Weighing module for continuous cultures (Chemostat)

  • Continuous cultures with highly reliable feed, harvest peristaltic pumps and constant automatic weight control (chemostat)
  • Scale module can be placed readily under the front part of MINIFOR fermentor and bioreactor, to control the weight and consequently the amount of culture
  • Weight control is independent of agitation, aeration, gas uptake, pressure, temperature and foaming
  • Peristaltic pumps with constant and reproducible flow rates for several weeks, without the risk of tubing rupture in long term continuous cultures (turbidostat, chemostat)
  • Programmable variable speed pump (up to 99 steps with pauses) and automatic switch-on and switch-off without using any timer
  • Easy sterility maintenance concept for long continuous runs (chemostat, turbidostat, perfusion)
  • Gentle and efficient mixing to maintain uniform culture conditions without cell damage

Weighing module for continuous cultures

The capability to run weight-controlled continuous processes is an important quality of advanced bioreactor and fermentor system. Therefore, all the MINIFOR bioreactors and fermentors are electronically prepared for the reception of an inexpensive scale module, which allows running a high quality continuous culture with constant culture weight control independent of agitation, aeration, gas uptake, pressure, foaming and temperature. It is an extremely compact, precise and easy to use device, which could be used for continuous fermentation and cell cultures.

The amount of medium in the MINIFOR fermentor and bioreactor vessel can be kept constant by a special weighing module placed under the front edge of the instrument. The feed and harvest pump will automatically maintain the weight of the culture constant.

The weighing module allows the selection of an optimal measuring weight range according to the vessel, instrumentation and medium volume used. It ranges from the smallest 0.3 L vessel and extends to the completely filled 7 L vessel (working volume range from 35 ml to 6 L).

Continuous cultures = LAMBDA MINIFOR fermentor / bioreactor + Feed Pump + Harvest Pump + Weighing module

(Speed of Feed Pump = Speed of Harvest Pump = Growth rate)

Peristaltic pumps for feed and harvest

Highly reliable LAMBDA peristaltic pumps PRECIFLOW, MULTIFLOW, HIFLOW and MAXIFLOW are specially developed for long continuous upstream processes to offer stable and reproducible flow rates (fed-batch, turbidostat, chemostat, perfusion, 3-stage fermentation).


0.2 µl/min - 600 ml/h


5 years warranty


0.2 µl/min - 600 ml/h


5 years warranty


1 µl/min - 3,000 ml/h


2 years warranty


3 µl/min - 10,000 ml/h


2 years warranty

Connected to the weighing module, the peristaltic pump will automatically add or remove the medium from the working vessel to attain the pre-set weight. The peristaltic pumps can be chosen according to the growth rate and dilution rate of the culture. The flow rate of the peristaltic pump can be calibrated in terms of weight (g/min) or volume (ml/min).

Continuous cultures (chemostat, turbidostat)

Reliable continuous culture experiments optimize the experiments faster, at lower cost and increases the productivity. In chemostat, the culture volume (weighing module) is kept constant by feeding the medium at a constant rate (feed pump) and culture is harvested at the same rate (harvest pump) to maintain the suboptimal growth rates of the microorganism. In turbidostat, the cell density (turbidity probe) of the culture is held constant by manipulating the rate at which medium is fed (feed pump).

Unlike batch culture where growth time is hours to days, continuous cultures can run for several days or weeks at steady state. It is important to use, convenient system with reliable peristaltic pumps for constant supply of medium, maintain aseptic conditions (LAMBDA easy sterility concept) with precise parameter control (pH, temperature, agitation, DO,…) for highly beneficial long continuous culture experiments.

Choosing the flow rate of the feed and harvest pumps depend on the dilution rate (D). Because, the factor that determines the growth rate in chemostat is the dilution rate, i.e. the rate of supply of the limiting nutrient. At steady state, the specific growth rate (μ) of the micro-organism is equal to the dilution rate (D).