Cocoa‐associated filamentous fungi for the biocontrol of aflatoxigenic Aspergillus flavus
Date
2023
Journal Title
Journal ISSN
Volume Title
Publisher
Journal of Basic Microbiology
Abstract
Aflatoxin and other mycotoxin contamination are major threats to global food
security and present an urgent need to secure the global food crop against
spoilage by mycotoxigenic fungi. Cocoa material is noted for naturally low
aflatoxin contamination. This study was designed to assess the potential for
harnessing cocoa‐associated filamentous fungi for the biocontrol of aflatoxigenic Aspergillus flavus. The candidate fungi were isolated from fermented
cocoa beans collected from four cocoa‐growing areas in Ghana. Molecular
characterization included Internal Transcribed Spacer (ITS)‐sequencing for
identification and polymer chain reaction (PCR) to determine mating type.
Effects of the candidate isolates on growth and aflatoxin‐production by an
aflatoxigenic A. flavus isolate (BANGA1) were assessed. Aflatoxin production
was monitored by UV fluorescence and quantified by enzyme‐linked
immunosorbent assay (ELISA). Thirty‐six filamentous fungi were cultured
and identified as Aspergillus, Cladosporium, Lichtheimia, or Trichoderma spp.
isolates. The isolates generally interacted negatively with BANGA1 growth
and aflatoxin production. The Aspergillus niger and Aspergillus aculeatus
biocontrol candidates showed the strongest colony antagonism (54%–94%) and
reduction in aflatoxin production (12%–50%) on agar. In broth, the A. niger isolates reduced aflatoxin production by up to 97%. Metabolites from the A.
niger isolates showed the strongest inhibition of growth by BANGA1 and
inhibited aflatoxin production. Four of the candidate isolates belonged to the
MAT1‐1 mating type and 12 identified as MAT1‐2. This may be indicative of
the potential for genetic recombination events between fungi in the field, a
finding which is particularly relevant to the risk posed by A. flavus biocontrol
measures that rely on atoxigenic A. flavus strains.
Description
Research Article
Keywords
aflatoxins, antagonism, Aspergillus flavus, Aspergillus niger, biocontrol