Morphogenesis and oxygen dynamics in phototrophic biofilms growing across a gradient of hydraulic conditions

Abstract

Biofilms are surface-attached and matrix-enclosed microbial communities that dominate microbial life in numerous ecosystems. Using flumes and automated optical coherence tomography, we studied the morphogenesis of phototrophic biofilms along a gradient of hydraulic conditions. Compact and coalescent biofilms formed under elevated bed shear stress, whereas protruding clusters separated by troughs formed under reduced shear stress. This morphological differentiation did not linearly follow the hydraulic gradient, but a break point emerged around a shear stress of~0.08 Pa. While community composition did not differ between high and low shear environments, our results suggest that the morphological differentiation was linked to biomass displacement and reciprocal interactions between the biofilm structure and hydraulics. Mapping oxygen concentrations within and around biofilm structures, we provide empirical evidence for biofilm-induced alterations of oxygen mass transfer. Our findings suggest that architectural plasticity, efficient mass transfer, and resistance to shear stress contribute to the success of phototrophic biofilms.

The structure–function relationship ofPseudomonas aeruginosain infections and its influence on the microenvironment

“…While there is a good understanding of such structure–function relationships in many natural biofilm communities (e.g. Depetris et al, 2021 , 2022 ), the question remains how bacteria are organized in chronic infections and whether a complex 3D structural organization and derived changes of their microenvironment confer any advantage for their persistence and resilience to the immune response or antibiotic treatment.…”

“…Surface-attached biofilms remain relevant to numerous systems such as fouling of industrial equipment (Flemming 2011 ) and aquatic plants (Noisette et al 2020 ), stream biofilms (Besemer et al 2012 , Depetris et al 2021 ), oral biofilms (Bowen et al 2018 ), and implant-associated infections (Arciola et al 2018 ). However, in most types of bacterial infections it is now becoming widely accepted that biofilms are not necessarily attached directly to a surface but rather suspended in an extracellular matrix (Bjarnsholt et al 2013 , Kragh et al 2016 ).…”

Synthetic periphyton as a model system to understand species dynamics in complex microbial freshwater communities

“…high nutrient concentration and specific actinic light exposure). Under another environmental filtering, community development and species succession might be therefore different [8,9,[70][71][72]. The absence of flow, as is the case in our experimental system, might also lead to a potential formation of gradients of light, oxygen, pH and nutrients within the biofilm [72,73], which in turn can affect the biofilm development, extracellular matrix production, species interactions and competition [74,75].…”

Non-invasive investigation of the morphology and optical properties of the upside-down jellyfishCassiopeawith optical coherence tomography

“…In this context, optical coherence tomography (OCT) presents an attractive alternative imaging modality (Fercher et al, 2003; Huang et al, 1991; Schmitt, 1999), as it enables non-invasive in vivo imaging of live specimens using near infrared (NIR) wavelengths, allows for high-resolution tomographic scanning of tissue in real time, and enables 3D reconstruction of large samples with a potential depth of penetration of several millimeters depending on the scattering properties of the sample (Schmitt, 1999; Wangpraseurt et al, 2017b). Previous studies have utilized OCT for visualizing and quantifying structural characteristics, such as surface area, volume, and porosity in biofilms (Depetris et al, 2021; Wagner et al, 2010), terrestrial plants (Hettinger et al, 2000), and marine invertebrates (Speiser et al, 2016), including scleractinian corals (Jaffe et al, 2022; Wangpraseurt et al, 2017b; Wangpraseurt et al, 2019).…”