Hyper-spectral imaging of biofilm growth dynamics

Spectrally resolved imaging was applied to study the growth dynamics of phototrophic biofilms comprizing a mixture of one cyanobacterial and one diatom species. Linear spectral unmixing was combined with liquid chromatography to quantitatively discriminate the areal biomass densities of the two populations. The grown biofilms exhibited highly heterogeneous distribution with patches of 1–2mm in size, although the conditions provided for growth, including substrate roughness, illumination and flow of the overlying water, were homogeneous. The biomass was initially dominated by cyanobacteria, which exhibited an exponential-like growth phase during days 2–7. Their population declined during days 9–17, which coincided with the growth phase of the diatom population. By allowing non-invasive and real-time measurements and data evaluation, the spectral imaging approach constitutes a useful tool for microbial ecologists.