The sustainable and practical degradation of intact chicken feathers by a newly isolated thermophilic bacterium Meiothermus ruber H328 was presented with extensive data. Aerobic cultivation with moderately thermophilic strain H328 at 55A degrees C for 6 days led to the apparently complete decay of the truly intact feathers and provided 1.89 mmol free amino acids and 7.32 mmol acid-hydrolyzed amino acids from 50 ml of culture containing 3% (w/v) intact chicken feathers. The amino acid components in the soluble fraction of the culture conspicuously agreed with those calculated from the intact feathers. This demonstrated that more than 55% of total keratin proteins were solubilized from the intact chicken feathers into the culture in the forms of free amino acid and/or soluble oligopeptide, and most of them are directly derived from the intact feathers by proteolytic digestion. Feather degradation by strain H328 surpasses that by any other microorganisms with regard to degradation efficiency, absence of requirement for pretreatment of the feathers, and product fidelity in the amino acid component. Furthermore, the culture containing the degradative products from the intact feathers was subjected to matrix-assisted laser desorption ionization mass spectrometry-time-of-flight analysis, and it was revealed that the molecular masses of the solubilized products, oligopeptides, were less than 1,000. This result allows us to investigate the bioactivities of oligopeptides derived from the degradation of chicken feathers by cultivation with strain H328 as well as the production of amino acids for feedstuffs.