No abstract

No 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.

The feasibility of inactivating microflora of foreign spices by means of gamma radiation, without causing significant organoleptic or chemical changes, was studied. Ground cinnamon, clove, coriander, nutmeg, white and black pepper were irradiated with doses of 7 and 10 kGy1 of 60Co. Chemical analysis were performed so as to verify the Argentine Alimentary Codex specifications and the effect of radiation on those characteristics by which spices are appreciated, such as color and volatiles. No differences between control and irradiated samples could be found in any of these parameters. Microbiological results showed that aerobic plate count was reduced by 2.5 to 4.0 log cycles with 7 kGy. At 10 kGy survivors could only be found in cinnamon (1.7 log cfu/g)2. Cinnamon and clove were sensorily evaluated. No differences due to irradiation were found. So, it can be concluded that 10 kGy of gamma radiation suffice the purpose of this work. This good market condition was held at least during one year.

No abstract