Yeasts from Different Habitats and Their Potential as Biocontrol Agents

Abstract

Ever since plant diseases began causing losses in viticulture, the control of phytopathogenic fungi has become of vital interest for winemakers. The occurrence of novel pests, fungicide resistance, and changed consumer expectations have led to an enormous demand for novel plant protection strategies. As part of integrated protection measures, antagonistic microorganisms have been investigated to a large extent. Such microorganisms can be applied not only in conventional, but also in organic farming as biological control agents (BCA). Particularly, yeasts were found to be interesting candidates for the development of BCA. Many of these eukaryotic microorganisms are found as part of the phylloplane microflora. In this study, we assessed a set of 38 yeast isolates from different habitats, including the guts of termites, for inhibitory effects against some phytopathogenic fungi that have received less attention in earlier studies. The majority of yeasts were found to interfere with fungi infecting grapevine (Eutypa lata, Botrytis cinerea, and Roesleria subterranea), stone fruits (Monilinia fructicola), or rice (Magnaporte oryzae), as well in vitro and in model experiment on fruits. Although most yeast strains secreted glycoside hydrolases and proteases, attempts to demonstrate direct antagonistic activities of lytic enzymes failed. However, in culture filtrates of the termite yeast Papiliotrema odontotermitis OO5, a low molecular thermostable antagonistic factor was detected. Iron depletion as a BCA mechanism was confirmed for strains of Metschnikowia pulcherrima but not for other yeasts.

Metschnikowia pulcherrima and Related Pulcherrimin-Producing Yeasts: Fuzzy Species Boundaries and Complex Antimicrobial Antagonism

“…These experiments were carried out with Metschnikowia isolates whose exact taxonomic affiliation could not be determined because their D1/D2 sequences differed from those of all type strains of the M. pulcherrima clade [ 6 ]. Correlation and causative relationship between iron depletion (pulcherrimin production) and antagonism was later observed in many other pulcherrimin-producing Metschnikowia strains, including the type strains of the species (e.g., [ 7 , 8 , 10 , 11 , 21 , 71 , 72 , 73 ]).…”

“…The strain NCYC 3728 (PBC-2) secreted chitinase after 5 and 7 days of incubation in YNB (yeast nitrogen base) medium supplemented with P. expansum cell wall [ 75 ]. In a recent study, seven strains showed modest extracellular chitinase activities [ 72 ]. In contrast, Parafati et al [ 10 ] detected neither β-1,3-glucanase nor chitinase secretion in a different collection of Metschnikowia strains.…”

Efficiency of Marine Bacteria and Yeasts on the Biocontrol Activity of Pythium ultimum in Ancho-Type Pepper Seedlings

“…Biological control with microorganisms has long been considered a viable alternative for controlling phytopathogens [36], among which bacteria and yeasts are the main antagonists [11,37]. In this study, different bacteria and yeasts decreased P. ultimum growth significantly in vitro; however, those that stood out most were the marine bacteria S. rhizophila (strain KM01 and KM02) and the marine yeast C. laurentii 2R1CB.…”

Research Advances of Beneficial Microbiota Associated with Crop Plants

“…For instance, Trichoderma spp., Ganoderma spp., and yeasts (Saccharomyces spp.) have been used as PGPFs in several studies under both normal growth and environmental stress conditions [70,[73][74][75][76][77][78][79]. For example, Jaroszuk-Scisel et al reported that a Trichoderma strain, isolated from a healthy rye (Secale cereale) rhizosphere with the ability to produce auxin, gibberellins, and ACC deaminase in vitro, and to inhibit the growth of Fusarium spp., could colonize the roots of wheat (Triticum aestivum) seedlings and enhance stem growth [73].…”