Humclean2647

Our results indicate that MaiA may potentially serve as an effective antibiofilm agent to prevent Gram-negative biofilm formation in future clinical applications.Microbial community composition and stability affect pollutant removal for biological/granular activated carbon (BAC/GAC) processes. selleck compound Here, we pre-loaded the organic carbon substrates sucrose, lactose, and Lysogeny Broth (LB) medium onto new GAC prior to use and then tested whether this substrate pre-loading promoted development of biofilms with high coverage that remained stable for prolonged operational periods. Temporal dynamics of the biomass and microbial community on the GAC were monitored via flow cytometry (FCM) and sequencing, respectively, in both batch and continuous-flow experiments. In comparison with the non-loaded GAC (control), the initial biofilm biomass on substrate-loaded GAC was 3-114 times higher, but the initial richness was considerably lower (only accounting for 13-28% of the control). The initial community compositions were significantly different between batch and continuous-flow column experiments, even when loaded with the same substrates. In the continuous-flow column experiments, both biomass and microbial community composition became remarkably similar to the control filters after 64 days of operation. From these findings, we conclude that substrate-loaded GAC could enhance initial colonization, affecting both biomass and microbial community composition. However, the biomass and composition did not remain stable during long-term operation due to continuous dispersal and competition from influent bacteria.Acanthamoeba castellanii is a pathogenic and opportunistic free-living amoeba that causes Acanthamoeba keratitis (AK) and granulomatous amebic encephalitis (GAE) in immunocompromised individuals. The biological and pathogenic characterizations behind this opportunistic protozoan is not fully understood. This study aimed to determine the biological functions of heat shock protein (HSP)-20 of A. castellanii (Ac-HSP20) involved in the maintenance of life cycle and the infectivity of A. castellanii. Immunoscreening A. castellanii cDNA library with A. castellanii infected rabbit sera identified three positive clones, one of them was a putative heat shock protein (Ac-HSP20). The recombinant 23 kDa Ac-HSP20 protein (rAc-HSP20) was successfully expressed in Escherichia coli BL21 (DE3) and purified using metal affinity chromatography. The rabbits immunized with rAc-HSP20 produced high titer antibody (125,600). Immunolocalization with the antibody identified the expression of native Ac-HSP20 on the surface of both A. castellanii trophozoites and cysts. Further, Western blot with antibody identified that the expression of native Ac-HSP20 was 7.5 times higher in cysts than in trophozoites. Blocking Ac-HSP20 on the membrane of trophozoites with specific antibody or silencing Ac-hsp20 gene transcription by siRNA inhibited their transformation into cysts at the early stage but returned to normal at the late stage by stimulating the transcription of Ac-hsp20. Incubation of trophozoites with anti-Ac-HSP20 IgG increased macrophage-involved phagocytosis to the protozoa and inhibited trophozoite infectivity on the cornea of rabbits compared with that without antibody. Our study provides that Ac-HSP20 is a surface antigen involved in the encystation and infectivity of A. castellanii and thus an important target for vaccine and drug development.Pseudomonas aeruginosa, a well-known cause of nosocomial infection, is frequently antibiotic resistant and this complicates treatment. Links between oxidative stress responses inducing antibiotic resistance through over-production of RND-type efflux pumps have been reported in P. aeruginosa, but this has not previously been associated with MFS-type efflux pumps. Two MFS efflux pumps encoded by mfs1 and mfs2 were selected for study because they were found to be sodium hypochlorite (NaOCl) inducible. Antibiotic susceptibility testing was used to define the importance of these MFS pumps in antibiotic resistance and proteomics was used to characterize the resistance mechanisms involved. The results revealed that mfs1 is NaOCl inducible whereas mfs2 is NaOCl, N-Ethylmaleimide and t-butyl hydroperoxide inducible. Deletion of mfs1 or mfs2 did not affect antibiotic or paraquat susceptibility. However, over-production of Mfs1 and Mfs2 reduced susceptibility to aminoglycosides, quinolones, and paraquat. Proteomics, gene expression analysis and targeted mutagenesis showed that over-production of the MexXY RND-type efflux pump in a manner dependent upon armZ, but not amgRS, is the cause of reduced antibiotic susceptibility upon over-production of Mfs1 and Mfs2. mexXY operon expression analysis in strains carrying various lengths of mfs1 and mfs2 revealed that at least three transmembrane domains are necessary for mexXY over-expression and decreased antibiotic susceptibility. Over-expression of the MFS-type efflux pump gene tetA(C) did not give the same effect. Changes in paraquat susceptibility were independent of mexXY and armZ suggesting that it is a substrate of Mfs1 and Mfs2. Altogether, this is the first evidence of cascade effects where the over-production of an MFS pump causes over-production of an RND pump, in this case MexXY via increased armZ expression.Toxin-producing cyanobacteria can be harmful to aquatic biota, although some grazers utilize them with often beneficial effects on their growth and reproduction. It is commonly assumed that gut microbiota facilitates host adaptation to the diet; however, the evidence for adaptation mechanisms is scarce. Here, we investigated the abundance of mlrA genes in the gut of the Baltic copepods Acartia bifilosa and Eurytemora affinis during cyanobacteria bloom season (August) and outside it (February). The mlrA genes are unique to microcystin and nodularin degraders, thus indicating the capacity to break down these toxins by the microbiota. The mlrA genes were expressed in the copepod gut year-round, being >10-fold higher in the summer than in the winter populations. Moreover, they were significantly more abundant in Eurytemora than Acartia. To understand the ecological implications of this variability, we conducted feeding experiments using summer- and winter-collected copepods to examine if/how the mlrA abundance in the microbiota affect (1) uptake of toxic Nodularia spumigena, (2) uptake of a non-toxic algal food offered in mixtures with N.