Cold-active　xylanases　are　of　great　interest　due　to　their　large　potential　for　application　in　the　food　industry.　In　this　study,　salt　bridges　of　the　eight　glycoside　hydrolase　(GH)　family　10　cold-active　xylanases　reported　to　date　were　predicted　and　the　salt　bridges　specific　to　the　cold-active　xylanase　XynGR40　were　identified.　Seven　mutants　were　constructed　to　disrupt　salt　bridges　specific　to　XynGR40.　The　results　suggested　that　five　mutants　lost　their　xylanase　activity,　while　the　other　two　mutants,　D3ON　and　D83N,　displayed　different　properties　when　compared　with　the　wild-type　XynGR40.　First,　both　mutations　showed　an　obvious　decrease　in　thermostability,　with　the　Tip　of　D3ON　and　D83N　at　50　degrees　C　being　about　one　half　and　one　sixth　of　the　wild-type,　respectively.　Second,　both　D3ON　and　D83N　had　a　higher　specific　activity　than　the　wild-type,　with　activities　about　13　and　163%　higher,　respectively.　Third,　both　D3ON　and　D83N　had　high　kat　and　K.　values,　which　resulted　in　a　higher　catalytic　efficiency　of　the　mutant　D83N,　but　a　lower　catalytic　efficiency　of　the　mutant　D3ON　compared　to　the　wild-type.　Our　results　suggested　that　salt　bridges　play　important　roles　in　both　the　activity　and　thermostability　of　the　cold-active　xylanase　XynGR40.　The　mutant　D83N　had　a　higher　k(cat)　and　higher　relative　activity　at　low　temperatures　than　the　wild-type,　and　is　a　good　candidate　for　application　in　the　food　industry.　(C)　2016　Elsevier　Inc.　All　rights　reserved.