RESUMEN
The thermo-alkalotolerant bacterium exhibiting heightened extracellular carbonic anhydrase (CA) activity, survived at 100â¯mM sodium bicarbonateand 5% gaseous CO2 was identified as Bacillus sp. by 16S rRNA sequencing. Extracellular carbonic anhydrase was purified by ammonium sulfate precipitation, gel filtration chromatography and affinity chromatography with a yield of 46.61% and specific activity of 481.66â¯U/mg. The size of purified carbonic anhydrase was approximately 28â¯kDa in SDS-PAGE gel filtration and further their role in calcium carbonate production was correlated. The purified enzyme was stable with half-life of 25.36â¯min at 90⯰C and pH 8. KM and Vmax values of the enzyme were 1.77â¯mg/mL and 385.69â¯U/mg respectively. The production of calcite was confirmed by Scanning Electron Microscopy (SEM) analysis, FTIR, and Energy-Dispersive X-ray (EDX) analysis. Carbonic anhydrase and calcite deposition coupled with CO2 fixingbacteria is a significant approach for CO2 sequestration.
Asunto(s)
Carbonato de Calcio , Dióxido de Carbono , Anhidrasas Carbónicas , Bacterias , Fenómenos Fisiológicos Bacterianos , Electroforesis en Gel de Poliacrilamida , ARN Ribosómico 16SRESUMEN
Due to industrialization and urbanization, as humans continue to rely on fossil fuels, carbon dioxide (CO2) will inevitably be generated and result in an increase of Global Warming Gases (GWGs). However, their prospect is misted up because of the environmental and economic intimidation posed by probable climate shift, generally called it as the "green house effect". Among all GWGs, the major contributor in greenhouse effect is CO2. Mitigation strategies that include capture and storage of CO2 by biological means may reduce the impact of CO2 emissions on environment. The biological CO2 sequestration has significant advantage, since increasing atmospheric CO2 level supports productivity and overall storage capacity of the natural system. This paper reviews CO2 sequestration mechanism in bacteria and their pathways for production of value added products such as, biodiesel, bioplastics, extracellular polymeric substance (EPS), biosurfactants and other related biomaterials.
Asunto(s)
Materiales Biocompatibles , Biocombustibles , Dióxido de Carbono , Bacterias , Carbono , Efecto Invernadero , HumanosRESUMEN
A chemolithotrophic bacterium, Bacillus sp. strain ISTS2, produced biosurfactant when enriched in the chemostat in presence of sodium bicarbonate as carbon source was evaluated for carbon dioxide (CO2) sequestration and biosurfactant production. CO2 sequestration efficiency of the bacterium was determined by enzymatic activity of carbonic anhydrase and ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). Biosurfactant production ability at 100 mM NHCO3 and 5% CO2 was screened by surface and interfacial tension measurement, emulsification stability test, hydrophobicity test, contact angle measurement, bacterial adhesion to hydrocarbon and purified by silica gel column (60-120 mesh). Thin layer chromatography (TLC) and gas chromatography-mass spectrometry (GC-MS) showed that the crude biosurfactant of ISTS2 were composed of lipopeptides and free fatty acids (FA) and its hydrophobic fraction contained five kinds of fatty acids (FA) with chain lengths of C14-C19. Thus Bacillus sp. strain IST2 can be used as a cleaner bioprocess for the utilization of industrial CO2 as alternate substrate.