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Summary: Volatile short-chain fatty acids such as butyric and acetic acid have been supplemented in poultry rations as a feed ingredient and nutritive supplement. A novel Clostridium fermentation solubles broth (MiruTyton), containing short-chain fatty acids, minerals, and amino acids, was supplemented in a standard corn/soybean meal–based ration at a rate of 750, 1,500, 3,000, and 6,000 mg/kg to achieve approximately 277, 554, 1,108, and 2,216 mg/kg of ammonium butyrate in the diet. After 6 wk, supplementation at all levels did not cause significant changes in the blood parameters or any live performance metric of mixed-sex Cobb-500 broilers (N = 1,920). In addition, administering 6,000 mg/kg of MiruTyton caused no significant lesions in any of the tissue examined except for an increase (P

Microbial fermentation yield is limited by CO2 loss in glycolysis. Here, the authors engineered Clostridium ljungdahlii for the anaerobic, non-photosynthetic mixotrophy production of acetone, increasing carbon product yield while reducing CO2emissions from a biogenic feedstock fermentation.

ABSTRACT 1-Butanol is a large-volume, intermediate chemical with favorable physical and chemical properties for blending with or directly substituting for gasoline. The per-volume value of butanol, as a chemical, is sufficient for investing into the recommercialization of the classical acetone-butanol-ethanol (ABE) (E. M. Green, Curr. Opin. Biotechnol. 22:337–343, 2011) fermentation process. Furthermore, with modest improvements in three areas of the ABE process, operating costs can be sufficiently decreased to make butanol an economically viable advanced biofuel. The three areas of greatest interest are (i) maximizing yields of butanol on any particular substrate, (ii) expanding substrate utilization capabilities of the host microorganism, and (iii) reducing the energy consumption of the overall production process, in particular the separation and purification operations. In their study in the September/October 2012 issue of mBio, Jang et al. [mBio 3(5):e00314-12, 2012] describe a comprehensive study on driving glucose metabolism in Clostridium acetobutylicum to the production of butanol. Moreover, they execute a metabolic engineering strategy to achieve the highest yet reported yields of butanol on glucose.