Effect of seeding materials on organic matter degradation and microbial community succession during model organic waste composting

The positive effect of seeding inoculation on the enhancement of organic matter decomposition has been reported only for specific substrates (lignocellulose and organic acids). However, in most cases (food waste or sludge), no effect has been reported. This study aimed to clarify the effect of seeding materials by quantitatively analyzing the relationship between organic matter degradation and microbial community succession during composting. Three seeding materials (one commercial seeding material and two commercial compost products) were compared in laboratory-scale composting of model organic waste. The results showed that the rates and degrees of organic matter degradation were similar irrespective of the seeding material. However, the microbial communities were different in each run, thereby indicating that the seeding materials greatly affected microbial community succession. The enzyme genes of the microorganisms were predicted by phylogenetic investigation of the communities via reconstruction of unobserved states. The abundance of most enzyme genes became similar as composting proceeded with different seeding materials. Therefore, the microorganisms present during composting may have similar enzymatic potential, even if they are in different microbial communities.