Studies On Isolation, Identification, And Physical And Chemical Characters Of A Radiation-resistant Microbe In Chinese Medicine

Radiosterilization has become a newly emerging sterilization craft widely applied onChinese medicine and food processing. But we may find unsatisfactory effect in somebatches of products if there are some radiation-resistant microbes in the products. "Jin SuoPill", a product of a certain pharmaceutical company. These pills were treated usingirradiation technology in our center but bacteria were still found when the total irradiationdose was accumulated to 9 kGy. "Jin Suo Pill", a kind of Chinese medicine was taken asa sample in this study. After irradiation, separation and Identification on the medicine andphysical and chemical characters of radiation-resistant microbes were studied thefollowing results were obtained:There were six groups of microbes after initial separation, these microorganisms wereisolated and purified. Only one still survived after it was irradiated at the dose of 8kGy. Aconclusion could be drawn that it was the radiation-resistant microbe. Theradiation-resistant microbe with the color of the milky white, in the shape of regularconcentric circles, and it was smooth and transparent when it was abstracted and purifiedfurther. The radiation-resistant microbe will become rough when cultured for a long timeand the color will turn to light-yellow or brown. There was not pigment sediment on theplate.Morphous observation were carried on the radiation-resistant microbe's morphous,structure, physiological and biochemical characters. It was found that this microbe was inthe shape of rod or ellipse. The length was1.556～2.148μm and width was 0.944～1.021μm and most of them were curved at certain stage. Some were arrayed in geminationor in short chains, and they did not move, without flagellae or capsule. They were aerobicbut not anti-acid, and they had spore. The gram stain was positive and the thallus culturedfor 2 or 3 days was bigger than that cultured for only one day. The negative reactions of theradiation-resistant included Mannose, arginine ambi-hydrolysis, cellobiose, Vogos-Prouska -uer test, M.R.test, arabinose, inositol, lysine, ornithine, esculin, lactose, glycogen, urea,raffinose, phenylalanine, xylose, desaminase, galactitol. The positive reactions were asfollows: Ribose, fructose, trehalose, sucrose, galactose, maltose, mannitol, glycose, andGelatin liquefaction. And this microbe could grow in the medium with 7% sodiumchloride solution. The optimal condition for the growth of the microbes was 34 to 37℃,with pH between 5 and 9.The radiation-resistant microbe was identified as Bacillus flexus based on the resultsof morphologic, physiological and biochemical properties and phylogenetic analysis of16S rDNA sequence. The sequence of 16S rDNA obtained in this study has been registeredat GenBank database and the accession number was AB021185.1.The D₁₀ of this purifiedradiation-resistant microbe is 6.75kGy and 7.18kGy in thenormal saline and filter paper respectively after irradiating at different doses.Theradiation-resistant microbe had the fairly powerful ability to endure the hightemperature, and some microbes still survived after treatment with 100℃for about 40minutes. The radiation-resistant microbes were exposured under the viltalight lamp (thepower was 40 watt) for 30 minutes, with the distance between the plate and viltalight lampbeing 0.8m. After that, theradiation-resistant microbes were cultured in the thermostaticcontainer. After 24 hours it was found that there still were 15% of the radiation-resistantmicrobes survived.