Microbial Community Structure During Composting With and Without Mass Inocula

Abstract

Inoculation of a mixture of household organics and shredded wood with inocula from the active phase of composting enhanced mineralization of organic matter and yielded a biologically stabilized product with a more favorable C/N ratio than in a non-inoculated treatment. Analysis of phospholipid fatty acids was used to determine total viable microbial biomass and relative amounts of bacteria, Gram positive and Gram negative bacteria, actinomycetes, fungi, thermophiles and nonthermophiles in compost. The initial viable microbial biomass was 6-fold higher in inoculated than in noninoculated compost. The thermophilic phase occurred immediately after inoculation and the total viable biomass afterwards followed the course of temperature. The ratio of viable (sum of phospholipid fatty acids) to dead (sum of diglyceride fatty acids) microbial biomass during this period was generally higher at lower composting temperatures in both inoculated and noninoculated compost. During composting, fluctuations in total viable microbial biomass and in the relative amounts of indicator PLFAs of all microbial groups except Gram negative bacteria was more intensive in noninoculated compost.