Improvement of Surface Erosion Resistance of Sand by Microbial Biopolymer Formation

Direct use of naturally occurring microbes for soil improvement has recently gained attention due to their ubiquitous and versatile characteristics in subsurface soil. Microbes produce soft and sticky extracellular polymeric substances (or biopolymers) that are known to alter the hydrological characteristics of soils; however, the mechanisms and extent of such soft biopolymers in altering soil erosion resistance remain scarcely explored. This study explored the role of microbial biopolymers in soil erosion resistance. The surface erosion resistance of sandy soils was evaluated by using a hybrid erosion function apparatus, in which the model bacteria Leuconostoc mesenteroides were stimulated to produce an insoluble biopolymer. The results revealed that the microbial biopolymer formation increased the critical shear stress and surface erosion resistance, which the researchers attributed to the increased cohesion by grain-coating biopolymer slimes and the reduced seepage flows due to pore clogging. This study provides baseline but promising results on how microbially grown biopolymers can be used to improve soil erosion resistance.