[Pseudomonas aeruginosa virulence factors as a therapeutic target in multidrug-resistant strains].

Pseudomonas aeruginosa (PSAE) is known for its ability to form biofilm and produce other virulence factors associated with a resistant phenotype. Multidrug-resistant (MDR) PSAE strains represent a serious problem in healthcare and are the focus of an increasing number of studies dealing with the therapy of infections caused by these bacteria. Nowadays, a number of studies focus on the presence of virulence factors rather than on the mechanisms of resistance to the antibiotics used, as it is the study of virulence factors that makes it possible to expand the possibilities of effective and efficient therapy. This review describes the virulence factors produced by the one of the five PSAE secretion systems that have the potential to become targets for so-called antivirulence therapy, have been described. These are mainly alkaline protease, elastase B, exotoxins A, S and Y and pyocyanin. In addition to specific virulence factors, recent studies have focused on the components of the PSAE secretion systems that mediate the transport of toxins and lytic enzymes out of the bacterial cell. Inhibition of specific molecules for type 2 and 3 secretion systems may prevent secretion of virulence factors into the extracellular space and host cells, which would have a significant impact on reducing PSAE virulence.

Truffle biogeography-A case study revealing ecological niche separation of different Tuber species.

Ecology of hypogeic mycorrhizal fungi, such as truffles, remains largely unknown, both in terms of their geographical distribution and their environmental niches. Occurrence of true truffles (Tuber spp.) was therefore screened using specific polymerase chain reaction (PCR) assays and subsequent PCR amplicon sequencing in tree roots collected at 322 field sites across the Czech Republic. These sites spanned a wide range of climatic and soil conditions. The sampling was a priori restricted to areas thought to be suitable for Tuber spp. inasmuch as they were characterized by weakly acidic to alkaline soils, warmer climate, and with tree species previously known to host true truffles. Eight operational taxonomic units (OTUs) corresponding to Tuber aestivum, T. borchii, T. foetidum, T. rufum, T. indicum, T. huidongense, T. dryophilum, and T. oligospermum were detected. Among these, T. borchii was the OTU encountered most frequently. It was detected at nearly 19% of the sites. Soil pH was the most important predictor of Tuber spp. distribution. Tuber borchii preferred weakly acidic soils, T. foetidum and T. rufum were most abundant in neutral soils, and T. huidongense was restricted to alkaline soils. Distribution of T. aestivum was mainly dictated by climate, with its range restricted to the warmest sites. Host preferences of the individual Tuber spp. were weak compared to soil and climatic predictors, with the notable exception that T. foetidum appeared to avoid oak trees. Our results open the way to better understanding truffle ecology and, through this new knowledge, also to better-informed trufficulture.