Isolation, screening and molecular identification of bacilli producing urease enzyme from the ‎barren lands of southern Iran and analyzing their ability to stabilize the soil

Microbial urease has specific applications in biotechnology, agriculture, medicine, construction ‎and geotechnical engineering. MICP technology is an ecological process based on microbial ‎urease activity that has recently been used for soil stabilization. Due to its catabolic ability and ‎high survival, Bacillus is considered as a suitable candidate for use in the biocementation ‎process. The aim of this study was isolating and identifying Bacillus with MICP potential from ‎various ecosystems of Iran.200 environmental samples were collected from the ecosystems of ‎Iran and were analyzed by microbiological and molecular methods including PCR amplification ‎and sequence analysis of gyrA and 16S rRNA genes in order to isolate and identify bacilli. ‎Growth in presence of urea, salinity, pH and different temperatures, SEM, XRD and wind ‎tunnel analysis were used to determine the ability of isolates to produce biocement. A total of ‎‎12 isolates(6%) were identified as urease-positive bacilli belonging to 4 different species, ‎including 4 isolates of Bacillus paramycoides(33.33%), 3 isolates of Bacillus ‎paralicheniformis(25%), and 3 isolates of Bacillus velezensis. isolate(25%) and Bacillus ‎Pasteuri 2 were isolated(16.66%). The optimal conditions for MICP by isolates are 30°C, pH 9 ‎and salinity 6%. After MICP, the ratio of soil loss in the flow rate of 95 km/h showed a 100-‎fold decrease. In conclusion, the results showed that bacilli have the potential ability to adapt to ‎harsh environmental conditions. Also, by using MICP-producing bacilli on the soil surface, we ‎can have a significant effect in reducing soil losses due to erosion.‎