Liquid samples were analyzed by using gas chromatography (GC; model 7890 A; Agilent technologies, U.S.A) equipped with a Durabond (DB)-WAXetr column (30 m 0.25 mm 0.25 mm, model 123-7334; J&W, U.S.A) and a flame ionization detector (FID). Fermentation products including acetone, butanol, ethanol, acetic and butyric acids were detected based on their retention time. Similarly, gaseous samples were analyzed with another GC (model GC-17A; Shimadzu, Japan) equipped with a thermal conductivity detector (TCD) and a Supelco 80/100, Porapak-N column, (2 m 1/8 inch stainless steel column) to detect hydrogen. A detailed methodology of analysis can be seen elsewhere [20].