Pseudomonas aeruginosa characteristics

Wang et al.2 and Najafpour et al.3A worked with immobilised microbial cells of Nitrobacer agilis, Saccharomyces cerevisiae and Pseudomonas aeruginosa in gel beads, respectively. They found separately that the cells retained more than 90% of their activity after immobilisation by using specific oxygen uptake rate (SOUR) [mg 02g 1 (dry biomass) h 11 as the biomass activity indicator. Such differences in immobilised biomass and activity between free and immobilised biomass activities depend strongly on the particular characteristics of the microbial systems and their interaction with the support matrix. 

The types of microorganisms found in various products are Pseudomonas species, including Pseudomonas aeruginosa, Salmonella, species, Staphylococcus aureus, and Escherichia coli. The USP and other pharmacopoeias recommend certain classes of products to be tested for specified microbial contaminants, e.g., natural plant, animal, and some mineral products for the absence of Salmonella species, suspensions for the absence of E. coli, and topically administered products for the absence of P. aeruginosa and S. aureus. Emulsions are especially susceptible to contamination by fungi and yeasts. Consumer use may also result in the introduction of microorganisms. For aqueous-based products, it is therefore mandatory to include a preservative in the formulation in order to provide further assurance that the product retains its pharmaceutically acceptable characteristics until it is used by the patient. 

Nadkarni, S.R. 1971. Studies on bacterial lipase. Part II. Study of the characteristics of partially purified lipase from Pseudomonas aeruginosa. Enzymologia 40, 302—313. 

Kim, N., Park, I.S., Kim, D.K (2004). Characteristics of a label-free piezoelectric immu-nosensor detecting Pseudomonas aeruginosa. Sens. Actuators B Chem. 100, 432 138... 

An important characteristic of microbial biofilms is their innate resistance to immune system and antibiotic killing (89, 90). This has made microbial biofilms a common and difficult-to-treat cause of medical infections (87,91,92). It has recently been estimated that over 60% of the bacterial infections currently treated in hospitals are caused by bacterial biofilms (91). Several ehronic infections (e.g. respiratory infections caused by Pseudomonas aeruginosa in the cystic fibrosis lung. Staphylococcal lesions in endocarditis, and bacterial prostatitis, primarily caused by Escherichia coli) have been shown to be mediated by biofilms (93). More notably, biofilms (particularly of Staphylococcus aureus, P. aeruginosa, and E. coli) are also a major cause of infections associated with medical implants (94, 95). The number of implant-associated infections approaches 1 million per year in the United States alone, and their direct medical costs exceed 3 billion annually (96). Thus, there is an urgent need to find novel approaches to eradicate biofilms. 

At least 12 genes are involved in the formation of nitrate reductase in various Enterobacteriaceae, 5 nar genes have been identified in Pseudomonas aeruginosa and 13 Chi mutations have been characterized in Bacillus licheniformis (Stouthamer, 1976). The physiological properties of chlorate-resistant mutants have been characterized and their location on the circular chromosome determined. Chi mutations have a pleotropic affect such characteristics as dehydrogenase activity, cytochrome distribution, and membrane protein composition may be influenced. The different Cfi/ mutants are able to synthesize various components of the complex nitrate reductase molecule. It is possible, in some instances, to form active enzyme by mixing components extracted from the appropriate mutants (Stouthamer, 1976). 

The complexity of confusions about MIC does not end with the various ways of naming it or mixing it up with other corrosion phenomena while it has been stated that there is unequivocal evidence that the observable physical or biochemical characteristics of sessile bacteria are profoundly different from those of their planktonic cousins, it has also been reported that, for example, only 1% of Pseudomonas aeruginosa genes have revealed differential expression in planktonic and biofilm cells. 

Production of a rhamnolipid biosurfactant by cells of Pseudomonas aeruginosa strain BN 10 immobilized into PEO and PAAm cryogels was investigated under semicontinuous shake flask conditions and compared to biosurfactant secretion by free cells [33]. The yield of rhamnolipids in the immobilized system exceeded that of the free bacterial cells, distinguishing an effective bioprocess. The polymer matrices possessed chemical and biological stability and very good physico-mechanical characteristics, which are prerequisites for a high life span of these materials for the production of rhamnolipids. 

Broderick et al indicated the presence of high-spin Fe(III) in a rhombic environment with tyrosine coordination, based on the results obtained from electronic absorption, EPR, and resonance Raman spectroscopies [100]. No evidence has been obtained for the histidine coordination which is verified by the solution of the X-ray crystal structure of Pseudomonas aeruginosa 3,4-PCD [33]. The visible spectrum is similar in both Amax (430 nm) and extinction coefficient (e= 3095 M cm" ) to those reported for the 1,2-CTD and 3,4-PCD enzymes. (Bhat et al also observed a band at 425 nm, e = 4700 M cm with 3,5-dichlorocatechol 1,2-dioxygenase [104].) EPR spectra exhibit resonances at = 4.25 and 9.79 (X-band) and those at 4.3 (gx = 4.21, gy = 4.18, gz = 4.32) and g = 9.83, indicating nonheme Fe(III) in a rhombic environment. The resonance Raman spectra (Agx = 647.1 nm) exhibit tyrosine ring vibrations characteristic of Fe(III) tyrosinate sites at 1604 and 1507 cm (C-C stretch), 1266 cm" (broad, C-0 stretch of two different tyrosine ligands), and 1183 cm (C-H stretch). 

It is well known that microbes, such as bacteria and fungi, emit characteristic odours that the human nose can smell, for example, an earthy smeU is associated with fungal-contaminated environments, a fishy smell is associated with bacterial vaginosis, or a grape-like smell is associated with Pseudomonas aeruginosa. These smells are a result of metabolic processes leading to an emission of characteristic VOCs from the microbes. Consequently, the analytical detection of these VOCs is a potential means for rapid microbial identification and is an interesting and fruitful area of research. 

Fig. 2.4 Mediators can achieve high power densities in MFCs. (A) Solvent extracts from an MFC showing characteristic biue-green coiors, typicai of phenazines such as pyocyanin and phenazine-1-carboxamide produced by bacteria such as Pseudomonas aeruginosa] (B) a recirculation tube stained blue, likely by adsorbed mediators (C) cation exchange membrane of 4 anodic chambers containing P. aeruginosa that produced different phenazines the mediators partially sorbed onto the membrane. [Photographs by K. Rabaey.]...

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