Radioresistance of an Acinetobacter species.

Abstract

In the course of studies on i-radiation for the sterilization of tampon using as medical implement at the National Commission of Atomic Energy of Argentina, we isolated a radioresistant, Gram-negative bacterium. So far, there are many reports for the radioresistance of Gram-positive bacteria, but there are a few reports (1-3) for that of Gram-negative bacteria. They are for Acinetobacter of THORNLEY et al. (1), for Pseudomonas radiora of ITO and IIZUKA (2), and for the intermediate type of Moraxella and Acinetobacter of ITo et al. (3). The new isolate, strain FO-1, from cotton to make tampon is an Acinetobacter species, and the radioresistance of this strain is stronger than that of the above mentioned Gram-negative bacteria. In this paper we describe experimental studies on radioresistivity and identification of the strain FO-1.The strain FO-l, isolated from the tampon's cotton sterilized by 3 Mrad irradiation of cobalt-60 1-ray, and the type strain ATCC 23055 of Acinetobacter calcoaceticus as a comparison were used in this study.The r-ray source used was a 100 kCi cobalt-60 irradiator of Takasaki Radiation Chemistry Research Establishment, Japan Atomic Energy Research Institute. The dose rate at the irradiation position determined by Frike dosimetry was 400 krad Jhr. The organisms were grown overnight in the nutrient broth, under constant aeration on a rotary shaker (220 rpm) at 30°. The cells were harvested and washed with 0.067 M phosphate buffer (pH 7.0) and resuspended in the same buffer.Cell suspensions prepared were irradiated under air-bubbling, air-equilibrium, or under N2-equilibrium conditions (wet state). In the case of the strain FO-1, the harvested cells were suspended in calf serum and 0.02 ml each of this suspension was packed in polyethylene-cellophane bags, dried in a desiccator, and irradiated in dry state at room temperature.

Taxonomic studies of Acinetobacter species based on outer membrane protein patterns.

“…The patterns of these strains were identical or almost so and were clearly different from those of other types examined. The results of the OMP patterns support the previously published data: DNA base composition (44.1-44.8 G + C mol%) (22), DNA homologies (>_ 91%) (22), the enzyme patterns (cluster Z-3) (23), and physiological and biochemical tests (15,16,19). We also studied the protein patterns of four strains from culture collections (A. calcoaceticus NCIB 8250 and CCM 2881, A. lwoffii NCIB 11520, and Acinetobacter sp.…”

“…The strains examined in this study are listed in Table 1. Twenty three of these strains were obtained from various culture collections and fifteen other strains were isolated from soil and cotton samples (15,16,19).…”

“…So far, we have isolated acinetobacters from soil and cotton samples and also conducted taxonomical studies, that is, physiological and biochemical tests (15,16,19), DNA analysis (22), cellular fatty acids (20), ubiquinone systems (24) and electrophoretic analysis of enzymes (23), using the strains containing authentic Acinetohacter strains from various culture collections. In the course of the study on the characteristics of the outer membrane (OM), we found that the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of the outer membrane proteins (OMPs) of the radiation-resistant strain FO-1 showed a specific pattern clearly distinguished from those of the type strain of A. calcoaceticus (21).…”

Discrimination of Acinetobacter Genomic Species by AFLP Fingerprinting

“…AFLP analysis of A. radioresistens. In 1979, an acinetobacter displaying elevated resistance against gamma rays was isolated from a cotton sample (42). This strain (FO-1) and other radioresistant Acinetobacter strains isolated from soil were characterized by phenotypic tests and DNA-pairing experiments (47,48), leading to the proposal in 1988 of a new species, A. radioresistens (49), with the FO-1 strain as the type strain.…”

Effects of acute γ-irradiation on the aquatic microbial microcosm in comparison with chemicals

“…The LD 90 s of P. putida and B. cereus are 250 and 400 Gy, respectively (Daly et al, 2004;Kotiranta et al, 1999). Acinetobacter has a wide range of the LD 90 s, i.e., 65-2200 Gy, depending on species and strains (Kairiyama et al, 1979). Philodina sp.…”