Genomic analysis reveals the biotecnhological ability of Enterococcus italicus to produce glutathione

Through the analysis of the recently available genome shotgun sequence of Enterococcus italicus DSM15952T type strain (Accession: PRJNA61487, ID: 61487), presence of a gene coding for a bifunctional enzyme was found. This protein, termed γ-GCS-GS or GshF, involved in glutathione production is not influenced by feedback inhibition. The gshF gene exhibited high sequence similarity to other reported sequences from Enterococcus genus and was found to be constitutively expressed both in common cultural conditions or under osmotic shock. By experimenting with various culture media and physiological stresses, and by working out cell extracts production on an appropriate scale, optimal conditions were found. E. italicus was able to accumulate up to 250 μM glutathione as the main thiolic compound present into cells. This is the first report regarding the production of intracellular glutathione by E. italicus, a species that thus could be used as a safe adjunct culture for glutathione-enriched dairy foods.