Effect of Bacillus spp. on Aspergillus westerdijkiae growth, sporulation and ochratoxin A production in green-coffee medium

Abstract

Aspergillus westerdijkiae is one of the most important spoilage and toxigenic fungi contaminating coffee beans and may produce ochratoxin A (DTA), a mycotoxin that characterize a health risk to the coffee consumers. Biological control strategies can be used for prevention of fungal invasion and decrease mycotoxin exposure. The aims of this study were to evaluate the in vitro effect of three Bacillus sp. biocontrol candidates on A. westerdijkiae mycelial growth, spore counts and DTA production. A green-coffee based medium was inoculated with A. westerdijkiae and Bacillus spp. (B. safensis RF69, B. amyloliquefaciens RP103 and B. subtilis RP242) and after incubation, the fungal growth, sporulation and mycotoxin production was evaluated. Mycelial growth rate was reduced in a range between 76-95% and conidial production was also significantly decreased. All isolates were capable of reducing DTA production in a range between 62-96%. The results showed that the biocontrol candidates may be an effective control method for A. westerdijkiae and DTA in coffee.Keywords: biological control; food mycology; mycotoxins; fungi; food safety. Practical Application:Intense inhibition of A. westerdijkie by Bacillus spp. in a coffee-based medium.

Growth and toxin production of phomopsin A and ochratoxin A forming fungi under different storage conditions in a pea (Pisum sativum) model system

“…In the present study, A. westerdijkiae MUCL 39539 OTA concentration in unautoclaved peas after 14 days ranged from approximately 100 µg/kg to approximately 1.2 mg/kg, which is much lower than the values for autoclaved peas that ranged between 1.44 g/kg and 3.35 g/kgboth at an a w value of 0.98. Inhibition of OTA production through microflora has also been observed with both with fungal microflora (strain NRRL 3174;Chelack et al 1991) and bacterial flora consisting of various Bacillus species (strain NRRL 3174 and another strain isolated from green coffee; Petchkongkaew 2008;Einloft et al 2017).…”

“…A. westerdijkiae was formerly assigned to Aspergillus ochraceus (Frisvad et al 2004). The saprophytic fungus grows and produces OTA on multiple substrates: cereal grains (Aldred et al 2008;Ramos et al 1998;Pardo et al 2004), fruit (Marino et al 2009), coffee (Akbar et al 2020;Einloft et al 2017;Gil-Serna et al 2015), and dried meat products such as ham and salami (Iacumin et al 2020;Vipotnik et al 2017;Meftah et al 2018;Parussolo et al 2019). Even though growth and OTA production of this fungus was not investigated in grain legumes yet, Aspergillus section Circumdati are present in grain legumes samples and products thereof.…”

The Potency of Bacillus siamensis LDR as Biocontrol Agent Against Fungal Phytopathogen

“…The antagonistic activity was done using dual culture method with streak [11,12] and pour plate technique [13,14] on PDA medium. In streak technique, B. siamensis LDR was streaked on PDA medium then the fungal phytopathogen, Fusarium sp., Ganoderma sp., and Chaetomium globosum InaCC F228 were inoculated 4 cm beside the bacteria.…”