Abstract: A bioreactor (1) is described of producing a culture of microorganisms (4) comprising at least one cylindrical container (2) and shaking and mixing means (11) to shake and mix said culture of microorganisms (4) contained in said container (2), said bioreactor (1) further comprising a source of sound waves (5) to irradiate said culture of microorganisms (4) with a sound wave (10). A method is further described of producing a culture of microorganisms (4) through a bioreactor (1), comprising the step of a) shaking and mixing said microorganisms (4) through said shaking and mixing means (11), and the step of b) irradiating said culture of microorganisms (4) with a sound wave (10). The bioreactor and method are characterized in that the frequency (f) of the sound wave (10) changes over time as a sawtooth function in a range comprised between 50 Hz and 8 kHz, preferably between 100 Hz and 6 kHz.