Growth of Moderately Thermophilic Iron-Oxidizing Bacterium Strain TI-1 in Synthetic Medium

概要

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The moderately thermophilic iron-oxidizing bacterium strain TI-1,which lacks enzyme systems involved in CO_2 fixation, grows at 45℃ in Fe^<2+> medium supplemented with yeast extract to give a maximum cell growth of 1.0×10^8 cells per ml, but does nor grow in Fe^<2+> medium without yeast extract. To elucidate the physiology of the strain, a synthetic medium was developed. It was found that the best synthetic medium was Fe^<2+> -6AA, containing Fe^<2+>, salts and the following six L-amino acids : alanine, aspartic acid, glutamic acid, arginine, serine, and histidine. In this medium, strain TI-1 showed a maximum cell growth of 10×10^8 cells/ml. The six amino acids in the Fe^<2+> -6AA medium were used not only as a carbon source but also as a source of nitrogen. Inorganic nitrogen sources, sich as ammonium ion, hydrazine, hydroxylamine, nitrite, and nitrate, were not used as a sole source of nitrogen, but rather strongly inhibited the utilization of the six amino acids at 1 mM. In the Fe^<2+> (10 mM)-6AA medium supplemented with 21 mM Fe^ <3+>, reduction of Fe^<3+> to Fe^<2+> that was dependent on the added amino acids was observed, suggesting another role of the amino acids in the growth of strain TI-1. Washed, intact cells of strain TI-1 had the activity to reduce Fe^<3+> to Fe^<2+>.
社団法人日本生物工学会の論文
1995-03-25