Microbiological Instruments

The BioTrac 4250 is appropriate for smaller laboratories and measures only the M-value. This incubator provides 21 measuring positions suitable for either disposable or reusable vials. The BioTrac is designed to operate with a laptop as a single incubator. The BacTrac 4300 Microbiological Analyser uses the unique impedance-splitting technology and measures the M-value (media impedance) and E-value (electrode impedance) giving a big variety of possible analyses. Each device contains two individually thermostated incubators for 32 samples each, which can accommodate either disposable or reusable vials. Up to 12 units (768 wells, 24 incubators) can be controlled by one PC.

The proprietary impedance splitting measurement technology of the BacTrac instruments enables even the use of nutrient media with higher conductivity and therefore significantly broadens the possible applications. In addition to the M-value, changes of the E-value (electrode impedance) will be registered within the impedance splitting concept. For registration of the electrode impedance value the capacitive component of the complex impedance value Z (influence of the electrochemical double layer of the electrode) is of central importance. The technique to measure this electrode impedance value is a special characteristic of the BacTrac measurement technology. The E-value is not significantly influenced by the composition of the growth media and is therefore of central importance when media with high salt content (i.e. addition of salts as selective components for the detection of pathogens) will be used.

Depending on the microorganisms to be analysed the time saved due to use of the BioTrac varies from 12 hours for coliforms to several days for yeasts and moulds, clostridia and beer spoiling bacteria. Furthermore it is not necessary to make dilutions after sample homogenisation and to poor plates and count colonies. Please contact SY-LAB for further details.

All aerobic proliferating micro-organisms produce CO2 as the terminal product of cell metabolism and are therefore suitable for detection with the indirect method.

Besides the direct measurement of impedance in the nutrient broth, the detection of carbon dioxide (CO2) produced via the microbial metabolism provides an additional option of recording the activity levels of microorganisms. In this process the impedance change is not detected directly in the nutrient, rather it is the change in impedance of a potassium hydroxide solution caused by the uptake of the CO2 formed that is detected. The indirect impedance measurement represents a rapid and very simple process with pronounced higher sensitivity for the detection of CO2 production. For the detection of yeasts and moulds in particular, whose changes occasionally are hardly registered in the direct method, the indirect method is far superior.