variability. Coefficients of genetic relatedness between genotypic classes were determined. Comparisons of relatedness included mean, highest, and lowest coefficients of genetic similarity. A dendrogram was constructed from similarity coefficients to provide further insights into the relationships of the shiitake lines examined in this study. Applications of this genetic information for commercial breeding of this fungus are discussed.
Single locus segregation was examined electrophoretically for six biochemical marker loci in single-spore-derived lines of Lentinus edodes. Only single banded electrophoretic patterns were observed, reflective of the hemizygous genetic constitution of these lines. Single locus segregation data for Aat-1 in one heterozygous line (131) was nonrandom by the chi-square test. Since only single spore recombinants for Aat-1 in this line were recovered and since another line (296) examined for Aat-1 segregated in Mendelian ratios, it is postulated that a locus carrying a lethal allele is tightly linked with Aat-1. One classical linkage was found (Gpi with Pgk, r=0.049) among 9 pairwise examinations for joint segregation.
The plasmid pSM1 carrying a single copy of IS1 has been shown to integrate into various sites on another plasmid pHS1, a temperature sensitive replication mutant of the tetracycline resistance plasmid pSC101. The resulting cointegrates (named pMZ plasmids) contain two IS1 sequences in a direct orientation, each at a junction of the integration. This paper describes a detailed analysis of such cointegrates and shows that the integration of pSM1 occurs frequently at a region of pHS1, resulting in inactivation of the pHS1 replication system. To do this, we attempted to isolate pHS1 containing IS1 (namely pHS1::IS1) from eight independently isolated cointegrates using the restriction endonuclease PstI, which cleaves at a single site within IS1 and no site within pHS1. After ligation of the PstI digests of a pMZ plasmid at DNA concentrations favorable for recircularization of each fragment in the digests and subsequent transformation of the ligated DNA, tetracycline resistant transformants were selected at 30°. Two cointegrates (pMZ3 and 7) did indeed give rise to the pHS1::IS1 plasmids which showed temperature sensitive DNA replication like pHS1, while the other six cointegrates (pMZ1, 2, 4, 5, 8 and 9) did not. This suggests that the cointegrates pMZ3 and 7 contain a functional pHS1 replication system, while the others contain an inactive system. The inactivation as a result of integration of pSM1 at its IS1 into sites within pHS1 is like translocation of the IS1 sequence itself which has been shown to inactivate various bacterial genes. We also describe the nucleotide sequence in a pHS1:: IS1 (named pMZ71), generated from pMZ7, of the junction region between the pHS1 and IS1 sequences as well as the entire IS1 sequence. PMZ71 would be a useful plasmid with which to study the IS1 sequence genetically and biochemically.
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Edited and published by : Applied Microbiology, Molecular and Cellular Biosciences Research Foundation/Center for Academic Publications Japan Produced and listed by : TERRAPUB, Center for Academic Publications Japan/Shobi Printing Co., Ltd. (-Vol.60,No12), Center for Academic Publications Japan/InternationalAcademic Printing Co., Ltd.(-Vol.54,No1)