Optimization and production of curdlan gum using Bacillus cereus PR3 isolated from rhizosphere of leguminous plant

ABSTRACT

Curdlan gum is a neutral water-insoluble bacterial exopolysaccharide composed primarily of linear β-(1,3) glycosidic linkages. Recently, there has been increasing interest in the applications of curdlan and its derivatives. Curdlan is found to inhibit tumors and its sulfated derivative possess anti-HIV activity. Curdlan is biodegradable, non-toxic towards human, environment and edible which makes it suitable as drug-delivery vehicles for sustained drug release. The increasing demand for the growing applications of curdlan requires an efficient high yield fermentation production process so as to satisfy the industrial needs. In this perspective, the present work is aimed to screen and isolate an efficient curdlan gum producing bacteria from rhizosphere of ground nut plant using aniline-blue agar. High yielding isolate was selected based on curdlan yield and identified as Bacillus cereus using gas-chromatography fatty acid methyl ester analysis. B. cereus PR3 curdlan gum was characterized using FT-IR spectroscopy, SEM, XRD and TGA. Fermentation time for curdlan production using B. cereus PR3 was optimized. Media constituents like carbon, nitrogen and mineral sources were screened using Plackett–Burman design. Subsequent statistical analysis revealed that Starch, NH₄NO₃, K₂HPO₄, Na₂SO₄, KH₂SO₄ and CaCl₂ were significant media constituents and these concentrations were optimized for enhancement of curdlan production up to 20.88 g/l.

KEYWORDS:

• Bacillus cereus
• characterization
• curdlan gum
• exopolysaccharides
• optimization

Acknowledgment

The authors acknowledge the support provided by International Research Centre, Kalasalingam Academy of Research and Education, Krishnankoil, Tamilnadu for material characterization facilities like FT-IR, SEM, XRD, Atomic Absorption Spectrophotometer and Sophisticated Test and Instrumentation Centre (STIC), Cochin University, Kerala for Thermo Gravimetric Analysis.