Survey of yeasts for antagonistic activity against Salmonella Poona in cantaloupe juice and wounds in rinds coinfected with phytopathogenic molds

Application of yeasts as biocontrol agents to prevent mold decay of fruits and vegetables has been described. We examined 10 yeasts for potential antagonistic activity against survival and growth of Salmonella Poona in cantaloupe juice and decay by Cladosporium cladosporioides and Geotrichum candidum in wounds on cantaloupe rind. Cantaloupe juice was inoculated using five schemes: Salmonella Poona only (1.10 log CFU/ml), high (3.93 to 5.21 log CFU/ml) or low populations (1.79 to 3.26 log CFU/ml) of yeasts only, and Salmonella Poona combined with high or low populations of yeasts. High initial populations of Debaryomyces hansenii, Pichia guilliermondii, and Pseudozyma sp. were antagonistic to Salmonella Poona in cantaloupe juice stored at 20 degrees C for 48 h. Wounds in cantaloupe rinds were inoculated with yeast and mold or yeast, mold, and Salmonella Poona, and cantaloupes were stored at 4 degrees C for 14 days or 20 degrees C for 7 days. The pH of rind tissue inoculated with C. cladosporioides and yeasts increased significantly (P < or = 0.05) at 20 degrees C. Wounds that were inoculated with P. guilliermondii, together with C. cladosporioides or G. candidum, did not show mold growth at 4 and 20 degrees C. Populations of Salmonella Poona (6.40, 7.26, and 7.98 log CFU per sample) were lower in wounds coinoculated with G. candidum and three of the test yeasts (D. hansenii, P. guilliermondii, and Cryptococcus albidus, respectively) compared to coinoculation with G. candidum or the other seven yeasts. Candida oleophila and Rhodotorula glutinis showed the most promise in reducing the population of Salmonella Poona in wounds in rinds of cantaloupes coinoculated with G. candidum and stored at 4 degrees C.