Bioprotective Role of Yeasts

Abstract

The yeasts constitute a large group of microorganisms characterized by the ability to grow and survive in different and stressful conditions and then to colonize a wide range of environmental and human ecosystems. The competitive traits against other microorganisms have attracted increasing attention from scientists, who proposed their successful application as bioprotective agents in the agricultural, food and medical sectors. These antagonistic activities rely on the competition for nutrients, production and tolerance of high concentrations of ethanol, as well as the synthesis of a large class of antimicrobial compounds, known as killer toxins, which showed clearly a large spectrum of activity against food spoilage microorganisms, but also against plant, animal and human pathogens. This review describes the antimicrobial mechanisms involved in the antagonistic activity, their applications in the processed and unprocessed food sectors, as well as the future perspectives in the development of new bio-drugs, which may overcome the limitations connected to conventional antimicrobial and drug resistance.

Yeasts from Different Habitats and Their Potential as Biocontrol Agents

“…The yeast has been extensively studied for applications against postharvest spoilage molds [15,25] and for wine biotechnology [32]. W. anomalus and other yeasts produce various volatile organic compounds (VOC), and the biocontrol activities of these microorganisms have been mainly ascribed to the action of ethyl acetate [11,50]. Furthermore, W. anomalus strains were found to inhibit the human pathogenic fungus Aspergillus flavus by secreting 2-phenyl ethanol, which prevents spore formation and reduces the biosynthesis of aflatoxins [24].…”

“…It is a permanent challenge to protect crops and foodstuffs against attack by pathogens through a variety of chemical and natural methods. The demand for biological measures is constantly increasing, as chemicals are often not safe for humans and the environment [10][11][12]. Moreover, fungi can develop resistance to chemical antifungal agents [4,5].…”

“…This strategy appears to be a promising alternative to conventional methods alone or as part of integrated pest management [12,13]. A wide range of bacteria (e.g., Bacillus, Pseudomonas, and Streptomyces), filamentous fungi (e.g., Trichoderma, Gliocladium, Chlonostachys, and Ulocladium), and yeasts (e.g., Aureobasidium and Candida) have been reported to exhibit inhibitory activity against fungus-incited diseases [10][11][12][13][14][15][16][17][18][19][20][21]. Especially with regard to wine production, yeasts as natural inhabitants of grapes and vine [22] appear less problematic than bacteria and fungi.…”

“…Ever since its discovery, this phenomenon has been studied intensively to open the way for new approaches in yeast biopesticide research. The antifungal properties are not based on a single activity pattern of the yeasts, but also involve competition for food and space and production of volatile secondary metabolites (e.g., ethanol, ethyl acetate, and CO 2 ) or lytic enzymes [10,11,24].…”

Effectiveness of convective drying to conserve indigenous yeasts with high volatile profile isolated from algerian fermented raw bovine milk (Rayeb)

“…I. orientalis, that assimilate glucose, is usually found in fermented dairy products because of it proteolytic and lipolytic activities; besides it has been reported to inhibit the growth of Colletotrichum capsicion on the surface of fruits and vegetables (Chanchaichaovivat et al, 2007). W. anomalus that ferments glucose but not disaccharides such as lactose, trehalose and maltose, produced ethyl acetate with antifungal activity against spoilage yeasts (Muccilli & Restuccia, 2015). K. marxianus, that able to ferment lactose and hydrolyze milk fat, enhanced the survival of Lactobacillus bulgaricus in yoghurt (Liu & Tsao, 2009).…”