Mapping Bacterial Surface Population Physiology in Real-Time: Infrared Spectroscopy of Proteus Mirabilis Swarm Colonies

Abstract

We mapped the space-time distribution of stationary and swarmer cells within a growing Proteus mirabilis colony by infrared (IR) microspectroscopy. Colony mapping was performed at different positions between the inoculum and the periphery with a discrete microscope-mounted IR sensor, while continuous monitoring at a fixed location over time used an optical fiber based IR-attenuated total reflection (ATR) sensor, or "optrode." Phenotypes within a single P. mirabilis population relied on identification of functional determinants (producing unique spectral signals) that reflect differences in macromolecular composition associated with cell differentiation. Inner swarm colony domains are spectrally homogeneous, having patterns similar to those produced by the inoculum. Outer domains composed of active swarmer cells exhibit spectra distinguishable at multiple wavelengths dominated by polysaccharides. Our real-time observations agree with and extend earlier reports indicating that motile swarmer cells are restricted to a narrow (approximately 3 mm) annulus at the colony edge. This study thus validates the use of an IR optrode for real-time and noninvasive monitoring of biofilms and other bacterial surface populations.

Chalcogenide glass fibers: Optical window tailoring and suitability for bio-chemical sensing

“…The complex vibrational signature of bio-molecules in the 6-12 lm region offers a very effective mean of identifying, monitoring or diagnosing bio-molecules and tissues [10,11,[39][40][41]. In that respect chalcogenide glass bio-sensors have been successfully used to diagnose cancerous tissues [42] or human serum [43], as well as to monitor the swarming of bacterial film [44] or the metabolism of live lung cell cultures [13] and to selectively identify different types of bacteria [15] or proteins [33].…”

Glasses for Seeing Beyond Visible

“…The The second series of investigation deals with the formation of a biofilm and was conducted with the aim of controlling the colonization of a surface by bacteria, for instance in hospital environments or in the food industry. [17] The selected target is the pathogen bacteria "proteus mirabilis" and its growing and colonizing ability were investigated on a gelose surface. As shown on Figure 12 the progression of the bacterial biofilm is followed by putting the fibre in contact with the surface of the gelose substrate.…”

An explanatory model to validate the way water activity rules periodic terrace generation in Proteus mirabilis swarm

“…From a long in situ observation campaign of Proteus mirabilis colonies (see Gué et al [17], Keirsse et al [23], Lahaye et al [24,25]) and knowledge of physical phenomena arising within complex fluids, we are convinced that the main physical explanations of Proteus mirabilis swarm come from the properties of the extra cellular matrix which is the complex fluid smothering the bacteria of the colony. More than ten years ago, Rauprich et al [38] hypothesised the key role of relative osmotic activities at the agar colony interface.…”