The present disclosure relates to a method for constructing a trehalose polyenzyme complex in vitro by mediation of an artificial scaffold protein, which mainly comprises the following steps: constructing a recombinant bacterium WB800n-ScafCCR for self-assembled scaffold protein module; constructing a recombinant bacterium WB800n-P43-phoD-treY-Ccdoc for self-assembled catalytic module; constructing a recombinant bacterium WB800n-P43-phoD-treZ-Ctdoc for self-assembled catalytic module; constructing a recombinant bacterium WB800n-P43-phoD-cgt-Rfdoc for self-assembled catalytic module; secretorily expressing the recombinant bacteria and self-assembling in vitro to obtain a recombinant trehalose multi-enzyme complex. The trehalose multi-enzyme complex constructed by the method of the present disclosure has a higher catalytic efficiency in preparing trehalose than that of mixed free enzymes, and the method can be used for production of high quality trehalose after immobilization with cellulose microspheres.

The present disclosure provides a bacterial composition, comprising: at least one genetically engineered bacterial strain that fixes atmospheric nitrogen in an agricultural system, wherein the bacterial strain comprises a modification in or one or more genes selected from the group consisting of bcsll, bcslll, yjbE, fhaB, pehA, glgA, otsB, treZ, and cysZ. The present disclosure further provides a bacterial composition and method for increasing the colonization of a plant growth promoting bacterial strain on a plant, wherein the plant growth promoting bacterial strain has been remodeled to increase colonization of said plant, In a further aspect, the present disclosure provides methods of increasing nitrogen or nitrogen fixation available to a plant.

The present invention discloses a maltooligosyl trehalose trehalohydrolase (MTHase) mutant and application thereof, belonging to the technical fields of gene engineering and enzyme engineering. The present invention provides a series of MTHase mutants to prepare trehalose, having a better effect. Further, the MTHase mutant is expressed in Escherichia coli BL21 (DE3) and the enzyme is optimized by fermentation, which can significantly increase the yield of enzymes.

The present invention discloses a maltooligosyl trehalose trehalohydrolase (MTHase) mutant and application thereof, belonging to the technical fields of gene engineering and enzyme engineering. The present invention provides a series of MTHase mutants to prepare trehalose, having a better effect. Further, the MTHase mutant is expressed in Escherichia coli BL21 (DE3) and the enzyme is optimized by fermentation, which can significantly increase the yield of enzymes.

The present disclosure relates to a method for constructing a trehalose polyenzyme complex in vitro by mediation of an artificial scaffold protein, which mainly comprises the following steps: constructing a recombinant bacterium WB800n-ScafCCR for self-assembled scaffold protein module; constructing a recombinant bacterium WB800n-P43-phoD -treY-Ccdoc for self-assembled catalytic module; constructing a recombinant bacterium WB800n-P43-phoD-treZ-Ctdoc for self-assembled catalytic module; constructing a recombinant bacterium WB800n-P43-phoD-cgt-Rfdoc for self-assembled catalytic module; secretorily expressing the recombinant bacteria and self-assembling in vitro to obtain a recombinant trehalose multi-enzyme complex. The trehalose multi-enzyme complex constructed by the method of the present disclosure has a higher catalytic efficiency in preparing trehalose than that of mixed free enzymes, and the method can be used for production of high quality trehalose after immobilization with cellulose microspheres.