Ozone reduces the fruit decay of postharvest winter jujube by altering the microbial community structure on fruit surface

Author:Yang Zhang , Md. Mahidul Islam Masum , Congcong Gao , Yudou Cheng , Junfeng Guan

Microbial community structure on fruit surface plays an important role in fruit decay during postharvest storage,
      although the underlying mechanism has not been fully elucidated. Winter jujube (Ziziphus jujuba Miller cv.
      Dongzao) is a unique fruit resource with high edible and commercial value in China, while postharvest decay has
      always been a severe problem leading to short shelf life and poor quality of fruit. Ozone treatment is regarded as
      one of the most effective means to control decay and extend shelf life because of its cost-effective and ecofriendly properties. In the present study, three concentrations of ozone (2.5, 5 and 10 μL L− 1
      ) were found to
      reduce significantly postharvest decay of winter jujube on days 10 and 15, which were produced from Huanghua
      City, Hebei, China. High-throughput sequencing revealed significant changes in the bacterial and fungal communities in response to the application of ozone treatment, while Didymella, Rhizopus, Alternaria, Phialemoniopsis
      and Mycosphaerella were found to be the most abundant in fungi, and Methylobacterium, Pseudomonas, Pantoea,
      Sphingomonas and Gluconobacter being the most abundant in bacteria. Results of linear discriminant analysis
      (LDA) effect size (LEfSe) indicated that ozone treatments considerably reduced the abundance of Rhizopus and
      Gluconobacter on the surface of winter jujube fruit. Furthermore, Pearson correlation analysis showed that
      Rhizopus was positively correlated with Gluconobacter (r = 0.97) while negatively correlated with Didymella (r =
      − 0.96). By predicting the metabolic function, ozone may inhibit metabolic pathways including nucleoside and
      nucleotide biosynthesis, amino acid biosynthesis, fatty acid and lipid degradation, respiration, and electron
      transfer, thereby reducing the incidence of fruit decay and maintaining the firmness of winter jujube fruit.

Key words:Ozone ,Jujube ,Microbial,community ,Firmness ,Decay