Production of organic acids

The production of organic acids by micro-organisms, and especially citric add, is considered in detail in Chapter 4. In this section therefore we will only briefly consider dtric add production, from an energetics perspective. 

The large scale production of organic acids by micro-organisms... 

Immobilisation of Microbial Cells for the Production of Organic Acid and Ethanol... 

A change of porosity, either an increase or decrease, depending on the equilibria of dissolved salts and products of organic acids [270]... 

Echigo, T. and Takenaka, T. (1974). Production of organic acids in honey by honeybees. Nippon Nogei Kagaku Kaishi 48,225-230. 

D. D. Davies, Anaerobic metabolism and the production of organic acids. The Biochemistry of Plants, Vol. 2, Academic Press, 1980, p. 581. 

Sauer, M., Porro, D., Mattanovich, D. and Branduardi, P. (2008) Microbial production of organic acids expanding the markets. Trends in Biotechnology, 26 (2), 100-108. 

Although the pH was not controlled during the experiments, it was monitored throughout. From an initial pH of 3.5, the pH rapidly dropped to around 2.5 due to the production of organic acids and then increased slightly as TOC was removed. 

Both dietary and endogenous ammoniagenic substrates are removed from the intestinal lumen by the osmotic cathartic action of nonabsorbable disaccharides such as lactulose and lactitol. These compounds are currently the main therapeutic agents for chronic HE. The efficacy of oral lactulose for the treatment of HE has been established in controlled trials [41-43]. Besides having a cathartic effect, lactulose lowers the colonic pH as a result of the production of organic acids by bacterial fermentation. The decrease in pH creates an environment that is hostile to the survival of urease-producing intestinal bac-... 

Vassilev N, Vassileva M (1992) Production of organic acids by immobilized filamentous fungi. Mycol Res 96 563-570... 

Lactic acid is one of the major organic acids produced by fermentation. AimuaUy about 35 000 tonnes are produced this way [56]. The work on NF-based membrane fermentors for the production of organic acids has been started with the observation that lactic acid retention of RO membranes shows a strong pH-depen-dence [57-59]. For selective removal of lactic acid a low pFI is necessary, however, this reduces the lactic acid productivity to about 1 g Compared with UF-... 

PAHs also react with OH. Removal of PAHs from the atmosphere by photolytic production of OH may be an important natural remediation mechanism. Because these compounds have limited water solubility, most studies have investigated gas phase reactions. Naphthalene was shown to be subject to a complex series of hydroxylations and peroxyl-induced ringopening reactions leading to the production of organic acids [37]. Although PAHs have low water solubility, they are often important water pollutants, attached to particles or colloids suspended in solution, or in aqueous sediments. PCBs have been shown to be susceptible to OH attack, resulting in dechlorination [38]. 

Horiuchi, J. I., Shimizu, T., Tada, K., Kanno, T., and Kobayashi, M. 2002. Selective production of organic acids in anaerobic acid reactor by pH control. Bioresour. Technol, 82, 209-213. 

Ahonen-Jonnarth, U., van Hees, P. A. W., Lundstrom, U. Finlay, R. D. (2000). Production of organic acids by mycorrhizal and non-mycorrhizal Firms sylvestris seedlings exposed to elevated concentrations of aluminium and heavy metals. New Fhytologist, 146, 557-67. 

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