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[en] The improvement of ecological and technological qualities of Maritza East coals after biodesulfurization with Pseudomonas is reported. It is underlined that after laboratory treatment of coals with species of Pseudomonas some decrease of total sulfur is found out if the treatment is done at 300oC= 6,8 – 6,9 and in media Reimond
[en] Highlights: • Crystal structure of PA4202 protein in complex with FMN and NE was determined. • A kinetic study reveals that the PA4202 enzyme may catalyze a neutral nitroalkane. • Our results provide the first structure-based substrate binding property of PA4202. Nitroalkane oxidase (NAO) and nitronate monooxygenase (NMO) are two different types of nitroalkane oxidizing flavoenzymes identified in nature. A previous study suggested that the hypothetical protein PA4202 from Pseudomonas aeruginosa PAO1 is NMO and utilizes only anionic nitronates. However, the structural similarity between the PA4202 protein and Streptomyces ansochromogenes NAO has motivated investigation for what features of the two enzymes differentiate between the NAO and NMO activities. Herein, we report the crystal structure of PA4202 in a ternary complex with a neutral nitroethane (NE) and flavin mononucleotide (FMN) cofactor to elucidate the substrate recognition mechanism using a site-directed mutagenesis. The ternary complex structure indicates that the NE is bound with an orientation, which is poised for the proton transfer to H183 (which is the essential first catalytic step with nitroalkanes), and subsequent reactions with FMN. Moreover, a kinetic study reveals that the catalytic reactions of the wild type and H183 mutants PA4202s with nitroalkane substrates may yield the products of hydrogen peroxide and nitrite that are specified to NAO, although they show a low catalytic efficiency. Our results provide the first structure-based molecular insight into the substrate binding property of the hypothetical protein PA4202, including the interactions with neutral nitroalkanes as the substrate.
[en] Pseudomonas aeruginosa is an improtant opportunistic pathogen that can cause infection in immunocompromised patient. Lipopolysaccharide (LPS), the major surface antigen of P. aeruginosa, is immunogenic and elieits protective antibodies in animals. The O-polysaccharids (O-PS) from international Antigenic typing Scheme (IATS) 10, the antigenic determinant of LPS, was coupled to recombinant exoprotein A (rPA) through adipic acid dihydrazide (ADH) mediated by carbodiimide condensation reaction. Mice were immunized with the conjugate emulsifield with monophosphoryl lipid A-trehalose dicorynomycolate (MPL-T) and freund's adjuvants. The conjiugate emulsified with MPL-T adjuvant elicited the highest level of IgG and IgM followed by freuns's adjuvant. IgG titers using both MPL-T and freund's adjuvants were recorded to be higher than IgM titers after the second post of the immunization. Immunization of mice with the prepared conjugates emulsified with MPL-T and freund's adjvaided provide high level of protection (100%) against ten times the LD50 of homologous strain of P. aeruginsoa. the elicited high IgG level and the in vivo protection test results provided good evidences for the possible protection of the conjugate aginst subsequent infection with the pathogen. These findings will enable us to use it as protective vaccine candidate (authors).
[en] Highlights: • P. putida MT54 is a temperature-sensitive p-nitrophenol degradation mutant strain of P. putida DLL-E4. • PnpB is essential for P. putida MT54 to degrade PNP at 37 °C. • PnpA is a psychrophilic enzyme that responsible for the temperature-sensitive degradation in P. putida MT54. Pseudomonas putida DLL-E4 can efficiently degrade para-nitrophenol and its intermediate metabolite hydroquinone at 37 °C and 30 °C. However, mutant strain Pseudomonas putida MT54, obtained by transposon mutagenesis from P. putida DLL-E4, could not degrade para-nitrophenol at 37 °C. The mutant genes including DW660143, DW660153 and pnpB were discovered in strain MT54 by whole genome resequencing. Gene knockout and complementation confirmed the necessity of PnpB in PNP degradation by temperature-sensitive strain MT54. PnpA catalyzes the first step in complete degradation of PNP, and we found its activity was significantly enhanced by PnpB. The measurement of bacterial two-hybrid system indicated that the effect was not mediated by the direct interaction between PnpA and PnpB, but caused by the elimination of product inhibition of PnpA. Furthermore, PnpA was characterized as a psychrophilic enzyme with optimum temperature of 20 °C. We concluded that the lowered activity of PnpA resulted from inactivation of PnpB at the restrictive temperature induced the temperature-sensitive characteristic of P. putida MT54.
