Analysis Of Heat-stress Metabolites Of Aspergillus Niger

Aspergillus niger is an important industrial microorganism with great application potential.Many products produced by fermentation have important application value in industrial production.Due to the increase of temperature during industrial production,the fermentation process of Aspergillus niger is affected.Many scholars have turned their attention to the research on the relative heat resistance of Aspergillus niger.In this study,Aspergillus niger 3.316 was used as a test object to study its thermotolerance mechanism at the metabolomic level after high temperature stress.The differential metabolites of Aspergillus niger at three temperatures before and after stress were compared to find the metabolites of heat stress and their major metabolic pathways.The specific findings are as follows:1.Comparison of the physiological changes of Aspergillus niger at 30?,40?,and 50? in different culture conditions of solid medium and liquid medium,and the hyphae balls of Aspergillus niger mycelia under liquid culture,comparison of density,diameter,and dry weight conditions.The results showed that the number of spores on the mycelia of Aspergillus niger showed a decreasing trend with the increase of the temperature of heat stress,but the mycelium still had cell activity after heat stress.The density of mycelial ball decreased with the increase of temperature,and the individual size also showed a trend of decreasing.The dry weight of mycelial ball also decreased gradually with the increase of temperature.2.Samples required for subsequent experiments were obtained by treating cultures of Aspergillus niger mycelia at heat stress temperature gradients of 30?,40?and 50?for 6 h,12 h and 24 h.The method of cell disruption was then investigated by ultrasonic disruption and liquid nitrogen milling and crushing,and metabolites were examined.The results showed that there were almost no visible peaks under the negative ions of the mass spectrum detected under the ultrasonic disruption cell method,and the visible peaks under the positive ions were rare and the peak intensity was weak;however,for the liquid nitrogen grinding and crushing method,the mass spectrum detected in the positive and negative ion modes was found.There are more peaks and the peak intensity is appropriate.Afterwards,liquid nitrogen was used to grind and crush.3.The use of liquid chromatography-mass spectrometry(LC-MS)technology for the analysis and detection of intracellular metabolic products under different groups,combined with multivariate statistical analysis of the principal component analysis(PCA)and partial least squares analysis(PLS-DA)and the univariate analysis in the multiple test and T test for the analysis of metabolic product identification,and then the P-value <0.05 of the metabolites were selected,from which to get 77 kinds of metabolites,and divided into eight categories These include blood lipids,fatty acids,saturated fatty acids,nucleic acids,nucleosides,carbohydrates,monosaccharides,and uronic acids.Based on the KEGG database analysis of metabolic pathways under three different heat stress times,it was found that there were 2,25,and 10 pathways annotated in KEGG at 6 h,12 h,and 24 h,respectively.