A process for preparing a high protein food comprises continuously supplying a C1-C30 hydrocarbon a non-limiting aqueous inorganic salts growth medium and excess oxygen-containing gas to a vigorously stirred reactor containing the hydrocarbon, aqueous medium and non-toxic hydrocarbon-consuming bacteria, the bacteria being in the phase (population increasing exponentially) of growth and being present in a concentration equal to or greater than that for which the exponential increase in population increment is equal to the increment continuously withdrawn, continuously removing a mixture of bacteria, aqueous medium and unconverted hydrocarbon, and separating the bacteria to obtain directly the proteinaceous food. The material separated from bacteria may be recycled to the reactor. Under preferred conditions the liquid residence time is 1.5 to 4 times the minimum generation time for the particular bacteria, and the oxygen-containing gas supplied to the reactor is 0.5-4 volumes of air/volume reactor liquid/minute. Thus Micrococcus cerificans may be cultivated with a residence time of 1.0-10 hours on a mixture of 0.1 to 10 weight % of a 190 DEG -400 DEG C. boiling normal paraffin feed, containing less than 0.1 weight % aromatics in an inorganic salts aqueous growth medium oxygen-enriched by air containing more than 90% of oxygen amounting to 1.5-2.5 lbs. per lb. dried bacteria recovered, and cells of the bacteria containing 72-93 weight % liquid based on dry cells are separated from the continuously removed mixture of bacteria, aqueous medium and unconverted paraffin with the aid of a cationic surfactant and dried. The composition of the inorganic salts aqueous growth medium is disclosed in detail. The final product cells after drying contain 7-10 weight % of total fat of which about 75% is made up of esters, and 5-9 weight % of inorganic salts. The C1-C30 hydrocarbon feeds are preferably gas oils boiling in the range of 190 DEG -400 DEG C. Other feeds are C1-C30 normal paraffins, isoparaffins, cycloparaffins, monoolefins, diolefins and aromatics. Feeds particularly suitable are C11-C30 normal paraffins from gas oils, light naphthas, and normally gaseous feeds such as methane, ethane, propane and natural gas. In the cultivation of Micrococcus cerificans any C6-C30 feed will require purification by a molecular sieve process to reduce the level of both mono- and poly-cyclic aromatics to below 0.5 weight %. The following species of bacteria are preferably employed: Micrococcus cerificans, Pseudomonas aeruginosa, Pseudomonas fluorescens, Nocardia opaca, Nocardia rubra, Nocardia coralina, Pseudomonas methanica, Pseudomonas desmolyticum and Mycobacterium phleie. Certain examples are directed to the effect of different feeds viz. gas oil fraction, slack wax and hexadecane, on bacterial yield and of the proteinaceous product upon animal growth (rats) in comparison with casein. It is stated that the unreacted hydrocarbon residues from the gas oil and slack wax are animal growth inhibitors.ALSO:A process for preparing a high protein food comprises continuously supplying a C1-C30 hydrocarbon, a non-limiting aqueous inorganic salts growth medium and excess oxygen-containing gas to a vigorously stirred reactor containing the hydrocarbon, aqueous medium and non-toxic hydrocarbon-consuming bacteria, the bacteria being in the log phase (population increasing exponentially) of growth and being present in a concentration equal to or greater than that for which the exponential increase in population increment is equal to the increment continuously withdrawn, continuously removing a mixture of bacteria, aqueous medium and unconverted hydrocarbon, and separating the bacteria to obtain directly the proteinaceous food. The material separated from bacteria may be recycled to the reactor. Under preferred conditions the liquid residence time is 1.5 to 4 times the minimum generation time for the particular bacteria, and the oxygen-containing gas supplied to the reactor is 0.5-4 volumes of air/volume reactor liquid minute. Thus Micrococcus cerificans may be cultivated with a residence time of 0.1-10 hours on a mixture of 0.1 to 10 weight per cent. of a 190 DEG -400 DEG C. boiling normal paraffin feed, containing less than 0.1 weight per cent. aromatics, in an inorganic salts aqueous growth medium oxygen-enriched by air containing more than 90% of oxygen amounting to 1.5-2.5 lbs. per lb. dried bacteria recovered, and cells of the bacteria containing 72-93 weight per cent. liquid based on dry cells are separated from the continuously removed mixture of bacteria, aqueous medium and unconverted paraffin with the aid of a cationic surfactant and dried. The composition of the inorganic salts aqueous growth medium is disclosed in detail. The final product cells after drying contain 7-10 weight per cent. of total fat of which about 75% is made up of esters, and 5-9 weight per cent. of inorganic salts. The C1-C30 hydrocarbon feeds are preferably gas oils boiling in the range of 190 DEG -400 DEG C. Other feeds are the C1-C30 normal paraffins, isoparaffins, cycloparaffins, mono-olefins, diolefins and aromatics. Feeds particularly suitable are C11-C30 normal paraffins from gas oils, light naphthas, and normally gaseous feeds such as methane, ethane, propane and natural gas. In the cultivation of Micrococcus cerificans any C6-C30 feed will require purification by a molecular sieve process to reduce the level of both mono- and polycyclic aromatics to below 0.5 weight per cent. The following species of bacteria are preferably employed: Micrococcus cerificans, Pseudomonas aeruginosa, Pseudomonas fluorescens, Nocardia opaca, Nocardia rubra, Nocardia coralina, Pseudomonas methanica, Pseudomonas desmolyticum and Mycobacterium phleie. Certain examples are directed to the effect of different feeds viz. gas oil fraction, slack wax and hexadecane, on bacterial yield and of the proteinaceous product upon animal growth (rats) in comparison with casein. It is stated that the unreacted hydrocarbon residues from the gas oil and slack wax are animal growth inhibitiors.