| Saccharomyces cerevisiae,a mature industrial strain,was widely modified and gene-edited as the high-tolerated expression model host,which had a great advantage of high-density fermentatiorn.Besides these,absorption and detoxification of free toxic heavy mental ion by S.cerevisiae can change toxic mental ions into high value-added products,such as selenium enriched yeast,etc.Cobalt,a toxic element,is the only core metal of VB12.Considering that cobalt ion is a toxic heavy metal for S.cerevisiae,little research has been done on the toxic effects of cobalt ion in S.cerevisiae.Therefore,improving the cobalt ion tolerance of S.cerevisiae may provide potential research basis for the future treatment of environmental pollution,the recovery of new cobalt-based batteries,and the production of cobalt ion-related biochemicals.Therefore,this study investigates the relationship between cobalt ion tolerance and both cell wall and cell membrane related genes in S.cerevisiae.In this study,we regulate cell wall and cell membrane related genes to increase cobalt ion tolerance in S.cerevisiae.Strains construction are achieved by using the CRISPR-Cas9 system or overexpression technology.In this paper,we constructed 32 different combinations by adjusting six genes of four metabolic pathways for knock-out or overexpression.Of the 32 strains,strains in which S.cerevisiae cobalt ion tolerance was significantly increased,the results are as follows.1.Overexpression of genes ERG4 and ERG6 in ergosterol metabolic pathway(cell membrane synthesis)of wild-type strain increased 1mM-cobalt-ion tolerance by-57%;2.Deletion of fks2(cell wall synthesis)increased ImM-cobalt-ion tolerance by-63%;however,overexpressing(ERG4,ERG6)or(RHO1,FKS2)or FKS2 over fks2?strain only increased cobalt ion tolerance by-40%;3.Deletion of sam2(SAM synthesis)and overexpression of RHOl&FKS2 had increased the ImM-cobalt-ion tolerance by-55%,although deletion of sam2 alone had no significant effect on cobalt ion tolerance. |
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