Tsutomu Kanehira

Pure isolation of a new chemoautotrophic ammonia-oxidizing bacterium on gellan gum plate

Abstract A chemoautotrophic ammonia-oxidizing bacterium (strain TK794) was screened from eighty-eight soil samples. One bacterium was purely isolated on a Gellan gum-solidified plate. The cell of strain TK794 was 0.5–1.0 × 1.5–2.0 μm in size, rod-shaped, Gram-negative, obligately aerobic and motile by means of subpolar fragella. Intracytoplasmic membranes characteristic of nitrifying bacteria were present. The G+C-content of the DNA was 50.6 mol%. The optimum concentrations of phosphate and ammonium sulfate for maximum cell yield in P-medium were 70 mM and 30 mM, respectively. The c-type cytochromes were thought to be of the c-552 type. Growth of the strain was possible in the presence of cephalothin sodium (500 μg/ml). Strain TK794 was identified as belonging to the genus Nitrosomonas, but had enzymologically different characteristics from Nitrosomonas europaea ATCC 25978, the type strain.

Characteristics of a high-concentration-ammonium sulfate-requiring ammonia-oxidizing bacterium isolated from deodorization plants of chicken farms.

A high-concentration-ammonium sulfate-requiring, ammonia-oxidizing bacterium, strain K1, was newly isolated from packed tower biological deodorization plants of chicken farms. The cells of strain K1 are rods (0.1-1.0 x 1.0-2.0 microm), gram negative, obligately aerobic, and nonmotile. Colonies (1-2 mm in diameter) on a plate culture are reddish, circular, and smooth. Intracytoplasmic membranes characteristic of nitrifying bacteria are present. The G+C content of the total DNA is 48.5 mol%. The similarity of 16S rRNA (%) to N. europaea ATCC 25978T (type strain) is 93.77%. This bacterium has a higher optimal growth temperature (35 degrees C) than is usually the case and tolerance up to 40 degrees C. The optimum concentration of ammonium sulfate in the medium is 303 mM, which should make it applicable for use in deodorization plants for enhancing the efficiency of deodorization. Phosphoglycerate kinase (PGK) and triosephosphate isomerase (TIM) were found to possess high specific activities (5700 and 4 x 10(5) U/mg, respectively) compared to the activities of these enzymes in strain ATCC 25978T (300 and 14 U/mg).

A New Psychrotrophic Ammonia-Oxidizing Bacterium, Nitrosovibrio sp. TYM9

Abstract A new psychrotrophic ammonia-oxidizing bacterium (strain TYM9) was isolated in a screening of 150 soil samples on a gellan gum-solidified plate. The cells of strain TYM9 are slender cuved rods (0.2–0.4×1.0–3.0 μm), gram negative, obligately aerobic and nonmotile. Colonies (1–2 mm in diameter) on a plate culture are reddish, circular and smooth. Intracytoplasmic membranes characteristic of nitriying bacteria are absent. The G + C content of the DNA is 53.0 mol%. The optimum temperature for maximum growth in HEPES medium is 20°C and minimum growth occurs at 5°C and 35°C. The optimum concentration of ammonium sulfate for growth is 20 mM. Growth of the strain is possible in the presence of cephaloridine (500 μg/ml). Hydroxylamine oxidase (HAO) was detected with high specific activity (346 U/mg) compared to that for N. europaea ATCC 25978T (4.5 U/mg). The level of RuBisCO activity in strain TYM9 is similar to that in strain ATCC 25978T. Strain TYM9 has morphologically and physiologically different characteristics from those of Nitrosovibrio tenuis and members of the genus Nitrosomonas. Strain TYM9 was identified as belonging to the genus Nitrosovibrio, and assigned the Nitrosovibrio sp. TYM9.

Newly isolated marine ammonia-oxidizing bacterium, Nitrosomonas sp. TNO632

Abstract A new marine ammonia-oxidizing bacterium (strain TNO632) was isolated in a screening of 80 sea-water samples on gellan gum-solidified plates. The cells of strain TNO632 are rods (0.7 – 0.9 × 1.0 – 2.0 μm), gramnegative, obligately aerobic, and nonmotile. Colonies (1–2 mm in diameter) on a plate culture are reddish, circular, and smooth. Intracytoplasmic membranes characteristic of nitrifying bacteria are present. The G+C content of the total DNA is 53.3 mol%. The similarity of 16S rRNA (%) to Nitrosomonas europaea ATCC 25978% (type strain) is 94.26%. The optimum temperature for maximum growth in marine ASW-medium is 27–29°C. The optimum concentrations of ammonium sulfate, sodium chloride, and magnesium chloride for growth are 26, 100 and 100 mM, respectively. Growth of the strain is imposiible when urea is used as the sole carbon source. Hydroxylamine cytochrome c reductase (HCR) and triosephosphate isomerase (TIM) were detected and found to possess high specific activities (980 and 140 U/mg, respectively) in TNO632 compared to those in ATCC 25978T (450 and 14 U/mg).