Degradation of Pure Aflatoxins by Tetrahymena pyriformis

Tetrahymena pyriformis W with nutrients, ca. 22 × 10⁶ cells, decreased the concentration of aflatoxin B₁ 58% in 24 hr and 67% in 48 hr. An unknown, bright-blue fluorescent substance was produced, with intensity about one-half that of the unchanged B₁, with an R_f of 0.52 compared with 0.59 for B₁ and 0.55 for B₂ on a thin-layer chromatography plate, and with an ultraviolet spectrum showing maxima of 253, 261, and 328 mμ. In a separate assay, the cells with nutrients did not degrade pure G₁. Starved, washed cells, ca. 11 × 10⁶, decreased the concentration of B₁ 50% in 10 hr, 70% in 22 hr, and 75% in 30 hr, producing the same unknown component. Ethyl alcohol, 1.96% (v/v), decreased cell populations and size, but the cells remained actively motile in broth plus the alcohol for 96 hr. In 72 hr, neither toxin (ca. 2 ppm) in combination with ethyl alcohol had more inhibitory effect on cell numbers, with or without nutrients, than was produced by alcohol alone. Aflatoxin B₁ had no observed effect on the viability of the starved cells for 30 hr or on the nourished cells for 72 hr. There was no noticeable effect of G₁ on the starved cells in 30 hr or on the nourished cells in 48 hr. After 72 hr with G₁ plus nutrients, many of the cells were round with blisters, nonmotile, and apparently dead or dying.