Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610213, China.
The College of Life Sciences, Sichuan University, Chengdu, 610041, China.
Environ Pollut. 2024 Dec 15;363(Pt 2):125156. doi: 10.1016/j.envpol.2024.125156. Epub 2024 Oct 24.
Low ambient temperature become the limiting factor of composting in cold regions, thus hindering the recycle of agricultural and forestry wastes. In this study, the composting of mushroom residue and wood chips (MRWC) under low temperature was successfully implemented with inoculation of psychrotolerant cellulolytic microbial agent. Composting entered thermophilic stage on third day and the peak temperature reached to 66.25 °C. After 84 days of composting, the degradation rate of cellulose and hemicellulose was 40.85% and 100%, respectively and the compost product was completely mature and met the requirements of organic fertilizer. Metagenomic and transcriptome sequencing were applied to reveal the microbial composition and their substrates conversion functions and adaptation mechanisms through low to high temperatures. Streptomyces, Mesorhizobium, Devosia, Aspergillus and Mucor were dominant genera in the microbial community that were rich in genes of lignocellulose degradation. Various genes related to low temperature adaptation (fatty acid, trehalose, mannitol, betaine metabolism and cold shock mechanism) and high temperature tolerance (heat shock and antioxidant) were detected during MRWC composting. These results indicated that microbes during composting constituted a high-efficiency lignocellulosic ultilization system in cold conditions. Besides, the microbes of microbial agent, especially Streptomyces and Aspergillus, possessed numerous genes involving in lignocellulose degradation and temperature adaptation and quite different temperature response patterns were found to perform in bacteria and fungi. The transcription levels of most these genes in Aspergillus exhibited significant differences under different substrates and temperature conditions, suggesting that the inoculum was crucial to the composting process and beneficial to maintain the temperature of piles. This study demonstrated that the application of psychrotolerant microbes was a promising strategy to increase the efficiency of composting in cold regions and these results could also provided the guidance for optimizing microbial agent.
低温成为寒冷地区堆肥的限制因素，从而阻碍了农业和林业废物的循环利用。在这项研究中，通过接种耐冷纤维素分解微生物剂，成功地实现了蘑菇渣和木屑（MRWC）在低温下的堆肥。堆肥在第三天进入高温阶段，最高温度达到 66.25°C。经过 84 天的堆肥，纤维素和半纤维素的降解率分别达到 40.85%和 100%，堆肥产品完全成熟，符合有机肥的要求。通过宏基因组和转录组测序，揭示了微生物组成及其在低温到高温下的底物转化功能和适应机制。在微生物群落中，链霉菌、根瘤菌、节杆菌、曲霉和毛霉是优势属，它们富含木质纤维素降解基因。在 MRWC 堆肥过程中，检测到与低温适应（脂肪酸、海藻糖、甘露醇、甜菜碱代谢和冷休克机制）和高温耐受（热休克和抗氧化）相关的各种基因。这些结果表明，堆肥过程中的微生物在低温条件下构成了一个高效的木质纤维素利用系统。此外，微生物剂中的微生物，特别是链霉菌和曲霉，具有许多涉及木质纤维素降解和温度适应的基因，并且发现细菌和真菌具有不同的温度响应模式。在不同的底物和温度条件下，曲霉中大多数这些基因的转录水平都有显著差异，这表明接种剂对堆肥过程至关重要，有利于保持堆肥的温度。本研究表明，应用耐冷微生物是提高寒冷地区堆肥效率的一种有前途的策略，这些结果也为优化微生物剂提供了指导。
