Microbial strategies and biochemical activity during lignocellulosic waste composting in relation to the occurring biothermal phases

Typically, hardly-degradable lignocellulosic waste is a component or a co-component of the composted mass. The aim of the work was to present the dynamics and succession of microbial communities during small temperature changes, conditioned by the availability of lignocellulosic polymer and feather waste (the presence of N) in composts with qualitatively and quantitatively different lignocellulosic waste, but most of all, to draw attention to the previously not considered microbial strategies in the composted mass. Decomposition of lignocellulose during composting was similar to the priming effect in the soil, because it was associated with the successive occurrence of two groups of microorganisms. The first group of microorganisms, using easily accessible fraction of the lignocellulose complex, was named the first-strategist group, i.e., non-nutritionally specialized group of microorganisms. The second group, utilizing the hard-to-degrade fraction of lignocellulose, was named second-strategist microorganisms, i.e., nutritionally-specialized group of microorganisms. Biodegradation of the lignocellulose complex in compost I enriched with grass (42.86% pine bark, 34.28% grass, 20.0% sawdust and 2.86% chicken feathers) was faster than in compost II that did not contain any grass, but included more hardly degradable components (25.54% pine bark, 10.63% wheat straw, 51.07% sawdust, 12.76% chicken feathers). In compost I, a higher temperature in the thermophilic phase was recorded; larger amounts of non-specialized mesophilic and thermophilic bacteria in the first weeks of composting and a higher abundance of ligninolytic, xylanolytic fungi and cellulolytic bacteria were observed already in biothermal phase 3 with limited access to easily available C and energy sources. During this period, phosphatase, dehydrogenase and respiratory activities were higher in compost I than compost II. This work demonstrates that the succession of particular groups of microorganisms may help determine the start of biodegradation of recalcitrant ligninocellulosic components during composting. (C) 2017 Elsevier Ltd. All rights reserved.