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Bacillus megaterium favours CO₂ mineralization into CaCO₃ over the ureolytic pathway
Abstract Microbially induced calcite precipitation (MICP) has long been the focus of material scientists, environmental microbiologists and civil engineers because of its potential to yield biosynthesized binders that can serve as alternatives to cement or resins. Several microbial strains play crucial roles in this process and catalyse pathways for the formation of minerals, which are believed to substantially reduce the environmental impact of building materials and activities. Among the studied strains, Bacillus megaterium is not as common as Sporosarcina species. The latter microorganisms are well known to drive the fastest ureolytic-driven MICP process, i.e., precipitation of CaCO3 after urea breakdown into carbonate and CaCl2 addition to the system. This paper sheds light on the activities of B. megaterium, which possesses dual enzymatic capabilities for MICP and is equipped with both the enzymes urease and carbonic anhydrase. We postulate that, depending on the growth conditions, B. megaterium can activate either of these genes to ultimately induce CaCO3 precipitation. Herein, experiments are carried out in open and closed systems. C13-labelled urea is employed to identify the carbon source in the precipitated CaCO3. The results from Fourier transform infrared spectroscopy (FTIR) revealed the precipitation of calcite. In the presence of urea and CO2 at atmospheric levels, B. megaterium activates the ureolytic pathway to perform urea hydrolysis. However, at increased CO2 levels, more precisely, at levels greater than 470 times the atmospheric level, carbonic anhydrase is activated, catalysing the hydration of the molecule to produce HCO3 −. When C13-labelled urea was utilized, only 6% of the precipitated CaCO3 mineral was linked to ureolysis, and it was found that the remaining 94% was formed due to the mineralization of CO2. Overall, in this work, we aim to introduce the process conditions and protocols that favour the sequestration of atmospheric CO2 as CaCO3 via the metabolic activities of B. megaterium.
From wind to seismic signature captured by seismometers in lake Lucerne
Biosourcing and optimization of fungal lipase production from cheap agro waste via solid state fermentation
Experimental and exergy evaluation of a PCM integrated active indirect solar dryer for Turkey berries with economic and environmental assessment
Systematic screening of metabolic pathways to identify two breast cancer subtypes with divergent immune characteristics
Esophageal cancer trends in the US from 1992 to 2019 with projections to 2044 using SEER data
Correlation of fibrinogen levels with acute myocardial infarction risk in the Chinese Han population
Modifying crude oil synergistic properties with carbon dots and ultrasonic waves
Antibacterial, self-healing, and pH-responsive PVA/ZIF-8@tannic acid nanocomposite hydrogel for sustained delivery of garlic extract
Circulating gamma-glutamyl transpeptidase, systemic inflammation biomarkers and risk of lung cancer in the UK biobank prospective cohort study
A novel isoquinoline mitophagy inducer ameliorates paclitaxel-induced peripheral neuropathy in Drosophila and mouse models
Extended exergy accounting of agricultural resources in China’s four provinces of mountains and rivers
Abstract The agricultural sector in China has to balance resource investment, environmental emissions and yields to satisfy the high dietary demands of the population. In this study, extended exergy accounting (EEA) was conducted to analyse the usefulness of resources invested in agriculture and the yields of strategic importance to China in Hebei, Shanxi, Shandong and Henan (four provinces of mountains and rivers) in 2017 from a thermodynamics perspective. The fluxes resources of energy, materials, environmental emissions, labour, capital and yields were measured in joules. The results revealed that the exergy from the natural environment, with an energy exergy value of 9.92 EJ, contributed the most to the agricultural sector in the region. The labour and capital exergy values were much lower than those of the other resources. The non-renewable resource inputs were exceeded by emissions. Animal wastes accounted for 80% of emissions. The resource conversion efficiency in Shandong was 0.46, which was higher than those in the region and China. Shanxi exhibited considerable potential to increase its resource conversion efficiency. EEA was applied in agroecological systems to diagnose the shortage of resource depletion and environmental emissions which could be adopted in other zones or sectors from sustainable development perspective.