Stat 44

1996 Science Teachers Association of Texas (STAT) Convention

Here are two flasks of Schramm and Hestrin Medium which have been innoculated with pure cultures of Acetobacter . The flask at the left has a thin membrane, while the flask at the right has a thick leathery pellicle membranes of cellulose. The bacteria are entrapped within the pellicle. The most recently-synthesized part is the top of the pellicle. As the pellicle grows, cells become entrapped within and die since Acetobacter is an obligate aerobe. Also, the thick membrane hinders the transport of nutrients to the growing layer at the top. This is an excellent example of a self-limiting process of cell growth and concommitant production of the microbial cellulose.

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