Simulatenous evaluation of composting experiments and metagenome analyses to illuminate the effect of Streptomyces spp. on organic matter degradation

Abstract

The effect of Streptomyces spp. on organic matter degradation was investigated in the present study. Streptomyces spp. isolated from compost systems were eliminated based on the results of cellulose, starch, xylan degradation tests, morphological inspection, and 16S rRNA analysis. The eliminated strains were re-given to compost systems to determine their effect on organic matter degradation and maturation. Sample analyses indicated that 15 days of composting had been adequate to maintain maturation. The amounts of strains added to the system were high enough to create a detectable change such as inhibition of other microbiota members. Results also indicated a variant change in organic matter degradation due to the added strain. The difference in organic matter degradation between strains depended partially on the segregation of secondary metabolites. On the other hand, strains also inhibited each other in the case of their binary and triple utilization in compost. Another explanation for variant activity was provided based on the enzymatic activity of the strains validated by metagenomic counts evaluation. Metagenome count numbers revealed the tendency of compost microbiota toward degradation products of cellulose. Findings obtained from composting experiments and metagenome analyses indicated the presence of a different degradation route based on xylan activity. Results also implied a decrease in competition between the dominant strain and microbiota members in the case of sequential xylan and cellulose degradation. Meticulous evaluation of results obtained from metagenome analysis also provided some insights on certain conditions regarding the progress of composting along with storage conditions of manure before use.