FIELD: molecular biology, biochemistry, pharmacy. SUBSTANCE: ribosomal fraction is obtained from at least one filamentous nonphoto- synthesizing bacterium of order Beggiatoales, species Beggiatoa, Vitreoscilla, Flexithrix or Leucothrix. Cosmetic or pharmaceutical composition has the indicated ribosomal fraction taken in the amount from 0.001% to 20% of total mass of composition and it shows immunostimulating effect. Method of cosmetic treatment involves application on skin, hair and/or mucosa the cosmetic composition containing indicated ribosomal fraction. Ribosomal fraction prepared on the basis of new microorganisms provides recovery of immune functions, especially, epidermis cells and enhances the natural skin protection. EFFECT: enhanced effectiveness of fraction, valuable medicinal properties. 7 cl, 3 ex
