Micrographs of CU428 and NP1 T. thermophila fed Congo Red dye at room temperature (RT) and 37°C.

Micrographs taken at 20X magnification, 1.5X zoom. (A) CU428 at RT. (B) NP1 at RT. (C) 428 at 37°C. (D) NP1 at 37°C. The absence of dark vacuoles in NP1 at 37°C indicates a nonfunctional oral apparatus.

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