By microorganisms

TABLE 7. Tertiary arsines via esters of arsenic(III) acids 

Arsine conflg. Wd Solvent Precursor conflg. [ ]d Solvent Ref. 

Via arsinous acid esters AsMePh(n-Pr) (65) R -4.0 MeOH As(OEt)MePh (128) R + 6.4 Neat 133 

AsBuEt(i-Pr) (138a) -11.3 MeOH As(OCinch)Et(i-Pr) (132a) +147.7 CH2CI2 134 

---

The amount of oxygen used in the degradation process is called the biochemical oxygen demand (BOD). A standard test has been devised to measure BOD in which the oxygen utilized by microorganisms in contact with the wastewater over a 5-day period at 20°C is measured. 

The metabohcaHy active form of pantothenic acid is coen2yme A. Pantothenic acid is produced only by microorganisms, starting from (R)-pantoate (22) and P-alanine. (R)-Pantoate is synthesi2ed by a set of en2ymatic reactions, as follows (63,64) ... 

Sludge is destroyed by microorganisms and the kinetics of their life processes is temperature dependent. Short anaerobic digestion detention times are obtained at 35°C. Even shorter detention times are possible at 52—54°C, but detention in this range is costly. An increase in detention time occurs at 35—43°C and then a progressive decrease takes place until 52—54°C. This variation is caused by a change in character of the dominant process organisms. 

Toxicity to fish is included in the data Hsted in Table 4. Marine life, particularly fish, may suffer damage from spills in lakes and streams. The chlorobenzenes, because they are denser than water, tend to sink to the bottom and may persist in the area for a long time. However, some data indicate that dissolved 1,2,4-trichlorobenzene can be biodegraded by microorganisms from wastewater treatment plants and also has a tendency to slowly dissipate from water by volatilization (34). 

A.ntibiotic is an organic chemical substance produced by microorganisms that has the capacity in low concentration to selectively destroy or inhibit the growth of other microorganisms without injuring the host cells. It may be adrninistered systemicaHy and be an antimicrobial chemotherapeutic agent. 

Until about 1950, the predominant method of producing industrial enzymes was by extraction from animal or plant sources by 1993, this accounts for less than 10%. With the exception of trypsin, chymosin, papain [9001 -73-2J, and a few others, industrial enzymes are now produced by microorganisms grown in aqueous suspension in large vessels, ie, by fermentation (qv). A smaH (5%) fraction is obtained by surface culture, ie, soHd-state fermentation, of microorganisms (13). 

Active attack is commonly caused by microorganisms. Four factors must be present for a diagnosis of microbiologically influenced corrosion ... 

Environmental Fate. A portion of releases of toluene to land and water will evaporate. Toluene may also be degraded by microorganisms. Once volatilized, toluene in the lower atmosphere will react with other atmospheric components contributing to the formation of ground-level ozone and other air pollutants. 

Environmental Fate. Most of the MEK released to the environment will end up in the atmosphere. MEK can contribute to the formation of air pollutants in the lower atmosphere. It can be degraded by microorganisms living in water and soil. 

Digester A tank in which sludge is placed to allow decomposition by microorganisms. Digestion may occur under anaerobic (most common) or aerobic conditions. 

Organic matter All of the degradable organics. Living material containing carbon compounds. Used as food by microorganisms. 

Biological reactors play a valuable role in tlie conversion of substrates by microorganisms and mammalian cells into a wide range of products such as antibiotics, insulin, and polymers. Figures 11-12, 11-13, and 11-14 illustrate various types of biological reactor, and Figure 11-15 shows the physical characteristics of a typical coimuercial fermentation vessel. 

Antibiotic A specific type of chemical substance that is administered to fight infections usually caused by bacteria, in humans or animals. Many antibiotics are produced by microorganisms some are chemically synthesized. 

Biodegradation The breakdown of substances by microorganisms, mainly by aerobic bacteria. 

All of the transport systems examined thus far are relatively large proteins. Several small molecule toxins produced by microorganisms facilitate ion transport across membranes. Due to their relative simplicity, these molecules, the lonophore antibiotics, represent paradigms of the mobile carrier and pore or charmel models for membrane transport. Mobile carriers are molecules that form complexes with particular ions and diffuse freely across a lipid membrane (Figure 10.38). Pores or channels, on the other hand, adopt a fixed orientation in a membrane, creating a hole that permits the transmembrane movement of ions. These pores or channels may be formed from monomeric or (more often) multimeric structures in the membrane. 

Biotechnological processes may be divided into fermentation processes and biotransformations. In a fermentation process, products are formed from components in the fermentation broth, as primary or secondary metabolites, by microorganisms or higher cells. Product examples are amino acids, vitamins, or antibiotics such as penicillin or cephalosporin. In these cases, co-solvents are sometimes used for in situ product extraction. 

Insulin is one of the important pharmaceutical products produced commercially by genetically engineered bactera. Before this development, commercial insulin was isolated from animal pancreatic tissue. Microbial insulin has been available since 1982. The human insulin gene is introduced into a bacterium like E. coli. Two of the major advantages of insulin production by microorganisms are that the resultant insulin is chemically identical to human insulin, and it can be produced in unlimited quantities. 

We make an assumption based on the fact that all of the dissolved oxygen in the fermentation broth is used or taken by microorganisms. In this case the DO goes to zero. The value for CAI can be zero since it is not given in the problem statement. Also the cell density has to be maximised. Therefore the above assumption is valid. In the above equation x represented the cell density, that is ... 

---