Candida Oleophila Proliferated and Accelerated Accumulation of Suberin Poly Phenolic and Lignin at Wound Sites of Potato Tubers

Candida oleophila is a type of biocontrol yeast offering effective postharvest disease control. To the best of our knowledge, the effect of C. oleophila upon the healing of tubers is yet to be studied. The present study addresses the existing knowledge gap by investigating the effect of C. oleophila on wound healing in potato tubers. The results show that C. oleophila colonized and proliferated at the wound sites during the early and intermediate stages of healing. In addition, C. oleophila reduced weight loss of wounded tubers, decreased disease index of inoculated tubers with Fusarium sulphureum, and accelerated accumulation of suberin poly phenolic (SPP) and lignin at wound sites. C. oleophila activated phenylpropanoid metabolism and increased the content of SPP monomers, total phenol, flavonoids, and lignin. Furthermore, the yeast increased H2O2 content as well as peroxidase activity.

Citric Acid Production of Yeasts: An Overview

Background Citric acid, an intermediate product of the Krebs cycle, has a wide usage area in the food industry since it has some functions such as acidulant, flavouring agent, preservative and antioxidant. Although molds are the most commonly used microorganisms in the citric acid production, it is known that there are significant advantages of using yeasts. Purpose and scope The microbial citric acid production mechanism needs to be well understood to make production more efficient. In this study, the yeasts used in the production, fermentation types and the factors affecting production were reviewed with studies. Methodology Although production of citric acid can be produced by chemical synthesis, the fermentation is preferred because of its low cost and ease of use. More than 90% of citric acid produced in the world is obtained by fermentation. Results Yarrowia lipolytica, Candida zeylanoides and Candida oleophila are evaluated for citric acid production with substrates such as molasses, glucose, sucrose and glycerol. On the other hand, there is great interest in developing processes with new substrates and/ or microorganisms. Conclusion Although the microbial strain is an important factor, the factors such as carbon, phosphorus and nitrogen sources, aeration, the presence of trace elements and pH are also parameters affecting the production.

Biocontrol yeasts: mechanisms and applications

Yeasts occur in all environments and have been described as potent antagonists of various plant pathogens. Due to their antagonistic ability, undemanding cultivation requirements, and limited biosafety concerns, many of these unicellular fungi have been considered for biocontrol applications. Here, we review the fundamental research on the mechanisms (e.g., competition, enzyme secretion, toxin production, volatiles, mycoparasitism, induction of resistance) by which biocontrol yeasts exert their activity as plant protection agents. In a second part, we focus on five yeast species (Candida oleophila, Aureobasidium pullulans, Metschnikowia fructicola, Cryptococcus albidus, Saccharomyces cerevisiae) that are or have been registered for the application as biocontrol products. These examples demonstrate the potential of yeasts for commercial biocontrol usage, but this review also highlights the scarcity of fundamental studies on yeast biocontrol mechanisms and of registered yeast-based biocontrol products. Yeast biocontrol mechanisms thus represent a largely unexplored field of research and plentiful opportunities for the development of commercial, yeast-based applications for plant protection exist.

Botrytis cinerea Pers. in postharvest apple fruit, control with Candida oleophila Montrocher strains and/or synthetic fungicides

As an alternative control method, to improve control and to reduce synthetic fungicide use, three Candida oleophila strains and/or four commercial synthetic fungicides were used to control Botrytis cinerea damage on postharvest apple fruit. Synthetic commercial fungicides; Cyprodinil+Fludioxonil, Thiabendazole and Benomyl, allowed Candida oleophila strains colony growth when challenged to the pressure of these fungicides. Synthetic commercial fungicide Captan did not allow any Candida oleophila strains colony growth. Control of Botrytis cinerea expressed in % of damage and damage reduction, gave an average control of; 100% for Cyprodinil+Fludioxonil; Captan, 97.5%; Thiabendazole, 94.1% and Benomyl, 93.7% All Candida oleophila strains, individually, gave a 100% control. Thiabendazole and Benomyl improved their efficiency to control Botrytis cinerea when combined with Candida oleophila. Control of Botrytis cinerea damage on postharvest Golden Delicious apple fruit can be achieved up to 100% either with Candida oleophila strains individually and/or with Cyprodinil+Fludioxonil alone. The use of Candida oleophila as an alternative method to control Botrytis cinerea damage on postharvest apple fruit means a reduction of synthetic fungicide use, plus avoiding fungicide residues on the treated apple fruit and on the environment, thus reducing the risk for human health damage.