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

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.
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.
The effect of Gamma radiation on microbial load such as total count, molds, yeasts and Coliform was significant (p