Department of Soil, Crop, and Atmospheric Sciences, Cornell University, Ithaca, New York 14853.
Appl Environ Microbiol. 1992 Aug;58(8):2523-30. doi: 10.1128/aem.58.8.2523-2530.1992.
In an earlier article, we reported that, under conditions in which neither exopolymers nor bacterial mats were produced, Arthrobacter sp. strain AK19 was an effective plugging agent in sand columns, whereas the bacterial strain SLI had no significant effect on the permeability of the medium. A laboratory experiment with sand columns was carried out to elucidate the causes of this difference in behavior. Measured values of the saturated hydraulic conductivity of the sand were explained in terms of biomass accumulation, which was estimated by solving a mass balance equation. The relationship between the saturated hydraulic conductivity and the biomass density within the sand was exponential, although two different exponential coefficients were needed to fit the data for biomass densities above or below 13 mg (wet weight) per cm, suggesting that two different clogging mechanisms may be involved in different ranges of biomass densities. The experimental results suggest that the SLI strain was a poor clogging agent partly because of its lower yield coefficient relative to the limiting nutrient (oxygen) and partly because 60% of the biomass produced in situ was washed out from the column, compared with only 1.2% in the case of Arthrobacter sp. strain AK19.
在之前的一篇文章中，我们报道了在既不产生胞外聚合物也不产生细菌垫的条件下，节杆菌 AK19 菌株是沙柱中有效的堵塞剂，而细菌菌株 SLI 对介质的渗透率没有显著影响。进行了一项带有沙柱的实验室实验，以阐明这种行为差异的原因。通过求解质量平衡方程来估算生物量积累，从而解释了沙的饱和水力传导率的实测值。饱和水力传导率与沙内生物质密度之间的关系呈指数关系，尽管需要两个不同的指数系数来拟合生物质密度高于或低于 13mg（湿重）/cm 的数据，这表明两种不同的堵塞机制可能涉及不同的生物质密度范围。实验结果表明，SLI 菌株是一种较差的堵塞剂，部分原因是其相对于限制营养物质（氧气）的产率系数较低，部分原因是 60%的原位生物量从柱中冲洗出来，而 Arthrobacter sp. strain AK19 的比例仅为 1.2%。
