Background: Xylanases of thermophilic origin are more robust and stable and hence
more suitable for industrial applications. The aim of the research was to develop a patent using a
robust mutant exhibiting enhanced xylanase activity. The strain (Bacillus aestuarii SC-2014) subjected
to mutagenesis is thermophilic in origin and hence it is envisioned that the enhancement of
its catalytic potential will enhance its industrial applicability.
Objective: The main aim was to develop a stable and vigorous mutant having higher xylanase
activity and improved thermostability.
Methods: The bacterial strain isolated from the Tattapani hot springs of Himachal Pradesh (India)
was mutagenized by single separate exposure of Ethyl methane sulphonate (EMS) and N-methyl
N-nitro N-nitrosoguanidine (MNNG).
Results: A mutant library was generated and extensive screening led to the identification of the
most potent mutant strain selected and designated as Bacillus sp. SC-2014 EMS200 (MTCC number
25046) which displayed not only enhanced xylanase activity and thermo stability but also appreciable
genetic stability. This strain displayed a 3-fold increase in enzyme activity and simultaneously,
a significant reduction in fermentation time from 72 h to 48 h was also observed. The xylanase
gene from wild and mutant strain was cloned, sequenced and subjected to molecular docking.
Two mutations H121D and S123T were present inside the binding pocket.
Conclusion: Mutation H121D made the binding pocket more acidic and charged, thus enhancing
the xylanase activity for mutant protein. Mutations also resulted in charged amino acids (Y99K
and H121D) which were identified as a probable cause for enhancing the thermostability of mutant