Saccharomyces cerevisiae and Saccharomyces bulardii were grown on spiny cactus peel extract medium for 35h of growth. The optimum culture conditions necessary for the maximum growth was 30°C, 20h incubation period, and pH 5.0. A general increase in dry weight was observed for both yeast strains with a maximum in biomass yield at the 20h of growth (14.60g% and 12.10g% respectively) and of polymeric contents (13.40-19.2g/l respectively). Total sugar concentration of the culture medium was decreased during the fermentation period from 36.40 g/1 to 9.20 g/1 after 20h of growth. S. cerevisiae and S. bulardii contained crude protein (39.40 % and 30.60% respectively) at the end of the logarithmic phase (20h), while their true protein was 31.40% and 27.20%. The amino acids content in protein of both yeast cells were estimated and comparable to the FAO standard. Suitable amounts of essential amino acids (42.37%-47.54%) and reasonable amounts of sulfur-containing amino acids were also found in both yeast strains. lipid contents (6.80% and 5.60 %, respectively) were also found. Therefore, spiny cactus peel extract (mainly glucose, arabinose and mannose) was considered as suitable carbohydrate source for growing of S.cerevisiae and S.bulardii and production of maximal microbial protein and polysaccharides contents.