Abstract

The study mainly demonstrated whether Bacillus mucilaginosus can use atmospheric carbon dioxide (CO₂) through the bacteria excreted carbonic anhydrase (CA) capturing atmospheric CO₂. It had been proved that CA could reversibly catalyze hydration of CO₂. When the bacteria was cultured in the medium containing limestone, Ca²⁺ concentration and CA activities simultaneously increased with the amount of limestone increasing in the medium. Analysis for the bacterial growth kinetics demonstrated Ca²⁺ concentration increased, CA activities enhanced and pH value of broth rose and residual glycerol concentration decreased with prolonging fermentation time. Ca²⁺ concentration of bacterial broth gradually increased with the increasing of amount CA supply and time extension when the bacteria were cultured in the Alexandrov medium containing limestone, in which CA synthesized was extremely low when limestone dissolved into water, CA could elevate Ca²⁺ concentration and pH value, and the bacteria might further elevated the Ca²⁺ concentration and pH value. Therefore, it is suggested that B. mucilaginosus can first capture atmospheric CO₂ by CA, then fix atmospheric CO₂ by bacteria metabolism, which complements the content of biology and provide a new strategy for CO₂ sequestration from the air.

Key words: Bacillus mucilaginosus, carbonic anhydrase equilibrium point, CO₂ utilization,

catalyze.