Figure 3

Model CO ₂ profile. Typical measurement of changes in carbon dioxide production rates during microbial conversion of a Whatman #3 paper chad cut at 6600 mm² footprint area (value accounts for both sides of the paper). The working definitions established and used throughout this paper are labeled and delineated: the lag phase from the moment of inoculation varies between seven to nine hours; start of growth is considered at 5 × 10^-5 mmoles/min carbon dioxide rate and the fermentation end-point at 10 × 10^-5 mmoles/min; the initial growth period is termed the ‘biofilm invasion’ region, which ends when near-all of accessible surface area (i.e., the ‘real estate’) of the paper has been colonized; it is followed by a ‘plateau region’ of stable, and maximal carbon dioxide output where biofilms advance through the depth of the paper chads (new surfaces become available at the same rate that colonized surfaces are depleted); the last ‘degradation’ region is characterized by rapid loss of available surface and chad integrity.