اثر ضدعفوني كننده اشعه گاما و گاز ازون بر بار ميكروبي بادرنجبويه (Melissa officinalis)

The Disinfectants effect of Gamma Radiation and Ozone Gas on Microbial Load of Meliss (Melissa officinalis)

امروزه گیاهان دارویی با روشهای مختلف ضدعفونی می¬شوند كه هر كدام از این روش‌ها تاثیرات متفاوتی بر بار میكروبی آنها می¬گذارد. بنابراین استفاده از روش‌هایی كه تاثیر زیادی در سالم¬سازی و كمترین تاثیر را روی مواد موثره این گیاهان داشته باشد ضروری است از این رو هدف از این تحقیق كه بصورت طرح كامل تصادفی وآزمایش فاكتوریل در قالب طرح كاملا تصادفی با سه تكرار انجام پذیرفت بررسی تاثیر پرتو¬تابی با اشعه گاما و گاز ازون بر بار میكروبی گیاه دارویی بادرنجبویه می¬باشد. به این صورت كه برگهای خشك شده بادرنجبویه در برابر دوزهای ۳، ۷، ۱۰ و ۱۵ كیلوگری اشعه گاما و غلظت¬های ۰/۳، ۰/۶ و ۰/۹میلیگرم در لیتر گاز ازون در مدت زمان¬های 10 و 30 دقیقه قرار گرفتند سپس بار میكروبی آنها مورد بررسی قرار-گرفت. نتایج نشان داد كه هر دو روش بار میكروبی بادرنجبویه را كاهش دادند. اما ازون¬دهی تاثیر بیشتری در كاهش بار میكروبی این گیاه داشت بیشترین تاثیر اشعه گاما بر بار میكروبی مربوط به دوز ۱۵ كیلوگری بود. و غلظت ۰/۹ میلیگرم در لیتر گاز ازون و زمان ۳۰ دقیقه بیشترین تاثیر را در كاهش بار میكروبی داشت. بطور كلی نتایج حاصل از تحقیق نشان داد كه استفاده از گاز ازون به منظور ضدعفونی بادرنجبویه روش ضدعفونی مناسبی می باشد. با توجه به این كه استفاده از ازون هزینه كمتری نسبت به اشعه گاما نیاز دارد . اما باید تحقیقات بیشتری در مورد زمان قرار گیری نمونه های گیاهی در برابر گاز ازون و تاثیر آن روی مواد موثره گیاهان داریی انجام شود.

Introduction: Today, tendency to use drugs and therapies with herbal and natural products are increasing because negative effects of chemical drugs and environmental pollution have been proved. Collection and handling of medicinal plants are not usually done in sanitary conditions and difference in cultivation conditions can also increase pollution, influencing the maintenance period and damaging the aspect and the potential benefit of medicinal plants. Medicinal plants decontaminate with different methods that each of these methods has different effects on their microbial load. Therefore it seems essential to use of methods that can have the highest effect on microbial load decrease and the lowest effect on active substance of these plants. Materials and Methods: In order to evaluate the effects of Ozone gas and gamma irradiation on microbial load of Melissa officinalis, an experiment was conducted based on randomized complete block design with three replications. Plant samples were collected from the Research farm of, Ferdowsi University of Mashhad. Meliss leaves were treated by Ozone gas concentrations 0.3, 0.6 and 0.9 ml/L for 10 and 30 min and irradiated at dosages 3, 7, 10 and 15 KGy by a Co60 source. Then microbial load of Meliss leaves were measured. Coliform bacteria were determined using Violet Red Bile lactose (VRBL) agar (Liofilchem Co., Italia), according to the method of ISO4832. According to ISO 7954, yeast extract of glucose chloramphenicol agar (Liofilchem Co., Italia) was used for determination of mold and yeast. The total count (plate count agar, Liofilchem Co., Italia) was determined by method of ISO 4833, that each replicate was tested with duplicate pour plates. Ozone gas was produced by corona discharge Ozone generator with production capacity 10 g/h of Ozone gas (OZONEAB co. A.S10. Iran). Analysis of variance and means comparison were calculated using SAS 9.1 (Cary, NC, USA, 2002-2003). Means square comparisons were different at the 5% significance level by the least significant difference test. Results and Discussion: The effect of Gamma radiation on microbial load such as total count, molds, yeasts and Coliform was significant (p <0.05), so the highest effect of irradiation on the microbial load was related to the dosage of 15 KGy. However 10 KGy decreased microbial load, but 3 and 7 KGy had no effect on reduction of total count, molds, yeasts and Coliform. According to results of this study, the use of ozone gas, exposure duration to the meliss samples and interaction of duration and ozone gas on microbial load was significant. The highest and lowest levels of contamination were observed in control and 0.9 ppm concentration of ozone gas for 30 min, respectively. Non-ozonation meliss samples showed maximum level of mold and yeast count. Also Coliform were eliminated with 0.9 ppm concentration of ozone gas for 30 min in meliss. It was found that by increasing the Ozone gas concentrations from 0.3 ppm to 0.9 ppm, microbial load reduced significantly (p <0.05). Conclusions: The result showed that both methods decreased microbial load of Meliss. Ozone gas had higher effect than gamma on reduction of microbial load of this plant. Concentrations of ozone gas utilized for decontamination of medicinal plants were 0.9 ppm ozone gas and 15 KGy dosages that those concentrations had the highest effect on total count, mold and yeast and Coliform. Control of environmental conditions and hygiene improvement in production process of medicinal plants such as meliss is essential. In addition, it is recommended to choose a suitable decontamination method for disinfection during packing of medicinal plants and post-packing manipulation and transport. This study showed that gamma irradiation can use as an important decontamination method to reduction the microbial load of meliss. Furthermore, the use of ozone as a method of disinfection for medicinal plants decontamination is a suitable method of decontamination. Finally, the results showed that the use of ozone for disinfection of Meliss is inexpensive and suitable disinfection techniques than gamma radiation. However, further research needs to improve our understanding on duration of exposure to ozone and its impact on active substances of Meliss.