LAMBDA INTEGRATOR replaces the need for optical density (OD) measurements
Frequently scientists want to know how their culture grows and what its metabolic activity during biotransformation is. For that reason, they are looking for instruments which can measure the optical density (OD) of the culture.
Optical density is a logarithmic function and increasing the number of light absorption unit by one means that the intensity of light passing through the sample has diminished 10 times! Needless to say that at an optical density of merely 4 the light intensity has decreased by a factor of 10‘000. It is a demanding task for electronics to measure such a low signal with precision. And what about OD 20 or 100? Even though many devices for the measurement of optical density of culture broths have been presented, none are really satisfactory.
There is much interference during such a measurement. The first and most problematic is that OD measurement also measures dead cells. If many dead cells are present in the culture the resulting metabolic activity will be wrong. Also small air bubbles are measured and counted as living cells! The number of microscopic air bubbles, especially in dense cultures, may be quite high. No need to say that any precipitation or coloration formed during the culture will distort the estimation of metabolic activity of the measured culture.
Determination of cell growth
Cell growth measurement is usually done by taking samples at different times:
- staining and counting of dead and alive cells (microscope) in case of mammalian cells
- total cell density (dead and alive) by OD 600-650nm in photometer for bacteria/yeasts or total cells density (dead and alive) by counting in a Neubauer cell counting chamber under the microscope
- alive cells by dilution of sample, incubation of 0.1ml on agar plate or incubation of 1ml in agar plate for 1-3 days at growth temperature in incubator, used in the case of bacteria/yeast
- by a “coulter counter” cell or particle counting system
In situ measurements
LAMBDA opens a new possibility to access the cell growth kinetics by measuring and recording amounts of acid or base necessary to keep the pH of the culture constant.
The growth of the culture is globally seen as a large complex of biochemical or chemical reactions, which use substrates and yield products in the form of the desired product or/and cell mass.
Cell growth always produces CO2 which is acidic and to keep the pH constant, this acid (which partially escapes) has to be compensated by the addition of another acid by a pH controller with an acid pump. (The formation of metabolic acids and bases other than CO2 are of course also taken into account by this measurement globally). In balanced regular growth the production of CO2 and the need of pH correcting acid is proportional to the growth (as the sum of all metabolic processes in the cell). Therefore, the amount of added pH correction solution (acid or base) is a precise indication of the growth extent of the culture. The controlled addition of acid equals in principle to an analytical titration and is therefore very precise.
The LAMBDA method using the INTEGRATOR is strictly connected with the real metabolic activity
The LAMBDA PUMP-FLOW INTEGRATOR transforms the impulses driving the motor of the pump into a voltage which can be recorded either on a recorder or shown on a screen by a PC using the fermentation software (FNet or SIAM).
The quantification of the INTEGRATOR signal can be easily obtained by using acids of known concentration and by calibration of the pump flow. This is easily done. Then, this value is correlated to the growth extent measured by another suitable growth rate method. Afterwards, the mere signal of the PUMP-FLOW INTEGRATOR allows precise and very inexpensive real growth kinetics. This is not so for many very expensive methods of growth rate measurement, e.g. the measurement of optical density (OD) of the culture. Such a measurement is not precise because also dead cells, air bubbles, precipitates and any other color or turbidity formation appear as an increase in cell concentration.
The trace obtained by the INTEGRATOR gives also indication about growth problems, contamination and the extent of the biotransformation. It is an important parameter when series of cultures have to be compared. It would be pity for any scientist not to use this easy and precise system for the following of the cell growth either in eukaryotic or prokaryotic cultures.
The pH trace obtained by the majority of competing bioreactors is almost always just a straight line saying nothing about the culture. However, if the required quantity of acid or base to keep the pH constant during the whole culture growth is visualized by the INTEGRATOR, this opens a new dimension full of valuable information for the scientist.
Below is one example of the trace of an acid pump activity transformed by the INTEGRATOR during one biotransformation culture (red trace with two resets). The red trace is the only one which is clearly exponential, as it should be. By totalizing the consumption of acid, the extent of transformation and the immediate state of the culture can be derived. No need to say how important such information can be for the control and reproducibility of different cultures.
