Abstract Microorganisms play an important role in soil aggregate formation; however, little is known concerning the impact of exopolysaccharide (EPS)-producing bacteria on water-stable soil macro-aggregate formation. In this study, a forest soil was collected and used for the isolation of EPS-producing Pseudomonas chlororaphis A20 and Bacillus proteolyticus A27. The isolation and purification of the EPS were made. Then, the strains and their EPS were investigated for their impact on water-stable soil macro-aggregate formation. Xylose and aldohexos were found in the EPS produced by these strains, whereas the EPS of strain A27 also contained rhamnose and glucose. The EPS of these strains demonstrated distinct Fourier transform-infrared spectrums. These strains increased the ratio of water-stable macro-aggregates (>0.25 mm) by 128–169%, polysaccharide content by 158–174%, and invertase activity by 153–193% in the soils compared with the controls. Strain A27 induced more water-stable soil macro-aggregates and higher invertase activity than strain A20. Furthermore, the EPS of strain A27 increased the ratio of water-stable macro-aggregates by 10–36% compared to that of strain A20. The results showed distinct bacterial impact on the water-stable macro-aggregate formation and suggested that higher bacterial activity and specific EPS of strain A27 may be responsible for increased water-stable soil macro-aggregate formation.

中文翻译：

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胞外多糖产生菌对土壤水稳性大团聚体形成的影响

摘要 微生物在土壤团聚体形成中起重要作用；然而，关于产生胞外多糖 (EPS) 的细菌对水稳性土壤大团聚体形成的影响知之甚少。在这项研究中，收集了森林土壤并用于分离产生 EPS 的绿脓假单胞菌 A20 和 Bacillus proteolyticus A27。对EPS进行了分离纯化。然后，研究了菌株及其 EPS 对水稳性土壤大团聚体形成的影响。在这些菌株产生的 EPS 中发现了木糖和己醛糖，而 A27 菌株的 EPS 也含有鼠李糖和葡萄糖。这些菌株的 EPS 表现出不同的傅立叶变换红外光谱。这些菌株将水稳定大团聚体 (>0.25 mm) 的比例增加了 128-169%，与对照相比，土壤中的多糖含量增加了 158-174%，转化酶活性增加了 153-193%。与菌株 A20 相比，菌株 A27 诱导了更多的水稳定性土壤大团聚体和更高的转化酶活性。此外，与菌株 A20 相比，菌株 A27 的 EPS 使水稳定大团聚体的比例增加了 10-36%。结果表明细菌对水稳性大团聚体形成有明显的影响，并表明 A27 菌株较高的细菌活性和特定的 EPS 可能是增加水稳性土壤大团聚体形成的原因。与菌株 A20 相比，菌株 A27 的 EPS 使水稳定大团聚体的比例增加了 10-36%。结果表明细菌对水稳性大团聚体形成有明显的影响，并表明 A27 菌株较高的细菌活性和特定的 EPS 可能是增加水稳性土壤大团聚体形成的原因。与菌株 A20 相比，菌株 A27 的 EPS 使水稳定大团聚体的比例增加了 10-36%。结果表明细菌对水稳性大团聚体形成有明显的影响，并表明 A27 菌株较高的细菌活性和特定的 EPS 可能是增加水稳性土壤大团聚体形成的原因。