Isolation of a Novel Kluyveromyces marxianus Strain QKM-4 and Evidence of Its Volatilome Production and Binding Potentialities in the Biocontrol of Toxigenic Fungi and Their Mycotoxins

Abstract

To overcome the economic losses associated with fungi and their toxic metabolites, environmentally safe and efficient approaches are needed. To this end, biological control using yeasts and safe bacterial strains and their products are being explored to replace synthetic fungicides. In the present study, the biocontrol effect of a yeast strain of Kluyveromyces marxianus , QKM-4, against the growth and mycotoxin synthesis potential of key toxigenic fungi was evaluated. In vitro assays were performed to find the application of yeast volatile organic compounds (VOCs) against fungal contamination on important agricultural commodities. The removal of ochratoxin A (OTA) and deoxynivalenol (DON) by living and heat-inactivated yeast cells was also explored. VOCs produced by strain QKM-4 were able to significantly limit the fungal growth of 17 fungal species belonging to genera Aspergillus , Penicillium , and Fusarium . Yeast VOCs were able to reduce OTA biosynthesis potential of Penicillium verrucosum and Aspergillus carbonarius by 99.6 and 98.7%, respectively. In vivo application of QKM-4 VOCs against Fusarium oxysporum and A. carbonarius infection on tomatoes and grapes, respectively, determined a complete inhibition of fungal spore germination. GC/MS-based analysis of yeast VOCs identified long-chain alkanes, including nonadecane, eicosane, docosane, heptacosane, hexatriacontane, and tetracosane. In vitro testing of the mycotoxin-binding potential of the living and heat-inactivated QKM-4 cells showed a reduction of OTA and DON up to 58 and 49%, respectively, from artificially contaminated buffers. Our findings clearly demonstrate the strong antifungal potential of K. marxianus QKM-4 and propose this strain as a strong candidate for application in agriculture to safeguard food and feed products.

Occurrence of Mycotoxins and Toxigenic Fungi in Cereals and Application of Yeast Volatiles for Their Biological Control

“…These values were significantly lower than the control, whereas at days 3, 5 and 7 the diameters were 32.5 ± 0.9 mm, 35.0 ± 1.0 mm and 40.0 ± 1.2 mm, respectively (Figures 2 and 3A). In line with these findings, diameters of A. flavus [23,25] and A. carbonarius [40] colonies were significantly reduced on exposure to yeast VOC. The biocontrol activity of the yeast VOCs is attributed to the release of different antifungal compounds, mainly 2-phenylethanol, which is known to inhibit the growth of fungi even at very low concentrations [41].…”

“…Additionally, the VOCs of Lachancea thermotolerans inhibited the germination and spread of F. oxysporum spores inoculated on tomato leaf surfaces [23]. In another study [25], a yeast, Kluyveromyces marxianus QKM-4, isolated from a local dairy product (laban), inhibited several fungal species from the genera Aspergillus, Penicillium and Fusarium. Moreover, this strain was able to inhibit OTA synthesis by A. carbonarius and P. verrucosum by 98.7% and 99.6%, respectively.…”

“…Currently, consumers prefer green-labeled, minimally proceeded and high-quality products, driving the food industry towards bio-preservation, which, in fact, safeguards nutritive quality and organoleptic characteristics. Several in vitro studies reported successful application of friendly yeast and bacterial strains against toxigenic fungi [23][24][25]. The volatile organic compounds (VOCs) of Lachancea thermotolerans, identified mainly as 2-phenylethanol, significantly inhibited A. parasiticus, P. verrucosum and F. graminearum in artificial media and suppressed their potential to synthesize mycotoxins.…”

Biocontrol Activity of Bacillus megaterium BM344-1 against Toxigenic Fungi

“…In our previous studies, we have reported yeast − and bacterial − cultures possessing strong antifungal potential against toxigenic fungi. This study was designed to investigate in vitro as well as in vivo effects of Bacillus megaterium (BM344-1) against the growth and toxin production potential of toxigenic isolates of A.…”

Exploring biotechnological and functional characteristics of probiotic yeasts: A review

“…Nine yeast isolates were carefully chosen, among those Pichia anomola as a biocontrol agent significantly reduced the progressive growth of Colletotrichum gloeosporioides with inhibition percentage of 79.63% and combination treatment of T. harianum and Pichia anomola , found to inhibit 93.22% of disease [56] . Fusarium species are one of the major contaminants found in the cereals [ 57 , 58 , 59 ].The biocontrol yeast Kluyveromyces marxianus QKM-4 showed the significant drop in the growth of fungal species of Aspergillus, Penicillium and Fusarium genera by the VOC production and percentage of reduction of OTA biosynthesis is 99.6% for Penicillium verecosum and 98.7% for A. carbonarious [60] . The strains of Debaryomyces hansenii , which produce the killer toxins significantly inhibited the fungal pathogen growth of Alternaria brassicola, Alternaria citri, Aspergillus niger and Rhizopus stolonifera as these fungal pathogens are most common causes of post-harvest decays on fruits like apple lemon and tomato [61] .…”