Hydrolyzate The pH of wood hydrolyzate (batch VI) was adjusted to 5.5±7.0 using 1 M sodium hydroxide and ethanol fermentation was studied. The 1.3-l batch reactor contained 1.2 l wood hydrolyzate (batch IV) with 0.85 g/l YNB and 4.41 g/l total nitrogen nutrients (1.13 g/l urea and 3.28 g/l peptone). Seventy milliliters of high-density recycled cells (second recycle) were inoculated into the reactor so that a final OD of 15 was achieved. The pH of reactor operation was initially adjusted in the range of 5.5±5.7 at 25±27°C. The reactor vessel was agitated at 250 rpm and sparged with air at 1.5 l/min. The pH was increased from 5.5 to 7.0 during fermentation run by addition of 1 M sodium hydroxide. Samples (2.5 ml) were taken periodically for cell density measurements and other analyses.