Soil pH stands as a decisive factor in shaping bacterial diversity and community composition, yet predicting the pH preferences and traits of individual bacterial taxa is still incomplete. We surveyed 942 samples from seven biomes worldwide to unravel the responses of individual bacterial genus to soil pH. Our findings indicate that soil pH surpasses the influences of spatial and climatic factors (biomes) in affecting bacterial composition and diversity. We observed that a comparable proportion of genera had low pH optima (21%), high pH optima (18%), and neutral pH optima (18%). However, apart from genera with optima groups, only a small percentage of genera were low pH tolerant (0.8%) compared to those that were high pH tolerant (21%). This suggests that a greater number of non-extremophiles genera can tolerate alkaline conditions compared to acidic conditions. Bacterial richness forms unimodal relationship with soil pH, consistently increasing from acidic levels to neutral across all biomes. However, the decline in richness when pH rises beyond neutral was less pronounced. This can be attributed to the higher number of alkaline-tolerant genera compared to acidic-tolerant genera. As expected, genera with acidic optima are more prevalent in humid climates, such as tropical forests, arctic tundra, and boreal forests, whereas genera with alkaline optima are generally dominant in arid grasslands and drylands. Collectively, our results indicate that the probability of existence of at least 75% of genera in specific soil pH conditions can be predicted, irrespective of biome. The identification of the actual niche spaces occupied by individual soil bacterial genera forms the foundation for developing comprehensive hypotheses regarding the response of soil communities to changing soil conditions worldwide.

中文翻译：

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土壤细菌属和多样性对 pH 的响应的整体分析


土壤 pH 值是塑造细菌多样性和群落组成的决定性因素，但预测单个细菌类群的 pH 偏好和特征仍然不完整。我们调查了来自全球七个生物群落的 942 个样本，以揭示单个细菌属对土壤 pH 值的反应。我们的研究结果表明，土壤 pH 值在影响细菌组成和多样性方面超越了空间和气候因素（生物群落）的影响。我们观察到，相当比例的属具有低最适 pH 值 (21%)、高 pH 值最适值 (18%) 和中性 pH 值最适值 (18%)。然而，除了具有最佳群体的属外，与耐高 pH 值的属 (21%) 相比，只有一小部分属耐低 pH 值 (0.8%)。这表明与酸性条件相比，更多的非极端微生物属可以耐受碱性条件。细菌丰富度与土壤 pH 值形成单峰关系，在所有生物群落中从酸性水平持续增加到中性水平。然而，当 pH 值上升到中性以上时，丰富度的下降就不那么明显了。这可以归因于与耐酸属相比，耐碱属的数量较多。正如预期的那样，具有酸性最佳值的属在潮湿气候中更为普遍，例如热带森林、北极苔原和北方森林，而具有碱性最佳值的属通常在干旱草原和旱地中占主导地位。总的来说，我们的结果表明，无论生物群落如何，至少 75% 的属在特定土壤 pH 条件下存在的概率是可以预测的。 确定各个土壤细菌属所占据的实际生态位空间，为制定关于土壤群落对全球土壤条件变化的响应的综合假设奠定了基础。