FIELD: production of yeast and bacteria. SUBSTANCE: heat-exchange plant has reservoir 34 and mixing device mounted along axis of reservoir 34. Mixing device is made in form of shaft 130 with impellers 156 and 158 revolving by means of drive 139. Arranged around shaft 130 are heat-exchange elements 1 made in form of inner and outer pipes inserted one in other at circular clearance which are connected to manifold pipes 8. Liquid is fed to heat-exchange elements 1 through intake device 30 and is removed through discharge device 36. When plant is used for fermentation, nutrient medium and carbon energy source are fed to reservoir 34; prior to mixing, gas is introduced and ready ferment is removed through hole 148 at simultaneous degassing of foam in the upper portion of reservoir 34. Ammonia is used as liquid medium. EFFECT: high quality of fermentation and easy cleaning of heat-exchange elements. 11 cl, 9 dwg
