Utilização de aditivos bacterianos no processo de compostagem e análise de sucessão microbiana por HRM

Abstract

Composting is the process of organic matter natural degradation done by environmental microorganisms, whose metabolic activities cause mineralization and partial humification of substances from the pile, originating a final product, the compost, which can be beneficially applied to the soil as organic fertilizer in horticulture and agriculture. The number of studies involving microbial inoculants has been growing, and they aim to improve the composting process and its final product. However, the behaviour of these inoculants and of the microorganisms during the process have not been described yet. In this context, this work aimed to investigate the effects of using a bacterial inoculum which can improve the composting process and to follow the bacterial population dynamics throughout the process using the High Resolution Melt (HRM) technique. The inocula Bacillus cereus, Bacillus megaterium, B. cereus + B. megaterium + Scytalidium thermophilum were analysed and compared to a control with no inoculum. Chemical and HRM analysis were carried out using samples collected in different stages of the process (5th to 110th days). The results of both tests showed that the bacterial inocula influenced the process of composting altering the cellulose and hemicelluloses breaking down, and caused alterations of the temperature and the nitrogen levels throughout the composting. The use of a universal primer (rDNA 16S) allowed the evaluation of the microbial succession during the process. However the design of a specific primer is necessary to follow the inoculum throughout the composting with more accuracy.