Down-regulation of a polynucleotide encoding a Sou2 sorbitol utilization protein to modify lipid production in microbial cells

A recombinant microbial cell comprising:

• (i) a down-regulation of an endogenous polynucleotide sequence encoding Sou2 sorbitol utilization protein comprising the amino acid sequence of an Sou2 sorbitol utilization protein selected from the group consisting of Asperqillus niger, Bifidobacterium dentium, Candida albicans, Candida dubliniensis, Candida orthopsilosis, Candida parapsilosis, Cordyceps militaris, Debaryomyces hansenii, Enterobacter hormaechei, Gaeumannomvces graminis, Glarea lozovensis, Lodderomyces elonqisporus, Maqnaporthe oryzae, Metarhizium acridum, Metarhizium anisopliae, Mycobacterium smeqmatis, Neurospora crassa, Neurospora tetrasperma, Paracoccidioides brasiliensis, Penicillium chrysoqenum, Scheffersomvces stipitis, Uncinocarpus reesii, Verticillium dahliae, and Yarrowia lipolytica, and
• (ii) a polyunsaturated fatty acid (PUFA) biosynthetic pathway, wherein said down-regulation increases the lipid content of the microbial cell and/or decreases the total amount of sugar alcohols produced by the microbial cell, as compared to a suitable control cell.