Use of Fourier transform infrared spectroscopy for rapid comparative analysis of Bacillus and Micrococcus isolates

The identification of foodborne microorganisms and their endospores in food products are important for food safety. The present work compares Bacillus (Bacillus licheniformis, Bacillus circulans and Bacillus subtilis) and Micrococcus (Micrococcus luteus) species with Fourier transform infrared (FTIR) spectroscopy. Our results show that there are several characteristic peaks belonging to both the Micrococcus and Bacillus species which can be used for the identification of these foodborne bacteria and their endospores. For Micrococcus species, a new band was observed at 1338 cm−1 which may be due to acetate oxidation via the carboxylic acid cycle. The bands at 1313 cm−1 and 1256 cm−1 can be explained by an exopolymer formation and the other bands at 1074 cm−1 and 550 cm−1, may be due to the glycogen-like storage material in Micrococcus spp. There are also characteristic peaks at 993 cm−1 and 801 cm−1 for these bacterial species. Different Bacillus species also showed characteristic peaks at 1000–500 cm−1 region. Dipicolinic acid (DPA) bands at ∼728 cm−1 and ∼703 cm−1 seen only in B. circulans were the marker of an endospore formation.