Effects Of Two Kinds Of Essential Oils On The Growth Of Penicillium Expansum And The Production Of Patulin

Penicillium expansum is the main pathogen which can cause blue mold on fruits. It will cause not only fruits rot, but also produce patulin which may cause teratogenicity, carcinogenicity and immunotoxicity on human and animals. Patulin can be existed in many kinds of fruits and their products which have caused wide public concern. Currently, chemical synthetic fungicides are mostly used as an effective postharvest disease control strategy, however, there are plenty drawbacks of chemical synthetic fungicides such as environment pollution, pesticide residue and production of resistant strain. Hence it is significant to find a safe and efficient method to control postharvest diseases of fruits. Cinnamon oil and clove oil are extracted from natural plant which belongs to medicinal and edible plants. Using this kind of natural materials to defeat pathogens has broad application prospect.Many research concentrated on the bacteriostatic activity of the two essential oils, but few research about the effects on the growth of Penicillium expansum and the production of patulin were reported. In this study, the effects of cinnamon oil and clove oil on the growth of Penicillium expansum and the production of patulin were investigated. The effects of the two essential oils and their main compounds on patulin biosynthetic related gene were analyzed. The main results were showed as below:(1) The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were tested on Penicillium expansum. Systematic research results indicated that the MIC of cinnamon oil, cinnamaldehyde, clove oil, eugenol was 5.20 μL/L、4.55 μL/L、32.5 μL/L、32.5 μL/L, respectively, and the MBC was 5.20 μL/L、4.55 μL/L、39.0 μL/L、39.0 μL/L, respectively.(2) Different concentrations of cinnamon oil, clove oil and their main compounds had moderate inhibition effects on fungi growth in solid medium by fumigation. These effects were concentration dependent.4.55 μL/L cinnamon oil,3.90 μL/L cinnamaldehyde,26.0 μL/L clove oil,26.0 μL/L eugenol had the strongest inhibition effect on the growth of Penicillium expansum and the production of patulin.(3) Clove oil showed evident inhibitory effect on mycelial growth in direct contact way.26.0 μL/L clove oil could significantly reduce spore germination rate, but at the same concentration, clove oil promoted the production of patulin in liquid medium and in vivo.(4) The chemical composition of volatile gas from cinnamon oil and clove oil was analysed by GC-MS. The results showed that the volatile gas of cinnamon oil had the highest amount of cinnamaldehyde (45.31%) and the volatile gas of clove oil had the highest amount of eugenol (46.66%). Combined with the bacteriostatic experiment of cinnamaldehyde and eugenol, it was showed that the main antifungal substance in the volatile gas of cinnamon oil and clove oil were cinnamaldehyde and eugenol, respectively.(5) The relative quantitative expression of gene about patulin synthesis process could be affected by treatment of cinnamon oil, cinnamaldehyde, clove oil and eugenol. The treatment of the four materials reduced the relative expression of PatK, PatM and PatN and increased the relative expression of PatC. There was no obvious effect on PatL.