1- butanol toxicity

Physiology and Enzymes of the Central Metabolic Pathway ABE Fermentation Processes, Butanol Toxicity, and Product Recovery... 

ABE FERMENTATION PROCESSES, BUTANOL TOXICITY, AND PRODUCT RECOVERY... 

Moreira AR, Ulmer DC, Linden JC (1981) Butanol toxicity in butylic fermentation. Biotechnol Bioengin Symp 11 567-579 Nagarajan V, Nakamura CE (1998) Production of 1,3-propanediol from glycerol by recombinant bacteria expressing recombinant diol dehydratase. US Patent 5821092... 

Great effort has been invested in research on biobutanol production, which is in the last preparation stages for an industrial-scale process, with pilot plants being built around the world. Some of the main issues are still butanol toxicity, low strain productivity, low yield, incomplete substrate usage, inability to use cheap lignocellulosic feedstock and high separation costs. Many of these problems are caused by butanol toxicity. 

One of the main reasons for expression of the ABE pathway in heterologous hosts is achieving higher butanol tolerance. Butanol toxicity is an obstacle that causes a whole other set of problems towards economically feasible butanol production—before all, high separation costs. 

Butanol toxicity is an issue that causes a chain of problems as described previously. In order to overcome butanol toxicity, two approaches have been applied ... 

Butanol toxicity is another great limitation, causing a whole new set of issues (low butanol titre and yield, lower substrate utilisation, higher separation costs). This problem can be addressed by strain development and in situ separation techniques (Xue et al. 2013a). 

The C-5 alcohols are more toxic and narcotic than the lower homologues. Toxicity to rats from amyl alcohols decreases in the order tertiary, secondary, primary. Toxicity of 3-methyl-1-butanol appears to have been studied the most. This alcohol caused a slight increase in cancerous tumors compared to controls in two studies (137,138). The tumors were located primarily in the stomach and Hver. 

Butyl glycol ethers, the largest volume derivatives of -butyl alcohol used ia solvent appHcations (10), are obtained from the reaction of 1-butanol with ethylene oxide. The most important of these derivatives, 2-butoxyethanol, is used principally ia vinyl and acryHc paints as well as ia lacquers and varnishes. It is also employed ia aqueous cleaners to solubilize organic surfactants. 2-Butoxyethanol [111-76-2] has achieved some growth at the expense of the lower alkoxyethanols (ie, methoxy and ethoxyethanol) because of 2-butoxyethanol s lower toxicity. 

AH four butanols are thought to have a generaHy low order of human toxicity (32). However, large dosages of the butanols generaHy serve as central nervous system depressants and mucous membrane irritants. Animal toxicity and irritancy data (32) are given in Table 4. 

Table 4.. Animal Toxicity and Irritancy Data for Butanols...

All four butanols are registered ia the United States on the Environmental Protection Agency Toxic Substances Control Act (TSCA) Inventory, a prerequisite for the manufacture or importation for commercial sale of any chemical substance or mixture ia quantities greater than a 1000 pounds (454 kg). Additionally, the manufacture and distribution of the butanols ia the United States are regulated under the Superfund Amendments and Reauthorization Act (SARA), Section 313, which requires that anyone handling at least 10,000 pounds (4545 kg) a year of a chemical substance report to both the EPA and the state any release of that substance to the environment. 

In 1996 the present writer offered the students a study of the 1-butanol/1-pentanol/cyclohexanol mixture using Scheffe s plan (mixture plan) which used a standard experimental matrix offered by LUMIERE software. The substance choice takes into account the limited possibilities of the Setaflash apparatus, the low toxicity of the chosen substances and their reciprocal chemical inertia. These had been... 

Schilling K, Kayser M, Deckardt K, et al Subchronic toxicity studies of 3-methyl-1-butanol and 2-methyl-1-propanol in rats. Hum Exp Toxicol 16(12) 722-6, 1997... 

The paraffins and 1-alcohols are relatively low-risk compounds. When we make a comparison of their TLV values versus the number of carbon atoms Ac, we find that paraffins from methane to propane are not considered toxic, but the paraffins from butane to nonane are increasingly more toxic with Ac, which is shown in figure 10.4. The 1-alcohols make a curious volcanic curve, starting from the toxic methanol to the relatively harmless ethanol, and the trend is downwards from propanol to butanol. The aromatics are much more toxic, but the lower molecular weight benzene is more toxic than toluene, which is more toxic than the higher molecular weight ethyl benzene. 

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