Slime Production by Pseudomonas aeruginosa

Using Pseudomonas aeruginosa culture IFO 3445, the nutritional requirements and cultural conditions suitable for slime production were investigated. A synthetic medium was established from the experimental results, which was composed of sodium glutamate, glucose, phosphate and magnesium salt. When a cellophane plate method was used, incubation at 37 C for 3 days attained the highest relative viscosity. In the presence of an oxidizable carbohydrate the relative viscosity of the culture fluid was reduced with the acidic reaction, and recovered if the reaction was adjusted to pH 7–8.     

Slime Production by Pseudomonas aeruginosa

Two samples of slime obtained from Pseudomonas aeruginosa strains, IFO 3445 and No. 24, the latter which produced mucoid colonies on brain heart infusion agar as well as on the synthetic agar medium, were investigated for their physicochemical properties, primarily for their viscosities. Results obtained indicated that the principal component of the slime from strain IFO 3445 might be a deoxyribonucleic acid-like substance, while the slime from the mucoid strain No. 24 might be an alginic acid-like substance.     

Slime Production by Pseudomonas aeruginosa

Chemical properties and compositions of slimes produced by two Pseudomonas aeruginosa strains of different colonial types were investigated. The main component of the slime from strain IFO 3445 was found to be DNA, contaminated with small amounts of protein. On the other hand, the slime from a mucoid-type strain No. 24 was an alginate-like substance consisting of mannuronic and glucuronic acids, and contained traces of protein and nucleic acid. Slimes from twenty clinical isolates of P. aeruginosa were investigated for their chemical compositions. Slimes from eighteen strains consisted of DNA, while, two strains of a mucoid-type produced slimes composed of polyuronic acid.     

Production of rhamnolipids by Pseudomonas aeruginosa

Pseudomonas aeruginosa produces glycolipidic surface-active molecules (rhamnolipids) which have potential biotechnological applications. Rhamnolipids are produced by P. aeruginosa in a concerted manner with different virulence-associated traits. Here, we review the rhamnolipids biosynthetic pathway, showing that it has metabolic links with numerous bacterial products such as alginate, lipopolysaccharide, polyhydroxyalkanoates, and 4-hydroxy-2-alkylquinolines (HAQs). We also discuss the factors controlling the production of rhamnolipids and the proposed roles this biosurfactant plays in P. aeruginosa lifestyle.     

Role of Iron and Sulfur in Pigment and Slime Formation by Pseudomonas aeruginosa

Media and an analytical scheme have been developed which allow both a qualitative and quantitative estimation of the formation of pyocyanine, related phenazines, pyorubrin, and a blue and a yellow-green fluorescent pigment by Pseudomonas aeruginosa. Use of the defined pyocyanine medium of Frank and DeMoss with sulfate or various organic sulfur sources allowed formation of pyocyanine, related phenazines, and pyorubrin. When sulfite was the sulfur source with or without iron, P. aeruginosa formed either a yellow-green or a blue fluorescent pigment. Formation of fluorescent pigments of P. aeruginosa is related to the ability of sulfite to act as a specific sulfur source. In an investigation of the role of both added iron and sulfur sources, complex patterns of pigment formation were observed. In addition to the fluorescent pigments, sulfite also supported the formation of slime by P. aeruginosa.     

