Bioreactor system and method for cloning the physiological state of microorganisms comprises in preferred embodiment of a mother-reactor and one or more daughter-reactors with sensors, stirrers, fluid and gas flow channels, scales, pumps, controllers, computer, software, valves and accessory devices. The bioreactors are inter-connected with culture transfer hose. To achieve the method, the mother-reactor is filled with necessary volume, inoculated, stabilised in continuous cultivation, the microbial culture's volume is increased in variable volume cultivation while maintaining constant physiology, microbial culture is transferred from the mother-reactor into the daughter-reactors while maintaining constant physiology, experiment in the daughter reactor follows. After the experiment daughter-reactors are sterilized and rinsed. During the experiment culture volume in the mother-reactor is increased anew, after the experiment in the daughter-reactors is finished another culture transfer follows and next experiment is conducted. This sequence—variable volume cultivation, culture transfer, experiment—is repeated until necessary data has been acquired.