this work was carried out with the purpose of attain a protein concentrate from microbial biomass with low content of nucleic acids. the yeast kluyveromyces marxianus var. marxianus was grown on deproteinized and supplemented whey with nitrogen and vitamins sources at ph 4.5; 32 to 35°c and an aeration rate of 1.22 volumes of air fed for volume of broth per minute (vvm). the average biomass yield obtained was 0.30 g/g lactose, a lactose consumption of 93.21% and a cellular concentration of 4.15 g/l at the end of the fermentation. two protein concentrates were obtained: the first one by alkaline extraction and isoelectric precipitation (c1) and the second one by alkaline extraction, phosphorylation and isoelectric precipitation (c2). chemical analysis of both concentrates shown significant differences (p < 0.05) in the content of ash, fat, crude protein, non protein nitrogen, rna and carbohydrates. there was significant (p < 0.05) the decrease in the rna content from 4.59% (c1) to 2.71% (c2), important fact for the use of this protein concentrates for human consumption. phosphorylation of the protein (c2) produced an increase in the water holding capacity (4.21 to 4.64 g water/g protein), solubility (32.43 to 41.74 g solubilized protein/g total protein) and emulsifying capacity (903.38 to 971.91 g oil/g protein), as well as a decrease in the oil absorption capacity (1.79 to 1.65 g oil/g protein). these characteristics are important when considering the use of such protein concentrates as ingredients in bakery or meat products.