A study was conducted to identify the bacterial flora present in outdoor and indoor swimming pools of a university facility used by healthy individuals and where the water quality was appropriately controlled. Bacteria that were isolated at high frequency throughout the year were gram-positive rods, Bacillus species, and gram-positive cocci, Staphylococcus species. All of the bacteria belonging to these two genera were essentially regarded as non-pathogenic. Other bacterial groups sampled from both pools were found to be members of medically non-problematic bacterial flora on the basis of their characteristics, showing that the water quality of the two pools was appropriately controlled. The swimming pools are appropriately managed, and treated with the disinfectant sodium hypochlorite at 0.4-1.0 ppm, as specified by Japanese law. Some species of the genera Pseudomonas and Serratia have recently been attracting attention as etiological agents of opportunistic infections. Therefore, P. aeruginosa and S. marcescens isolated in this study were subjected to a step-wise sodium hypochlorite sensitivity disk-test. Both bacteria formed an inhibition zone only around (on) a disc containing sodium hypochlorite at a very high concentration of 50 ppm, showing that some species of Pseudomonas and Serratia detected in the swimming pools were resistant to sodium hypochlorite.
Summary Euglena grown to stationary phase in the dark without aeration accumulated lipids. When these high lipid cells are transferred to an inorganic medium and aerated, lipids were rapidly metabolized and the respiratory rate declined concomitant with the decline in cellular lipid content. Prolamellar bodies, propyrenoids and prothylakoids developed within the proplastid of dark aerated cells and the cells developed an increased capacity for chlorophyll synthesis manifested upon subsequent exposure to light. Lipid content did not decline in cells exposed to nitrogen and chlorophyll synthesis ability did not increase. The addition of an organic carbon source to cells at the start of aeration did not prevent lipid degradation. Organic carbon source addition and inhibitors of RNA and protein synthesis did however inhibit the development of an increased capacity for chlorophyll synthesis. These results suggest that oxygen triggers light independent proplastid development with the oxidative metabolism of lipids providing the carbon and energy for the synthesis of nucleic acids and proteins required for proplastid development in the dark. Growth of microorganisms requires carbon and energy for the synthesis of cellular components. Autotrophs utilize sunlight or the energy released by oxidization of inorganic compounds for growth while the breakdown of organic compounds provides the energy needed for the growth of heterotrophs. Most pathogenic bacteria, protozoa, and fungi are heterotrophs. The objective of this study was to analyze the mechanism of conversion from heterotrophy to autotrophy using the unicellular alga, Euglena gracilis. Key wordsEuglena gracilis grows heterotrophically on a variety of carbon sources in the dark showing a typical animal-type metabolism and when it is placed in the light on an inorganic medium it grows autotrophically exhibiting plant-type metabolism. Euglena is the only organism that can reversibly switch from animal-like heterotrophic metabolism to plant-like autotrophic metabolism making its taxonomic classification as a plant or animal problematic (Johnson 1968). Schiff's group (Osafune et al. 1990, Schiff andSchwartzbach 1982) has studied the transformation from a heterotroph to a phototroph, the greening of Euglena gracilis var. bacillaris, by transferring dark grown non-dividing cells, resting cells, into the light to induce chloroplast development. They found that the breakdown of the storage carbohydrate paramylum provided carbon and energy for the light induced synthesis of proteins, nucleic acids and lipids needed for chloroplast development (Schwartzbach et al. 1975, Rosenberg et al. 1964 found that lipids, mainly wax esters, accumulated in the cytoplasm of dark grown stationary Euglena and their breakdown was induced by light exposure providing an additional source of carbon and energy for light induced chloroplast development.
SummaryThe presence of plastids has been accepted as morphologically crucial evidence for the Prototheca species being the green alga. In the present study, a clinical isolate of Prototheca wickerhamii was examined for plastid DNA and 2 chloroplast proteins by immunoelectron microscopy. Cells of P. wicherhamii contained double-membraned plastids which enclosed starch grains. Membraneous, lamella-like structures developed in plastids of cells grown under light. Deposition of anti-DNA immunogold particles showed the presence of DNA in the plastids. The chloroplast DNA-coded large subunit of the CO 2 -fixing enzyme, ribulose-1,5-bisphosphate carboxylase (RuBisCO), was found in plastids of cells grown under either light or darkness. The nuclear DNAcoded small subunit of RuBisCO was distributed in the cytoplasm and plastids. The nuclear-coded thylakoid protein, light-harvesting chlorophyll a/b-binding protein in photosystem II apoprotein (LHCP II), was also detected in both the cytoplasm and plastids of cells grown under light, but not in cells grown under darkness. These results show that the genus Prototheca retains the ability to synthesize some of chloroplast proteins despite defect in chlorophyll synthesis.
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