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Journal of Zhejiang University SCIENCE B
ISSN 1673-1581(Print), 1862-1783(Online), Monthly
2025 Vol.26 No.5 P.477-492
Metagenomics reveals an increased proportion of an Escherichia coli-dominated enterotype in elderly Chinese people
Abstract: Gut microbial communities are likely remodeled in tandem with accumulated physiological decline during aging, yet there is limited understanding of gut microbiome variation in advanced age. Here, we performed a metagenomics-based enterotype analysis in a geographically homogeneous cohort of 367 enrolled Chinese individuals between the ages of 60 and 94 years, with the goal of characterizing the gut microbiome of elderly individuals and identifying factors linked to enterotype variations. In addition to two adult-like enterotypes dominated by Bacteroides (ET-Bacteroides) and Prevotella (ET-Prevotella), we identified a novel enterotype dominated by Escherichia (ET-Escherichia), whose prevalence increased in advanced age. Our data demonstrated that age explained more of the variance in the gut microbiome than previously identified factors such as type 2 diabetes mellitus (T2DM) or diet. We characterized the distinct taxonomic and functional profiles of ET-Escherichia, and found the strongest cohesion and highest robustness of the microbial co-occurrence network in this enterotype, as well as the lowest species diversity. In addition, we carried out a series of correlation analyses and co-abundance network analyses, which showed that several factors were likely linked to the overabundance of Escherichia members, including advanced age, vegetable intake, and fruit intake. Overall, our data revealed an enterotype variation characterized by Escherichia enrichment in the elderly population. Considering the different age distribution of each enterotype, these findings provide new insights into the changes that occur in the gut microbiome with age and highlight the importance of microbiome-based stratification of elderly individuals.
Key words: Gut microbiome; Aging; Elderly population; Escherichia-dominated enterotype; Enterotype; Escherichia coli
机构：1南京理工大学，安全科学与工程学院（应急管理学院），中国南京，210094；2同济大学，土木工程学院，中国上海，200092
目的：当盾构隧道全线中只有部分衬砌环周边超载时，其承载性能明显不同于全线超载的情况。现有研究多取一环或几环衬砌环为研究对象，在选取的衬砌环上施加荷载以分析衬砌结构的性能演化规律，未能揭示局部超载时盾构衬砌环的承载与破坏特性。本文通过建立三维精细化有限元模型对比分析盾构衬砌环在全线与局部超载时的承载特性与破坏机制，并提出适用于局部超载作用时的衬砌环加固方法。
创新点：1.研究了局部超载作用时盾构衬砌环的力学性能演化规律，揭示了其破坏机制；2.分析了局部超载作用时钢环施作在衬砌环环内与环间两种加固方式时的加固效果，并提出了最佳的衬砌环加固方式。
方法：1.在管片接缝抗弯试验验证的基础上，建立三维精细化有限元模型，分析超载作用时盾构衬砌环内力与变形、衬砌接缝变形及螺栓应力等的变化规律，并在此基础上提出局部超载作用时盾构衬砌环的破坏特性。2.对比分析局部超载作用下采用钢环在衬砌环环内与环检加固时衬砌环内力与变形、衬砌接缝变形、螺栓应力及钢环应力的变化规律，并提出适用于局部超载作用时的钢环加固衬砌环布置方法。
结论：1.盾构隧道全线超载时的衬砌环变形、管片接缝张开量与管片接缝螺栓应力、管片中混凝土塑性区分布范围均大于局部超载作用时的情况，但局部超载时衬砌环中环间接缝的错台量及环间接缝位置螺栓的应力大于全线超载作用时的情况；在分析实际工程中更为常见的局部超载作用下的衬砌环的性能演化规律时，应充分考虑环间接缝错台变形及环间接缝螺栓的受力对盾构衬砌环承载与破坏特性的影响。2.采用钢环环内加固的方案时，因钢环施作在衬砌环内，无法与环间接缝的螺栓一起限制相邻衬砌环之间环间接缝的错台变形；采用钢环环间加固的方案，不仅可提高衬砌环的刚度，布置在相邻衬砌环之间的钢环还可与环间接缝位置的纵向螺栓共同限制环间接缝的错台变形，减小相邻环之间纵向螺栓的应力。综上所述，在盾构隧道上部某一区间存在局部超载时，钢环环间加固的方案更为有效。
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DOI:
10.1631/jzus.B2400341
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On-line Access:
2025-05-28
Received:
2024-07-08
Revision Accepted:
2024-09-13
Crosschecked:
2025-05-29