Tibihenda Cevin, Zhong Hesen, Liu Kexue, Dai Jun, Lin Xiaoqin, Motelica-Heino Mikael, Hou Shuyu, Zhang Menghao, Lu Ying, Xiao Ling, Zhang Chi
College of Natural Resources and Environment, South China Agricultural University, Guangzhou, China.
Tanzania Agricultural Research Institute, Dodoma, Tanzania.
Front Microbiol. 2023 Oct 4;14:1240707. doi: 10.3389/fmicb.2023.1240707. eCollection 2023.
Food chain contamination by soil lead (Pb), beginning with Pb uptake by leafy vegetables, is a threat to food safety and poses a potential risk to human health. This study highlights the importance of two ecologically different earthworm species (the anecic species and the epigeic species ) as the driving force of microbial hotspots to enhance Pb accumulation in the leafy vegetable at different Pb contamination levels (0, 100, 500, and 1,000 mg·kg). The fingerprints of phospholipid fatty acids (PLFAs) were employed to reveal the microbial mechanism of Pb accumulation involving earthworm-plant interaction, as PLFAs provide a general profile of soil microbial biomass and community structure. The results showed that Gram-positive (G) bacteria dominated the microbial community. At 0 mg·kg Pb, the presence of earthworms significantly reduced the total PLFAs. The maximum total of PLFAs was found at 100 mg·kg Pb with inoculation. A significant shift in the bacterial community was observed in the treatments with inoculation at 500 and 1,000 mg·kg Pb, where the G/G bacteria ratio was significantly decreased compared to no earthworm inoculation. Principal component analysis (PCA) showed that had a greater effect on soil microbial hotspots than , thus having a greater effect on the Pb uptake by . Redundancy analysis (RDA) showed that soil microbial biomass and structure explained 43.0% (R = 0.53) of the total variation in Pb uptake by , compared to 9.51% of microbial activity. G bacteria explained 23.2% of the total variation in the Pb uptake by , significantly higher than the other microbes. The Mantel test showed that microbial properties significantly influenced Pb uptake by under the driving force of earthworms. inoculation was favorable for the G bacterial community, whereas inoculation was favorable for the fungal community. Both microbial communities facilitated the entry of Pb into the vegetable food chain system. This study delivers novel evidence and meaningful insights into how earthworms prime the microbial mechanism of Pb uptake by leafy vegetables by influencing soil microbial biomass and community composition. Comprehensive metagenomics analysis can be employed in future studies to identify the microbial strains promoting Pb migration and develop effective strategies to mitigate Pb contamination in food chains.
土壤铅（Pb）对食物链的污染，始于叶菜类蔬菜对铅的吸收，这对食品安全构成威胁，并对人类健康造成潜在风险。本研究强调了两种生态不同的蚯蚓物种（表栖种和内栖种）作为微生物热点驱动力的重要性，以增强在不同铅污染水平（0、100、500和1000 mg·kg）下叶菜类蔬菜中铅的积累。利用磷脂脂肪酸（PLFA）指纹图谱揭示涉及蚯蚓 - 植物相互作用的铅积累的微生物机制，因为PLFA提供了土壤微生物生物量和群落结构的总体概况。结果表明，革兰氏阳性（G）细菌主导了微生物群落。在0 mg·kg铅含量下，蚯蚓的存在显著降低了总PLFA。在接种的情况下，100 mg·kg铅含量时发现PLFA总量最高。在500和1000 mg·kg铅含量的接种处理中，观察到细菌群落发生了显著变化，与未接种蚯蚓相比，G/G细菌比率显著降低。主成分分析（PCA）表明，内栖种对土壤微生物热点的影响大于表栖种，因此对叶菜类蔬菜吸收铅的影响更大。冗余分析（RDA）表明，土壤微生物生物量和结构解释了叶菜类蔬菜吸收铅总变异的43.0%（R = 0.53），而微生物活性解释了9.51%。G细菌解释了叶菜类蔬菜吸收铅总变异的23.2%，显著高于其他微生物。Mantel检验表明，在蚯蚓的驱动下，微生物特性显著影响叶菜类蔬菜对铅的吸收。接种内栖种有利于G细菌群落，而接种表栖种有利于真菌群落。这两种微生物群落都促进了铅进入蔬菜食物链系统。本研究为蚯蚓如何通过影响土壤微生物生物量和群落组成来启动叶菜类蔬菜吸收铅的微生物机制提供了新的证据和有意义的见解。未来的研究可以采用综合宏基因组学分析来鉴定促进铅迁移的微生物菌株，并制定有效的策略来减轻食物链中的铅污染。
