A Shotgun Metagenomic Sequencing Exploration of Cabernet Sauvignon Grape Must Reveals Yeast Hydrolytic Enzymes

  • S. Ghosh Department of Genetics, Faculty of Natural and Agricultural Sciences, University of the Free State, Bloemfontein
  • B. Divol South African Grape and Wine Research Institute, Stellenbosch University, Stellenbosch
  • M.E. Setati South African Grape and Wine Research Institute, Stellenbosch University, Stellenbosch

Abstract

Shotgun sequencing was employed to explore the community structure (phylotyping of rRNA genes) andfunctional potential of Cabernet Sauvignon grape must microbiome. A metagenomic library, representing92.6 Mb of genetic information, was generated from DNA obtained from Cabernet Sauvignon grapemust.. Fungi were identified as the dominant domain (59.5%) followed by Streptophyta (39%). Amongthe 84 fungal species, 22 were yeasts of various genera. Additionally, grapevine endophytes such asDavidiella sp., Botryotinia fuckeliana, Alternaria sp., and Cladosporium sp. were identified. An unusuallyhigh prevalence of Mucor spp. was evidenced. Functional annotation revealed sequences of genesinvolved in metabolism (35.6%), followed by poorly characterized categories (28.3%), cellular processesand signalling (18.4%), and finally information storage (17.8%). Among the former, glycosidases wereabundant followed by glycogen debranching enzyme, 6-phosphofructokinase and trehalose-6-phosphatesynthase. Furthermore, the taxonomic analysis of the functional sequence data exhibited the eukaryoticgene pool that predominantly contains sequences derived from Streptophyta (mainly Vitis vinifera) 60% >Ascomycota (32%) > Basidiomycota (5%) > Bacteria (2.5%). Finally, sequences of a variety of hydrolyticenzymes of potential oenological relevance were retrieved, thereby confirming that grape juice is a richreservoir for valuable biocatalysts that should be explored further.

Author Biographies

S. Ghosh, Department of Genetics, Faculty of Natural and Agricultural Sciences, University of the Free State, Bloemfontein
South African Grape and Wine Research Institute, Stellenbosch University, Stellenbosch Department of Genetics, Faculty of Natural and Agricultural Sciences, University of the Free State,Bloemfontein
B. Divol, South African Grape and Wine Research Institute, Stellenbosch University, Stellenbosch
South African Grape and Wine Research Institute, Stellenbosch University, Stellenbosch
M.E. Setati, South African Grape and Wine Research Institute, Stellenbosch University, Stellenbosch
South African Grape and Wine Research Institute, Stellenbosch University, Stellenbosch
Published
2021-10-22
Section
Articles