Isolation and characterization of a resistance Bacillus subtilis for soil stabilization and dust alleviation purposes

Abstract

Dust poses environmental, geological, health, and economic concerns, and microorganisms can help mitigate these adverse consequences by improving soil properties. Microbial calcium carbonate precipitation (MICP) has been found to be an efficient strategy for increasing soil strength, reducing soil porosity, and preventing erosion; however, severe environmental conditions such as pH and high temperatures may impede this process. To identify the best strain for MICP, 60 bacteria strains were obtained from arid soils using the enrichment culture technique. They were tested for the capacity of calcium carbonate deposition and biocement synthesis in stress environments. Phenotypic characterization indicated that the majority of the bacterial isolates were gram-positive and rod-shaped, with strong catalase and oxidase enzyme activity. Furthermore, MALDI-TOF MS identification revealed that the isolates were from the Bacillus and Pseudomonas genera. Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) were used to analyze the microstructures and composition of bacterial cement. The results represented that B. subtilis isolate S56 has a higher production yield and forms distinctive calcite crystals as a result of fast urease synthesis. B. subtilis isolate S56 can be applied in situ to reduce soil erosion and dust pollution. This study reveals the potential of the B. subtilis S56 strain for soil consolidation and dust prevention in harsh environments and has the prospect of promoting its application in desertification control and ecological restoration.