Influence of Microbial Activities in Reducing Erodibility of Sand

Abstract

Microbe-induced reduction of soil erodibility, since natural, is expected not to disrupt the natural environmental system. Although the role of bacteriogenic EPS in aggregating soil particles is widely recognized but the impact of various environmental parameters e.g., groundwater velocity and nutrient availability on bacteriogenic EPS in reducing the erodibility of soil is not very clear. In this study, a species of EPS producing soil bacteria Bacillus megaterium RB-05 isolated from a naturally cemented intertidal silt site was used to investigate the influence of flow velocity and nutrient availability on microbially mediated reduction of erodibility of sand. Durations of nutrient availability and media circulation velocity were observed to influence the bacterial population, amounts and composition of EPS found within sand specimens. Drained shear strength of loose sand samplers was found to increase due to EPS-related interparticle aggregation. EPS produced under fluvial activities seems to be more capable in aggregating sand grains as well as reducing erodibility of sand. Results of model sand erosion test further strengthen this conclusion.