Bacterial inhibitors

Small amounts of hydrogen peroxide in raw milk can activate the lactoperoxidase-catalyzed oxidation of thiocyanate to produce a bacterial inhibitor (Hogg and Jago 1970). Inhibitory compounds resulting from oxygen metabolism can produce initially slow starter culture growth in industrial dairy fermentations if the milk has been excessively agitated. 

Reiter, B. and Oram, J.D. 1967. Bacterial inhibitors in milk and other biological fluids. Nature 216, 328-330. 

The possibilities of modifying the contents of such mixtures so as to contain a bacterial inhibitor has been alluded to. 

But due to flotation (bubble-film extraction), the products of bacterial metabolism and the products of bacterial degradation together with other water contaminants are ranoved continuously from recirculation flow through the bubble-film extractor. As a result, another positive feedback is realized in filtration-flotation system. The essence of this effect lies in the inhibition of vital functions of bacteria with increasing microbial metabolite concentration according to the law of chemical kinetics. And in accordance with the same law, bacterial activity is increased as the products of bacterial metabolism are removed from treated water [20]. Thus, we are able to add one more component, namely, AK, to the magnitude (/fj + AK2). The component AK represents the increase in biofiltration efficiency due to bacterial inhibitors removed by means of bubble-film extraction. In such a way, the resulting rate constant of the process takes the form ( fi + AK2 + AKi). 

EMCs are generally manufactured from cheese pastes that are made from the cheese of the same type. Additional components such as butterfat or cream may be added to add extra precursors when appropriate. Noncheese ingredients such as MSG, yeast extract, diacetyl, or other flavorants may also be added, but they may have to be declared on the label of the final product. Consistency in this base material is critical to the production of a standardized EMC product. Off-flavors may develop during incubation of the paste/enzyme slurry since the conditions are optimal for microbial growth. Equipment must be sterilized and precautions taken to prohibit miCTobial contamination. Bacterial inhibitors such as nitrates, sorbate, or nicin may be used. Free fatty acids generated by lipase enzymes afford some inhibition. Incubation time and temperature influence enzyme action and must be carefully controlled. 

The glue manufacturer often feels frustrated because some customers have inadequate mixing equipment and/or housekeeping problems. Although glues contain bacterial inhibitors the situation can get out of control if the equipment is not clean, and fresh glue solution is continually run in on the remains of older batches. 

Other compounds tested for their ability to inhibit or activate sialidase include iodoacetamide (10 m). AT-ethylmaleimide (10 m) and Mersalyl (10 m). On partially purified sialidase from pig kidney, these had no effect (Tuppy and Palese, 1968) a-chymotrypsin with sialidase from bovine brain caused an increase in activity (Gielen and Harprecht, 1969) EDTA, p-hydroxymercuribenzoate (formerly was believed to be p-chloromercuribenzoate), tested on sialidase in rat liver and kidney, had no effect (Mahadevan et al., 1967) the bacterial inhibitors 2-deoxy-2,3-dehydroneuraminic acid and p-nitrophenyloxamic acid tested on purified sialidase from rat heart muscle had no effect (Tallman and Brady, 1973) while l-(4-methoxyphenoxymethyl)-3,4-dehydroisoquino-line and p-hydroxymercuribenzoate were inhibitory with ganglioside Goia substrate. The effect of specific inhibitors on purified sialidase may give useful information about the active site, an unknown entity at this time. 

Bacterial removal of sterol side chains is carried out by a stepwise P-oxidation, whereas the degradation of the perhydrocyclopentanophenanthrene nucleus is prevented by metaboHc inhibitors (54), chemical modification of the nucleus (55), or the use of bacterial mutants (11,56). P-Sitosterol [83-46-5] (10), a plant sterol, has been used as a raw material for the preparation of 4-androstene-3,17-dione [63-05-8] (13) and related compounds using selected mutants of the P-sitosterol-degrading bacteria (57) (Fig. 2). 

P-lactam antibiotics, exert thek antibacterial effect by interfering with the synthesis of the bacterial cell wall. These antibiotics tend to be "kreversible" inhibitors of cell wall biosynthesis and they are usually bactericidal at concentrations close to thek bacteriostatic levels. Cephalospotins are widely used for treating bacterial infections. They are highly effective antibiotics and have low toxicity. 

Aristeromycin. Aristeromycin (36), the first carbocyhc analogue of adenosine, was isolated from the culture filtrates of S. citricolor as part of a search for inhibitors of bacterial leaf blight (1—4). A herbicidaHy active hypoxanthine analogue of (36), coaristeromycin, has also been isolated (108). Several chemical syntheses of (36) have appeared (1—4,109). It inhibits Aanthomonas OTjc e and Eyricularia bacterial leaf blight, blast disease of rice plants, and... 

The antiviral activity of (5)-DHPA in vivo was assessed in mice inoculated intranasaHy with vesicular stomatitis vims ( 5)-DHPA significantly increased survival from the infection. (5)-DHPA did not significantly reduce DNA, RNA, or protein synthesis and is not a substrate for adenosine deaminase of either bacterial or mammalian origin. However, (5)-DHPA strongly inhibits deamination of adenosine and ara-A by adenosine deaminase. Its mode of action may be inhibition of Vadenosyl-L-homocysteine hydrolase (61). Inhibition of SAH hydrolase results in the accumulation of SAH, which is a product inhibitor of Vadenosylmethionine-dependent methylation reactions. Such methylations are required for the maturation of vital mRNA, and hence inhibitors of SAH hydrolase may be expected to block vims repHcation by interference with viral mRNA methylation. 

The biochemical basis of penicillin action continues to be an area of active investigation. Penicillins are highly specific inhibitors of enzyme(s) involved in the synthesis of the bacterial cell wall, a structure not present in mammalian cells. Three principal factors are thought to be important for effective antibacterial action by a penicillin ... 

Inhibitors as well as substrates bind in this crevice between the domains. From the numerous studies of different inhibitors bound to serine pro-teinases we have chosen as an illustration the binding of a small peptide inhibitor, Ac-Pro-Ala-Pro-Tyr-COOH to a bacterial chymotrypsin (Figure 11.9). The enzyme-peptide complex was formed by adding a large excess of the substrate Ac-Pro-Ala-Pro-Tyr-CO-NHz to crystals of the enzyme. The enzyme molecules within the crystals catalyze cleavage of the terminal amide group to produce the products Ac-Pro-Ala-Pro-Tyr-COOH and NHs. The ammonium ions diffuse away, but the peptide product remains bound as an inhibitor to the active site of the enzyme. 

Corrosion inhibitor 1 Bacterial control J Cooling-water system Consumption depends on make-up Chemicals are used to provide adequate reserve... 

Sulphate in general appears to behave very similarly Hatch and Rice have shown that small concentrations in distilled water increase corrosion more than similar concentrations of chloride". In practice, high-sulphate waters may attack concrete, and the performance of some inhibitors appears to be adversely affected by the presence of sulphate. Sulphates have also a special role in bacterial corrosion under anaerobic conditions. Both sulphates and nitrates are acceptable in low-pressure boiler feed water as they are believed to be of value in controlling caustic cracking. 

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