Optimization of culture parameters of Pseudomonas alcaligenes for crack healing in concrete

Abstract

Crack formation is a commonly observed phenomenon in concrete. It effects the durability of concrete due to increased permeability and consequent ingress of harmful chemicals through these cracks. The introduction of certain microorganisms in concrete can remediate these cracks through calcium carbonate precipitation. The present study aims at evaluating the potential of Pseudomonas alcaligenes in crack healing of concrete by optimizing the growth parameters of the culture for concrete environment. The internal pH of cementitious concrete system is around 13 and the temperature is around 37 °C. It is essential to identify the survival and sustenance of the bacterial colonies under these conditions. Culture parameters like temperature and inoculum volume have been studied for P. alcaligenes. Conventional methods like single parameter optimization keeping the other variables constant have been employed to find optimum growth conditions of the bacteria to be studied for crack healing in concrete. The optimum operating conditions were obtained based on the optical density of bacterial cells at 600 nm in the culture broth in the form of colony forming units (CFU) varying the inoculum volume from 0.5%, 1%, 1.5% to 2% and temperature from 35 °C, 37 °C, 40 °C to 42 °C. Based on the findings of this study, recommendations will be provided for the practical application of Pseudomonas alcaligenes in the construction industry.