(Heba AbdelAleem*; Tarek Dishisha; Yasser Gaber; Amal Saafan (AEA-Scholars

Heba AbdelAleem*; Tarek Dishisha; Yasser Gaber; Amal Saafan

Association of Egyptian-American Scholars

Background:

Microbial geotechnology; through the use of microorganisms and/or their derivatives to alter engineering properties of soil [2]. This can be achieved by different means including microbial induction of calcite (calcium carbonate) formation, which fills the pores between soil particles in a process known as biocementation [2]. Ureolytic microorganisms hydrolyze urea present in the soil by the action of urease enzyme giving carbonate (Eq. 1) that interacts with calcium yielding calcium carbonate (Eq. 2) [1].

Purpose:

Roads are synthetic arteries of any country, which play a vital role in economic development so there extensive efforts seeking more economic alternative to the current mechanical road pavement technology.

Methods. Nine different Egyptian soils (sandy, loamy and clay soils) were sampled and used for isolating urease-producing bacteria. Isolates were identified through morphological examination, biochemical tests and 16S rRNA gene sequencing. The kinetics of microbial growth were calculated. Subsequently, the different strains were cultured in a urea-containing medium for determining the optimum urease-producers. The strains with the highest activity were cultured in a urea-containing media and the cell-free supernatants were evaluated for soil stabilization. The preparations will be compared to commercial soil stabilizing solutions. Results:

Sixteen ureolytic bacterial isolates were obtained belonging to Bacillus and Pseudomonas genera. The optimum pH for growth was determined. Urease activity of each strain was determined. Some of these strain showed high urease activity.

Conclusion:

lndogenous bacteria can stimulate soil biocementation and can alter engineering properties of soil in a way better than mechanical means. This way can be used as a simple technique for pavement of new roads in villages that are not accessible for large mechanical road pavement tools. It has also potential in repairing road and building cracks.

Acknowledgement

The Egyptian Academy of Scientific Research and Technology is acknowledged for financial support of the project.

This article was published in 3alamaltanmya

sponsored by Future Builders International Academy

Led by Dr.Maha Fouad