Investigation on lignocellulosic saccharification and characterization of haloalkaline solvent tolerant endo-1,4 β-d-xylanase from Halomonas meridiana APCMST-KS4

The bacterial strain Halomonas meridiana isolated from marine sediment sample was used for the production of xylanase enzyme and it was also purified and characterized. Xylanase was purified to its homogenecity by using ammonium sulphate precipitation and DEAE Sepharose Fast Flow anion exchange chromatography with 17.23% total enzyme recovery and 15.83 fold purification. The molecular weight of the purified xylanase was 41 kDa and it was observed as an alkaline thermophilic. The optimum enzyme activity was found at pH 8 and also at 50 °C temperature. Further this xylanase was stable at wide pH range between 6 and 9 and temperature between 40 and 50 °C. This enzyme was active at 1.5 M NaCl. Metal ions such as manganese sulphate, zinc sulphate, zinc chloride, copper sulphate and magnesium chloride showed the highest influence on enhancing xylanase activity. The xylanase activity was also influenced by surfactants such as Tween 20, Tween 40 and Tween 60 and it was resistant to SDS. The enzyme metallo-xylanase was highly inhibited by EDTA. The other additives like beechwood xylan, birchwood xylan and all the tested organic solvents were positively influenced the enzyme activity when compared to the control. The enzyme registered maximum saccharification rate on pretreated rice bran, wheat straw and Ulva respectively.