Journal of Microbiology

Characterization of azomonas agilis PY101, a cadmium-resistant strain isolated from anyang stream: You, Kyung Man , Lee, Ji Hyun , Kim, Jeong Kook , Hah, Nam Ju , Lee, Yung Nok , Park, Yong Keun; J. Microbiol. 1996;34(3):289-293.

Abstract: A cadimium-resistant strain isolated from Anyang stream, Azomonas agilis PY101 exhibited strong resistance to 1000 ppm of cadmium ion (Cd^2+). A agilis PY101 also exhibited resistance to various antibiotics, such as amoxicillin, amplicilin, bacitracin, cefazolin, erythromycin, penicilin, tetracycline, and vancomycin. In the presence of Cd^2+, the growth of A. aglis PY101 started after an extended lag phase and produced a green-fluorescent pigment induced by cadmium. The dramatic decrease (approximately 400ppm) of concentration of cd^2+ in the culture medium during the growth phase of A. agilis PY101 was confirmed by the inductively coupled plasma-atomic emission spectrophotometer. Transmission electron microscopic analysis revealed that A. agilis PY 101 actively accumulated Cd^2+ in the cytoplasm.

Isolation and Characterization of Pigment-deficient Mutants from Azomonas agilis PY101: You, Kyung Man , Lee, Sang Hyeon , Park, Yong Keun; J. Microbiol. 1999;37(1):45-49.

Abstract: To investigate the mechanism of cadmium tolerance in a cadmium-resistant Azomonas agilis PY101 that produces a specific fluorescent pigment promoted by cadmium, we carried out Tn5 mutagenesis and isolated four pigment-deficient mutants. In these mutants, Ppg1, Ppg2, and Ppg3 remarkably reduced the pigment production to 15.3%, 11.2%, and 13.9%, respectively. Especially, Ppg4 mutant did not produce the pigment at all. None of the mutants grew in the presence of 1500 ppm of CdCl₂in growth medium, and they exhibited differential sensitivities to cadmium. Ppg1, Ppg2, Ppg3, and Ppg4 mutants were sensitive to 900 ppm, 1100 ppm, 1000 ppm, and 800 ppm of CdCl2, respectively. These mutants also showed noticeable increase, from 8.8-fold to 13.2-fold, in the size of growth inhibition zone compared with that of the will type after treatment with cadmium. Therefore, the pigment production of A. agilis PY101 was found to decrease the toxic effects of cadmium to the bacterium.

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