Purification and characterization of fructan and fructansucrase from Lactobacillus fermentum AKJ15 isolated from Kodo ko jaanr, a fermented beverage from north-eastern Himalayas

Abstract

Fructansucrase and fructan produced from Lactobacillus fermentum AKJ15 were isolated from seeds of Kodo ko jaanr, a fermented mild-alcoholic beverage prepared in North East India. The strain was identified by 16S rRNA gene sequence analysis and biochemical characterization. The strain displayed maximum fructansucrase activity of 4.3 U/ml (1.02 U/mg) at 28°C at 180 rpm. The enzyme purified by polyethylene glycol-400 gave specific activity of 5 U/mg and showed 90 kDa band on non-denaturing Sodium Dodecyl Sulphate-Poly Acrylamide Gel Electrophoresis (SDS-PAGE). The purified enzyme confirmed the presence of fructan by periodic acid Schiff's staining which showed magenta colour bands with both sucrose and raffinose. The strain produced 10.2 mg/ml fructan in broth under optimized culture conditions. The purified fructansucrase displayed V_max of 5.42 U/mg and K_m of 16.65 mM. The enzyme showed maximum activity at 30°C and at pH 5. The structure of fructan was analysed by ¹H and ¹³C NMR spectra confirming β-(2-1) and β-(2-6) linkages.

Keywords::

• Lactobacillus fermentum
• fructansucrase
• fructan

Acknowledgement

The authors are thankful to the Indian Institute of Technology Guwahati, India, for providing the research facilities.

Declarations of interest: The research work and the fellowship to DD were supported by a project grant from Council of Industrial and Scientific Research (CSIR), New Delhi, India to A. Goyal. A. Goyal was not supported by the grant.