THE BUTANOLOGENTIC CELLULOSOME OF CLOSTRIDIUM SACCHAROPERBUTYLACETONICUM

Clostridium saccharoperbutylacetonicum (“Berry”) is a mesophilic, anaerobic butanol-producing bacterium originally isolated from soil ¹. It was recently reported that C. saccharoperbutylacetonicum possesses multiple cellulosomal elements ². Theoretically, this cellulosome is among the smallest known in nature. It thus has a “minimalistic” cellulosome with only 8 dockerin-bearing enzymes and 2 cohesins (Cohs) of the scaffoldin in the sequenced genome ². In this study, each cellulosome-related module (cohesin, dockerin, enzyme and carbohydrate-binding modules) was cloned, expressed and purified, and the recombinant components were tested for enzymatic activity on cellulosic substrates and binding activity using ELISA-based techniques. All the enzymes were tested for their comparative enzymatic activity on 7 different substrates, and the data revealed 4 cellulases, a xylanase, a mannanase, a xyloglucanase, and a lichenase. All dockerin-containing enzymes interacted with the Coh-2 module, while Coh-1 was more restricted in its interaction pattern. We also tested the ability of C. saccharoperbutylacetonicum to produce bio-butanol from 4 different agrowaste sources (potato peel, apple pomance, brewer’s spent grain, and coffee silverskin). Our preliminary results showed that Berry produced the highest amount of butanol when grown on tryptone-yeast extract-acetate media with potato peel as the carbohydrate source, yielding a total product of 5.4 g/L butanol.

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