Microbial phytase-induced calcium-phosphate precipitation — a potential soil stabilization method

Abstract

ABSTRACT. Two hypotheses were tested: (1) microbial dephosphorylation of phytate in the presence of Ca 2+ ions will result in the precipitation of hydroxyapatite-like crystals and (2) precipitation of calcium-phosphate crystals on and between sand-like particles can cause cementation. A growing culture of the dimorphic phytase-active yeast Arxula adeninivorans was introduced into a column filled with quartz particles and subsequently a liquid growth medium amended with calcium phytate was pumped through the column resulting in increased strength and stiffness of the quartz particle matrix. Environmental scanning electron microscope analysis combined with energy-dispersive X-ray measurement revealed cementation of the quartz particles by calcium-phosphate crystals. This microbial mineralization process could provide a novel approach to improving the mechanical properties like strength and stiffness of sandy soils. Microbial metabolic activities often contribute to selective cementation processes by producing relatively insoluble organic and inorganic compounds. Microbially induced biomineralization, such as calcite (CaCO 3 ) and calcium hydroxyapatite [Ca 5 (PO 4 ) 3 OH] precipitation, has been described in a wide variety of environments (Boquet et al. 1973;Schmittner and Giresse 1999;Belzer et al. 2006;Canaveras et al. 2006;Kremer et al. 2008). The formation of calcium hydroxyapatite has received considerable attention as a result of its importance in biological calcification. Calcium phosphates are the main constituent of teeth and bones and have been found in pathological mineral deposits in the form of urinary and kidney stones.The importance of microbially induced cementation has been widely recognized in petroleum, geological and civil engineering (Dejong et al. 2006;Ivanov and Chu 2008). There is a growing interest in methods to improve the mechanical properties of sandy soils using microbially induced biochemical reactions in the subsurface (Whiffin et al. 2007). These methods simulate natural diagenetic processes that transform loose sand to sandstone. It has been documented that cracks in rock formations, especially in oil reservoirs, could be remediated by microbial mineral precipitation (Jack 1991).Phytic acid salts or phytates (myo-inositol hexakisphosphates) are abundant plant constituents. They typically account for 60-90 % of total seed phosphorus. Phytate is a natural by-product of fermentation processes and a waste product in the fermentation industry.Phytases, a specific group of phosphatases, catalyze hydrolysis of the phosphate ester bonds of phytates (by the addition of water) (Cosgrove 1966;Mullaney et al. 2000). They have been found in various eukaryotic and prokaryotic microorganisms (Lassen et al. 2001;Lim et al. 2007). Extracellular phytases from several filamentous fungi and yeasts have been studied in detail. The dimorphic yeast A.a. can utilize phytate as a sole C and P source by secreting high level of phytase into its environment (Sano et al. 1999).This paper aims to explore the po...

Utilization of Phosphoric Acid and Lime for Stabilizing Laterite for Lateritic Bricks Production

“…According to Rooselers and Van Loosdrecht [18], the most stable calcium salt is calcium phosphate which is formed as presented in Equation 2.…”

State-of-the-Art Review on Engineering Uses of Calcium Phosphate Compounds: An Eco-Friendly Approach for Soil Improvement

“…To control the calcium-phosphorus ratio, different calcium and phosphorus resources and concentrations could be used. To control and increase the pH of solution, microorganisms [ 68 , 69 , 70 ] or ureases [ 71 , 72 , 73 ] can be used. However, CPCs precipitation is possible even without pH control [ 74 , 75 , 76 , 77 , 78 , 79 , 80 ].…”

“…Numerous microorganisms contain an enzyme called phytase, which can liberate phosphate groups from phytate [ 103 ]. Phytases are secreted by different groups of microbes, yeast, and bacteria [ 69 ]. Among the yeasts, Aspergillus niger , Aspergillus ficuum , Aspergillus fumigatus , and Saccharomyces cerevisiae are widely adopted strains for commercial phytase production [ 98 , 99 ].…”

“…CPC precipitation through the phytase decomposition of phytate was first implemented for the biocementation of glass beads and showed the formation of monetite, whitlockite, and hydroxyapatite after 3 days [ 69 ]. The application of phytate and the phytase enzyme also has the potential to fix radionuclides and metal contaminants in groundwater systems by co-precipitating these pollutants with calcium phosphate [ 69 , 73 ].…”

Geotechnical properties of biocement treated sand and clay

“…Recent studies have shown that many types of microbes are capable of producing biocementation. These include urease producing bacteria (UPB), iron reducing bacteria (IRB), nitrifying bacteria, oligotrophic microaerophilic bacteria, sulphate reducing bacteria (SRB), and dimorphic phytase-active yeast for the production of calcium-phosphate precipitation (Dejong et al, 2006;Ivanov and Chu, 2008;Chu et al, 2009;Roeselers & van Loosdrecht, 2010). The microbially induced calcium carbonate precipitation (MICP) process has been identified as the most effective approach for biocementation and bioclogging so far.…”