[en] Highlights: • Ocular P. aeruginosa isolates induce autophagy in human corneal epithelial cells. • T3SS mutants were defective in inducing autophagy and becn1 expression. • T3SS (−)ve strains were less sensitive to external autophagy modulators. • Pro-autophagic role of T3SS regulates intracellular survival of P. aeruginosa. Corneal ulcers caused by Pseudomonas aeruginosa may lead to severe visual disability due to impaired bacterial clearance from corneal tissues. Our purpose was to study the role of autophagy in the intracellular clearance of P. aeruginosa from human corneal epithelial cells (HCET) and its regulation by the bacterial type III secretion system (T3SS) toxins. Nine different corneal ulcer isolates of P. aeruginosa, PAO1 and T3SS mutants of PAO1 were used to infect HCET cells. Induction of autophagy (Immunofluorescence and Western blot) and pro-inflammatory gene expression (real time PCR) by P. aeruginosa and the role of autophagy in intracellular bacterial clearance were studied in the context of T3SS genotypes. The clinical isolates and PAO1 induced autophagy irrespective of the T3SS genotype, whereas the T3SS mutants were relatively defective in inducing autophagy and becn1 gene expression. External induction of autophagy significantly reduced the intracellular load of P. aeruginosa strains that were associated with worst clinical outcomes. The T3SS negative isolate and PAO1ΔexoST were less sensitive to pharmacological modulation of autophagy and had relatively higher replication potential, suggesting a possible mechanism of bacterial survival in the absence of T3SS toxins. Overall, our results highlight a selective role for autophagy in bacterial clearance from corneal epithelial cells and emphasize the pro-autophagic role of bacterial toxins in the context of corneal ulcers.
[en] Polyhydroxyalkanoates (PHAs) have been produced by various bacteria as natural polymers stored in bacterial cells as a source of carbon and energy. They are currently preferred biomaterials for use in many industrial fields instead of conventional non-degradable plastics. Due to their unique properties they can reduce pollution caused by the increasing global polymer demand. Pseudomonas species have been chosen as PHAs producers in many recent studies. Being metabolically versatile and possessing a remarkable tolerance to a wide range of carbon sources, these bacteria have become an efficient cell factory for PHAs production. Currently, attention is focused on the design of Pseudomonas strains to increase their ability to accumulate PHAs in the cell and modifying their biosynthetic pathways to obtain strains with modified compositions and improved properties. This article discusses the current state of knowledge of polyhydroxyalkanoates synthesized by Pseudomonas species which are industrially important microorganisms. This review provides an overview of recent trends towards PHA production, focusing on the utilization of low-cost carbon sources, fermentation strategies, PHAs properties and their uses as valuable bioproducts.
[en] The bacterial community of an anaerobic granular sludge associated with uranium depletion was investigated following its exposure to uranium under different initial pH conditions (pH 4.5, 5.5, and 6.5). The highest uranium removal efficiency (98.1%) was obtained for the sample with an initial pH of 6.5, which also supported the highest bacterial community richness and diversity. Venn diagrams visualized the decrease in the number of genera present in both the inoculum and the uranium-exposed biomass as the initial pH decreased from 6.5 to 4.5. Compared with the inoculum, a significant increase in the abundances of the phyla Chloroflexi and Proteobacteria was observed following uranium exposure. At initial pH conditions of 6.5 to 4.5, the proportions of the taxa Anaerolineaceae, Chryseobacterium, Acinetobacter, Pseudomonas, and Sulfurovum increased significantly, likely contributing to the observed uranium removal. Uranium exposure induced a greater level of dynamic diversification of bacterial abundances than did the initial pH difference.
[en] The results of examination of 143 children with acute purulent destructive pneumonia caused by Gram-negative microorganisms (in a monoculture or in association with staphylococcus) have been analyzed. The X-ray appearance of acute purulent destructive pneumonia caused by Pseudomonas aeruginosa is presented. The importance of X-ray examination for the early diagnosis of acute purulent destructive pneumonias is emphasized: a conjecture can thus be made on the etiology of the disease and specific treatment initiated