The aim of the present preliminary study on processing feather waste with pine bark by means of the composting method was to evaluate the efficiency of keratinolytic and ligninolytic fungi inoculum on the growth dynamics of microorganisms taking part in these transformations. The studies were carried out in laboratory conditions. The scope of studies included the determination of the total number of bacteria and fungi and amount of keratinolytic and cellulolytic fungi after 1, 3, 5 and 7 months of composting. It was shown that the application of inoculum exerted a weak stimulatory influence on the development of microorganisms in compost material which was only visible at the initial phase of transformation and in relation to some sets of microorganisms. A more intense development of fungi and bacteria was observed in the non-vaccinated objects than in the vaccinated objects. It proved to have a higher efficiency of native sets of microorganisms. Keratinolytic fungi were the best adapted group among the groups of microorganisms studied. The above was observed in a number of these microorganisms related to feather decomposition. Development of microorganisms in the keratin-bark composts studied depended on a succession of taxonomically and physiologically differentiated sets: bacteria, keratinolytic fungi and ubiquitous fungi.