Acid-tolerant organisms

Rare Earth Metal Trifluoromethanesulfonates as Water-Tolerated Lewis Acid Catiaysts Organic Synthesis," Kobavashi. Synlett, 1994, 679... 

Decomposition rates of some organic substrates are reduced. Substantial changes in the species composition of primary producers occur. The richness of phytoplankton species is reduced, while biomass and productivity of phytoplankton are not reduced by acidification. The biomass of herbivorous and predaceous zooplankton is probably reduced because of reductions in numbers of organisms and/or reduction in their average size. Many benthic invertebrates such as species of snails, clams, crayfish, amphipods, and various aquatic insects are intolerant of low pH and are seldom found in acidic lakes. However, certain large aquatic insects such as water boatmen and gyrinids are very acid tolerant and may become the top predators in some acidified lakes. Acidification of aquatic systems has major effects on fish population. 

If the inherited defect involves certain enzymes then an enzyme inhibitor could also be effective. Allopurinol is a xanthine oxidase inhibitor, or purine antagonist, which can reduce the level of uric acid in organs and tissues. Its primary metabolite, alloxanthine, is also active which extends its half-life in the body (half-life of allopurinol is 2-3 hours, for alloxanthine is 18-30 hours). The drug is well-tolerated with few side... 

In contrast to reservoir patches, there is no risk of dosedumping a with matrix patch, which releases buprenorphine from a prolonged-release matrix in direct contact with the skin for at least 3 days. The improved solubility necessary to achieve an adequate concentration of dissolved buprenorphine base is obtained by means of well tolerated organic acids that do not form practically insoluble salts with buprenorphine in the undercooled mass in the matrix of the TTS. In Europe transdermal buprenorphine was developed by Grunenthal as Transtec , which was launched in Germany in 2001 and recently approved in major Europoean markets with dosages of 35, 52.5 and 70 pg/h containing 20, 30 and 40 mg buprenorphine per TDS respectively (Fig. 10 Terlinden et al., 2000). 

The natural penicillins, primarily G and V, have a relatively narrow spectrum. They act mostly on gram-positive organisms. The fact that proper selection of precursors could lead to new variations in the penicillin side chain offered the first source of synthetic penicillins. Penicillin V, derived from a phenoxy-acetic acid precursor, attracted clinical use because of its greater acid tolerance, which made it more useful in oral administration. Also, the widespread use of penicillin eventually led to a clinical problem of penicillin-resistant staphylococci and streptococci. Resistance for the most part involved the penicillin-destroying enzyme, penicillinase, which attacked the beta-lactam structure of the 6-aminopenicillanic acid nucleus (6-APA). Semisynthetic penicillins such as ampicillin and carbenicillin have a broader spectrum. Some, such as methicillin, orafi-cillin, and oxacillin, are resistant to penicillinase. In 1984, Beecham introduced Augmentin, which was the first combination formulation of a penicillin (amoxicillin) and a penicillinase inhibitor (clavulanic acid). Worldwide production of semisynthetic penicillins is currently around 10,000 tons/year, the major producers are Smith Kline Beecham, DSM, Pfizer, and Toyo Jozo. 

This response is interpreted by engineers to mean that acid-forming organisms can tolerate adversity better than gas formers and that an accumulation of Phase I waste products (the acids) can be tolerated by acid formers to a rather marked degree. 

Greenacre, E.J., Brocklehurst, T.F., Waspe, C.R., et al. 2003. Salmonella enterica Serovar Typhimurium and Listeria monocytogenes acid tolerance response induced by organic acids at 20°C optimization and modeling. Applied and Environmental Microbiology 69 3945-3951. 

Type of bacteria Sensitive to organic acid activity Resistant to organic acids Acid tolerance... 

ATR as a function of the acid used may be due to the maintenance of internal pH (pH,) of the cell (Alvarez-Ordonez et al., 2009). Some organic acids enter the cell more easily than others, and, as a result, may alter the pH of the cell more easily (Greenacre et al., 2003). The pH is crucial for maintenance of acid tolerance. The ATR complex phenomenon is strongly affected by environmental factor interaction, prevailing during acid adaptation and acid inactivation (Alvarez-Ordonez et al., 2009). 

The ability of pathogens to cause disease is greatly influenced by acid. Resistance to acid pH may permit pathogens to survive in acid foods and allow them to survive exposure to acid in the human body and then to proceed in causing disease (Roering et al., 1999 Casey and Condon, 2002). The acid tolerance of E. coli 0157 H7 makes it especially important to elucidate the effect of organic acids on this pathogen (Casey and Condon,... 

In E. coli 0157 H7 acid tolerance is also strongly dependent on the growth phase, with higher levels of tolerance or resistance found in stationary-phase or starved cultures compared to exponential-phase cultures (Jordan, Oxford, and O Byrne, 1999). The level of acid tolerance is influenced by extracellular components, often proteins, that are produced in response to chemical and physical stresses (Ryu and Beuchat, 1999). Decreased membrane fluidity may also result in increased acid resistance in E. coli 0157 H7 (Yuk and Marshall, 2005). E. coli 0157 H7 cultures, grown anaerobically, will more easily be induced to extreme acid resistance than those grown aerobically (Diez-Gonzalez and Russell, 1999). Acid resistance is an important property of E. coli to enable the organism to survive... 

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