Clients of LAMBDA are so convinced about the usefulness of the INTEGRATOR, that they put INTEGRATORs on almost any controlled parameter. No wonder, cells are so complicated that any additional information can only be beneficial.
LAMBDA does not provide OD or biomass probes for the reasons outlined previously. However, the user can add such probes on its own at a later point. Their output can be connected to the channel “X” or, alternatively, it can be visualized by the SIAM software. The MINIFOR vessel has 6-8 side necks and thus there is room to put additional probes. However, it should be kept in mind that such measurement methods (the probes and the corresponding controllers) are usually very expensive.
more aboutMINIFOR and its use at universities and high schools
Why is the LAMBDA MINIFOR laboratory fermenter and bench-top bioreactor so attractive to universities and high schools? It’s not only because of its functionality and accuracy…
- The modular concept
- Safe and easy use during practical lessons
- The loner in parallel runs
“In addition to the standard 1L vessel we can also supply 0.3L (with a minimal working volume of 35ml), 0.4L, 3L and 7L reactor vessels. The vessels can be replaced easily and at low cost. What else can we do for you?”
This is only one example of the modularity of the fermenter system. Each MINIFOR unit has its own measurement and control electronics for all parameters (pH, pO2, temperature, agitation, aeration rate and one additional selectable parameter). You can decide which parameters and accessories are needed for your work. This allows low acquisition costs.
“Your MINIFOR adapts to your project goals – not vice versa!”
If your project changes you can add additional modules at any time (other vessel sizes, pumps, integrators, mass flow gas controllers, software…).
Is your new project less complex? Then use the surplus modules as autonomous devices in your lab. (Peristaltic pumps, mass flow gas flow controllers …)
“Don’t be afraid of sterilization ...”
No additional safety measures are required as in the case of “in place” sterilization (SIP): The MINIFOR is sterilized in common autoclaves.
“Watch your MINIFOR, because your handy laboratory fermenter-bioreactor can be carried away by a single person!"
The MINIFOR laboratory bioreactor unit requires the surface of approximately an A4 sheet of paper.
The MINIFOR requires very little bench space and all ports are easily accessible: The side necks for the probes and connections are positioned at an angle of 30°. The space gained in this way allows for simple sterile work.
“MINIFOR runs without the need of frequently replacing consumables.”
Instead of O-rings or other seals which have to be replaced frequently, MINIFOR uses heavy-duty silicone membranes and multipoint seals.
The peristaltic pumps perfectly work with even lowest cost silicone tubing without excessive wear out. This ensures accurate liquid dosage in long-term processes.
The special concept of the MINIFOR fermenter-bioreactor offers lowest maintenance costs and short dead times for installation and dismantling between experiments.
“MINIFOR is not only a loner. It is also a great team player in parallel processes – without losing its independence.”
Unlike conventional systems, the MINIFOR units do not need to be placed next to each other during parallel processes, but can be distributed across your labs. Each MINIFOR unit has its own console which regulates all parameters locally and shows at one single glance the actual and set values as well as high and low alarms of each parameter.
Several MINIFOR units can be connected to you PC and the optional software allows remote control and data processing. For connecting multiple MINIFOR fermenter-bioreactor units to the PC no additional software licenses are necessary.
Laboratory fermenter and bioreactor MINIFOR: The solitary team player in parallel processes
Why is MINIFOR perfectly suited for your parallel processes?
- Each unit stays independent
“The MINIFOR fermenter-bioreactor is not only a solitary worker. You can also let it work in a team, in parallel cultures, without loss of independence in parameter regulation.”
Each LAMBDA MINIFOR unit is equipped with a control panel and display and shows at a single glance the set values and actual values as well as the high and low-alarms of each parameter. All parameters are regulated locally inside each fermenter unit.
This allows fast and precise parameter regulation and never having to worry about leaving a vessel unattended. A further advantage is that in case there are problems with one unit, the other units will still keep running. This is not the case when problems occur in a tower-controlled system.
- I’d like to compare the data of the different runs. What about data saving, data comparison and remote control?
