摘要
The gene for the catalytic domain of thermostable endo-β-1,3-glucanase （laminarinase） LamA was cloned from Thermotoga maritima MSB8 and heterologously expressed in a bioengineered Synechococcus sp. PCC 7002. The mutant strain was cultured in a photobioreactor to assess biomass yield, recombinant laminarinase activity, and CO2 uptake. The maximum enzyme activity was observed at a oH of 8.0 and a temoerature of 70℃. At a CO2 concentration of 5%, we obtained a maximum specific growth rate of 0.083 h^-1 a biomass productivity of 0.42 g· L^-1·d^-1 a blomass concentration of 3.697 g.L^-1 , and a specific enzyme activity of the mutant strain of 4.325 U.mg^- 1 dry mass. All parameters decreased as CO2 concentration increased from 5% to 10% and further to 15% CO2, except enzyme activity, which increased from 5% to 10% CO2. However, the mutant culture still 1 1 grew at 15% CO2 concentration, as reflected by the blomass productwlty （0.26 g.L .d ）, biomass concentration （2.416 g.L^- 1）, and specific enzyme activity （3.247 U.mg^-1 dry mass）.
The gene for the catalytic domain of thermostable endo-β-1,3-glucanase （laminarinase） LamA was cloned from Thermotoga maritima MSB8 and heterologously expressed in a bioengineered Synechococcus sp. PCC 7002. The mutant strain was cultured in a photobioreactor to assess biomass yield, recombinant laminarinase activity, and CO2 uptake. The maximum enzyme activity was observed at a oH of 8.0 and a temoerature of 70℃. At a CO2 concentration of 5%, we obtained a maximum specific growth rate of 0.083 h^-1 a biomass productivity of 0.42 g· L^-1·d^-1 a blomass concentration of 3.697 g.L^-1 , and a specific enzyme activity of the mutant strain of 4.325 U.mg^- 1 dry mass. All parameters decreased as CO2 concentration increased from 5% to 10% and further to 15% CO2, except enzyme activity, which increased from 5% to 10% CO2. However, the mutant culture still 1 1 grew at 15% CO2 concentration, as reflected by the blomass productwlty （0.26 g.L .d ）, biomass concentration （2.416 g.L^- 1）, and specific enzyme activity （3.247 U.mg^-1 dry mass）.
