Determination of biologically active substances using microorganisms
The use of microorganisms to determine biologically-active substances is tried and tested. In doing so, it is possible to reliably detect B-vitamins and antibiotics.
Microorganisms only grow under certain conditions: some bacteria, for example, require a specific pH-value, a specific temperature range and a specific nutrient in order to grow. These specific characteristics of microorganisms can be taken advantage of in the analysis.
VitaFast® – microbiological microtiter plate to determine the vitamin concentration
The microbiological microtiter plates for the VitaFast® product line are easy tests that can be used to determine the vitamin content in food, drinks, animal feed and pharmaceutical products. The vitamin is extracted from the sample material for the verification. The extract is diluted and together with the assay medium, it is mixed in the cavities of the microtitre plates that are coated with a specific microorganism. If the vitamin in question is present in the sample, this microorganism will continue to grow until the vitamin is completed used up. After an incubation period, the microbiological growth is measured as turbidity and compared with a standard concentration series. The measurement takes place in a microtiter plate photometer.
Premi®Test – a microbial rapid screening test for the detection of antibiotics
The Premi®Test is a microbial screening test for the detection of antibiotic residues in food and animal feed in less than four hours. The test enables a fast and easy screening of meat (beef, pork, poultry), fish, prawns, eggs, liver, kidney, urine and animal feed to check for the residues of β-lactam, cephalosporin, macrolide, tetracycline, sulfonamide, aminoglycoside, quinolone, amphenicol and polypeptide antibiotics and can be used during the entire manufacturing chain by slaughterhouses to meat processing companies through to analytical laboratories.
The test is based on the sensitivity of the thermophilic bacteria, Bacillus stearothermopilus for antimicrobial substances. A defined number of spores are embedded into the nutrient agar in ampules. If a sample is tested, which is free of antibiotic residues, the spores germinate during the three-hour incubation phase and produce an acid during the following growth phase. This leads to a drop in the pH-value and there is a change in color—from the original violet to yellow— of the pH-indicator bromocresol found in the agar. However, if a sample is tested that does contain antibiotic residues, the germination of the spores is inhibited and the ampules violet color does not change after incubation.