Biocontrol ability of marine yeasts against postharvest diseases in mangos caused by Colletotrichum gloeosporioides and Lasiodiplodia theobromae

Anthracnose and stem-end rot are among the most devastating pathogens affecting mangos, leading to significant losses due to rotting during storage. This study aimed to investigate marine strains' potential as biocontrol agents against the postharvest pathogenic fungi Colletotrichum gloeosporioides and Lasiodiplodia theobromae. A total of 415 marine yeast strains isolated from marine environments were evaluated for their antifungal activities against C. gloeosporioides and L. theobromae using a dual culture method. Out of these, 115 yeast strains were found to inhibit the growth of C. gloeosporioides, while 31 strains inhibited the growth of L. theobromae. Among these yeast strains, only eighteen proved effective against both pathogenic fungi. The strains Meyerozyma guilliermondii ARU3232-1 and Pichia kudriavzevii DMKUJC44-2 demonstrated the most significant inhibition of radial mycelial growth. The production of volatile organic compounds (VOCs) showcased an in vitro inhibitory effect on the growth of both C. gloeosporioides and L. theobromae. However, assays testing the production of cellulase, chitinase, pectinase and protease by these antagonistic yeasts yielded negative results. Additionally, there was no observed Fe3+ binding competition between the yeast and mold. M. guilliermondii ARU3232-1 showed strong biofilm formation, while P. kudriavzevii DMKUJC44-2 demonstrated moderate biofilm formation. In vivo assays indicated that M. guilliermondii ARU3232-1 reduced anthracnose disease severity by 71 +/- 3%, whereas P. kudriavzevii DMKUJC44-2 decreased stem-end rot severity by 61 +/- 3%. Therefore, both antagonist marine yeasts have the potential to be used as biocontrol agents against anthracnose and stem-end rot diseases of mango fruits.