Ocean acidification (OA) in estuaries is becoming a global concern, and may affect microbial characteristics in estuarine sediments. Bacterial communities in response to acidification in this habitat have been well discussed; however, knowledge about how fungal communities respond to OA remains poorly understood. Here, we explored the effects of acidification on bacterial and fungal activities, structures and functions in estuarine sediments during a 50-day incubation experiment. Under acidified conditions, activities of three extracellular enzymes related to nutrient cycling were inhibited and basal respiration rates were decreased. Acidification significantly altered bacterial communities and their interactions, while weak alkalization had a minor impact on fungal communities. We distinguished pH-sensitive/tolerant bacteria and fungi in estuarine sediments, and found that only pH-sensitive/tolerant bacteria had strong correlations with sediment basal respiration activity. FUNGuild analysis indicated that animal pathogen abundances in sediment were greatly increased by acidification, while plant pathogens were unaffected. High-throughput quantitative PCR-based SmartChip analysis suggested that the nutrient cycling-related multifunctionality of sediments was reduced under acidified conditions. Most functional genes associated with nutrient cycling were identified in bacterial communities and their relative abundances were decreased by acidification. These new findings highlight that acidification in estuarine regions affects bacterial and fungal communities differently, increases potential pathogens and disrupts bacteria-mediated nutrient cycling.

中文翻译：

---

与河口沉积物中的真菌群落相比，细菌群落对海洋酸化更敏感

河口的海洋酸化（OA）成为全球关注的问题，并可能影响河口沉积物中的微生物特征。在该生境中对酸化反应的细菌群落已进行了充分的讨论。但是，关于真菌群落如何对OA做出反应的知识仍然知之甚少。在这里，我们在50天的温育实验中探索了酸化对河口沉积物中细菌和真菌活性，结构和功能的影响。在酸化条件下，与养分循环有关的三种细胞外酶的活性受到抑制，基础呼吸速率降低。酸化作用显着改变了细菌群落及其相互作用，而弱碱化对真菌群落影响较小。我们区分了河口沉积物中的pH敏感/耐性细菌和真菌，并发现只有pH敏感/耐性细菌与沉积物基础呼吸活动具有很强的相关性。FUNGuild分析表明，酸化可大大增加沉积物中动物病原体的丰度，而植物病原体则不受影响。基于高通量定量PCR的SmartChip分析表明，在酸性条件下，与养分循环相关的沉积物多功能性降低。在细菌群落中鉴定出与营养循环相关的大多数功能基因，并且通过酸化降低了它们的相对丰度。这些新发现表明，河口地区的酸化对细菌和真菌群落的影响不同，