Physiological Gradients in Biofilm Communities
Biofilms exhibit regions of oxygen limitation and nutrient deficiency that, in contrast
to planktonic cultures, are non-uniformly distributed.31 Bacteria located within
starvation zones may be metabolically dormant and thus it has been suggested that
growth-dependent changes in cellular processes may contribute to reduced sensitivity
to many classes of antimicrobial agents.2,7,32,33 For example, Anderl et al.34 demonstrated
reduced susceptibility of Klebsiella pneumoniae colony biofilms to ampicillin and
fluoroquinolone exposure through nutrient limitation. Importantly, bacteria dispersed
from these colony biofilms exhibited increased sensitivities to these antibiotics when
introduced back into a nutrient-complete media.