Microbiological assay with Bacillus licheniformis for the easy detection of quinolones in milk

This paper proposes a microbiological method in microtitre plates for the detection of residues of quinolones in milk. The method uses spores of Bacillus licheniformis in culture medium with a redox combination of indicators and gives a response time of 5.5 h. This method detects 92 μg L−1 of ciprofloxacin, 63 μg L−1 of danofloxacin, 109 μg L−1 of enrofloxacin, 101 μg L−1 of marbofloxacin and 109 μg L−1 of sarafloxacin in milk. Therefore, the assay is easy to develop and to use in laboratory, allowing analysis of large numbers of samples at low cost. Due to its good sensitivity to quinolones, this assay can be used as a complementary test of commercial microbiological methods and thereby improve food security.