Antibiotics, production

Monofunctional, cyclohexylamine is used as a polyamide polymerization chain terminator to control polymer molecular weight. 3,3,5-Trimethylcyclohexylamines ate usehil fuel additives, corrosion inhibitors, and biocides (50). Dicyclohexylamine has direct uses as a solvent for cephalosporin antibiotic production, as a corrosion inhibitor, and as a fuel oil additive, in addition to serving as an organic intermediate. Cycloahphatic tertiary amines are used as urethane catalysts (72). Dimethylcyclohexylarnine (DMCHA) is marketed by Air Products as POLYCAT 8 for pour-in-place rigid insulating foam. Methyldicyclohexylamine is POLYCAT 12 used for flexible slabstock and molded foam. DM CHA is also sold as a fuel oil additive, which acts as an antioxidant. StericaHy hindered secondary cycloahphatic amines, specifically dicyclohexylamine, effectively catalyze polycarbonate polymerization (73). 

To obtain reproducible antibiotic production by fermentation, it is necessary to obtain a pure culture of the producing organism. Pure cultures are isolated from mixed soil sample populations by various streaking and isolation techniques on nutrient media. Once a pure culture has been found that produces a new antibiotic typically on a mg/L scale, improvement in antibiotic yield is accompHshed by modification of the fermentation medium or strain selection and mutation of the producing organism. Production of g/L quantities may take years to accomplish. 

I eplanocins. Neplanocins A—D and E (37—41) are carbocycHc nucleoside antibiotic products oi Ampullariella regularis (1,4) that are stmcturaHy related to (36) in that they contain either a cyclopentene or epoxy cyclopentane ring (121,122). The chemical syntheses of (37—41) and the 3-deazaneplanocins have been reported (123—126). Compound (37), which is converted to its 5 -triphosphate, has potent antitumor and antiviral activities (127—129). It strongly inhibits SAM in ceUs and vimses (128—131) and is converted to the 3 -keto derivative by A-adenosyUiomocysteine hydrolase (132,133). 

Most of the fermentation and isolation processes for manufacture of the tetracyclines are described in patents (71,72). Manufacture begins with the cultivated growth of selected strains of Streptomjces in a medium chosen to produce optimum growth and maximum antibiotic production. Some clinically useful tetracyclines (2—4) are produced directly in these fermentations others (5—7) are produced by subjecting the fermentation products to one or more chemical alterations. The purified antibiotic produced by fermentation is used as the starting material for a series of chemical transformations (59). 

The pharmaceutical industry has employed materials of plant and animal origin as sources of drugs. The industry has utilized the life processes of either plants or animals and microorganisms to produce medicinal and antibiotic products. 

Prior to sterilizing the abovedescribed medium, adjust the pH to 8. Aerobically ferment for 66 to 90 hours while stirring at 250 rpm with air input at 4.5 C/)2/min and 25 psi. The potency of the antibiotic produced at the end of this period reaches a peak of 150 to 225 jug/ml and remains relatively constant. The pH of the fermentation medium changes slightly during the antibiotic production, varying in the range of 6.8 to 7.3. 

There are many approaches that may be used here. One approach is to screen related new strains, organisms to see if a higher yielding strain may be obtained. Alternatively, the culture "culture conditions used to cultivate the antibiotic-producing strain may be modified with the conditions objective of increasing antibiotic production. This may include manipulation of physical... 

We will leave the story of cephalosporin here, since much of the subsequent modifications depend more upon synthetic chemistry than upon biotechnology. It is for example possible to convert deacetoxycephalosporin, exomethylenecephain and demethylcephalosporin derivatives using synthetic chemical procedures. If you wish to follow up this aspect of antibiotic production in more detail, we would recommend Sebek K. O "Antibiotics" in Biotechnology - Volume 6a, edited by Kieslich, K. 1984. Verlag Chemie, Weinheim. 

For antibiotic production, the fermentation broth needs a pretreatment tank to produce crude and highly purified antibiotic products. The bioprocesses involved in producing antibiotics are spray or continuously dried crude solids and pure solid in the form of crystalline antibiotic. 

