Chitinases　play　an　important　role　in　the　process　of　chitin　bioavailability.　In　this　study,　we　cloned　a　new　chitinase　gene　and　characterized　its　recombinant　protein.　The　new　1251　bp　gene　of　chitinase　(ChiT-7)　was　cloned　from　the　metagenome　of　the　mangrove　tidal　flat　soil　in　the　city　of　Zhangzhou　in　Fujian　Province　(China)　by　genome　walking.　The　gene　encoded　a　mature　protein　with　381　amino　acids,　which　manifested　certain　sequence　similarity　(59%　identity)　to　characterized　GH18　chitinases.　The　mature　protein　of　ChiT-7　was　successfully　expressed　in　E.　coli　BL21　(DE3).　After　purification,　the　specific　activity　of　the　recombinant　enzyme　was　0.63　U/mg　at　the　optimal　pH　of　6.0　and　the　optimal　temperature　of　45　°C.　The　rChiT-7　was　active　over　a　wide　pH　range,　and　the　residual　enzyme　activity　reached　80%　or　higher　at　30　°C–50　°C.　rChiT-7　hydrolyzed　colloidal　chitin　with　(GlcNAc)2　and　GlcNAc　as　the　main　final　products.　Structural　analysis　of　ChiT-7　indicated　that　ChiT-7　could　be　a　processive　chitinase.　rChiT-7　manifested　characteristics　analogous　to　those　of　fungi　and　actinomycetes　and　exhibited　sequence　homology.　©　2020