Open AccessVariation in fungal microbiome (mycobiome) and aflatoxins during simulated storage of in-shell peanuts and peanut kernels
Author(s) -
Fuguo Xing,
Ning Ding,
Xiao Liu,
Jonathan Nimal Selvaraj,
Limin Wang,
Lu Zhou,
Yang Zhao,
Yan Wang,
Yang Liu
Publication year - 2016
Publication title -
scientific reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.24
H-Index - 213
ISSN - 2045-2322
DOI - 10.1038/srep25930
Subject(s) - biology , rhizopus , aflatoxin , food science , internal transcribed spacer , water activity , aspergillus , aspergillus flavus , rhizopus oryzae , mycotoxin , botany , water content , biochemistry , fermentation , ribosomal rna , gene , geotechnical engineering , engineering
Internal transcribed spacer 2 (ITS2) sequencing was used to characterize the peanut mycobiome during 90 days storage at five conditions. The fungal diversity in in-shell peanuts was higher with 110 operational taxonomic units (OTUs) and 41 genera than peanut kernels (91 OTUs and 37 genera). This means that the micro-environment in shell is more suitable for maintaining fungal diversity. At 20–30 d, Rhizopus , Eurotium and Wallemia were predominant in in-shell peanuts. In peanut kernels, Rhizopus (>30%) and Eurotium ( > 20%) were predominant at 10–20 d and 30 d, respectively. The relative abundances of Rhizopus , Eurotium and Wallemia were higher than Aspergillus , because they were xerophilic and grew well on substrates with low water activity ( a w ). During growth, they released metabolic water, thereby favoring the growth of Aspergillus . Therefore, from 30 to 90 d, the relative abundance of Aspergillus increased while that of Rhizopus , Eurotium and Wallemia decreased. Principal Coordinate Analysis (PCoA) revealed that peanuts stored for 60–90 days and for 10–30 days clustered differently from each other. Due to low a w values (0.34–0.72) a nd low levels of A. flavus , nine of 51 samples were contaminated with aflatoxins.