Soil Application of a Formulated Biocontrol Rhizobacterium, PCL1606, Induces Soil Suppressiveness by Impacting Specific Microbial Communities.

Biocontrol bacteria can be used for plant protection against some plant diseases. PCL1606 (PcPCL1606) is a model bacterium isolated from the avocado rhizosphere with strong antifungal antagonism mediated by the production of 2-hexyl, 5-propil resorcinol (HPR). Additionally, PcPCL1606 has biological control against different soil-borne fungal pathogens, including the causal agent of the white root rot of many woody crops and avocado in the Mediterranean area, .

Rhizosphere-Associated Pseudomonas Suppress Local Root Immune Responses by Gluconic Acid-Mediated Lowering of Environmental pH.

The root microbiome consists of commensal, pathogenic, and plant-beneficial microbes [1]. Most members of the root microbiome possess microbe-associated molecular patterns (MAMPs) similar to those of plant pathogens [2]. Their recognition can lead to the activation of host immunity and suppression of plant growth due to growth-defense tradeoffs [3, 4].

Aspergillus fumigatus establishes infection in zebrafish by germination of phagocytized conidia, while Aspergillus niger relies on extracellular germination.

Among opportunistically pathogenic filamentous fungi of the Aspergillus genus, Aspergillus fumigatus stands out as a drastically more prevalent cause of infection than others. Utilizing the zebrafish embryo model, we applied a combination of non-invasive real-time imaging and genetic approaches to compare the infectious development of A. fumigatus with that of the less pathogenic A.

Functional analysis of three putative galactofuranosyltransferases with redundant functions in galactofuranosylation in Aspergillus niger.

Galactofuranose (Galf)-containing glycostructures are important to secure the integrity of the fungal cell wall. Golgi-localized Galf-transferases (Gfs) have been identified in Aspergillus nidulans and Aspergillus fumigatus. BLASTp searches identified three putative Galf-transferases in Aspergillus niger.

Comparative genomics reveals high biological diversity and specific adaptations in the industrially and medically important fungal genus Aspergillus.

Background: The fungal genus Aspergillus is of critical importance to humankind. Species include those with industrial applications, important pathogens of humans, animals and crops, a source of potent carcinogenic contaminants of food, and an important genetic model. The genome sequences of eight aspergilli have already been explored to investigate aspects of fungal biology, raising questions about evolution and specialization within this genus.

Transcriptomic and molecular genetic analysis of the cell wall salvage response of Aspergillus niger to the absence of galactofuranose synthesis.

The biosynthesis of cell surface-located galactofuranose (Galf)-containing glycostructures such as galactomannan, N-glycans and O-glycans in filamentous fungi is important to secure the integrity of the cell wall. UgmA encodes an UDP-galactopyranose mutase, which is essential for the formation of Galf. Consequently, the ΔugmA mutant lacks Galf-containing molecules.

Identification and functional analysis of two Golgi-localized UDP-galactofuranose transporters with overlapping functions in Aspergillus niger.

Background: Galactofuranose (Galf)-containing glycoconjugates are present in numerous microbes, including filamentous fungi where they are important for morphology, virulence and maintaining cell wall integrity. The incorporation of Galf-residues into galactomannan, galactomannoproteins and glycolipids is carried out by Golgi-localized Galf transferases. The nucleotide sugar donor used by these transferases (UDP-Galf) is produced in the cytoplasm and has to be transported to the lumen of the Golgi by a dedicated nucleotide sugar transporter.

A new vector for efficient gene targeting to the locus in .

Background: The possibility for efficient gene targeting for the controlled integration of DNA constructs is an important tool in fungal genetics.

Findings: In this study, we report a new targeting vector based on the marker in . The DNA sequence to be targeted is surrounded by two fragments of the gene to allow homologous recombination of the recombinant DNA at the locus.

Identification of the UDP-glucose-4-epimerase required for galactofuranose biosynthesis and galactose metabolism in .

Background: Galactofuranose (Gal)-containing glycoconjugates are important to secure the integrity of the cell wall of filamentous fungi. Mutations that prevent the biosynthesis of Gal-containing molecules compromise cell wall integrity. In response to cell wall weakening, the cell wall integrity (CWI)-pathway is activated to reinforce the strength of the cell wall.

Induction of A. fumigatus-specific CD4-positive T cells in patients recovering from invasive aspergillosis.

After allogeneic stem cell transplantation patients are at risk of invasive aspergillosis, especially during the period of neutropenia. Recent data suggest that impaired T-cell immune reconstitution after transplantation plays an important role in this increased risk. In this study we investigated whether Aspergillus-specific T cells are involved in the recovery from invasive aspergillosis by analyzing the Aspergillus-specific T-cell response in patients with invasive aspergillosis.

Fungal α-arabinofuranosidases of glycosyl hydrolase families 51 and 54 show a dual arabinofuranosyl- and galactofuranosyl-hydrolyzing activity.

