蚯蚓对污泥堆肥过程中活性真核微生物的影响

Effects of earthworms on active eukaryotic microbial community during vermicomposting of dewatered sludge

为揭示蚯蚓对污泥堆肥中真核微生物的调控作用,以赤子爱胜蚓处理脱水污泥,以无蚯蚓添加为对照处理,采用叠氮溴化丙锭(Propidium Monoazide, PMA)对样品进行预处理,探究蚯蚓对其肠道消化期(0~20 d)和腐熟期(20~30 d)中活性真核微生物数量和种群结构变化的影响.结果表明:与对照处理相比,第30 d时蚯蚓处理有机物降解量和矿化度分别提高16.36%和82.49%(p<0.01).真核微生物数量在肠道消化期呈上升趋势,但在第20 d时蚯蚓处理真核微生物数量比对照处理显著下降54.45%(p<0.01).蚯蚓处理真核微生物种群Shannon指数和Simpson指数呈先增后减趋势,在腐熟期剧烈下降,第30 d时比对照处理分别显著降低31.33%(p<0.05)和45.29%(p<0.01).第20 d时,与对照处理相比,蚯蚓处理使丝足虫与纤毛虫的相对丰度分别降低84.82%(p<0.01)和66.74%,而子囊菌和担子菌的相对丰度分别增加1.24倍和23.42倍(p<0.01).第30 d时隐真菌占主导地位,其在蚯蚓处理的相对丰度较对照处理显著增加60.58%(p<0.01).研究结果揭示蚯蚓能够显著降低污泥堆肥体中原生动物相对丰度,增加真菌相对丰度,从而实现有机物的快速降解,促进污泥矿化稳定.

In order to reveal the regulatory effect of earthworms on eukaryotic microorganisms,the effects of earthworms on the changes in eukaryotic microbial density and community structure were investigated during vermicomposting of dewatered sludge with and without earthworms Eisenia fetida.The experimental process was divided into an intestinal digestion period(0~20 d)and a decomposition period(20~30 d).The collected samples were pretreated with propidium monoazide(PMA)to explore the active eukaryotic microbes during vermicomposting.The results showed that,on the 30th day,the electrical conductivity and degradation of organic matter in treatment group with earthworms were significantly higher(p<0.01)with 82.49%and 16.36%than of these in treatment without earthworms(control group),respectively.The number of eukaryotes exhibited an upward trend in the intestinal digestion period.Compared to the control group,the number of eukaryotic microorganisms in treatment group significantly lowered(p<0.01)with 54.45%on the 20th day.Similarly,the Shannon and Simpson indexes of the eukaryotic microbial community in treatment group sharply declined during the decomposition period and then separately reduced with 31.33%(p<0.05)and 45.29%(p<0.01)than of these in control group in the end of vermicomposting.In detail,on the 20th day,the relative abundances of Cercozoa and Ciliophora in the treatment group significantly debated(p<0.01)with 84.82%and 66.74%,respectively,compared to the counterpart;while the relative abundances of Ascomycota and Basidiomycota significantly(p<0.01)enhanced with 1.24 times and 23.42 times,respectively.The Cryptomycota,dominant on the 30th day significantly(p<0.01)enriched with 60.58%in earthworm treatment,relative to the control group.The results suggest that the earthworms can significantly reduce the relative abundance of protozoa and increase the relative abundance of fungi in the eukaryotic microorganisms during vermicomposting of dewatered sludge,and thus realizing the rapid degradation of organic matter and promoting the stability of sludge mineralization.