Adaptive changes of bifidobacteria in the presence of 5-fluorouracil

To observe the characteristics for the adaptive changes of bifidobacteria under the influence of 5-fluorouracil (5-FU). METHODS: The growth and morphological characteristics of bifidobacteria in the presence of 5-FU were acquired by drug-sensitivity test, gram stain and atomic force microscopic scan- ning as well as the identification of the 5-FU- resitant isolates.. RESULTS: In the presence of 5-FU, bifidobac- teria were lengthened with fewer ruptures, becoming filament-like, with a length of more than 10 μm. The bifidobacteria were ramose at both ends and the relative height was about 1 μm. The 5-FU-resistent bifidobacteria were also found within the inhibition zone. Given the normal growth conditions, the filament-like bifi - dobacteria restored to the normal growth again. CONCLUSION: 5-FU can directly influence the growth of bifidobacteria, whereas bifidobacteria exhibit significant adaptive changes to the action of 5-FU.