The invention relates to a bioreactor comprising a tank (100) capable of being operated for a working period, said tank (100) being intended to receive a culture medium comprising a cellular culture of photosynthetic microorganisms, a light source (200) arranged to emit incident light having a chosen incoming light intensity (Iin) in the direction of the tank, a temperature probe (400) for measuring the temperature of said culture medium in the tank, and a temperature regulator (500) capable of raising and lowering the temperature of said culture medium in the tank, and further comprising a control (700) of the temperature regulator arranged to adjust the temperature of the culture medium to a low setpoint value (VCB) during a first period, and to adjust the temperature of the culture medium to a high setpoint value (VCH) during a second period, the succession of said first and second periods making it possible to induce a cellular stress in at least some of said photosynthetic microorganisms during the working period.