Inhibiting growth

The various sulphonamides differ in their specificity to various bacteria and in their ease of absorption and excretion. They are bacteriostatic (inhibiting growth) and not bactericidal, acting by allowing the natural body mechanisms to destroy the bacteria. 

Interferons (lENs) (52,53), a family of species-specific vertebrate proteins, confer nonspecific resistance to a broad range of viral infections, affect cell proliferation, and modulate immune responses. AH three principal interferons, a-interferon (lEN-a) produced by blood leucocytes, P-interferon (lEN-P) by fibroblasts, and y-interferon (lEN-y) by lymphocytes, also have antiviral activity. The abiUty of interferons to inhibit growth of transplantable and carcinogen-induced tumor led to research showing the direct antiproliferative and indirect immune-mediated antitumor activities (see Chemotherapeutics, anticancer). IENs have been found to be efficacious in certain malignancies and viral infections, eg, hairy cell leukemia (85% response) and basal cell carcinoma (86% response). However, the interferons do have adverse side effects (54). 

Organic acids may inhibit growth when present in the undissociated form because of their abiHty to change the pH inside the ceU. The most efficient are benzoic acid and sorbic acid, but formic, acetic, and propionic acid also have this effect. The parabens, ie, -hydroxy benzoic acid esters, are also used because of their antimicrobial effect over a broad pH range. 

Antibiotic Organic substance produced by one species of organism that in low concentrations will kill or inhibit growth of certain other organisms. 

In the presence of suffident metal ions such as zinc, phosphate defidency is known to inhibit growth and increase yields of dtric add. However, phosphate is added not only as a source of phosphorus but also as phosphoric add to addify the medium. Restricted growth but good citric add yield is also achieved by maintaining iron and zinc defidency hence low phosphate levels are not necessary. 

Trace metals have to be removed, notably manganese, ferrous ions and zinc. This is often accomplished using the compound potassium hexacyanoferrate which predpitates or complexes the metals and, in excess, acts to inhibit growth and indirectly promotes dtric add production. The amount of potassium hexacyanoferrate required is variable depending on the nature of the ion content of the carbon source. 

Leaves of Eucalyptus rostrata were shown to contain substances that inhibited growth and germination (90). Four active fractions were obtained from the crude leaf extract. Inhibitory constituents were shown to contain a carbonyl group and a carbon-carbon double... 

The processes involved for low molecular weights are diverse and are determined by the material, the orientation of the face, the temperature of the face and the medium from which it is growing. All of the processes will have some effect on the growth rate, however, if any one inhibits growth more than the others then... 

Antifungal drugp exert a local effect by inhibiting growth of the fungi. Examples of antifungal drugs and their uses are ... 

Any substance present in great excess can inhibit growth or even cause death. Metabolic products are often toxic to the organism that produces them. Thus, a batch fermentation can be limited by accumulation of products as well as by depletion of the substrate. A simple model for growth in the presence of an inhibitor is... 

Lactoferrin j Iron-binding protein May inhibit growth of certain bacteria by binding iron and may be involved in regulation of proliferation of myeloid cells... 

Figure 1 shows that high superficial gas velocity in the airlift bioreactor obviously inhibited growth of H. pluvialis. In this study, the best superficial gas velocity for growth of H. pluvialis was found at the lower limit of the experiment (0.4 cm s ), which providing the maximum cell density and maximum specific growth rate of 77x10 cells mL (2.79 g L of... 

Type I interferons induce a vims-resistant state in human cells, whereas Type II are more active in inhibiting growth of tumour cells. 

Tests considered to date have, without exception, measured unequivocally the bactericidal effect. In some instances it is useful to know the minimum concentration which inhibits growth (reproduction) rather than those concentrations which achieve a rapid kill. The implications ofthe terms bactericide and bacteriostat were discussed earlier (see section 1.1, Fig. 11.1). 

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