Antibiotics are produced by fermentation. The process may take a few days to obtain an extractable amount of product. Antibiotic production is done by the batch process. Oxygen transport is the major concern therefore sufficient polymeric sugar and protein with a trace amount of elemental growth factors are used to enhance production. An anti-biogram test is used to observe the amount of antimicrobial agent in the fermentation broth. A bioassay determines the activity unit of the bactericides. 

There is only one choice for the antibiotic production process the synthesis of benzyl-penicillin (penicillin G, originally known as penicillin ). This, the most renowned antibiotic and the first one have been manufactured in bulk, is still universally prescribed.5 Although originally made by surface liquid culture, penicillin G is now produced by air-lift fermentation under aerated conditions. 

The constant shear concept has been applied for bioreactor scale-up that utilises mycelia, where the fermentation process is shear sensitive and the broth is affected by shear rate of impeller tip velocity. For instance, in the production of novobicin, the yield of antibiotic production is dependent on impeller size and impeller tip velocity. 

The manufacture of benzylpenicillin (penieillin G, originally just penicillin ) is chosen as a model for the antibiotic production process. It is the most renowned of antibioties and is the first to have been manufactured in bulk. It is still universally prescribed and is also in demand as input material for semisynthetic antibiotics (Chapter 5). Developments associated with the penicillin fermentation process have been a significant factor in the development of modem bioteehnology. It was a further 30 years, i.e. not until the 1970s, before there were signifieant new advances in industrial fermentations. 

The growth phase passes rapidly into the antibiotic-production phase. The optimum pH and temperature for growth are not those for penicillin production and there may be changes in the control of these parameters. The only other event that marks the onset of the production phase is the addition ofphenylacetic acid (PAA) by continuous feed. 

The relative importance of antibiotic production versus production of siderophores for disease suppression has recently been studied by Mulya and co-... 

Bioassay on Solid Medium. A-9, a medium previously shown to be favorable for antibiotic production by actinomycetes in shake flasks (36), was modified for bioassays on solid medium. We halved the concentration of components in A-9 and adjusted the pH to 6.9-7.1 with KOH to reduce the possibility of osmotic or toxic effects of medium components themselves on seed germination and seedling growth. The medium was amended with 15 g agar per liter and poured into 10 x 10 x 1.5 cm square plastic petri dishes, about 60 ml per plate. 

Butler, M.J., Bruheim, P, Jovetic, S. et al. (2002) Engineering of primary carbon metabolism for improved antibiotic production in Streptomyces lividans. Applied and Environmental Microbiology, 68, 4731 4739. 

Stevenson IL (1954) Antibiotic production by actinomycetes in soil demonstrated by morphological changes induced in Helminthosporium sativam. Nature 174 598-599... 

Vaidyanathan et al. performed a critical evaluation of models developed for an industrial submerged bioprocess for antibiotic production.56 Both transmission and reflection techniques were employed on a number of reactions. Oil and tylosin were the analytes followed throughout the reaction. 

Woodruff HB. (1966) The physiology of antibiotic production The role of the producing organism. Symp Soc Gen Microbiol 16 22 6. 

Chater KF, Bibb MJ. (1997) Regulation of antibiotic production. In H-J Rehm... 

Early detection of mastitis and immediate treatment reduces pathologic damage and increases the likelihood of eliminating the infection. Because therapy is given without identification of the pathogen involved, a product with a broad antibacterial spectrum is essential (4. The desirable kinetic and other properties of an intramammary antibiotic product for treatment in lactation have been summarized by Ziv (23). 

In the U.S., unlike most nations, some antibiotic products for mastitis therapy are available to the dairyman without a veterinary prescription. For FDA approval of an over-the-counter intramammary infusion product, it is required that adequate directions for use be written so that the layman can use the drug safely and for the purposes for which it is intended. The following antibiotics are currently approved and marketed for intramammary infusion in treatment of bovine mastitis (26) ... 

For the past 35 years. U.S. livestock and poultry producers have used antibiotics (products of microbial synthesis) and chemotherapeutics (chemically synthesized products). The drugs are administered in relatively large dosages to treat sick animals (therapeutically) and in lower dosages to prevent disease in exposed animals (prophylactica11 y). More commonly, small amounts... 

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