Oxygen Microenvironments in Biofilm Nutrient Transport Channels: Insights from Complementary Sensing Approaches.

Chemical gradients and the emergence of distinct microenvironments in biofilms are vital to the stratification, maturation and overall function of microbial communities. These gradients have been well characterised throughout the biofilm mass but the microenvironment of recently discovered nutrient transporting channels in biofilms remains unexplored. This study employs three different oxygen sensing approaches to provide a robust quantitative overview of the oxygen gradients and microenvironments throughout the biofilm transport channel networks formed by macrocolony biofilms.

The histidine kinase NahK regulates pyocyanin production through the PQS system.

Many bacterial histidine kinases work in two-component systems that combine into larger multi-kinase networks. NahK is one of the kinases in the GacS Multi-Kinase Network (MKN), which is the MKN that controls biofilm regulation in the opportunistic pathogen . This network has also been associated with regulating many virulence factors secretes to cause disease.

MpaR-driven expression of an orphan terminal oxidase subunit supports biofilm respiration and development during cyanogenesis.

Cyanide is an inhibitor of heme-copper oxidases, which are required for aerobic respiration in all eukaryotes and many prokaryotes. This fast-acting poison can arise from diverse sources, but mechanisms by which bacteria sense it are poorly understood. We investigated the regulatory response to cyanide in the pathogenic bacterium , which produces cyanide as a virulence factor.

Spatial heterogeneity in biofilm metabolism elicited by local control of phenazine methylation.

Within biofilms, gradients of electron acceptors such as oxygen stimulate the formation of physiological subpopulations. This heterogeneity can enable cross-feeding and promote drug resilience, features of the multicellular lifestyle that make biofilm-based infections difficult to treat. The pathogenic bacterium produces pigments called phenazines that can support metabolic activity in hypoxic/anoxic biofilm subzones, but these compounds also include methylated derivatives that are toxic to their producer under some conditions.