Vector for co-expressing genes of interest

An expression vector for the co-expression of a first and second polynucleotides of interest in microalgal cells, wherein said first and second polynucleotides of interest are provided respectively in a first and second expression cassettes, each expression cassette comprising a 5′ cis regulatory region and a 3′ cis regulatory region operatively linked with the first and second polynucleotides and wherein both the 5′ and 3′ cis regulatory regions of the first expression cassette are different from the 5′ and 3′ cis regulatory regions of the second expression cassette, wherein the 5′ cis regulatory regions comprise a sequence selected from the group consisting of a HSP70A/RBCS2 chimeric promoter, the RPL23 gene promoter, the FDX gene promoter and the 3′ cis regulatory regions comprise a sequence selected from the 3′UTR of the RBCS2 gene, the 3′UTR of the RPL23 gene and 3′UTR of the FDX gene.