Bacterial inoculum enhances keratin degradation and biofilm formation in poultry compost

Native microbial populations can degrade poultry waste, but the process can be hastened by using feather-degrading bacteria. Strains of Bacillus licheniformis and a Streptomyces sp. isolated from the plumage of wild birds were grown in a liquid basal medium and used to inoculate feathers in compost bioreaction vessels. Control vessels had only basal medium added to the feathers, litter and straw. Temperature, ammonia, carbon and nitrogen were monitored for 4 weeks. Scanning electron microscopy of the feather samples showed more complete keratin-degradation, more structural damage, and earlier microbial biofilm formation on inoculated feathers than on uninoculated feathers. A diverse community of aerobic bacteria and fungi were cultured early, but declined rapidly. Thermophilic B. licheniformis and Streptomyces spp. were abundant throughout. Enteric gram-negative bacteria, (e.g., Salmonella, E. coli) originally found on waste feathers were not recovered after day 4. Vessel temperatures reached 64-71 degrees C within 36 h and stabilized at 50 degrees C. When tumble-mixed at day 14, renewed activity peaked at 59 degrees C and quickly dropped as available carbon was used. Feathers soaked in an inoculum of B. licheniformis and Streptomyces degraded more quickly and more completely than feathers that were not presoaked. Inoculation of feather waste could improve composting of the large volume of feather waste generated every year by poultry farms and processing plants.