MICROBIAL SYSTEMS

Other Microbial Systems. In addition to the systems described, gene cloning is routinely performed in several other bacterial strains including Streptoccocus Staphylococcus Brevibacterium BJdodobacter Comyebacterium Glucanobacter Acetobacter and Zanthomonas species. 

Three more antibiotics, all discovered about 1953, are also derivatives of cytosine. Amicetin, bamicetin and plicacetin may all be isolated from Streptomyces plicatus and all have some activity against some acid-fast and Gram-positive bacteria as well as some other microbial systems (69MI21301). Structural work in this area is fascinating (62JOC2991). 

Although dynamic responses of microbial systems are poorly understood, models with some basic features and some empirical features have been found to correlate with actual data fairly well. Real fermentations take days to run, but many variables can be tried in a few minutes using computer simulation. Optimization of fermentation with models and reaf-time dynamic control is in its early infancy however, bases for such work are advancing steadily. The foundations for all such studies are accurate material Balances. 

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. 

A number of studies describing the oxidation of sulfides to sulfoxides by biological oxidizing agents have been published over the years2 9,13,107- Microbial systems are often... 

The perceived sensitivity of plant cells to the hydrodynamic stress associated with aeration and agitation conditions is typically attributed to the physical characteristics of the suspended cells, namely their size, the presence of a cell wall, the existence of a large vacuole, and their tendency to aggregate. Table 1 illustrates some of the differences between plant cells and other biological systems. Chalmers [19] attributed shear sensitivity in mammalian cultures at least in part to the fact that these cells occur naturally as part of a tissue, surrounded by other cells. The same is true for plant cells. The more robust microbial systems, on the other hand, exist in nature as single organisms or mycelial structures, very close to the forms they assume in submerged culture. 

MOLECULAR GENETICS AND REGULATION OF PECTINASE BIOSYNTHESIS IN SAPROPHYTIC AND PHYTOPATHOGENIC MICROBIAL SYSTEMS... 

Rosazza JP (1978) Antitumor antibiotic bioactivation, biotransformation and deriva-tization by microbial systems. Recent Results Cancer Res 63 58-68... 

R. Goodacre, Characterisation and quantification of microbial systems using pyrolysis mass spectrometry introducing neural networks to analytical pyrolysis, Microbiol. (Europe), 2 19 (1994). 

Where high pH system is needed then a combination of 2,4-Dichlorobenzyl Alcohol with phenoxyethanol is used.such as Midtect PFP type mixtures from Microbial Systems International of Nottingham UK. 

The table 1 summarises the challenge test data using Myavert C 5 part enzyme based preservation in a face mask 1 including speed of kill test to justify positive marketing claims for the anti-microbial system used in the product. Table 2 uses conventional chemical anti-microbials for a foot product at much higher levels than would be allowed for face application yet the speed of kill of the enzyme system is superior yet much more mild. 

Rosenkranz HS, Poirier LA. 1979. Evaluation of the mutagenicity and DNA-modifying activity of carcinogens and noncarcinogens in microbial systems. J Natl Cancer Inst 62 873-892. 

El-Sharkawi S, Yusuf Z, Pihie AHL, Ali AM. Metabolism of goniothalamin in animal and microbial systems. Bull Chim Farmaceutica 1996 135 35-40. 

Nigan P and Singh D. 1995. Enzyme and microbial systems involved in starch processing. Enzyme Microb Technol 17 770-778. 

Microbial systems Consortium comprised of three bacterial strains capable of degrading several textile dyes including azo dyes in a rotating biological contactor Sludge from a domestic... 

Method/technique Microbial systems Parameters studied References... 

Recombinant DNA technology facilitates not only production of human insulin in microbial systems, but also facilitates generation of insulins of modified amino acid sequences. The major aims of generating such engineered insulin analogues include ... 

Therefore the catalytic activity of these enzymes varies enormously and it is in theory possible that at least in some cases the quantity or activity of the hydrogen evolving enzyme could limit the overall process. However, there is little evidence for this being the limiting factor in any system. Indeed, in many microbial systems, potential catalytic activity far surpasses the amount of hydrogen produced, suggesting that other metabolic factors are limiting. 

When a pilot-scale fermenter is run in continuous mode with a fresh feed flowrate of 65 1/h, the effluent from the fermenter contains 12 mg/1 of the original substrate. The same fermenter is then connected to a settler-thickener which has the ability to concentrate the biomass in the effluent from the tank by a factor of 3.2, and from this a recycle stream of concentrated biomass is set up. The flowrate of this stream is 40 1/h and the fresh feed flowrate is at the same time increased to 100 1/h. Assuming that the microbial system follows Monod kinetics, calculate the concentration of the final clarified liquid effluent from the system. /x, = 0.15 h-1 and Ks = 95 mg/1. 

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