“MINIFOR is not a lone fighter – it also connects to others to exchange data.”
Several MINIFOR-units can be connected and controlled by fermentation control software on a PC. This allows you to have control of all connected fermenters remotely and to compare the culture parameters. The connection of several MINIFOR-units to the control software does not require additional licenses.
- How important is the slow-down in parameter regulation when running 12 reactors in parallel?
“The number of connected fermenter units to the PC has no influence on the quality of the parameter measurement and regulation!”
An important aspect to consider – which, however, does not play a role in the LAMBDAMINIFOR parallel system because each MINIFOR fermenter comes with its proper regulation unit that measures and controls all parameters locally. As a consequence the quality of the measurement and regulation is not affected by long transmission times and dead times in regulation.
Of course this does not hinder the transmission of all fermentation data of each fermenter to be saved on your PC!
- What happens, if the measurement and regulation of one parameter or even the whole unit fails?
“Everything is exchangeable – even the exceptional MINIFOR!”
A failure occurred? All other bioreactor units of your parallel system continue working, as if nothing had happened!
Not only can the fermenter vessel be removed from the base unit in seconds but also the peristaltic pumps and additional accessories. This offers decisive advantages for maintenance and customer service:
Each pump or the whole MINIFOR-unit can be quickly and easily exchanged.
- The parallel system adapts to your premises
“MINIFOR only requires minimal space, for example in the last corner of your lab or it can also stand in file on your laboratory bench – it’s your choice!”
In contrast to traditional systems, the MINIFOR-units do not need to stand next to each other in parallel processes, but can be distributed in your labs, depending on your lab space availability.
- How much space does a MINIFOR unit require?
“Do you still have space for a sheet of paper? Then, there’s still place for the MINIFOR!”
Footprint: approximately a sheet of paper
Dimensions: 22 cm x 38 cm x 40 cm (W x H x D)
- MINIFOR on the move
“Watch your MINIFOR because this handy fermenter can be carried away by a single person!”
Are you facing reorganization? Don’t worry, MINIFOR goes along with (almost) everything: Weight per MINIFOR unit: 7.5 kg.
Furthermore the LAMBDA peristaltic pumps can be also used anytime as stand-alone instruments without the fermenter.
- How can I work with such a compact instrument?
“MINIFOR does not drive you crazy – you also do not need to book a relaxation course.”
Although LAMBDA MINIFOR only takes minimal laboratory bench surface, the connections are easily accessible: The side necks for the probes and ports are arranged at an angle of 30°. The gained space allows for easy sterility.
more aboutHow to compare the cost and real value of a laboratory fermentor-bioreactor?
This guide should help colleagues to judge better what they get for their money when buying a laboratory fermentor. Some producers try to lower the initial selling price by supplying equipment and components with minimal value. Unaware clients decide to buy lower priced instruments without consideration of the much lower value obtained, future costs and lower efficiency of such material which inevitably will decrease the productivity of their work for many years. Today, the cost of wages, of laboratory space and infrastructure are orders of magnitude larger than the acquisition costs of a laboratory fermenter or bioreactor. This certainly justifies the truth, that only the best is good enough.
more aboutInnovation in application
A major effort has been invested in making applications of this bioreactor more efficient.
This goal has been achieved in several steps
Firstly, a replacement of the traditional rotation movement by an oscillating up and down movement of stirring discs driven by an electromagnet yields several important advantages. A soft, whole volume movement of the medium results in optimal gas distribution throughout the medium and is also advantageous for cell growth. No vortex is formed and the elimination of baffles simplifies the construction of the bioreactor. A single silicone membrane efficiently replaces traditional seals and assures perfect sterility. In the case of extremely sensitive cells gas distribution tubing can be wound on aspiral fixed to the axis. The up and down movement facilitates the gas transfer and simultaneously provides a gentle movement of the medium.
Secondly, a new heat radiation system has also been introduced. A heating spiral in a gilded parabolic reflector has been placed under the bottom of the vessel. The IR rays efficiently heat up the culture without overheating it at any volume of medium. Several innovations allow the construction of high quality bioreactors at lower cost.
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