Antifungal and biocontrol potential of <i>Rhodotorula</i> carotenoid pigments against mycotoxigenic <i>Aspergillus</i> species in cereal-based infant foods

Abstract This study investigated the occurrence of fungal contaminants in commercially available cereal-based infant foods and explored the potential of pigmented Rhodotorula yeast isolates as natural antifungal agents. A total of six fungal isolates were recovered from corn-, rice-, and wheat-based infant foods, representing four genera: Aspergillus (A. niger, A. versicolor, A. terreus), Mucor, Rhizopus, and Saccharomyces cerevisiae. Toxigenicity assays revealed that A. versicolor and A. niger produced mycotoxins, while aflatoxin quantification via HPLC detected total aflatoxin concentrations ranging from 0.56 ± 0.04 µg/g to 9.20 ± 0.02 µg/g across the samples.100 environmental samples yielded 23 pigmented yeasts, from which three distinct Rhodotorula strains (YP1, YP2, YP3) were selected based on robust pigment production and growth characteristics. Carotenoid pigments were extracted using acetone and petroleum ether, with storage optimised under dark conditions at 4°C. Protein profiling by SDS-PAGE revealed that all three yeast isolates shared similar banding patterns. Antifungal activity of the yeast-derived pigments against toxigenic Aspergillus isolates shows YP3 exhibited the strongest inhibition, producing zones of 21 mm against A. versicolor and 19 mm against A. niger, more than antifungal agents (fluconazole, ketoconazole, itraconazole, amphotericin B), which showed limited activity (1–5 mm inhibition zones).