Optimización de las condiciones ambientales de Bacillus subtilis usado en la fabricación de bioconcreto con sílice de cascarilla de arroz.

Abstract

Bioconcrete is a material that has significant benefits for sustainable construction. One of the most important components in the production of bioconcrete is the Bacillus subtilis bacteria, given its ability to form calcium carbonate from calcium lactate, and a nutritional source. as is yeast extract. Used to improve the resistance and durability of the material. This research seeks to optimize the environmental conditions in the production of a strain of Bacillus subtilis, isolated from a biofertilizer, selecting the incubation times and temperature, as well as the ideal concentration of calcium lactate, to finally be delivered in nutrient broth. But for this bacteria to be able to maintain itself in different adverse environmental situations such as changes in temperature, pH, humidity, etc., it is necessary to initially determine if it was in its sporulated stage, which allows it to have greater resistance to the conditions mentioned above, the Concrete is characterized by its high resistance to compression but even so one of the most common failures is the appearance of cracks producing a water leak, the bacterial spores that are in a dormant state will be reactivated to begin the metabolic process of precipitation of calcium carbonate (CaCO3), thus generating the sealing of the cracks and pores of the material, directly relating to a longer useful life, reduction of additional costs in construction, reduction of CO2 generated indirectly in cement production, this being gas the main cause of the greenhouse effect. After determining that the Bacillus subtilis strain is in its sporulated phase and that it produces calcium carbonate at calcium lactate concentrations of 1.5% and 5%, we proceeded to calculate the concentration of spores that the bacterial strain has with in order to establish the bacterial concentrations that best favor the formation of carbonates. Therefore, it was established that concentrations of 105, 107, 109 and 1011 CFU/ml would be used. It was evident that the mixtures containing 1x10⁷ CFU/ml of Bacillus subtilis in 1.5% lactate and 1x10⁵ CFU/ml of Bacillus subtilis in 5% lactate presented the highest resistance values reported in Mega pascals and with respect to the units forming registered colonies where the concentration of 105 presents the highest growth, 107 and 109, present growth, but lower than that initially mentioned, thus discarding 1011 since its growth was low. This agrees with several investigations carried out worldwide in recent years and allows us to deduce that the mixture of concrete added with rice husk ash and Bacillus subtilis enriched with calcium lactate in specific concentrations allows obtaining bioconcrete that naturally improves quality. of structures in addition through innovation studies in infrastructure, industry and strengthening, and favor the creation of sustainable cities and communities through the exploration of new knowledge that allows contributing to the fulfillment of Sustainable Development Goals 9 and 11 in our country.