Bacteria, acid effects

Besides acid stability and resistance against /flactamases, the ideal antibiotic should feature broad-spectrum utility against various bacteria and effectiveness against bacterial problem strains which cannot be combated by naturally occurring antibiotics or which develop resistance, such as the problem strain in hospitals, Staphylococcus aureus. 

Nakayama, K., Z. Sato and S. Kinoshita Growth of a glutamic acid producing bacterium and related bacteria, I. Effect of iron salts, ferrichrome, amino acids and some other compounds. J. Gen. Appl. Microbiol. 10, 143 (1964). 

Patel, M. A., Ou, M., Harbrucker, R., Aldrich, H., Buszko, M., Ingram, L., and Shanmugam, K. 2006. Isolation and characterixation of acid-tolerant, thermophilic bacteria for effective fermentation of biomass-derived sugars to lactic acid. Appl. Environ. Microbiol., 72, 3228-3235. 

The activation of B-hydroxybutyric acid which is the monomer for the biosynthesis of the poly(B-oxybutyrate) which serves as a food stock in numerous bacteria, is effected in a different way. The carbonyl group is attached to coen-zyme-A, and thus, activated in the form of a CO-S bond. 

Bacteria require p-aminobenzoic acid to biosyn thesize folic acid a growth factor Structurally sul fanilamide resembles p-aminobenzoic acid and is mistaken for it by the bacteria Folic acid biosynthesis IS inhibited and bacterial growth is slowed suffi ciently to allow the body s natural defenses to effect a cure Because animals do not biosynthesize folic acid but obtain it in their food sulfanilamide halts the growth of bacteria without harm to the host... 

In addition to alcohoHc fermentation, a malolactic fermentation by certain desirable strains of lactic acid bacteria needs to be considered. Occasionally, wild strains produce off-flavors. Malolactic fermentation is desirable in many red table wines for increased stabiUty, more complex flavor, and sometimes for decreased acidity. Selected strains are often added toward the end of alcohoHc fermentation. AH the malic acid present is converted into lactic acid, with the resultant decrease of acidity and Hberation of carbon dioxide. Obviously this has more effect on the acidity the more malic acid is present, and this is the case in wine from underripe, too-tart grapes. Once malolactic fermentation has occurred, it does not recur unless another susceptible wine is blended. 

Most of the bacteria, yeasts, molds, and higher fungi of interest for SCP production are deficient in methionine and must be supplemented with this amino acid to be suitable for animal feeding or human food appHcations. Also, lysine—arginine ratios should be adjusted in poultry rations in which yeast SCP is used (62). Human feeding studies have shown that only limited quantities of yeast such as Candida utilis can be added to food products without adverse effects on flavor (63). 

The nutrient sparing effect of antibiotics may result from reduction or elimination of bacteria competing for consumed and available nutrients. It is also recognized that certain bacteria synthesize vitamins (qv), amino acids (qv), or proteins that may be utilized by the host animal. Support of this mode of action is found in the observed nutritional interactions with subtherapeutic use of antibiotics in animal feeds. Protein concentration and digestibiHty, and amino acid composition of consumed proteins may all influence the magnitude of response to feeding antibiotics. Positive effects appear to be largest... 

Soil Nutrient. Molybdenum has been widely used to increase crop productivity in many soils woddwide (see Fertilizers). It is the heaviest element needed for plant productivity and stimulates both nitrogen fixation and nitrate reduction (51,52). The effects are particularly significant in leguminous crops, where symbiotic bacteria responsible for nitrogen fixation provide the principal nitrogen input to the plant. Molybdenum deficiency is usually more prominent in acidic soils, where Mo(VI) is less soluble and more easily reduced to insoluble, and hence unavailable, forms. Above pH 7, the soluble anionic, and hence available, molybdate ion is the principal species. 

Cooling water pH affects oxidizing antimicrobial efficacy. The pH determines the relative proportions of hypochlorous acid and hypochlorite ion or, in systems treated with bromine donors, hypobromous acid and hypobromite ion. The acid forms of the halogens are usually more effective antimicrobials than the dissociated forms. Under some conditions, hypochlorous acid is 80 times more effective in controlling bacteria than the hypochlorite ion. Hypochlorous acid predominates below a pH of 7.6. Hypobromous acid predominates below pH 8.7, making bromine donors more effective than chlorine donors in alkaline cooling waters, especially where contact time is limited. 

Based on the above equilibria, the concentration of HOCl in the normal pH range varies inversely with the total concentration of cyanurate. Increased concentration of cyanuric acid, therefore, should decrease the biocidal effectiveness of FAC. This has been confirmed by laboratory studies in buffered distilled water which showed 99% kill times of S.faecalis at 20°C increasing linearly with increasing cyanuric acid concentration at constant av. Cl at pH 7 and 9 (45). Other studies in distilled water have found a similar effect of cyanuric acid on kill times of bacteria (46—48). Calculations based on the data from Ref. 45 show that the kill times are highly correlated to the HOCl concentration and poorly to the concentration of the various chloroisocyanurates, indicating that HOCl is the active bactericide in stabilized pools (49). 

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