The adaptability of soil microbial communities to prolonged periods of drought is influenced by their ability to produce extracellular polymeric substances (EPS) with sufficient water retention properties. Microbial EPS have been extensively investigated as water reservoirs during drought, but it remains unknown how carbon substrate accessibility to soil microbial communities will affect the chemical properties of the EPS they generate, and whether this in turn will alter their water retention characteristics. In this work, we observed that the accessibility of carbon substrates influenced microbial community structure and, consequently, the chemical properties of EPS produced by the microbial communities. Our results demonstrated that an insoluble carbon substrate (i.e., chitin), stimulated microbial communities to produce EPS with measurably better water retention properties in emulated soil microenvironments in comparison to a soluble carbon substrate (i.e., N-acetylglucosamine; NAG). In all, this study demonstrates the importance of carbon substrate accessibility by soil microorganisms in regulating the community structure and consequently, the EPS carbon chemistry, which in turn can greatly influence the adaptability of soil microbial communities to drought.

土壤微生物群落对长时间干旱的适应性受其产生具有足够保水性的细胞外聚合物（EPS）的能力影响。微生物EPS已作为干旱期间的蓄水池进行了广泛研究，但尚不清楚碳基质对土壤微生物群落的可及性将如何影响其产生的EPS的化学性质，以及是否反过来会改变其保水特性。在这项工作中，我们观察到碳底物的可及性影响了微生物群落的结构，进而影响了微生物群落产生的EPS的化学性质。我们的结果表明，不溶性碳底物（即几丁质）与可溶碳基质（即N-乙酰氨基葡萄糖； NAG）相比，在模拟的土壤微环境中，刺激微生物群落产生的EPS的保水性能明显好得多。总而言之，这项研究表明土壤微生物对碳底物的可及性在调节群落结构中具有重要意义，因此，EPS碳化学也可以极大地影响土壤微生物群落对干旱的适应性。