| Saccharomyces cerevisiae is one of the important applied microorganisms in foodindustry.Promoting its proliferation and enhancing its fermentative performancewere required by brewing industry.The addition of polypeptides into yeast culturemedium could significantly promote its proliferation and enhance its fermentati-veperformance.Therefore,it is a research focus to expose polypeptides which canefflciently promote proliferation and enhance fermentative performance in brewingindustry.Some shellfish lectins could agglutinate yeast and promote its proliferation.Therefore,these shellfish lectins will become potential polypeptides to adjust S.cerevisiae proliferation and metabolism.In this study,proteomics and metabolomics were applied to discover the interation of lectin from Cyclina sinensis(CSL)with S.cerevisiae.The main results are as follows:(1)CSL could bind to peptidoglycan from S.cerevisiae cell wall.The combination was concentration-dependent and inhibited by D-mannose and N-acetyl-D-galactosamine.The interaction of CSL with S.cerevisiae cell wall resulted in yeast surface area changing.The increasing ethanol production by S.cerevisiae treated withCSL may not be related to the intracellular calcium pathway.(2)The changes in the protein expression profiles of S.cerevisiae after 24 h of incubation with CSL were analyzed using label-free quantitative proteomics.A total of 1410 proteins were identified,but only 117 proteins showed significant differences in normalized volume(p<0.05).Among these proteins,24 proteins were up-regulated,and 93 were down-regulated.Analysis of the proteome revealed that CSL triggered increasedexpress of hexokinase,glyceraldehyde 3-phosphate dehydrogenase as well as enolase,and decreased express of dihydrolipoamide dehydrogenase,citrate synthase,aldehyde dehydrogenase as well as malate synthase.The 3 increased and 4 decreased enzymes indicated that the ability of S.cerevisiaes to produce ethanol increased by CSL affecting Embden-Meyerhof Pathway(EMP)and tricarboxylic acid(TCA)in S.cerevisiaes.(3)Samples of S.cerevisiaes cultured with CSL(T group)and without(C group)were analysed using Q-TOF mass spectrometer coupled to UHPLC on a HILIC column in the full survey scan.The MS/MS data were generated using Information Dependent Acquisition(IDA).The ion chromatogram peaks were picked and the metabolites were identified using XCMS software.The results showed that the response intensity and retention time of each chromatogram peak overlapped basically in T group and C group,which means better parallel in the two groups.Principle component analysis(PCA)was performed with T group and C group.In positive and negative ions modes,the data of PC1 and PC2 have obvious separation trend.The results of orthogonal partial least squares discrimination analysis(OPLS-DA)models showed that the models could well distinguish between T group and C group metabolites.The figures of volcano plot of the data in positive and negative ions modes showed that the screened metabolites from T group had significant differences compared from C group(FC>2.0 and p<0.05).There were 98 significantly different metabolites in T group compared to C group(p<0.05)in positive ions modes,in which 55 metabolites were increased and 43 were decreased.And 79 significantly different metabolites in negative ions modes(p<0.05),in which 64 were increased and 15 were decreased.The results of increased a-D-glucose and D-glucose-6-phosphate in T group compared to C group showed that CSL promoted glycolysis in S.cerevisiaes.Nicotinamide adenine dinucleotide(NAD+),L-malic acid and L-aspartate were also significantly increased,which could accelerate the change between NAD+ and NADH inside and outside the mitochondrial membrane,resulting in less rate of TCA than that of EMP,and thus producing more ethanol.Gutathione(GSH)was a concomitant product during ethanol fermentation,and the content of GSH increased with the ethanol producing.In conclusion,CSL could affect EMP and TCA in S.cerevisiaes to produce more ethanol. |
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