Microorganism tolerant

Fed-batch and continuous modes of operation require agitation, either to mix in fresh substrates or nutrients, or to move the substrate bed along the bioreactor from inlet to outlet. Therefore these modes of bioreactor operation can only be used if the process microorganism tolerates mixing. 

Water-miscible ionic liquids are usually toxic to microorganisms, but some microorganisms tolerate small amounts of water-miscible ionic hquids. For ejomple, Pichia... 

There are two popular microorganisms that can produce high concentrations of alcohol. Their tolerance to high concentrations of ethanol and substrates are stated in the literature.3-5 The most common are Zymomonas mobilis and Saccharomyces cerevisiae. 

The body possesses an efficient natural defence mechanism which restricts microorganisms to areas where they can be tolerated. A breach of this mechanism, allowing them to reach tissues which are normally inaccessible, results in an infechon. Invasion and multiplicahon of the organism in the infected host m result in a pathological condihorr, the clirrical entity of disease. 

Another important factor affecting microbial activity is pH. Microorganisms that can grow under acidic (pH < 4) or alkaline (pH > 10) conditions are termed acidophiles or alkalophiles, respectively. Most bacteria, however, are neutrophiles. Neutrophiles can tolerate pH levels between 5 and 9, but their optimum growth is observed in a relatively narrow range around neutrality, i.e., between... 

One of the main obstacles for whole-cell microbial transformation in an organic solvent is its biocompatibility, which has led to screening for organic-solvent-tolerant microorganisms. Numerous organic-solvent-tolerant microorganisms have been found and their tolerance mechanisms have been reviewed [14,33,34]. Two-phase biotransformation systems have been successfully implemented for the production of pharmaceutically relevant metabolites. 

The sol-gel-entrapped microbial cells have shown excellent tolerance to different alcohols [99], The immobilized E. coli cells followed the Michaelis-Menten equation when quantified with the (3-glucosidase activity via the hydrolysis of 4-nitrophenyl-(3-D-galactopyranosdie [142], The sol-gel matrices doped with gelatin prevented the cell lysis, which usually occurs during the initial gelation process [143], Microorganisms are now widely used in the biosorption of different pollutants and toxicants. Bacillus sphaericus JG-A12 isolated from uranium mining water has been entrapped in aqueous silica nanosol for the accumulation of copper and uranium [144], Premkumar et al. [145] immobilized recombinant luminous bacteria into TEOS sol-gel to study the effect of sol-gel conditions on the cell response (luminescence). The entrapped and free cells showed almost the same intensity of luminescence (little lower), but the entrapped cells were more stable than the free cells (4 weeks at 4°C). This kind of stable cell could be employed in biosensors in the near future. 

Schmitt H, Flaapakangas H, van Beelen P (2005) Effects of antibiotics on soil microorganisms time and nutrients influence pollution-induced community tolerance. Soil Biol Biochem 37 1882-1892... 

Extremes of pH would also cause problems for mammals that have a body pH controlled very close to around 6.7 in the blood, but some microorganisms have developed a tolerance to extreme pH conditions of 0-12.5. The organisms work... 

Smittle RB and Flowers RS. 1982. Acid tolerant microorganisms involved in the spoilage of salad dressings. J Food Prot 45 977-983. 

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