Growth and Survival of Flavobacterium aurantiacum in Peanut Milk¹

Tryptone-yeast extract-glucose (TYG) and trypticase soy broth (TSB) were evaluated for production and recovery of Flavobacterium aurantiacum stationary phase cells. In addition, growth of F. aurantiacum in peanut milk was tested, Trypticase soy broth was chosen as the best medium for producing stationary phase cells. Both non-defatted peanut milk (NDPM) and partially defatted peanut milk (PDPM) supported growth of F. aurantiacum . The growth of F. aurantiacum in both kinds of peanut milk was not inhibited by aflatoxin B₁ (1 mg/ml). About 10⁹ stationary phase cells were inoculated in 0.067 M phosphate buffer (PB) at pH 5.0, 5.5, 6.0, 6.5, and 7.0, and in both peanut milks (pH 6.3 and 6.9). After a 24-h incubation period, the viable cell number decreased slightly in PB (pH 7.0, 30°C), but decreased 2-3 logs in other buffers. About 0.6-0.8 log decrease was observed in NDPM and PDPM. Phosphate buffer (0.067 M, pH 7.0), NDPM and PDPM were determined to be adequate for use in studies to investigate the removal of aflatoxin B₁ by F. aurantiacum .