金沙土遗址土壤细菌群落结构和推测的代谢特征

Diversity and speculative metabolism of bacteria from soil of Jinsha earthen site

【背景】金沙土遗址被认为是3 200年前商周时期大型祭祀场所,具有重要的古文化和历史意义,目前金沙土遗址在物理、化学、生物等因素的影响下已出现不同程度的劣化,物理、化学因素的影响已有报道,而生物因素尚鲜有关注。【目的】研究金沙土遗址中微生物群落结构组成,解析微生物菌群活性及代谢特征,为金沙土遗址的科学保护提供依据。【方法】根据遗址目前的保存状况,从金沙土遗址采集具有代表性的土壤样品,所采区域样品的劣化程度依次为J4>J3>J2>J1,应用Biolog平板法与PCR-DGGE技术对各样品中的微生物群落结构组成和代谢功能多样性进行研究。【结果】Biolog结果显示,随着金沙土遗址的劣化,各土壤样品中的微生物功能多样性存在较大差异,各样品的微生物群落代谢活性依次为:J2>J3>J4>J1,表明随着土壤的劣化,微生物的代谢活性表现出增大的趋势。主成分分析结果反映出4个样品中的微生物碳代谢方式具有显著的变化,样品J2中的细菌群落对底物碳源利用种类最多,且偏好的碳源类型与其它样品存在明显的不同。PCR-DGGE图谱显示,金沙土遗址不同土壤样品中的细菌多样性和种群组成存在明显差异,在DNA和RNA水平上,各样品的微生物组成多样性依次为:J2>J4>J3>J1。主成分分析结果显示,除了样品J1,劣化样品的细菌群落结构和活性细菌群落结构具有较高的一致性,表明随着金沙土遗址的劣化,土壤中微生物多样性呈现出上升趋势。DGGE图谱主要条带的测序结果表明,样品中主要的细菌类群归属于放线菌门(Actinobacteria)、酸杆菌门(Acidobacteria)、变形菌门(Proteobacteria)和异常球菌-栖热菌门(Deinococcus-Thermus),分属于7个属,在DNA和RNA水平上均能检测到红色杆菌属(Rubrobacter)和短波单胞菌属(Brevundimonas)。【结论】首次对金沙土遗址的细菌群落结构组成和功能进行分析,结果表明随着金沙土遗址劣化程度的增加,土壤微生物类群及功能多样性都随之增大,其中仅在劣化土壤样品中检出或者具有高表达活性的红色杆菌属、Tellurimicrobium、短状杆菌属细菌可能参与了土壤劣化过程,这为今后土遗址的科学保护提供了理论依据。

[Background] Jinsha earthen site is considered as a large ritual site in the Shang and Zhou dynasties 3 200 years ago, which play an important role in ancient culture and history. But now it has exhibited different degrees of degradation under the influence of physical, chemical and biological factors. The effects of physical and chemical factors have been reported, while very little is known about the influence of biological factors on earthen site. [Objective] To study the microbial diversity and metabolic characteristics in Jinsha earthen site soil, it is important to provide scientific evidences for the conservation of Jinsha earthen site. [Methods] Four types of representative samples from Jinsha earthen site that have undergone different degree of degradation were collected to analyze the microbial diversity and metabolic function by Biolog plate methods and denaturing gradient gel electrophoresis(PCR-DGGE). The degree of degradation of samples is followed by J4>J3>J2>J1. [Results] Biolog analysis result showed that the function of soil microbial diversity was significantly varied in different samples and the order of microbial metabolic activity was followed by J2>J3>J4>J1, implying that the microbial metabolic activity of samples showed an increasing trend with the degradation of soil. PCA analysis of Biolog indicated the utilized types of carbon sources by soil microbes in Jinsha earthen site was significantly varied. The microorganisms in sample J2 could utilize most types of substrate carbon sources in plate compared to that in other samples, and the preferred carbon sources of sample J2 was obviously different from that of other samples. The bacterial diversity and structure of different soil exhibited significant difference by DGGE analysis. The order of microbial community diversity was followed by J2>J4>J3>J1 both in DNA and RNA level and the PCA result of DGGE revealed that the total and active bacterial community showed high consistency except sample J1, which indicated the microbial diversity increased with the degradation of soil. Based on the sequence analysis of DGGE, the major community of bacteria in soil samples were belonged to Actinobacteria, Acidobacteria, Proteobacteria and Deinococcus-Thermus. Rubrobacter and Brevundimonas were detected in all samples, including DNA and RNA level. [Conclusion] It is first time that microbial and functional diversity of soil from Jinsha earthen site were analyzed in this study. The results exhibited the microbial and functional diversity increased with the degradation of soil. The genera Rubrobacter, Tellurimicrobium and Brachybacterium that were detected only in degraded soil samples or had high expression activity may be involved in the soil degradation process. The results could provide theoretical basis for the scientific conservation of Jinsha earthen site.