Fig. 1

Sudan black staining of lipids produced by Yarrowia lipolytica in the oil production broth. The oil production broth samples collected at different time intervals after inoculation, i.e., 0 h (a), 24 h (b), 48 h (c) and 72 h (d), were stained with Sudan Black B dye, followed by counterstaining with safranin dye and then observed under oil immersion at 100× magnification. Cells appearing red, represent staining by counterstain safranin and absence of intracellular lipids (a). Cells stained black, represent intracellular lipid accumulation (b–d). Small black droplets (stained with Sudan Black B dye) outside the cells represent extracellular oil in the broth (d)