Studies On The Correlation Between Saccharification Power And Sporulation Of Aspergillus Niger In Vinegar Brewing And Amyiase Components Analysis Of Fuqu

Aspergillus niger is a kind of important fungi in fermentation industry.Having powerful amylase systems,Aspergillus niger could be used in the brewing of many kinds of vinegars as saccharifying agent alone or auxiliary saccharifying agent.And saccharifying power is also an important biochemical index of Aspergillus niger Fuqu.Aspergillus niger spores of Zhongqu is inoculated to sterile bran to making Fuqu by solid fermentation.The sporulation ability of Aspergillus niger is an important index affecting the quality of Zhongqu.In this paper,Aspergillus niger strains with different colony morphology and sporulation ability were isolated from Fuqu and then identified by molecular method;and the correlation between saccharifying power and sporulation ability was analyzed;the sporulation conditions of Aspergillus niger was optimized;the amylase components of Fuqu from Aspergillu niger were analyzed.The main results are as follows:In this study,10 Aspergillus strains were isolated from Fuqu by plate culture method,and all of them were identified as Aspergillus niger by colony characteristics18S r DNA sequence analysis method.The influence of different culture medium,such as modified CA,PDA and wheat bran extract medium,on the colony characteristics and sporulation ability of Aspergillus niger were compared.It was found that PDA made from fresh potato and wheat bran extract medium were favorable for spore formation.Compared with the spores Aspergillus niger,the highest number of spores was AW1（9.55×10⁹per gram）,followed by N3 and D11（9.35×10⁹per gram and8.97×10⁹per gram）,AY2 and AY1 were lower（4.13×10⁸per gram and 1.95×10⁸per gram）.The conidia head of AW1,N3,AY1and AY2 were compared by scanning electron microscope（SEM）.The conidia head of AW1 and N3 were large and tightness,and the conidia head of AY1 and AY2 were small and loose.Qualitative analysis of saccharifying power by hydrolytic circle was carried out on Modified CA medium at 30°C for 3 days,and it was found that hydrolytic circle was clearer after3 days after iodine staining.The hydrosphere/colony diameter ratios of AY1,and N3strains were higher,with the hydrosphere/colony diameter ratios were 2.364 and1.286.About DNS quantitative analysis,Aspergillus niger AY1,N3 and N1 were found to have higher saccharifying power,with the saccharification power were3158.2 U,2991.9 U and 1919.2 U,respectively.The qualitative and quantitative results of saccharifying power were consistent,but there was no significant correlation between saccharifying power and the number and color of Aspergillus niger spores.The effects of shaking flask,grain size,temperature,nitrogen source,inorganic salt and moisture on the sporulation of Aspergillus niger N3 were optimized.The results showed that the optimized condition for sporulation were as follows:Zhongqu were produced by wheat bran sieved by 40 mesh,the material-water ratio between10:9 and 10:13,without adding nitrogen source and inorganic salt,the culture was carried out at 36℃for 60 h,shaking the bottle every 10 hours or so until the end of fermentation,and the concentration of Zhongqu spores achieved 1.06×10¹⁰per gram under this conditions.From Aspergillus niger strains with higher saccharifying power,strain AY1 with the lowest sporulation and N3 with the higher sporulation were selected to underwent SDS-PAGE and Starch-PAGE electrophoresis.The results showed that the samples of Fuqu extractions from two strains had similar transparent bands.The transparent bands were cut and then identified by Mass Spectrometry（MS）to be about 1080peptides and 190 proteins.Among them,the protein G3Y7U0 and E3VX23 had the maximum unique peptide counts with 13,the two proteins had high reliability,and they belong to Glucoamylase（EC:3.2.1.3）from Aspergillus niger.This is consistent with their high saccharifying power.Protein A0A254UMA1 and F1C3F8 were next,and the number of unique peptide was 12 and 11,respectively.They were allα-amylase（EC:3.2.1.1）with high reliability.Protein A0A165CYJ5 was also alpha-amylase,but the number of unique peptide was 3,which was less than the former,they all come from Aspergillus niger.In addition,there are six proteases involved in glucose metabolism derived from Aspergillus niger.Once again,it provided the support of higher saccharification power from molecular level.