“Cable Bacteria” Interact with a Photosynthetic Biofilm
Filamentous bacteria capable of transmitting electricity across centimeter-scale distances have recently been discovered in marine sediments. Using microsensor profiling, Malkin and Meysman (p. 948–956) demonstrated that these “cable bacteria” can interact with a photosynthetic biofilm in a salt marsh sediment. Oxygen produced by the biofilm during photosynthesis caused cable bacteria to immediately increase sulfide oxidation down to a depth of several centimeters within the sediment. Additionally, a behavioral response of cable bacteria was revealed on the time scale of hours, suggesting that these bacteria have the capacity to sense and respond to changes in their redox environment.
The Exposed Moiety of the Lipopolysaccharide Is Important for Cellular Cohesion and Biofilm Compaction
The lipopolysaccharide (LPS) of proteobacteria has shown important antigenic properties and several protective functions. However, the role of LPS in cell-cell interactions is not fully understood. Studies by Russo et al. (p. 1013–1023) show that the exposed portion of the Rhizobium leguminosarum LPS, i.e., the O-antigen core moiety, is crucial for intimate and lateral contacts between bacterial cells and for the formation of compact biofilm structures on both abiotic and biotic surfaces. These observations may have interesting implications in the interplay between the exposed portion of the LPS and other extracellular factors involved in biofilm formation.
Metals and Methanotrophy
Methanotrophs are well known to be sensitive to the presence of copper, with expression and activity of the two known forms of methane monooxygenase changing dramatically as copper concentrations vary. Here, Kalidass et al. (p. 1024–1031) show that methanobactin, synthesized by methanotrophs for the binding and uptake of copper, can be “fooled” into binding metals other than copper, with significant effects on methanotrophic activity. This discovery suggests that methanotrophic communities in situ may be affected by a broader range of metals than previously thought, and it also suggests new strategies for enhanced pollutant and/or methane degradation via methanotrophy.
Evolution Happens: an Intracellular Symbiont Quickly Adapts to a Mutant Host
The maternally transmitted, obligate intracellular symbiont Wolbachia pipientis infects 40 to 60% of insect species on the planet. Although Wolbachia is not genetically tractable, Newton and Sheehan (p. 1032–1037) took advantage of Drosophila melanogaster genetics to bottleneck Wolbachia and select for mutant bacterial strains. Their results show that Wolbachia is not a monoculture within an individual and that adaptation to a new host occurs rapidly, after only three generations. The authors used deep sequencing to uncover potential candidate genes involved in bacterial adaptation. This approach, analogous to forward genetics in other systems, may help identify mechanisms for Wolbachia-host interaction in a nonculturable bacterium.
Risk for Pathogen Contamination of Leafy Greens Grown near Cattle Feedlots
Fresh produce, such as spinach and lettuce, is typically consumed raw, so preventing pathogen contamination in the production environment is essential for protecting public health. Berry et al. (p. 1101–1110) investigated Escherichia coli O157:H7 contamination of leafy greens planted at different distances near and downwind of a cattle feedlot. Airborne transport of E. coli O157:H7 from the feedlot was indicated, and leafy green contamination decreased as the distance from the feedlot was increased. These findings provide information to the produce industry for use in assessing the risks associated with growing produce crops near cattle production facilities and for setting guidelines for setback distances to reduce contamination risk.
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- “Cable Bacteria” Interact with a Photosynthetic Biofilm
- The Exposed Moiety of the Lipopolysaccharide Is Important for Cellular Cohesion and Biofilm Compaction
- Metals and Methanotrophy
- Evolution Happens: an Intracellular Symbiont Quickly Adapts to a Mutant Host
- Risk for Pathogen Contamination of Leafy Greens Grown near Cattle Feedlots
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