Research data for Effects of sample storage on the quantification of soil extracellular polymeric substances

Soil extracellular polymeric substances (EPS) are increasingly recognized as a critical microbially derived carbon with important roles in carbon cycling and soil structure. However, the impact of soil storage conditions on EPS quantification remains poorly constrained, limiting data comparability across studies. Here, we systematically evaluated seven common soil storage protocols across four distinct soil types short-term (two-month) and long-term (one-year) durations, utilizing mean-normalized root mean square deviation and cosine similarity to assess absolute and relative variations. Our results show that while polysaccharides (EPS-Poly) showed high variability and were largely restored to baseline levels through a 14-day preincubation, proteins (EPS-Prot) underwent an irreversible and substantial reduction (23%–97%) under all conditions. The carbon content of EPS remained relatively stable during long-term storage due to compensatory increases in EPS-Poly. Despite these strong effects on absolute concentrations, the relative variation in EPS components among soils was well preserved across all treatments. While stored soils remain suitable for comparative analyses, caution is warranted due to compositional shifts toward EPS-Poly. Overall, these findings highlight the necessity of standardized storage protocols and provide a robust methodological framework for future soil biogeochemical research.

土壤胞外聚合物（Soil extracellular polymeric substances, EPS）作为一类关键的微生物衍生碳组分，其在碳循环与土壤结构维持中的重要作用日益受到学界认可。然而，土壤保存条件对EPS定量分析的影响仍未得到明确约束，这限制了不同研究间的数据可比性。本研究系统评估了七种常用土壤保存方案在四种不同土壤类型、短期（2个月）与长期（1年）两种时长下的效果，采用均值归一化均方根偏差（mean-normalized root mean square deviation）与余弦相似度（cosine similarity）分别评估绝对与相对变异程度。结果显示，尽管多糖组分（polysaccharides, EPS-Poly）存在较高变异，但通过14天预培养即可基本恢复至基线水平；而蛋白质组分（proteins, EPS-Prot）在所有保存条件下均出现不可逆且显著的降低（降幅23%~97%）。由于多糖组分出现代偿性增加，EPS总碳含量在长期保存过程中保持相对稳定。尽管这些因素对EPS绝对浓度存在显著影响，但不同土壤间EPS组分的相对差异在所有处理组中均得到较好保留。尽管保存后的土壤仍可用于比较分析，但由于组分向多糖组分偏移，开展相关研究时仍需谨慎。综上，本研究结果凸显了标准化土壤保存方案的必要性，并为未来土壤生物地球化学研究提供了可靠的方法学框架。