Nature has been synthesizing sustainable, durable and self-healing materials in ambient conditions in a carbon neutral or even carbon negative way for millions of years, via microbially induced carbonate precipitation (MICP) as seen in natural formations of coral reefs, shells, caves and stromatolites. The current construction sector on the other hand is facing the biggest challenge of non–sustainability due to huge production of greenhouse gases and consumption of large amounts of materials and energy. Learning from Nature and harnessing natural formations of MICP by infusing properties into engineered structures holds the key solution to sustainability challenge.
MICP technology which relies upon the ability of microbes for generation of carbonates has been found to be a promising way of emulating Nature recently. MICP scores high on sustainability as it happens at ambient conditions and thus, greatly reduces energy consumption and emission of greenhouse gases. Prior research has been widely attempted upon utilization of single ureolytic bacterial culture for production of carbonate cements in sterile soils but in field conditions, plethora of microbes exist which might affect the efficacy of supplied foreign cultures due to competition. We have investigated microbial dynamics and carbonate precipitation via stimulation of native cultures and augmentation of ureolytic (UA) and carbonic anhydrase (CA) bacterial cultures in the non sterile soils under different nutrient conditions. Significant changes in the indigenous bacterial populations were noticed upon different enrichments which had significant effect on pH, enzyme activity, extra polymeric substances, crystal composition and carbonate precipitation. Successful carbonate precipitation was seen in all nutrient rich environments but stimulation as well as augmentation through UA route was found to be more effective compared to CA route. Organic carbon content in soils has been seen to play an important role in determining the success of stimulation. Further studies are necessary to determine the efficacy of MICP in soils from different environments with varying organic carbon content to enhance our knowledge on application of this technology for soil improvement.