Investigation of Pseudomonas fluorescens strain 3JW1 on preventing and reducing aflatoxin contaminations in peanuts.

Xiaona Yang,Peiwu Li,Qi Zhang,Zhi-Yuan Chen,Hongxia Liu,George-John Nychas

doi:10.1371/journal.pone.0178810

Abstract

Pseudomonas fluorescens strain 3JW1, which has a broad-spectrum antimicrobial activity, was studied to investigate whether it affects the amounts of aflatoxin B1 (AFB1) produced by Aspergillus flavus. It was found that the bacterium reduced the amounts of AFB1 in potato dextrose broth (PDB) and peanut medium by 97.8% and 99.4%, respectively. It also reduced AFB1 by ~183 μg/kg (55.8%) when applied onto peanut kernels. This strain reduced AFB1 via three mechanisms. First, it significantly inhibited A. flavus growth; second, our data showed that strain 3JW1 inhibits aflatoxin biosynthesis by A. flavus; and third, P. fluorescens strain 3JW1 is capable of degrading AFB1 at a rate as high as 88.3% in 96 hours. This is the first report demonstrating that Pseudomonas fluorescens can reduce toxin contamination caused by A. flavus on peanut kernels. Our findings indicate that P. fluorescens strain 3JW1 had multiple effects including reducing A. flavus infection and aflatoxin contamination. And the results also highlight the potential applications of the strain 3JW1 for the biological control of aflatoxin contamination in peanuts and other susceptible crops.

Highlights

Aspergillus flavus belongs to Aspergillus Section Flavi
The present study aimed to investigate the efficacy of a previously isolated Pseudomonas fluorescens strain 3JW1 in reducing aflatoxin B1 (AFB1) produced by A. flavus, and to explore the potential of applying P. fluorescens strain 3JW1 to reduce AFB1 in peanuts
When A. flavus and other strains were cultured together in potato dextrose broth (PDB), the results showed that E. coli in the culture had no effect on AFB1 production

Summary

Introduction

Peanuts are usually threatened by pre-harvest infection of A. flavus and A. parasiticus when their fruits are tender or wounded and encounter rainy days at about 22–35 ̊C and by inadequate storage conditions with relatively high moisture (over 85%) and temperature (over 22 ̊C), which are often two of the main contributing factors that lead to moldy peanuts, reduced seed viability and increased seed rot [11, 14]. For these reasons, determining how to effectively reduce A. flavus infection and subsequent aflatoxin contaminaiton has extremely important theoretical and practical significance. The efficacy of this strain in suppressing aflatoxin contamination in peanut and on degrading AFB1 was investigated

Materials and methods

Methods

Results and discussions