Activity

Bacteria in the genus Geobacter thrive in iron- and manganese-rich environments where the divalent cobalt cation (CoII) accumulates to potentially toxic concentrations. Consistent with selective pressure from environmental exposure, the model laboratory representative Geobacter sulfurreducens grew with CoCl2 concentrations (1 mM) typically used to enrich for metal-resistant bacteria from contaminated sites. We reconstructed from genomic data canonical pathways for CoII import and assimilation into cofactors (cobamides) that support the growth of numerous syntrophic partners. We also identified several metal efflux pumps, including one that was specifically upregulated by CoII. Cells acclimated to metal stress by downregulating non-essential proteins with metals and thiol groups that CoII preferentially targets. They also activated sensory and regulatory proteins involved in detoxification as well as pathways for protein and DNA repair. In addition, G. sulfurreducens upregulated respiratory chains that could have contributed to the reductive mineralization of the metal on the cell surface. Transcriptomic evidence also revealed pathways for cell envelope modification that increased metal resistance and promoted cell-cell aggregation and biofilm formation in stationary phase. These complex adaptive responses confer on Geobacter a competitive advantage for growth in metal-rich environments that are essential to the sustainability of cobamide-dependent microbiomes and the sequestration of the metal in hitherto unknown biomineralization reactions.Surface proteins in Gram-positive bacteria are often involved in biofilm formation, host-cell interactions, and surface attachment. Here we review a protein module found in surface proteins that are often encoded on various mobile genetic elements like conjugative plasmids. This module binds to different types of polymers like DNA, lipoteichoic acid and glucans, and is here termed polymer adhesin domain. We analyze all proteins that contain a polymer adhesin domain and classify the proteins into distinct classes based on phylogenetic and protein domain analysis. Protein function and ligand binding show class specificity, information that will be useful in determining the function of the large number of so far uncharacterized proteins containing a polymer adhesin domain.A Viable but non-culturable (VBNC) state is a bacterial survival strategy under reverse conditions. It poses a significant challenge for public health and food safety. In this study, the effect of external environmental conditions including acid, nutrition, and salt concentrations on the formation of S. aureus VBNC states at low temperatures were investigated. Different acidity and nutritional conditions were then applied to food products to control the VBNC state formation. Four different concentration levels of each factor (acid, nutrition, and salt) were selected in a total of 16 experimental groups. Nutrition showed the highest influence on the VBNC state formation S. aureus, followed by acid and salt. The addition of 1% acetic acid could directly kill S. aureus cells and inhibit the formation of the VBNC state with a nutrition concentration of 25, 50, and 100%. A propidium monoazide-polymerase chain reaction (PMA-PCR) assay was applied and considered as a rapid and sensitive method to detect S. aureus in VBNC state with the detection limit of 104 CFU/mL.We have isolated and characterized a novel antibacterial peptide, CMB001, following an extensive screening effort of bacterial species isolated from diverse environmental sources. The bacterium that produces CMB001 is characterized as a Gram (+) bacillus sharing approximately 98.9% 16S rRNA sequence homology with its closest match, Paenibacillus kyungheensis. The molecule has been purified to homogeneity from its cell-free supernatant by a three-step preparative chromatography process. Based on its primary structure, CMB001 shares 81% identity with subtilin and 62% with nisin. CMB001 is active mainly against Gram-positive bacteria and Mycobacteriaceae but it is also active against certain Gram-negative bacteria, including multi-drug resistant Acinetobacter baumannii. It retains full antibacterial activity at neutral pH and displays a low propensity to select for resistance among targeted bacteria. Based on NMR and mass spectrometry, CMB001 forms a unique 3D-structure comprising of a compact backbone with one α-helix and two pseudo-α-helical regions. Screening the structure against the Protein Data Bank (PDB) revealed a partial match with nisin-lipid II (1WCO), but none of the lantibiotics with known structures showed significant structural similarity. Due to its unique structure, resistance profile, relatively broad spectrum and stability under physiological conditions, CMB001 is a promising drug candidate for evaluation in animal models of bacterial infection.Ca2 +/calmodulin-dependent phosphatase calcineurin is one of the important regulators of intracellular calcium homeostasis and has been investigated extensively in Saccharomyces cerevisiae. However, only a few reports have explored the function of the Crz1 homolog in filamentous fungi, especially in Fusarium graminearum. In this study, we identified Fg01341 as a potential ortholog of yeast Crz1. Fg01341 could interact with calcineurin and initiate nuclear transport in a calcineurin-dependent manner. The ΔFg01341 mutant exhibited normal hyphal growth on basic medium and conidia formation, but sexual reproduction was partially blocked. Pathogenicity assays showed that the virulence of the ΔFg01341 mutant in flowering wheat heads and corn silks dramatically decreased and was thus consistent with the reduction in deoxynivalenol production. Unexpectedly, the sensitivity to osmotic stress of the deletion mutant and that of the wild-type strain did not present any differences. buy DOX inhibitor The deletion mutant showed higher sensitivity to tebuconazole than the wild-type strain. Results also showed that the transcription factor Fg01350 might be the calcineurin target and was independent of Crz1. Furthermore, ΔFg01350 showed defects in hyphal growth, sexual production, virulence, and deoxynivalenol production. Collectively, the results indicate that these two proteins functionally redundant and that the calcineurin-Crz1-independent pathway is particularly important in F. graminearum.