Cell-to-cell communication by chemical signals, termed quorum sensing (QS), is a common regulatory scheme in the microbial world. Pseudomonas aeruginosa¸ an opportunistic pathogen of burn wounds and cystic fibrosis lungs, uses QS to control the expression of hundreds of genes, particularly those necessary for population level benefits such as biofilm...
Many bacteria possess cell density-dependent quorum-sensing (QS) systems that often regulate cooperative secretions involved
in host-microbe or microbe-microbe interactions. These secretions, or “public goods,” are frequently coregulated by stress and
starvation responses. Here we provide a physiological rationale for such regulatory complexity in the opportunistic pathogen
Pseudomonas aeruginosa. Using minimal-medium...
Nitrosomonas europaea is a chemolithoautotrophic bacterium that oxidizes ammonia (NH₃) to obtain energy for growth on carbon dioxide (CO₂) and can also produce nitrous oxide (N₂O), a greenhouse gas. We interrogated the growth, physiological, and transcriptome responses of N. europaea to conditions of replete (>5.2 mM) and limited inorganic carbon...
Peptide phosphorodiamidate morpholino oligomers (PPMO) are synthetic DNA mimics that bind complementary RNA and inhibit bacterial gene expression. (RFF)₃RXB- AcpP PPMO (R, arginine; F, phenylalanine; X, 6-aminohexanoic acid; B, β-alanine) is complementary to 11 bases of the essential gene acpP (encodes acyl carrier protein). The MIC of (RFF)₃RXB-AcpP was 2.5...
Cooperative behaviors in bacteria are increasingly appreciated for their relevance to microbial ecology and utility as model systems for social evolution. One example is the secretion of siderophores, a structurally diverse group of compounds that chelate extracellular iron. Siderophore production is considered cooperative because the benefits can be shared with...
Nitrification is the process within the global Nitrogen Cycle where ammonia (NH3) is oxidized to nitrate (NO₃⁻) and can be carried out by two distinct groups of bacteria. The ammonia-oxidizing bacteria (AOB) first oxidize NH₃ to nitrite (NO₂⁻), and second, the nitrite-oxidizing bacteria (NOB) oxidize NO₂⁻ to NO₃⁻. In aerobic...
Nitrification is a critical step in the global nitrogen cycle involving the biological oxidation of ammonia (NH₃) to nitrite (NO₂⁻ ) and then to nitrate (NO₃⁻). The first step in nitrification is carried out by NH₃-oxidizing bacteria (AOB) and archaea (AOA), and the second by NO₂⁻-oxidizing bacteria (NOB). In addition...
Soil acidity, expressed by low soil pH, causes reduced crop growth and significant economic loss. It is the most commonly overlooked and poorly understood yield-limiting factor in western Oregon and a developing concern in eastern Oregon. This publication describes the concept of soil acidity and the limitations it causes for...
Wheat (Triticum aestivum) is a highly valuable crop that makes up a large portion of the world’s food. However, breeding for improved varieties with desirable characteristics can be a challenge. This research examined two different issues wheat breeders deal with throughout the selection process all the way to production of...