Biological monitoring

Biological monitoring is increasingly important for testing the quality of water. Several biological test systems using different organisms exist. However, the test involving light emitting bacteria, is found to be the fastest and most reliable method. The ToxTracer System is a bioassay is based on this principle of inhibition of the natural bioluminescence of the marine bacterium Vibrio fischeri. Toxicants in the water sample inhibit the light emission of V. fischeri what can be measured with the Skalar ToxTracer Luminometer.
The test permits the user to detect rapidly toxic compounds in aqueous solutions. Especially when it concerns unknown poisonous chemicals, the method is preferable over the time consuming and laborious physical / chemical methods. Because of the fast metabolism of the bacterial cell this assay is much faster then other comparable bio-tests. The test can be accomplished within 30 minutes using the Skalar ToxTracer system.

Toxicity testing

The easiest way to perform the test is using the reagent kit SC 801000. The kit contains vials with freeze-dried bacteria, which can be stored for almost a year in the freezer without loss of sensitivity. They should be considered as a biochemical, which you dissolve and subsequently use in an assay.

The method is simple: First, the freeze-dried bacteria are re-constituted. While the bacteria equilibrate for 15 minutes, the sample is prepared: the osmotic value is adjusted and a dilution series prepared. Next the samples are added to the bacteria. After an exposure time of 5 to 30 minutes the light production is measured in the ToxTracer luminometer. If a reduction of the light emission is registered, toxic compounds are present.

Toxicity testing using freshly prepared bacteria according to ISO 11348-1
International standards require the use of either freeze-dried bacteria as well as freshly prepared bacteria. Skalar organises training courses in using freshly prepared bacteria for the test according to ISO 11348-1. The procedure with those bacteria provides the user with an almost inexhaustible source of bacterial reagent what is especially cost saving when many measurements have to be done. As compared to the freeze-dried bacterial preparations, the use of freshly prepared bacteria gives the user a better insight in the bio-availability of toxicants and improves the interpretation of the results.

Software

The ToxTracer luminometer can act as a stand-alone instrument. During measurement the inhibition values are directly shown on the display of the luminometer. It is also possible to store the measured inhibition values on your PC by using the ToxTracer software. The results are expressed in a table and for the dilution series the data are plotted in a graph. Automatically the dilution at 50% inhibition is extrapolated from the graph. The results shown in this screen can be printed out as a report.

Training Course

"CULTIVATION OF VIBRIO FISHERI"

Skalar offers the availability to cultivate your own luminescent bacteria according to ISO-11348-1. In a short course we train people in the cultivation of marine bacterium Vibrio fisheri (NRRL B-11177). International standards require the use of either freeze-dried bacteria as well as freshly prepared bacteria. Skalar organises training courses in using freshly prepared bacteria for the test according to ISO 11348-1. The method using freshly prepared bacteria provides the user with an almost inexhaustible source of bacterial reagent what is especially cost saving when many measurements have to be done. It is easy to perform with reliable results. The method is especially interesting when confronted with long shipment duration what is disastrous for the freeze-dried bacteria. The Skalar training program includes: Practical learning of the common standard microbiological methods for handling the bacteria. This includes the preparation of sterile culture medium, the transfer of the bacteria to liquid medium or agar plates and the cultivation of Vibrio fisheri (NRRL B-11177) and storage of the bacteria in the freezer. Also the preparation of the Standard Cell Suspension (SCS) and the application of the SCS in a bioluminescence assay with toxicants will be learned.