Appl Microbiol Biotechnol (2005) 67: 412–419 DOI 10.1007/s00253-004-1788-y ENVIRONMENTAL BIOTECHNOLOGY S. M. Tiquia . J. M. Ichida . H. M. Keener . D. L. Elwell . E. H. Burtt Jr. . F. C. Michel Jr. Bacterial community profiles on feathers during composting as determined by terminal restriction fragment length polymorphism analysis of 16S rDNA genes Received: 13 May 2004 / Revised: 10 September 2004 / Accepted: 2 October 2004 / Published online: 22 December 2004 # Springer-Verlag 2004 Abstract Composting is one of the more economical and environmentally safe methods of recycling feather waste generated by the poultry industry, since 90% of the feather weight consists of crude keratin protein, and feathers con- tain 15% N. However, the keratin in waste feathers is resistant to biodegradation and may require the addition of bacterial inocula to enhance the degradation process during composting. Two keratin-degrading bacteria isolated from plumage of wild songbirds and identified as Bacillus liche- neformis (OWU 1411T) and Streptomyces sp. (OWU 1441) were inoculated into poultry feather composts (1.13×10 8 cfu g -1 feathers) and co-composted with poultry litter and straw in 200-l compost vessels. Composting temperatures, as well as CO 2 and NH 3 evolution, were measured in these vessels to determine the effects of inoculation on the rate and extent of poultry feather decomposition during com- posting. Terminal restriction fragment length polymorph- isms of 16S rRNA genes were used to follow changes in microbial community structure during composting. The results indicated that extensive carbon conversion occurred in both treatments (55.5 and 56.1%). The addition of the bacterial inocula did not enhance the rate of waste feather composting. The microbial community structure over time was very similar in inoculated and uninoculated waste feather composts. Introduction The poultry industry produces an enormous quantity of wastes, particularly litter. Each year, poultry processors produce thousands of tons of feather waste, which accounts for 5–7% of the total weight of mature chickens (D. Jensen, Animal Welfare Information Center, USDA-ARS, Belts- ville, Md., personal communication in 1995). Feather waste is largely β-keratin protein (Fisher et al. 1981). In its native state, β-keratin is not degradable by common proteolytic enzymes such as trypsin, pepsin, and papain (Kim et al. 2001). Nonetheless, β-keratin does not accumulate in na- ture. Moreover, keratinolytic activity has been reported in a variety of Bacillus (Kim et al. 2001) and Streptomyces species (Ichida et al. 2001). At present, feathers generated from the poultry industry are used on a limited basis as a dietary protein supplement for animal feed, and feather meal (Papadopoulos 1985). Prior to being used as feather meal, feathers are steam pres- sure-cooked or chemically treated to modify their poly- peptide and disulfide bond structure to make them more digestible (Papadopoulos 1985). These treatment methods, however, require significant amounts of energy. Compost- ing is one of the more economical and environmentally safe methods of recycling feather wastes. Feathers contain ap- proximately 15% N (Ichida et al. 2001) and can be utilized as N fertilizer. Animal waste composts have been used as a nutrient source in crop production (Dick and McCoy 1993). Over the last three decades, research has been conducted to improve the agronomic utilization of animal wastes, including poultry wastes, via composting (Tiquia 2002). During composting, organic materials are mixed to create a moist, aerobic environment where organic matter decom- position and humification occur at rapid rates. The nutrients S. M. Tiquia (*) Department of Natural Sciences, The University of Michigan, Dearborn, Michigan, 481281, USA e-mail: smtiquia@umd.umich.edu Tel.: +1-313-5935148 Fax: +1-313-5934937 J. M. Ichida Department of Botany/Microbiology, Ohio Wesleyan University, Delaware, Ohio, 43015, USA H. M. Keener . D. L. Elwell . F. C. Michel Jr. Department of Food, Agricultural, and Biological Engineering, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio, 44691, USA E. H. Burtt Jr. Department of Zoology, Ohio Wesleyan University, Delaware, Ohio, 43015, USA