## Materials and Methods
### Cloning of the \(\beta\)-Mannanase Gene and Sequence Analysis  
The cloning of \(\beta\)-mannanase gene was carried out according to the standard method. The genomic DNA extracted from _Enterobacter aerogenes_ B19 was used as the template DNA and amplification of \(\beta\)-mannanase gene was performed by PCR method. In the light of the gene sequence of a published\(\beta\)-mannanase from _Pantoea agglomerans_ A021 (GenBank accession no. AN30272), we input the amino acid sequence of \(\beta\)-mannanase (published) from _Pantoea agglomerans_ A021 into NCBI to search for homologous sequences, and highly homologous sequences from _Enterobacter ludwigii_ strains and _Enterobacter cloace_ complex strains were obtained. We analyzed 5\({}^{\prime}\)-terminal sequence and 3\({}^{\prime}\)-terminal sequence of these homologous proteins and designed a pair of degenerate primers. The forward primer was 5\({}^{\prime}\)-CGCGGATCCATGATGACTTTTACTGTAGTACCCG-3\({}^{\prime}\) and the reverse primer was 5\({}^{\prime}\)-CCCAAGCTTTTAAACTCAAGACGTCCGTTCCAT-3\({}^{\prime}\). The PCR reaction system was composed of 1 \(\mu\)L DNA template (1 ng \(\mu\)L\({}^{-1}\)), 2 \(\mu\)L each primer (10 \(\mu\)mol L\({}^{-1}\)), 20 \(\mu\)L double-distilled H\({}_{2}\)O and 25 \(\mu\)L 2\(\times\) premix LA Taq. The PCR amplification was carried out as follows: initial template denaturation at 94 \({}^{\circ}\)C for 5 min, then 35 cycles, each containing 30 s at 94 \({}^{\circ}\)C, 30 s at 58 \({}^{\circ}\)C, 90 s at 72 \({}^{\circ}\)C, and finally an extension for 10 min at 72 \({}^{\circ}\)C. The PCR products were assayed by agarose gel electrophoresis and purified by the DNA Purification Kit. The target gene was ligated to plasmid pMD19-T (Takara) by T4 ligase to construct the recombinant vectors. Then, the recombinant vectors were transferred into _Escherichia coli_ DH5\(\alpha\). The recombinant positive clones were cultured overnight, and a plasmid extraction kit was used to extract the recombinant vectors and further verified by DNA sequencing. The gene sequence of the \(\beta\)-mannanase was analyzed by the NCBI ORF Finder tool ([[https://www.ncbi.nlm.nih.gov/orffinder/](https://www.ncbi.nlm.nih.gov/orffinder/)]([https://www.ncbi.nlm.nih.gov/orffinder/](https://www.ncbi.nlm.nih.gov/orffinder/))). The corresponding amino acid sequence of the \(\beta\)-mannanase was translated by EMBOSS Transeq ([[http://www.ebi.ac.uk/Tools/st/emboss_transeq/](http://www.ebi.ac.uk/Tools/st/emboss_transeq/)]([http://www.ebi.ac.uk/Tools/st/emboss_transeq/](http://www.ebi.ac.uk/Tools/st/emboss_transeq/))), and the isoelectric point and molecular weight were predicted by ProtParam ([[http://web.expasy.org/protparam/](http://web.expasy.org/protparam/)]([http://web.expasy.org/protparam/](http://web.expasy.org/protparam/))). Signal peptide was examined by SignalP 4.0 [30] ([[http://www.cbs.dtu.dk/services/SignalP/](http://www.cbs.dtu.dk/services/SignalP/)]([http://www.cbs.dtu.dk/services/SignalP/](http://www.cbs.dtu.dk/services/SignalP/))). The homologous sequences of the amino acid sequence of Man26E were searched out by BLASTp tool ([[http://www.ncbi.nlm.nih.gov/BLAST/](http://www.ncbi.nlm.nih.gov/BLAST/)]([http://www.ncbi.nlm.nih.gov/BLAST/](http://www.ncbi.nlm.nih.gov/BLAST/))). Alignment of multiple sequences were carried out by Clustal Omega tool ([[https://www.ebi.ac.uk/Tools/msa/clustalo/](https://www.ebi.ac.uk/Tools/msa/clustalo/)]([https://www.ebi.ac.uk/Tools/msa/clustalo/](https://www.ebi.ac.uk/Tools/msa/clustalo/))).