Biological Control of Phytopathogenic Fungi by Kluyveromyces marxianus and Torulaspora delbrueckii Isolated from Iraqi Date Vinegar

Abstract

Yeasts are distributed in all environments and have been reported as potential biocontrol agents against various phytopathogenic fungi. To investigate their enzymatic and biological activities, 32 yeasts were isolated from 15 date vinegar samples. Evaluation of the antagonistic activities of isolated yeasts against the plant pathogens Fusarium oxysporium, Sclerotinia sclerotiorum, and Macrophomina phaseolina indicated that there are two yeasts had the highest inhibitory effect against plant pathogens, these yeasts identified as Kluyveromyces marxianus and Torulaspora delbrueckii using traditional and molecular methods. These yeast isolates were tested for fungal cell wall degrading enzymes (in vitro), and results indicated that the yeasts had strong protease and amylase enzyme activity and moderate chitinase and cellulase enzyme activity. The antagonistic activities of each yeast were evaluated using a dual culture technique. The results showed that K. marxianus inhibited the mycelial growth of F. oxysporium, S. sclerotiorum, and M. phaseolina by 70.5, 57.5, and 75.5%, respectively, whereas T. delbrueckii inhibited mycelial growth of F. oxysporum, S. sclerotiorum, and M. phaseolina by 55.3%, 66.2%, and 31.11%, respectively. The biofilm production assay indicated that the tested yeast could form biofilms as a mechanism of antagonistic activity against phytopathogenic fungi.

Dissecting an ancient stress resistance trait syndrome in the compost yeastKluyveromyces marxianus

“…Though wellrecognized as an industrial dairy yeast 7,[36][37][38][39] , K. marxianus was likely domesticated for this purpose fairly recently, as inferred for K. lactis 22 . And though K. marxianus can be isolated from rotting fruit 40,41 , it may not have specialized narrowly to such substrates: a neighboring clade that includes Saccharomyces cerevisiae produces more ethanol than do any of the Kluyveromyces species 6 , suggesting a weaker drive in the latter toward this putative mechanism to kill off microbial competitors in high-sugar environments. Perhaps most compelling among microbial ecology findings is the prevalence of K. marxianus in decomposing plant material beside fruit, including leaf litter and pine needles 42 , cow dung 19 and industrially processed cocoa beans 43 , agave 44 , and sugar cane 16,45 .…”

Biotechnological Importance of Torulaspora delbrueckii: From the Obscurity to the Spotlight

“…Honey sugar Rapidly ferment sugar Large-scale productions only in combination with S. cerevisiae [7] Olive oil Black olives Easy hydrolyzation of olive oil Growth inhibition at concentrations higher than 0.5% (w/v) of oleuropein [81] Coffee Coffee cherries Improve coffee's sensorial quality Pronounced astringency depending on the coffee variety [82,83] Bio-protection -Reduction in the use of chemical preservatives to control food spoilage - [50,84] Another highly sought product in the food market is honey. This is produced by honeybees (namely Apis mellifera) and is a natural source of fermentable sugar ready to be used by fermentative yeasts [7].…”

“…Da Mota et al [ 82 ] showed that T. delbrueckii inoculation exhibited the best performance in natural coffee compared to S. cerevisiae and to the control (without inoculation), by positively improving the sensorial quality of the final product. Nevertheless, other authors also reported that the performance of T. delbrueckii may vary according to coffee varieties, production regions, processing methods, and microbial species naturally present in the fruit [ 83 , 84 , 85 ]. In general, the use of T. delbrueckii during coffee fermentation can result in coffees with distinct aromas and flavours that increase the possibility of producing speciality coffees, adding value to the product.…”