Harris Kristian J, Bennett Alison E
Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, Ohio, USA.
Environ Microbiol Rep. 2025 Oct;17(5):e70191. doi: 10.1111/1758-2229.70191.
The Stress Gradient Hypothesis (SGH) predicts that interspecific interactions shift from competition under low stress to facilitation under high stress. Historically, this framework has been extensively studied in plants, but its application to microbial communities remains underexplored. Here, we review literature to examine bacterial interactions under heavy metal stress, using selenium (Se) stress as a model for heavy metal-induced environmental pressures. Se, a naturally occurring and anthropogenic metalloid contaminant, provides oxidative stress on bacteria, which will modify competitive and facilitative behaviours under the SGH framework. At low Se concentrations, bacterial interactions are predominantly competitive, driven by resource competition and antimicrobial strategies. However, as Se stress increases, we predict facilitative interactions to increase, including detoxification mechanisms that reduce toxicity for Se intolerant species. We discuss methodologies to measure bacterial competition and facilitation, propose experimental approaches to identify the transition between these interaction modes, and explore the implications of species richness in microbial stress resilience. Understanding these interactions provides insights into microbial ecology, biogeochemical cycling and potential applications in bioremediation.
压力梯度假说（SGH）预测，种间相互作用会从低压力下的竞争转变为高压力下的促进作用。从历史上看，这个框架在植物中得到了广泛研究，但其在微生物群落中的应用仍未得到充分探索。在这里，我们回顾文献，以研究重金属胁迫下的细菌相互作用，将硒（Se）胁迫作为重金属诱导环境压力的模型。硒是一种天然存在的和人为产生的类金属污染物，会对细菌产生氧化应激，这将在SGH框架下改变竞争和促进行为。在低硒浓度下，细菌相互作用主要是竞争性的，由资源竞争和抗菌策略驱动。然而，随着硒胁迫的增加，我们预测促进性相互作用会增加，包括减少对硒不耐受物种毒性的解毒机制。我们讨论了测量细菌竞争和促进作用的方法，提出了识别这些相互作用模式之间转变的实验方法，并探讨了物种丰富度在微生物应激恢复力中的意义。了解这些相互作用有助于深入了解微生物生态学、生物地球化学循环以及生物修复中的潜在应用。
