Biodegradation of chicken feathers waste directed by Bacillus subtilis DB100 (p5.2) cells was successfully carried out in 14 L Bio Flo 110 laboratory scale fermentor. Seven liters of feathers-based modified basal medium II, feathers-based tap water and feathers-based distilled water separately in the fermentor were inoculated with activated bacterial cells. The fermentation processes were conducted at 37 degrees C, 700 rpm agitation speed and 0.7 vvm air flow rate in the absence of kanamycin. Highest net levels of released feathers hydrolysis end products [soluble proteins and NH2-free amino groups] and keratinolytic alkaline protease activity in the fermentor were greatly comparable to those of shake flasks. Interestingly, the plasmid (p5.2) inside the recombinant B. subtilis cells growing in the fermentor displayed 100% stability till the fifth day of incubation and this presents a great challenge. Data certainly would encourage the transfer to larger scale fermentors to carry out feathers biodegradation process. (C) 2010 Elsevier Ltd. All rights reserved.