Stress-Induced Outer Membrane Vesicle Production by Pseudomonas aeruginosa

As an opportunistic Gram-negative pathogen, Pseudomonas aeruginosa must be able to adapt and survive changes and stressors in its environment during the course of infection. To aid survival in the hostile host environment, P. aeruginosa has evolved defense mechanisms, including the production of an exopolysaccharide capsule and the secretion of a myriad of degradative proteases and lipases. The production of outer membrane-derived vesicles (OMVs) serves as a secretion mechanism for virulence factors as well as a general bacterial response to envelope-acting stressors. This study investigated the effect of sublethal physiological stressors on OMV production by P. aeruginosa and whether the Pseudomonas quinolone signal (PQS) and the MucD periplasmic protease are critical mechanistic factors in this response. Exposure to some environmental stressors was determined to increase the level of OMV production as well as the activity of AlgU, the sigma factor that controls MucD expression. Overexpression of AlgU was shown to be sufficient to induce OMV production; however, stress-induced OMV production was not dependent on activation of AlgU, since stress caused increased vesiculation in strains lacking algU. We further determined that MucD levels were not an indicator of OMV production under acute stress, and PQS was not required for OMV production under stress or unstressed conditions. Finally, an investigation of the response of P. aeruginosa to oxidative stress revealed that peroxide-induced OMV production requires the presence of B-band but not A-band lipopolysaccharide. Together, these results demonstrate that distinct mechanisms exist for stress-induced OMV production in P. aeruginosa.     

Production of cytotoxin by clinical strains of Pseudomonas aeruginosa

Presence of cytotoxin was studied in extracts of 57 strains of Pseudomonas aeruginosa (46 bacteremia, 4 environmental, and 7 Fisher immunotype), 10 Pseudomonas species, and 7 nonpseudomonas isolates. Cytotoxin was identified by Western immunoblot in extracts of all P. aeruginosa isolates. None of the Pseudomonas species or nonpseudomonas isolates were shown to produce this protein. No immunologic cross-reactivity was observed between cytotoxin antibody and P. aeruginosa alkaline protease, toxin A, or elastase. In partially purified extracts of two bacteremia strains and PA 158 (parent strain for cytotoxin production), detection of cytotoxin by Western immunoblot was correlated with biological activity, as measured by the cell swelling assay. Cytotoxin appears to be produced by all strains of P. aeruginosa and biological activity can be demonstrated in extracts of the strains tested. This biological activity is neutralized by specific antibody. Because of its known marked cytotoxic effect on most eukaryotic cells, P. aeruginosa cytotoxin might be an important factor in the pathogenesis of P. aeruginosa infections.     

Interaction of Pseudomonas Bacteriophage 2 with the Slime Polysaccharide and Lipopolysaccharide of Pseudomonas aeruginosa Strain BI

Purified slime polysaccharide B and lipopolysaccharide of Pseudomonas aeruginosa strain BI were shown to possess receptor-like properties in inactivating Pseudomonas phage 2, whereas lipoprotein and glycopeptide fractions were devoid of activity. On a weight basis, slime polysaccharide B was more effective than lipopolysaccharide in inactivating phage. The specificity of the reaction with slime polysaccharide B was indicated by the fact that slime polysaccharide A of P. aeruginosa strain EI failed to inactivate phage 2. Electron micrographs showed phage 2 in typical, tail-first position of attachment on intact cells of strain BI, slime polysaccharide B, and lipopolysaccharide. Tail fibers were discernible during phage attachment.     

Production and properties of an inhibitor of the Pseudomonas autoinducer by Pseudomonas aeruginosa

An inhibitor was found in the culture fluid of Pseudomonas aeruginosa PAO1, which could inhibit the activity of the Pseudomonas autoinducer (PAI). The maximal inhibitory activity occurred in stationary phase culture sup ernatant. The PAI inhibitor did not influence the cell growth and the PAI production by P. aeruginosa PAO1 when the PAI inhibitor was added into culture medium. The induced expression of lacZ in the reporter strain Agrobacterium tumefaciens NT1 was suppressed by this PAI inhibitor, whereas inhibition could be relieved by increasing the auto inducer concentration. The quorum sensing of P. aeruginosa was inhibited presumably by inhibiting the inducing activity of Pseudomonas autoinducer but not by inhibiting the production of Pseudomonas autoinducer. It was demonstrated that the structure of the PAI inhibitor was different from that of acyl-homoserine lactones.     

