Inhibitory Effect of PgAFP and Protective Cultures on Aspergillus parasiticus Growth and Aflatoxins Production on Dry-Fermented Sausage and Cheese

Abstract

Aflatoxigenic molds can grow and produce aflatoxins on dry-fermented meat and cheese. The small, basic, cysteine-rich antifungal protein PgAFP displays a time-limited inhibitory ability against unwanted molds by increasing reactive oxygen species (ROS), which can lead to increased aflatoxin production. However, calcium abolishes the inhibitory effect of PgAFP on certain Aspergillus spp. To maximize the antifungal effect, this protein may be combined with protective cultures. Yeasts and lactic acid bacteria may counteract the impact of calcium on PgAFP fungal inhibition. The objective of this work was to study the effect of PgAFP and different combined treatments with Debaryomyces hansenii and/or Pediococcus acidilactici against growth of and aflatoxin production by an aflatoxigenic strain of Aspergillus parasiticus in both culture media and dry-fermented foods with low or high calcium levels. Aflatoxins production was increased by PgAFP but dramatically reduced by P. acidilactici in low calcium culture medium, whereas in the Ca-enriched culture medium, all treatments tested led to low aflatoxins levels. To study whether PgAFP and the protective microorganisms interfere with ROS and aflatoxin production, the relative expression of genes foxA, which is involved in peroxisomal β-oxidation, and aflP, which is required for aflatoxin biosynthesis, were evaluated. The aflatoxin overproduction induced by PgAFP seems not to be linked to peroxisomal β-oxidation. The combination of PgAFP and D. hansenii provided a successful inhibitory effect on A. parasiticus growth as well as on aflatoxin production on sliced dry-fermented sausage and cheese ripened up to 15 days, whereas P. acidilactici did not further enhance the protective effect of the two former agents. Therefore, the combined treatment of PgAFP and D. hansenii seems to provide a promising protective mean against aflatoxin-producing A. parasiticus on dry-fermented foods.

Biofungicidal Potential of Neosartorya (Aspergillus) Fischeri Antifungal Protein NFAP and Novel Synthetic γ-Core Peptides

“…Different APs from Penicillium or Aspergillus spp. can effectively inhibit the growth of several plant pathogens (Vila et al, 2001;Moreno et al, 2003Moreno et al, , 2006Theis et al, 2005;Barna et al, 2008;Garrigues et al, 2018;Tóth et al, 2020) and foodborne and postharvest mycotoxigenic fungi (Barakat et al, 2010a,b;Delgado et al, 2015Delgado et al, , 2017Delgado et al, , 2018Garrigues et al, 2016). Topical application of the Aspergillus giganteus AP (AFP) (Moreno et al, 2003) and the Penicillium chrysogenum AP (PAF) (Barna et al, 2008) on plant leaves proved to protect Pelargonium, barley and wheat, respectively, against fungal pathogens without causing any detrimental effects to the host.…”

“…Topical application of the Aspergillus giganteus AP (AFP) (Moreno et al, 2003) and the Penicillium chrysogenum AP (PAF) (Barna et al, 2008) on plant leaves proved to protect Pelargonium, barley and wheat, respectively, against fungal pathogens without causing any detrimental effects to the host. Laboratory studies further demonstrated that the AFP (Barakat et al, 2010a) and the P. chrysogenum AP (PgAFP) (Delgado et al, 2018) decreased the level of mycotoxin contamination caused by Fusarium species and Aspergillus parasiticus on stored barley and dry-fermented food products, respectively. Furthermore, expression systems using generally recognized as safe (GRAS) microorganisms, such as Pichia pastoris (López-García et al, 2010;Virágh et al, 2014) and P. chrysogenum (Sonderegger et al, 2016;Garrigues et al, 2018;Tóth et al, 2018), are already available to produce correctly folded and functional APs in high amounts.…”

Selection and Evaluation of Staphylococcus xylosus as a Biocontrol Agent against Toxigenic Moulds in a Dry-Cured Ham Model System

“…Among the different antifungal strategies, one of the most promising for dry-cured meat products is the use of microorganisms usually found in them as bioprotective agents. In this sense, several yeasts [12,[24][25][26][27][28], non-toxigenic moulds [25,[29][30][31], and lactic acid bacteria [32,33] have shown their capacity to reduce the development of toxigenic moulds and decrease mycotoxins production and they have been proposed as potential protective cultures in dry-cured meat products. However, the possibility of using gram-positive, catalase-positive cocci (GCC+) in dry-cured ham has not been evaluated yet.…”

Insights into existing and future fungal and mycotoxin contamination of cured meats

“…D. hansenii has also been shown to stimulate AFB1 production by A. parasiticus at 0.99 aw, and conversely a reduction of aflR and aflS gene expression and toxin at 0.92 aw in the meat-model system, in dry-cured ham and dryfermented sausage slices [86]. The combination of PgAFP with D. hansenii provided a successful inhibitory effect on A. parasiticus growth as well as on aflatoxin production on sliced dry-fermented sausages [89]. Saccharomycopsis fibuligera and D. hansenii were tested against Aspergillus ochraceus and P. nordicum during speck production [90] and OTA was not detected.…”