超高温堆肥微生物群落强化产热功能特征分析

Characteristics of Enhanced Microbial Thermogenic Functions in Hyperthermophilic Composting

超高温堆肥技术较普通堆肥技术在氧化亚氮减排、氮素保留、抗性基因去除等方面具有显著优势。这些优势与超高温过程密切关联,然而超高温产生的原因却仍然未知。利用PICRUSt(phylogenetic investigation of communities by reconstruction of unobserved states)预测并分析了鸡粪超高温堆肥和普通堆肥微生物功能变化,重点比较了产热相关代谢通路和功能基因丰度的变化。研究发现,超高温堆肥可达到超过80℃的超高温阶段并持续5天以上,该阶段可显著提高微生物能量代谢、碳水化合物代谢等产热相关代谢通路丰度,有氧呼吸链中NADH脱氢酶功能基因和琥珀酸脱氢酶基因的丰度在超高温阶段显著增加(P<0.05),并且上述代谢通路和功能基因丰度与超高温堆肥温度变化显著相关(P<0.05)。采用随机森林回归模型将预测的堆肥温度与实际堆肥温度进行比较发现,两种处理各自预测温度结果与实际温度相关性显著(对于超高温堆肥,校正R^(2)=0.96;对于普通堆肥,校正R^(2)=0.97)。该模型表明,K03943(NADH脱氢酶黄蛋白2)、K15862(细胞色素c氧化酶cbb3型亚基I/II)和K05580(NADH醌氧化还原酶亚基I)的丰度变化是影响超高温堆肥温度的最重要因素。相比之下,普通堆肥温度最高不超过70℃,且上述产热相关代谢通路和功能基因丰度与堆肥温度呈显著负相关(P<0.05)。以上结果表明,超高温堆肥微生物群落可能通过显著提高有氧呼吸链相关功能基因丰度,使超高温堆肥群落更迅速地代谢有机物,从而提高ATP合成速率,进而产生更多热量。

【Objective】Hyperthermophilic composting(h TC) exhibits significant advantages during organic solid waste treatment such as nitrous oxide mitigation, nitrogen retention, antibiotic resistance genes removal compared with those of conventional composting(c TC). Such advantages are closely linked with hyperthermophilic temperatures However, the reason for extremely high composting temperature remains unclear. 【 Method】 Here, by using PICRUSt(physiological investigation of communities by reconstruction of unobserved states), the variations in microbial function during h TC and c TC using chicken manure were studied. The reason for the extremely high composting temperature in h TC was explored. 【Result】Results show that the composting temperature could reach up to 80℃ and last for more than 5 days in h TC. h TC exhibited significant differences in both the composition of the microbial community and their metabolic pathways abundance during the hyperthermophilic stage. The abundances of thermogenesis related metabolic pathways(such as energy metabolism, carbohydrate metabolism) and aerobic respiration chain-related genes(such as NADH dehydrogenase gene, succinate dehydrogenase gene)were significantly increased during the hyperthermophilic stage(P<0.05). Furthermore, the abundance of the enriched metabolic pathways and functional genes was significantly correlated with the temperature variation of h TC(P < 0.05). Random forest regression models comparing the predicted to actual composting temperatures found strong correlations in both treatments(for h TC, adjusted R^(2) =0.96;for c TC, adjusted R^(2) =0.97). The model indicated that the abundances of K03943(NADH dehydrogenase flavoprotein 2), k15862(cytochrome c oxidase cbb3-type subunitⅠ/Ⅱ) and k05580(NADH-quinone oxidoreductase subunitⅠ)were the most important factors affecting the composting temperature in h TC. By comparison, the highest composting temperature of c TC was below 70℃, and the abundance of metabolic pathways and functional genes related to heat production was significantly negatively correlated with compost temperature(P<0.05).【Conclusion】Our results suggest that the h TC community might metabolize organic matter more rapidly by significantly increasing the abundance of functional genes related to the aerobic respiration chain, thus increasing the rate of ATP synthesis and generating more metabolic heat.