A protein hydrolysate composition derived from a microorganism, such as a chemoautotrophic microorganism, and methods of preparing and using the same are provided. The protein hydrolysate composition may be produced sustainably through fixation of carbon dioxide from biogenic or atmospheric sources. The protein hydrolysate composition finds use in supplementing culture media for serum-free culturing of animal cells as well as for growing other types of cells such as probiotics and lactic acid bacteria. Thus, the present disclosure provides sustainable, humane processes for culturing cells for pharmaceutical and nutraceutical application as well as for human consumption as a food ingredient or product, including cultured meat.