Cellulose Metabolism by the Termite Flagellate Trichomitopsis termopsidis

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The end products of cellulose metabolism by the trichomonad flagellate Trichomitopsis termopsidis from the termite Zootermopsis sp. were investigated by growing axenic flagellates on [14C]cellulose. The growth of T. termopsidis resulted in the release of label into the supernatant fraction of the culture fluid, and > 75% was volatile under acid conditions. The label was analyzed for 14CO2 and for [14C]volatile compounds by vacuum distillation under acid and alkaline conditions in disposable micro-distillation vessels. The distillate and undistilled culture supernatant fluid were chromatographed on cellulose thin layers to identify the labeled end product. T. termopsidis produced 14CO2 and [14C]acetate which accounted for 25 to 30% and 55 to 60% of the labeled end products, respectively. The ratio of label in CO2 to acetate suggests that they are produced in equimolar amounts. No neutral volatile compounds were produced. The remaining unidentified end product (10 to 20%) was not volatile nor extractable into ether. Hydrogen was produced by T. termopsidis, and the cells were killed by the drug metronidazole. Enzymatic activities were found which account for these end products: pyruvate:ferredoxin oxidoreductase and hydrogenase. The results indicate that acetate is the end product of T. termopsidis cellulose metabolism and is available to the termite for energy metabolism and biosynthesis.

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