Study On The Inhibition Mechanism Of Isooctanol Against Aspergillus Ochraceus And The Effect Of Anti-mold On Grain

Aspergillus ochraceus was a common fungus that causes grain mildew during grain storage.The flavour and quality of mouldy grain were severely impaired and the ochratoxin A produced can also be harmful to human health.As a volatile compound with antifungal activity,isooctanol has a promising application as it can easily enter stored grain by diffusion.This thesis first investigates the inhibitory effect of isooctanol on A.ochraceus,then further investigates the mechanism of inhibition and investigates the effectiveness of its fumigation treatment of high moisture grain against mould.The MIC of isooctanol on the growth of A.ochraceus was measured at 1 562.5μL/L under miscible conditions using the sesquidilution method,while the MIC and MBC of isooctanol on the growth of A.ochraceus were measured at 112 μL/L and 281μL/L,respectively,under volatile conditions using the plate coupling method.Isooctanol can inhibit A.ochraceus spore germination,mycelial growth,affect mycelial morphology,reduce spore production and toxin production,and the inhibitory effect of isooctanol on A.ochraceus was dose-dependent.Isooctanol treatment can significantly stimulate the generation of intracellular reactive oxygen species,and the accumulation of reactive oxygen species can cause oxidative damage to A.ochraceus spores.Isooctanol treatment can lead to the loss of membrane integrity,DNA damage,and decreased ergosterol content.Due to the destruction of the structure and function of the cell membrane,the permeability of the cell membrane increases and the intracellular conductive particles were released,resulting in the increase of extracellular conductivity and the loss of spore contents,resulting in dryness and depression in appearance.Intracellular cytoplasmic wall separation,cytoplasmic loss and massive dissolution of organelles,cell necrosis.Isooctanol treatment down-regulated the expression of OTA synthesis gene,ergosterol synthesis gene and global regulatory factors,A.ochraceus could not grow normally and toxin,and A.ochraceus was killed finally.Isooctanol fumigation treatment of high moisture wheat,maize,peanut and paddy were all delayed or inhibited mould growth to varying degrees within 7 d.The colony counts of the treated groups were all significantly lower than those of the control group.Isooctanol fumigation treatment significantly reduced or retarded the increase in fatty acid values,while reducing or retarding the production of MDA,protecting high moisture grain from oxidative damage and avoiding quality degradation,especially when applied to wheat where the inhibition effect was best,but less effective in peanuts with high oil content.Isooctanol fumigation significantly inhibits the production of OTA in grain and even slowly reduces the level of OTA in grain,and ochratoxin production was best in wheat.Isooctanol fumigation does not affect the colour of grain and significantly delays the darkening and yellowing of grain in storage due to high moisture content and mould growth.The inhibition of A.ochraceus growth by isooctanol was found to be more effective under volatile conditions,mainly by disrupting the cell membranes of A.ochraceus,and the inhibition was significant in high moisture grain,which may provide a theoretical basis for its development and application in the prevention of moulds in grain.