Clostridium tyrobutyricum is well documented as a fermentation strain for the production of butyric acid. In this work, using high-energy carbon heavy ion irradiated C. tyrobutyricum, then butyric acid fermentation using glucose or alkali and acid pretreatments of Eucommia ulmoides Oliv. as a carbon source was carried out. Initially, the modes at pH 5.7-6.5 and 37 degrees C were compared using a model medium containing glucose as a carbon source. When the 72 g L (1) glucose concentration was found to be the highest yield, the maximum butyric acid production from glucose increased significantly, from 24 g L (1) for the wild type strains to 37 g L (1) for the strain irradiated at 126 AMeV and a dose of 35 Gy and a 10(7) ions/pulse. By feeding 100 g L (1) acid pretreatments of E. ulmoides Oliv. into the fermentations, butyrate yields (5.8 g L (1)) and butyrate/acetate (B/A) ratio (4.32) were achieved. (C) 2014 Elsevier Ltd. All rights reserved.