Aspergillus niger possesses a galactofuranosidase activity, however, the corresponding enzyme or gene encoding this enzyme has never been identified. As evidence is mounting that enzymes exist with affinity for both arabinofuranose and galactofuranose, we investigated the possibility that α-L-arabinofuranosidases, encoded by the abfA and abfB genes, are responsible for the galactofuranosidase activity of A. niger.

Vacuolar H(+)-ATPase plays a key role in cell wall biosynthesis of Aspergillus niger.

The identification of suitable targets is crucial for the discovery and development of new antifungals. Since the fungal cell wall is an essential organelle, the identification of genes involved in cell wall biosynthesis is expected to help discover new antifungal targets. From our previously obtained collection of cell wall mutants with a constitutively active cell wall stress response pathway, we selected a thermosensitive, osmotic-remediable mutant with decreased resistance to SDS for complementation analysis.

Do biofilm formation and interactions with human cells explain the clinical success of Acinetobacter baumannii?

Background: The dramatic increase in antibiotic resistance and the recent manifestation in war trauma patients underscore the threat of Acinetobacter baumannii as a nosocomial pathogen. Despite numerous reports documenting its epidemicity, little is known about the pathogenicity of A. baumannii.

Biofilms on tracheoesophageal voice prostheses: a confocal laser scanning microscopy demonstration of mixed bacterial and yeast biofilms.

The aim of this study was to demonstrate the presence of yeast and bacterial biofilms on the surface of tracheoesophageal voice prostheses (TVPs) by a double-staining technique with confocal laser scanning microscopy (CLSM). Biofilms of 12 removed TVPs were visualized by scanning electron microscopy, then stained with ConA-FITC and propidium iodide for CLSM. Microbial identification was by partial 16S rRNA gene analysis and ITS-2 sequence analysis.

Genetic tools for tagging Gram-negative bacteria with mCherry for visualization in vitro and in natural habitats, biofilm and pathogenicity studies.

Live-cell imaging techniques are essential to gain a better understanding of microbial functioning in natural systems, for example in biofilms. Autofluorescent proteins, such as the green fluorescent protein (GFP) and the red fluorescent protein (DsRed), are valuable tools for studying microbial communities in their natural environment. Because of the functional limitations of DsRed such as slow maturation and low photostability, new and improved variants were created such as mCherry.

Maggot excretions/secretions are differentially effective against biofilms of Staphylococcus aureus and Pseudomonas aeruginosa.

Objectives: Lucilia sericata maggots are successfully used for treating chronic wounds. As the healing process in these wounds is complicated by bacteria, particularly when residing in biofilms that protect them from antibiotics and the immune system, we assessed the effects of maggot excretions/secretions (ES) on Staphylococcus aureus and Pseudomonas aeruginosa biofilms, the clinically most relevant species.

Methods: We assessed the effects of ES on biofilms using microtitre plate assays, on bacterial viability using in vitro killing and radial diffusion assays, and on quorum sensing systems using specific reporter bacteria.

The heat shock genes dnaK, dnaJ, and grpE are involved in regulation of putisolvin biosynthesis in Pseudomonas putida PCL1445.

Pseudomonas putida PCL1445 produces two cyclic lipopeptides, putisolvins I and II, which possess surfactant activity and play an important role in biofilm formation and degradation. In order to identify genes and traits that are involved in the regulation of putisolvin production of PCL1445, a Tn5luxAB library was generated and mutants were selected for the lack of biosurfactant production using a drop-collapsing assay. Sequence analysis of the Tn5luxAB flanking region of one biosurfactant mutant, strain PCL1627, showed that the transposon had inserted in a dnaK homologue which is located downstream of grpE and upstream of dnaJ.

Role of chemotaxis toward fusaric acid in colonization of hyphae of Fusarium oxysporum f. sp. radicis-lycopersici by Pseudomonas fluorescens WCS365.

Pseudomonas fluorescens WCS365 is an excellent competitive colonizer of tomato root tips after bacterization of seed or seedlings. The strain controls tomato foot and root rot (TFRR) caused by the phytopathogenic fungus Fusarium oxysporum f. sp.

Rhizoremediation: a beneficial plant-microbe interaction.

Worldwide, contamination of soil and ground water is a severe problem. The negative effects of pollutants on the environment and on human health are diverse and depend on the nature of the pollution. The search for alternative methods for excavation and incineration to clean polluted sites resulted in the application of bioremediation techniques.

Characterization of two Pseudomonas putida lipopeptide biosurfactants, putisolvin I and II, which inhibit biofilm formation and break down existing biofilms.

Pseudomonas putida strain PCL1445 was isolated from roots of plants, grown on a site polluted with polycyclic aromatic hydrocarbons. PCL1445 produces biosurfactant activity at the end of the exponential growth phase. High-performance liquid chromatography (HPLC) analysis of supernatant extracts of PCL1445 showed two peaks with surface-tension reducing activity, tentatively assigned as biosurfactants putisolvin I and putisolvin II and was followed by structural analyses.