摘要
      肥料堆肥和生物炭改良土壤被广泛用于提高土壤肥力和促进植物生长，其对土壤微生物群落和抗性的影响已被充分证明。然而，关于它们对蔬菜内生菌的影响的信息很少，蔬菜内生真菌是人类生吃时接触病原体和抗生素抗性基因（ARGs）的主要来源。在这里，我们研究了粪肥堆肥或生物炭添加对土壤-莴苣连续体中细菌群落组成和ARGs的影响，包括土壤、种子、叶子和根样本。培养60天后，在所有样品中总共检测到137个ARGs和31个可移动遗传元件（MGE）。ARGs的相对丰度和细菌群落的多样性从土壤到根内生菌，再到叶内生菌呈现出持续下降的趋势。添加粪肥增加了土壤中ARG的多样性和丰度，而在添加粪肥或生物炭或两者后，叶内生菌的ARG谱和细菌群落没有观察到显著变化。双部分网络分析表明，种子微生物组是植物内生菌和ARGs的主要来源之一。从生菜中分离出20种潜在的人类病原体，表明食用生生菜有潜在的病原体暴露风险。这些结果表明，粪肥和生物炭的添加对生菜内生菌的影响有限，并突出了种子微生物组对内生菌ARG谱的贡献。
Abstract
Soil amendment with manure compost and biochar is widely adopted to improve soil fertility and promote plant growth, and their effects on soil microbial communities and resistome have been well documented. However, there is sparse information regarding their effects on vegetable endophytes, which represent a major source of human exposure to pathogens and antibiotic resistance genes (ARGs) when eaten raw. Here, we investigated the impacts of manure compost or biochar addition on the bacterial community compositions and ARGs in the soil-lettuce continuum including soil, seed, leaf, and root samples. A total of 137 ARGs and 31 mobile genetic elements (MGEs) were detected in all the samples after 60 days of cultivation. The relative abundance of ARGs and the diversity of bacteria communities presented a consistent decreasing trend from soil to root endophytes, then leaf endophytes. Manure compost addition increased the diversity and abundance of ARGs in soil, while significant changes in the ARG profiles and bacterial communities were not observed in leaf endophytes after manure compost or biochar addition, or both. Bipartite networks analysis suggested that seed microbiome was one of the major sources of plant endophytes and ARGs. Twenty potential human pathogens were isolated from lettuce, indicating potential exposure risk to pathogens via the consumption of raw lettuce. These results suggest limited impacts of manure compost and biochar addition on lettuce endophytes and highlight the contribution of seed microbiome to endophyte ARG profiles.

https://www.sciencedirect.com/science/article/abs/pii/S0048969722076173