Effects of a novel thermophilic cellulose-degrading agent on the quality of compost and change in microbial community of garden waste

Abstract

12Knowledge about the microbial communities in composting has advanced, but definitive 13 knowledge concerning the application of actinomycetal communities in garden waste 14 composting is still lacking. In this study, we compared the effects of amending compost with 15 mixed agent M1 (five high-degradability strains) and other agents on the physicochemical 16 indices and microbial community succession. The results showed that Pile A (only applying 17 M1), exhibited a pH closer to neutral, the complete degradation of organic matter, and the 18 highest remaining levels of nitrogen, phosphorus, and potassium. The seed germination rate, 19 root length, and seed germination index values were significantly higher in piles amended 20 with M1 and/or commercially available agents than in piles without exogenous microbial 21 agents. Analyzing the microbial communities, these treatments were dominated by 22 Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes during composting. The amount 23 of Streptomyces was negatively correlated with the carbon/nitrogen ratio and positively 24 correlated with total phosphorus and total potassium. Adding M1 increased microbial 25 diversity, and the dominant microbial communities at the end of composting were similar to 26 those found in the commercial microbial inoculum. Overall, agent M1 can shorten the 27 composting process and increase the extent of degradation. This research provides additional 28 insights into the potential function of Actinomycetes in compost ecology. 29 30 31 thermophilic cellulose-degrading bacteria 32 33 34 35 36 37 38 39 40 41 42 43 45 Waste management is one of the main issues affecting all developing nations [1]. In 46 China, with the acceleration of urbanization, the amount of green area coverage is increasing, 47 but tons of organic solid waste are produced with no means for effective decomposition, 48 representing added stress to the environment [2]. The main components of garden waste, 49 lignin and cellulose, are recalcitrant to degradation, leaving only landfilling and direct 50 burning as traditional disposal methods. Traditional landfilling and incineration methods not 51 only use land resources, but also cause other problems, such as dust particle production, soil 52 and groundwater contamination, pathogenic bacteria growth, and air pollution [3]. To lessen 53 the effects of garden waste disposal on the environment and mitigate environmental pollution, 54 biological composting employs microbial action in waste piles to transform organic solid 55 waste into stable humus and organic fertilizer. Biological composting can directly transform 56 large amounts of organic waste for compost production; however, the unreliability of the 57 quantity and biodegradability of the indigenous functional microbial community in compost 58 often leads to low composting efficiency and undesirable compost quality [4]. 59 Many studies have shown that inoculation with exogenous microorganisms is an 60 effective method for the biodegradation of organic matter a...