Organic acids inhibition

Despite their various chemical structures, all organic acids inhibit microorganisms in a similar fashion. For example, all show increased inhibition at low pH, microbes are inhibited rather than killed, lag phases are prolonged, yields reduced, and active transport prevented (Stratford and... 

Nakai, S.A. and Siebert, K.J. 2004. Organic acid inhibition models for Listeria innocua, Listeria ivanovii, Pseudomonas aeruginosa and Oenococcus oeni. Food Microbiology 21 67-72. 

The LMW-OM (e.g., monosaccharides, amino acids, and organic acids) inhibits the activity (end-production inhibition) and represses the synthesis (catabolic repression) of ectoen-zymes in heterotrophic bacteria. 

Carpenter, C. E., Broadbent, J. R. (2009). External concentration of organic acid anions and pH key independent variables for studying how organic acids inhibit growth of bacteria in mildly acidic foods. Journal of Food Science, 74, 12-15. 

HERBICIDE TYPE I. Amino acid or organic acid inhibition. 

Resist Printing. In resist printing, print pastes are used that can inhibit the development or fixation of different dyes that are apphed to the textile prior to or after printing. These resists can be of a chemical or mechanical nature, or combine both methods. For example, fiber-reactive dyes, which require alkaU for their fixation, can be made resistant by printing a nonvolatile organic acid, such as tartaric acid, on the textile. Colored resists are obtained by printing pigments with a nonvolatile acid. 

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. 

Wastage was caused by exposure to oleic acid and short-chain organic acids in the rolling oil. Fatty acids break down to form shorter-chain acids in service. However, oleic acid, of and by itself, is fairly corrosive. Attack due to oleic acid can be reduced substantially using appropriate chemical inhibition. 

Mixtures of aldehydes with surfactants are active in preventing corrosion, in particular in the presence of mineral or organic acids [646]. The aldehyde may be trans-cinnamaldehyde. The surfactant may be N-dodecylpyridinium bromide or the reaction product of trimethyl-1-heptanol with ethylene oxide [645]. Such aldehyde and surfactant mixtures provide greater and more reliable corrosion inhibition than the respective compositions containing aldehydes alone. 

Especially in dicotyledonous plant species such as tomato, chickpea, and white lupin (82,111), with a high cation/anion uptake ratio, PEPC-mediated biosynthesis of carboxylates may also be linked to excessive net uptake of cations due to inhibition of uptake and assimilation of nitrate under P-deficient conditions (Fig. 5) (17,111,115). Excess uptake of cations is balanced by enhanced net re-lea,se of protons (82,111,116), provided by increased bio.synthesis of organic acids via PEPC as a constituent of the intracellular pH-stat mechanism (117). In these plants, P deficiency-mediated proton extrusion leads to rhizosphere acidification, which can contribute to the. solubilization of acid soluble Ca phosphates in calcareous soils (Fig. 5) (34,118,119). In some species (e.g., chickpea, white lupin, oil-seed rape, buckwheat), the enhanced net release of protons is associated with increased exudation of carboxylates, whereas in tomato, carboxylate exudation was negligible despite intense proton extrusion (82,120). 

Aliphatic compounds Several water-soluble simple organic acids and alcohols are cannon plant and soil constituents. They include methanol, ethanol, n-propanol and butanol (40), and crotonic, oxalic, formic, butyric, lactic, acetic and succinic acids (41, 42), all of which inhibit seed germination or plant growth. Under aerobic conditions, however, aliphalic acids are metabolized in the soil and therefore, should not be considered a major source of allelopathic activity (40). 

The reported (14) mechanisms of action of allelochemlcals Include effects on root ultrastructure and subsequent Inhibition of Ion absorption and water uptake, effects on hormone-induced growth, alteration of membrane permeability, changes In lipid and organic acid metabolism, inhibition of protein synthesis and alteration of enzyme activity, and effects on stomatal opening and on photosynthesis. Reduced leaf water potential Is one result of treatment with ferulic and p-coumaric acids (15). Colton and Einhellig (16) found that aqueous extracts of velvetleaf (Abutllon theophrastl Medic.) Increased diffusive resistance In soybean fGlycine max. (L.) Merr.] leaves, probably as a result of stomatal closure. In addition, there was evidence of water stress and reduced quantities of chlorophyll In Inhibited plants. 

Grafe et al. (2001) found that arsenate sorption onto goethite was reduced by humic and fulvic acid, but not by citric acid, whereas arsenite sorption was decreased by all three organic acids between pH 3.0 and 8.0 in the order of citric acid > fulvic acid > humic acid. Del Gaudio (2005) showed that the inhibition of malate (Mai) on arsenate sorption was negligible onto ferrihydrite (100% Arsenate surface coverage) even when malate was added before arsenate but not onto Al(OH)x. At an initial Mal/As molar ratio of 1, the sorption of arsenate onto Al(OH)x after 24 hrs of reaction was reduced by 40% (Fig. 5). 

However, if the raw materials are contaminated or the composting process is incomplete, unfavorable effects must be expected. Heavy metals may be introduced into the compost with communal waste. To ensure that these do not enter the food chain, authorised limit values must be strictly adhered to. The same is true of organic contaminants (particularly polyaromatic or chlorinated hydrocarbons), the effect of which is extremely complex. If the fermentation process is not satisfactory, putrefaction will occur, the by-products of which (S02, NH3, N02, organic acids, cadaveric alkaloids, etc.) inhibit plant growth and attract pests. 

Rylander, L.A., Gandolfi, A.J. and Brendel, K. (1985). Inhibition of organic acid/base transport in isolated rabbit renal tubules by nephrotoxins. In In Vitro Toxicology. A progress report from Johns Hopkins Center for Alternatives to Animal Testing. Vol. 3 (Goldberg, A.M., Ed.). Mary Ann Liebert, New York, pp. 235-247. 

Hence, it can be assumed that the inhibition of dark process, Fc7H202, occurred due to the formation of Fe -complexes resulting with a lack of OH radicals in bulk produced through bulk Fenton reaction, while the mineralization efficiency of UV/Fe°/H202 process was inhibited by the formation of large amounts of OH radical attack resistant organics acids. That is in accordance with the observation from Figure 7, where the appearance of new peaks occurred after 30. minute of treatment process. 

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