In this study, high-throughput promoter screening was employed to optimize the heterologous expression of Mesorhizobium loti carbonic anhydrase (MlCA) in order to reduce the costs associated with carbon capture and storage (CCS). To simplify the complexity of traditional vectors, a fusion protein expression system was constructed using superfolder green fluorescent protein (sfGFP) and MlCA. The synthetic promoter library in Escherichia coli was utilized for efficient one-step screening. Based on fluorescence intensity on agar plates, a total of 143 monoclonal colonies were identified, forming a library with varying expression levels. The top four recombinants with the highest fluorescence intensity were selected, among which MlCA driven by the promoter 342042/+ exhibited the highest enzymatic activity, with a specific activity of the 34.6 Wilbur-Anderson units (WAU)/mg. Optimization experiments revealed that MlCA exhibited the best performance when cultured for 4 days under pH 7.0 and 40 ℃ conditions. The Michaelis constant (K_m·hdy) and maximum reaction rate (V_max·hdy) for CO₂ hydration were determined to be 62.46 mmol/L and 0.164 mmol/(s·L), respectively. For esterase hydrolysis, MlCA showed the K_m and V_max of 639.8 mmol/L and 0.035 mmol/(s·L), respectively. MlCA accelerated the CO₂ hydration process, promoting CO₂ mineralized into CaCO₃ within 9 min at low pH and room temperature conditions. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses confirmed that the precipitated product was calcite. This study provides a low-cost and environmentally friendly alternative for future CCS applications.
Carbonic Anhydrases/biosynthesis* ; Promoter Regions, Genetic/genetics* ; Escherichia coli/metabolism* ; Carbon Sequestration ; Carbon Dioxide/metabolism* ; Green Fluorescent Proteins/metabolism*

The physigues of eighty pupils in a primary school in Shanyang were investigated after taking additional L-lysine hydrochloride with meals between classes for 12 weeks. They were derided into 3 groups: 1) ordinary diet plus 0.5g lysine; 2) ordinary diet plus 0.5g lysine and 5 mg iron (lysine and lysine-iron group were referred to as fortified group) and 3) ordinary diet only as control. After 12 weeks of experiment the results showed that the average increase in height, weight and chest measurement of the fortified group was higher than that of the control group, particularly the increase of weight was more remarkable. The increase in subcutaneous fat, however, showed no difference among the three groups, suggesting that weight gain was probably not due to the increase in the subcutaneous fat of the trunks and limbs but to the muscular and other tissues development promoted by the supplementary substances in diet.From a raise in the Hb value and the number of red blood cells in the experimental group, it was proposed that lysine may be good enough for the prevention or treatment of iron dificiency anemia.So that, to supply meals with lysine between classes was considered to be a simple and convenient means for promoting the health of pupils.