Obligate methylotroph, Pseudomonas RJ-3 showed remarkable sensitivity to various exogenously added organic compounds in the growth medium. Ribose, glucose, galactose, mannose, malatose, lactose, most of the amino acids, carboxylic acids, and vitamins inhibited the growth.
Cell-free extract of California strain of Spiroplasma cirri contained activities of arginine deiminase, ornithine transcarbamylase, and carbamyl phosphokinase but not those of argininosuccinic acid sythetase, argininosuccinase, and arginase. When washed cells suspended in buffer were supplied with arginine, the disappearance of arginine was accompanied by appearance of citrulline, ornithine, and ammonia. Addition of rifampicin or cycloheximide to culture medium at the time of inoculation prevented the appearance of activity of arginine deiminase, the first enzyme of arginine dihydrolase pathway. These results show that arginine degradation in S. citri is via arginine dihydrolase pathway and that arginine deiminase, and possibly the other two enzymes of this pathway, are inducible.
Growth and nitrogenase activity were studied in cultures of Spirillumlipoferum growing with dinitrogen and combined nitrogen. Not much difference is observed in the growth rates in culture growing with and without dinitrogen except that the lag phase is shortened in culture growing with combined nitrogen. The nitrogenase activity was repressed by ammonium chloride but, after exhaustion of ammonia, the activity was derepressed. With respect to PO2, maximum nitrogenase activity in this bacterium is observed at PO2=0.004atm, indicating that nitrogen is fixed microaerophilically by Spirillum. Free amino acid pools extracted from growing cultures of Spirillum lipoferum is also reported here, suggesting that the free amino acid pool contains a variety of amino acids with glutamic acid and amide glutamine being present in much higher concentrations than others.
Tricarboxylic acid transport systems in Proteus mirabilis IFO 3849, which utilized citric, isocitric, and cis-aconitic acids, were characterized. The results show that P. mirabilis possesses three inducible transport systems for the tricarboxylic acids. The first system is induced by citrate, isocitrate, or cis-aconitate and transports citric and isocitric acids. The affinity of isocitric acid for this system is lower than that of citric acid. The second system, induced by the same acids as in the first system, transports cis-aconitic acid, requires Mg2+ ions, and is stable at pH 8.6 but unstable at pH 7. The third system is induced by citrate and carries citric acid.
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