While some fungi (molds or yeasts) such as Candida, Aspergillus, Histoplasmosis, and Cryptococcus can cause life threatening infections, other fungi (beneficial yeasts) are useful in biocontrol for preventing/ controlling growth of more pathogenic Fungal and Bacterial species in plants and animals 1.
What are the advantages of Yeasts for Biocontrol?
Single cell yeast fungi are especially useful for biocontrol applications since they can be quickly and economically grown in bioreactors/ fermenters and disseminated/ applicated in liquid media 1. Beneficial yeasts can form biofilms which help to crowd out more harmful bacteria and fungi 1. Enzymes produced by beneficial yeasts can also help control bacterial and fungal growth 1. Four yeasts which are now commercially employed to prevent plant diseases include the following:
Candida oleophilia was the first yeast to be developed as a plant fungi biocontrol agent 1. It is used extensively in apple and pear production to prevent harmful fungal growth.
The saphyrophytic ascomycete Aureobasidium pullulans has been used to protect against fireblight disease caused by the bacteria Erwinia amylovora. Aureobasidium pullulans (in Blossom-Protect®) has be used to prevent storage and rot disease in a number of crops including strawberries, plums, and cherries 1.
Metschnikowia Fructicola are yeasts have been used to control a wide range of fungal and bacterial plant rot diseases in a wide range of crops including sweet potato, carrot, peaches, strawberries, and grapes 1.
Saccharomyces Cerevisiae are common yeasts. In human, oral preparations have been associated with significantly reduced risk of the life threatening pathogen Clostridium difficile A review of 6 published studies reported that use of oral Saccharomyces cerevisiae was associated with a 41% significantly reduced risk of Clostridium difficile related diarrhea (RR= 0.59, 95% CI 0.41-0.85, p =0.005) 2. In plant protection, Saccharomyces cerevisiae and its extracts have a broad range of activity against many fungal pathogens such as multiple Aspergillus species, multiple Fusarium species, Sclerotium, Botrytis, and Rhizoctonia. Romeo ® is a plant protection agent made from cell wall extracts of Saccharomyces cervisiae and is used to treat a wide range of vegetables and fruits including grapes 1.