A high yielding synthesis of racemic hongconin

Racemic hongconin 1 has been synthesized from adduct 2 formed by reaction between 1-methoxycyclohexa-1,4-diene and benzoquinone. The synthetic strategy includes Fries and Claisen rearrangements, base and cerium(IV) initiated pyran ring formation, C-4 pyran ring hydroxylation and silver(II) mediated oxidation

Pseudomonas aeruginosa uses type III secretion system to kill biofilm-associated amoebae

Bacteria and protozoa coexist in a wide range of biofilm communities of natural, technical, and medical importance. Generally, this interaction is characterized by the extensive grazing activity of protozoa on bacterial prey populations. We hypothesized that the close spatial coexistence in biofilms should allow opportunistic pathogenic bacteria to utilize their eukaryote-targeting arsenal to attack and exploit protozoan host cells. Studying co-cultures of the environmental pathogen Pseudomonas aeruginosa and the amoeba Acanthamoeba castellanii, we found that P. aeruginosa rapidly colonized and killed biofilm-associated amoebae by a quorum sensing independent mechanism. Analysis of the amoeba-induced transcriptome indicated the involvement of the P. aeruginosa type III secretion system (T3SS) in this interaction. A comparison of mutants with specific defects in the T3SS demonstrated the use of the secretion apparatus and the effectors ExoU, ExoS, and ExoT in the killing process, in which ExoU had the greatest impact. Virulence towards A. castellanii was found to be controlled by the global regulators RpoN and RpoS and through modulation of cAMP and alginate biosynthesis. Our findings suggest that conserved virulence pathways and specifically the T3SS play a central role in bacteria-protozoa interactions in biofilms and may be instrumental for the environmental persistence and evolution of opportunistic bacterial pathogens

Key Biochemical Attributes to Assess Soil Ecosystem Sustainability

Soil is not a renewable resource, at least within the human timescale. In general, any anthropic exploitation of soils tends to disturb or divert them from a more “natural” development which, by definition, represents the best comparison term for measuring the relative shift from soil sustainability. The continuous degradation of soil health and quality due to abuse of land potentiality or intensive management occurs since decades. Soil microbiota, being ‘the biological engine of the Earth’, provides pivotal services in the soil ecosystem functioning. Hence, management practices protecting soil microbial diversity and resilience, should be pursued. Besides, any abnormal change in rate of innumerable soil biochemical processes, as mediated by microbial communities, may constitute early and sensitive warning of soil homeostasis alteration and, therefore, diagnoses a possible risk for soil sustainability. Among the vastness of soil biochemical processes and related attributes (bioindicators) potentially able to assess the sustainable use of soils, those related to mineralisation-immobilisation of major nutrients (C and N), including enzyme activity (functioning) and composition (community diversity) of microbial biomass, have paramount importance due to their centrality in soil metabolism. In this chapter we have compared, under various pedoclimates, the impact of different agricultural factors (fertilisation, tillage, etc.) under either intensive and sustainable managements on soil microbial community diversity and functioning by both classical and molecular soil quality indicators, in order to outline the most reliable soil biochemical attributes for assessing risky shifts from soil sustainability