TECHNOLOGY FOCUS - BIOLOGY - Preferred Components: The microbial lipids are obtained from a yeast comprising Cryptococcus curvatus, Cryptococcus terricolus, Candida spp., Lipomyces starkeyi, Lipomyces lipofer, Endomycopsis vernalis, Rhodotorula glutinis, Rhodotorula gracilis, Rhodosporidium toruloides(preferred) or Yarrowia lipolytica.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The microbial lipids comprise a triglyceride content of 40-70 wt.% and a free fatty acid content of 10-30 wt.%. The feed comprises yeast-lipids (2-30 (preferably 5-20) wt.%). The feed further comprises a hydrocarbon co-feed derived from mineral crude oil. The hydrocarbon co-feed is a hydrotreated gas oil fraction. Preferred Process: The process further comprises isolating the microbial lipids from a microbial population. The hydrogenation catalyst of step (a) and/or the hydroisomerization catalyst of step (c) is sulfided in-situ by co-feeding hydrogen sulfide or sulfur comprising hydrocarbon stream. The hydrotreatment catalyst of step (a) and/or step (c) comprises sulfided nickel and sulfided tungsten or molybdenum as hydrogenation components on a carrier comprising amorphous silica-alumina and/or a zeolitic compound. EXAMPLE - The oleaginous yeast R. toruloides 444 was cultured in a fermentor at pH of 5-6, at 30 degrees C. An aeration of about 1 volumer/volume/minute was maintained in the fermentor. The culture medium used comprised a basal media comprising a carbon source based on glucose in a concentration of 60 g/l, peptone (20.3 g/l) and yeast extract (20.3 g/l). The fermentor was inoculated with a seed inoculum which has grown in two stage culture preferably in a YMY medium with a glucose source. The fermentation was operated in fed-batch mode using a concentrated carbon source solution, which was fed when the initial carbon source was consumed. Three different feeds were added during the fermentation to increase carbon source concentration up to 100 g/l. After the first feeding when the concentration of nitrogen was consumed, the yeast started to accumulate lipids. The yeast lipids were extracted after cell disruption and centrifugation to remove the lipids, followed by a solvent extraction from the aqueous medium. The yeast lipids comprised of triacylglycerides (54 wt.%), diglycerides (3.9 wt.%), monoglycerides (0.2 wt.%) and free fatty acids (19.5 wt.%). The yeast lipids were diluted (18 wt.%) in dodecane and 1 g oil per ml catalyst was supplied to the top bed of a fixed bed microflow unit per hour at 300 degrees C and 60 bar. A gas stream comprising hydrogen sulfide (2.5 vol.%) and hydrogen (97.5 vol.%) was supplied to the top bed at a gas-to-oil ratio of 2000 N1/kg to give product containing 55 wt.% 17C, 18C paraffins and 30 wt.% 15C, 16C paraffins.