The Inhibitory Activity And Preliminary Mechanism Of Cuminaldehyde On The Growth Of Aspergillus Flavus

Aspergillus flavus is widely distributed in nature,which is a major factor in food mildew.Moldy food will not only make the nutritional value to reduce made significant direct economic losses,and some strains also produced AFB₁and other carcinogenic toxins,serious harming public health.Plant essential oil is an efficient and non-toxic natural bacteriostatic substance,It has a good application prospect in the control of fungi such as Aspergillus flavus.Previous studies found that cumin essential oil can inhibit the growth of Aspergillus flavus,However,its mechanism of action is still unclear.Therefore,this paper firstly investigated the cuminaldehyde which was the inhibitory effect of the main component of the cumin essential oil,on the growth and production of Aspergillus flavus from the spore germination,mycelial growth and ultrastructure,AFB₁ synthesis and so on.Then explore the application of cumin essential oil in peanut storage and preservation;The effect of cumaldehyde on the gene transcription and protein expression levels of Aspergillus flavus gene using RNA-Seq and DIA technology for transcriptome and proteomics sequencing,to obtain the differentially expressed genes and proteins,A target for predicting the inhibition of cumaldehyde on Aspergillus flavus;Finally,the inhibitory effects of cuminaldehyde on the growth of Aspergillus flavus were analyzed from the aspects of gene transcription,protein expression and metabolic pathway,and the preliminary research on its mechanism was explored.The main results are as follows:1.Cuminaldehyde can obviously inhibit the growth of Aspergillus flavus,Compared with the control group,When the concentration of cuminaldehyde is0.8?L/mL,the spore germination inhibition rate was 93%,and most conidia lost germination ability,and the mycelial biomass inhibition rate was as high as99.8%;1.5?L of cuminaldehyde volatilized,the colony growth rate was reduced by 67.2%,and the lag phase was increased to 3.8 times,at the same time,the stereoscopic morphology of the colonies was significantly observed by stereomicroscope observation;The surface microstructure of Aspergillus flavus spores and mycelium was further observed by SEM and TEM,malformation or even distortion,the cell structure was ambiguous and the shape was irregular;The inhibition rate of toxin production under the action of cuminaldehyde was95.54%,It shows that cuminaldehyde can effectively inhibit the growth of Aspergillus flavus and inhibit its toxin production.In the peanut preservation applications,the cumin essential oil can effectively prevent and control aflatoxin contamination,after 9 months of storage,the inhibition rate of Aspergillus flavus spores on peanut surface was 95.31%,and the inhibition rate on toxin production was 95.45%.2.Analysis of the transcriptome data of Aspergillus flavus showed that there were 5685 differentially espressed genes caused by cuminaldehyde,down-regulated by 2568,up-regulated by 3117.The down-regulated gene was mainly involved growth related pathway:integral component of plasma membrane transmembrane transport with the growth and development related pathway,the gene transcription of the membrane component ergosterol and toxin synthesis gene cluster;And the up-regulated by major gene classification was iron exporter.The data of Aspergillus flavus proteome was analyzed and it was found that puroaldehyde caused significant differential expression of 242proteins of Aspergillus flavus,of which 142 proteins were down-regulated and100 proteins were up-regulated.The action of cuminaldehyde on Aspergillus flavus affects its biosynthesis and metabolic process,regulates the cell growth and development process,principal component on cell membrane and related transporter,The down-regulated protein was mainly involved the biosynthesis of conidial pigments,the main component of the cell membrane and its related transporter,cell cycle control protein,and affects the growth and development of spores;Up-regulated the sterol receptor proteina and plasma membrane glycosyltransferase.The action of cuminaldehyde on Aspergillus flavus regulates its transcriptional translation process,A comprehensive analysis of the transcriptome and proteome results revealed that the action of cuminaldehyde caused changes in the transcription and protein expression levels of the main components of the membrane and transport-related genes,Thereby affecting its physiological and biochemical metabolism and infection characteristics.3.Based on the analysis of transcriptome and proteomics data of Aspergillus flavus,it was preliminarily determined that the target of cuminaldehyde was the cell membrane,Therefore,research on the cell membrane development.The increase of intracellular ROS level under the action of cuminaldehyde was about three times that of the control group.Excessive accumulation of intracellular ROS can cause oxidative stress leading to lipid peroxidation,making the cell membrane permeability change,It inhibits the growth to a large extent.At the same time,quantitative analysis showed that the decrease of extracellular pH indicates that it can destroy the proton pump and affect the plasma membrane transport function;The extracellular conductivity increased by 13%,the intracellular K⁺and Na⁺release increased,and the nucleic acid protein leakage increased about 40 times that of the control group.Comprehensive description of the action of cuminaldehyde makes the membrane permeability of Aspergillus flavus change,affecting cell membrane transport,transmembrane transport and so on.The effects of purine on the biosynthesis of Aspergillus flavus ergosterol and AFB₁ were further studied by qRT-PCR.The results showed that cuminaldehyde down-regulated the transcriptional levels of Erg9,Erg24,Erg4 and other genes,reducing the biosynthesis of ergosterol?inhibition rate is 92.79%?;Down-regulation of the transcription levels of aflatoxin gene aflA,aflD,aflM,aflQ and transcriptional regulators aflS and aflR,which reduced the synthesis of AFB₁?inhibition rate was 95.54%?.The research topic may be to enable people to deepen the research on the growth inhibition effect of cuminaldehyde on Aspergillus flavus,and provide a theoretical basis for the development of new,natural and high-efficiency plant-derived bacteriostatic agents and mildew-preserving agents.