Pseudomonas rates

Although Brevundimonas (Pseudomonas) diminuta (ATCC 19146) is most commonly used for steriliziug-grade filter vaUdation, iu certain appHcations other bacteria are used. For example, when it is necessary to demonstrate removal of mycoplasma in appHcations involving sera and tissue culture media, membranes having a smaller pore size rating, eg, 0.1 p.m, are frequentiy used. For these membranes,laidlawii may be employed for vaHdation purposes (9). 

Specific information about the optimum conditions for the synthesis and the activity of the enzyme has been reported for Pseudomonas fluorescens screening of various micro-organisms resulted in the selection of a P. fluorescens strain with an initial rate of conversion of 3 g P h 1 in an imoptimised state. The following conclusions could be made concerning the production of L-phenylalanine by P. fluorescens ... 

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 low-temperature method has been applied to some primary and secondary alcohols (Fig. 1) For example, solketal, 2,2-dimethyl-1,3-dioxolane-4-methanol (3) had been known to show low enantioselectivity in the lipase-catalyzed resolution (lipase AK, Pseudomonas fluorescens, E = 16 at 23°C, 27 at 0oc) 2ia however, the E value was successfully raised up to 55 by lowering the temperature to —40°C (Table 1). Further lowering the temperature rather decreased the E value and the rate was markedly retarded. Interestingly, the loss of the enantioselectivity below —40°C is not caused by the irreversible structural damage of lipase because the lipase once cooled below —40°C could be reused by allowing it to warm higher than -40°C, showing that the lipase does not lose conformational flexibility at such low temperatures. 

An issue of particular relevance in the context of bioremediation is illustrated by the increased rate of cell death in an established naphthalene-degrading Pseudomonas putida G7 brought about by the substrate (naphthalene) under conditions of oxygen (or combined oxygen and nitrogen) limitation (Ahn et al. 1998). 

Whereas degradation of the readily extractable tolnene in spiked soil by Pseudomonas putida was rapidly accomplished, there was a reside that was degraded mnch more slowly at a rate that was apparently dependent on its desorption (Robinson et al. 1990). 

Immobilization of neutral xenobiotics in soils by qnatemary ammoninm cations has been established, and its significance on the bioavailability of naphthalene to bacteria has been examined. Bioavailability was determined by the rates of desorption, and these differed between a strain of Pseudomonas putida and one of Alcaligenes sp. (Crocker et al. 1995). 

The metabolism of fluorobenzoates has been examined over many years. Early studies using Nocardia erythropoUs (Cain et al. 1968) and Pseudomonas fluorescens (Hughes 1965) showed that although the rates of whole-cell oxidation of fluorobenzoates were less than for benzoate, they were comparable to, and greater than for, the chlorinated analogs. As for their chlorinated analogs, both dioxygenation and hydrolytic pathways may be involved, and studies have revealed that the different pathways depended on the positions of the fluorine substituents. 

Increased removal of phenanthrene from soil columns spiked with the rhamnolipid mixture synthesized by Pseudomonas aeruginosa UG2 has been demonstrated, and shown to depend both on the increased desorption of the substrate and on partitioning into micelles (Noordman et al. 1998). However, the addition of the biosurfactant from the same strain of Pseudomonas aeruginosa UG2 or of sodium dodecyl sulfate had no effect on the rate of biodegradation of anthracene and phenanthrene from a chronically contaminated soil. 

Density indicator strips are used to monitor the rate of microbial growth. These strips are attached to the culture vessel. As the microbes multiply, the solution becomes cloudy, obscuring some of the shaded strips. The degree of visibility of the shaded strips indicates the density of the microbes. In this activity, you will observe the bioremediation effectiveness of the fungus Penicillium and the bacteria Pseudomonas on a sample of oil. 

A summary of the industrial-scale process development for the nitrilase-catalyzed [93] route to ethyl (/ )-4-cyano-3-hydroxy-butyrate, an intermediate in the synthesis of Atorvastatin (Pfizer Lipitor) from epichlorohydrin via 3-hydroxyglutaronitrile (3-HGN) was recently reported (Figure 8.15) [94], The reaction conditions were further optimized to operate at 3 m (330 gL ) substrate, pH 7.5 and 27 °C. Under these conditions, 100% conversion and product ee of 99% was obtained in 16 h reaction time with a crude enzyme loading of 6% (based on total protein, 0.1 U mg-1). It is noted that at pH < 6.0 the reaction stalled at <50% conversion and at alkaline pH a slowing in reaction rate was observed. Since the starting material is of low cost and the nitrilase can be effectively expressed in the Pfenex (Pseudomonas) expression system at low cost, introduction of the critical stereogenic center... 

Another Pseudomonas strain P. delafieldii R-8 was reported to remove 90.5% sulfur from highly desulfurized diesel oil [259], The biocatalyst achieved desulfurization via a pathway similar to the 4S pathway. The rate of desulfurization was reported to be 11.25 mmol sulfur/kg dcw/h, with the sulfur being reduced from 591 to 56 mg/L. This was achieved via two biocatalyst treatments lasting 20 hours each, although the biocatalyst was active only for first 6h in each treatment. Up to C4-DBTs were reported to be removed. Almost 100% of Q and C2 DBTs were removed and about 94% C3 DBTs and 97% C4 DBTs were removed. This strain of Pseudomonas thus appears to have a mechanism to uptake up to C4 DBTs through its cell membrane. 

Loukidou et al. (2005) fitted the data for the equilibrium sorption of Cd from aqueous solutions by Aeromonas caviae to the Langmuir and Freundlich isotherms. They also conducted, a detailed analysis of sorption rates to validate several kinetic models. A suitable kinetic equation was derived, assuming that biosorption is chemically controlled. The so-called pseudo second-order rate expression could satisfactorily describe the experimental data. The adsorption data of Zn on soil bacterium Pseudomonas putida were fit with the van Bemmelen-Freundlich model (Toner et al. 2005). 

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