Production of Proteinase on Noncarbohydrate Carbon Sources by Pseudomonas aeruginosa

Proteinase production by Pseudomonas aeruginosa was studied in medium containing noncarbohydrate materials, especially various hydrocarbons, as the sole carbon source. On heavy oil, kerosene, n-paraffinic hydrocarbon of C₁₂, C₁₄, or C₁₆, and propylene glycol, the bacteria grew well and high protinase production was observed. However, production on paraffinic hydrocarbon differed remarkably with strains of varied origins. The elastase-positive strain, IFO 3455, showed abundant growth and high proteinase production on medium containing a paraffin of C₁₂, C₁₄, or C₁₆, whereas the elastase-negative strain, IFO 3080, showed little growth on the same medium. Neither elastase-positive nor elastase-negative strains, however, utilized n-paraffins of C₅ to C₁₀, or various aromatic hydrocarbons such as benzene, naphthalene, phenanthrene, and anthracene. The proteinases produced on the noncarbohydrate medium were identical with those produced in glucose medium.     

铜绿假单胞菌产酰化高丝氨酸内酯信号分子抑制剂的生产及分离

目的：通过自体诱导信号分子抑制剂的生产获得部分分离纯化的酰化高丝氨酸内酯（AHL）抑制剂。方法：病原菌铜绿假单胞菌经摇床培养后获得AHL抑制剂,采用溶解度差异性和树脂进行分离纯化。结果：铜绿假单胞菌PAO1不仅分泌自体诱导信号分子,而且在生长的后期还合成一种信号分子抑制剂,该信号分子抑制剂对群体感应中的AHL类信号分子有明显的抑制作用;该抑制剂具有醇溶性和水溶性,采用乙醇溶解可以除去糖类和无机小分子等不溶于醇的物质;大孔吸附树脂不具有吸附抑制剂的能力,但可以除去醇溶性糖类物质;阴离子交换树脂能够吸附信号分子抑制剂,具有较好的分离效率。结论：获得了除去大部分杂质,得到部分分离纯化的AHL抑制剂。     

Production of a peptidoglycolipid bioemulsifier by Pseudomonas aeruginosa grown on hydrocarbon

A strain of Pseudomonas aeruginosa isolated from a polluted soil was found to produce an extracellular bioemulsifier when cultivated on hexadecane as sole carbon source. The emulsifier was precipitated with acetone and redissolved in sterile water. Dodecane, crude oil and kerosene were found to be good substrates for emulsification by the bioemulsifier. Growth and bioemulsifier production reached the optimal levels on the fourth and fifth day, respectively. Emulsifying activity was observed over a pH range of 3.5 to 10.0 with a maximum at pH 7.0. The activity of the bioemulsifier was heat stable up to 70 degrees C while about 50 percent of its activity was retained at 100 degrees C. The components of the bioemulsifier were determined, it was found to contain carbohydrate, protein and lipid. The protein complex was precipitated with ammonium sulphate and fractionated on a Sephadex G-100. Gel electrophoresis of the bioemulsifier showed a single band whose molecular weight was estimated as 14,322 Da. The bioemulsifier was classified as a peptidoglycolipid. Certain strains of P. aeruginosa produce peptidoglycolipid in place of rhamnolipid.     

Production of d-proline from l-arginine using Pseudomonas aeruginosa

Several microorganisms that can use (S)-5-[(amino-iminomethyl) amino]-2-chloropentanoic acid (l-Cl-arginine) as a nitrogen source have been isolated, the most interesting of which is a spontaneous mutant of Pseudomonas aeruginosa PAO1 (DSM 10581). In a fermenter, this unique biocatalyst hydrolysed l-Cl-arginine to (S)-5-amino-2-chloropentanoic acid (l-Cl-ornithine), which spontaneously converted to d-proline with inversion of configuration at an apparent average rate of 0.12 mmol ^−l h⁻¹ OD⁻¹. The enzyme, for which we suggest the name Cl-arginine amidinohydrolase, was best induced by using the substrate l-Cl-arginine as inducer and l-arginine as nitrogen source. The results presented here describe a new route for the production of d-proline from l-arginine, involving a chemical step and a biocatalytic step followed by a spontaneous chemical cyclisation.