N-Acetylglucosamine As A Booster:Inducing Rhodosporidium Paludigenum To Enhance The Inhibition Of Penicillium Expansum

Fruits face a great threat of pathogens in the postharvest stage,which becomes more unignorable over time.Among the many methods to deal with postharvest decay of fruits,biocontrol is considered to be irreplaceable and effective.This research aimed to improve the biocontrol ability of Rhodosporidium paludigenum.Including the antagonistic ability to pathogenic fungus Penicillium expansum in vivo and in vitro,they have ability to survive under heterogeneous stress environments.The fluctuations in physiological indicators of anti-oxidative stress and intracellular amino acids were evaluated to explore the mechanism initially.The key gene of its biocontrol capabilities has been discovered through bioinformatics and biomolecular technology.The different strains of zebrafish helped to evaluate the feasibility of yeast as a biological control agent.The main research results of this subject are as follows:1.R.paludigenum evinced potential antagonism to P.expansum in vivo and in vitro,due to the ancillary supplement of 0.1% N-acetylglucosamine or 2% sodium glutamate.Meanwhile,additives-induced R.paludigenum was also exhibited predominant tolerance under various stress conditions.2.It was also found that manifold antioxidant-related enzymes were up-regulated after adding 0.1% N-acetylglucosamine or 2% sodium glutamate,which might prompt one of the possible mechanisms for SG to stimulate yeast.The reactive oxygen species and amino acids did not change significantly with the treat of 0.1% Nacetylglucosamine.However,an addition of 2% sodium glutamate caused an outbreak of the reactive oxygen species in the later stage.Threonine,glutamic acid,alanine and arginine also increased significantly,which may also be a reason for yeasts to improve its defense ability.3.By comparing the transcriptome data of the R.paludigenum obtained from a normal synthetic medium and an additional 0.1% N-acetylglucosamine medium,Tpo1 is one of the key genes for yeast to enhance its biocontrol effect.Tpo1 was analyzed and predicted the function as well.4.Saccharomyces cerevisiae heterologously expressing Tpo1 had been verified to show better biocontrol effects than wild-type Saccharomyces cerevisiae.Tpo1 could improve the vitality and stress resistance of Saccharomyces cerevisiae according to the yeast biomass and cell mortality under stress.It is inferred that Tpo1 can reduce toxin damage by eliminating patulin since the concentration of patulin in the recombinant cells is also lower.6.Recombinant yeast did not appear to have an additional effect on the initial development or survival rate of zebrafish in the safety evaluation.Yeast has an alleviating effect on the poisoned zebrafish caused by patulin.