From bush to glass: unlocking the potential of indigenous microbes in Australian wines

Abstract

Global trends in the wine industry are changing, which is caused by consumer demands for aroma and flavour innovation. Producers in Australia, the sixth globally ranked wine producing country, are embracing this trend by exploring non-conventional yeast species to improve sensory qualities and achieve fermentation advantages. Bioprospecting in the Australian Bush is a novel approach to domesticate favourable environmental microorganisms for use in industry. Australia has over 24,000 unique plant species in which lie potential niches for novel microbes. One of these is Eucalyptus gunnii, commonly known as the Cider Gum tree. Historically, the tree sap was used by Aboriginal Australians to produce a sweet, naturally fermented drink called way-a-linah, and which is an excellent place to search for novel yeast strains. We collected samples from E. gunnii and have begun to isolate and identify yeast species using ITS profiling. Fermentations of isolates in 96-well plates were performed using a Chemically Defined Grape Juice (CDGJM), where growth and sugar utilisation were measured. Isolates with efficient sugar utilisation capabilities were screened on a larger scale, and their secondary metabolites and volatile compounds were analysed using HPLC and GC-MS. Out of the more than 550 isolates identified, the most abundant genera found were Hanseniaspora, Kregervanrija and Zygosaccharomyces. Out of all the screened isolates, 54% were able to use more than 90% of sugars in CDGJM. We expect this project will result in the identification and characterisation of novel yeast unique to Australia, suitable for wine fermentation.