Fermentative production of xylitol from a newly isolated xylose reductase producing Pseudomonas putida BSX-46

Biotechnological process using xylose reductase (XR) is an ecofriendly method for production of xylitol in contrast to energy intensive chemical processes. XR is an industrially important enzyme which catalyzes the reduction of xylose into xylitol. Most of the previous data on XR producing microorganisms has been available with yeasts only. Hence, the present study on isolation of novel XR producing bacterial strain for bioconversion of xylitol was undertaken. A total number of 60 isolates were isolated from soil samples and screened for XR and xylitol production. The best xylitol producing bacterial isolate i.e. BSX-46, was characterized through polyphasic approach and found that it belongs to Pseudomonas putida. The bacterial cells were Gram negative, rod shaped, and can grow over a wide range of temperature (20 degrees C-37 degrees C), pH (5.0-7.5) and salt concentration (up to 15%, w/v). The isolate showed a very less generation time of 2 h 40 min with maximum XR activity of 48.76 +/- 0.05 IU/mg of cells after 36 h of growth. This isolate has shown a good potential for the bioconversion of xylitol (35.2 g/L) with 0.98 g/L/h volumetric productivity. The results demonstrate a promising sustainable solution for xylitol production using efficient novel bacterial isolate.