TEM images of <i>F</i>. <i>succinogenes</i> S85 harvested during mid-exponential growth on cellulose (A, B), cellulose stationary growth (C, D), glucose mid-exponential growth (E) and glucose stationary growth (F).

<p>Grooves in the cellulose were observed in the cellulose mid-exponential and stationary phases. Vesicles were present in only the cellulose stationary phase (arrows in D). Scale bars are 1 μm (A,C) and 0.5 μm (B-F). Vesicles are indicated by arrows. Grooves are indicated by curves.