Optimization, Purification and Physicochemical Characterization of Curdlan Produced by Paenibacillus Sp. Strain NBR-10

Mohamed Helal El-Sayed^1,2*, Hussam H. Arafat^1,3, Islam A. Elsehemy⁴ and Mona Basha⁵

¹Department of Biology, Faculty of Science and Arts, Northern Border University (Rafha), Saudi Arabia.

²Department of Botany and Microbiology, Faculty of Science, Al-Azhar University, Cairo, Egypt.

³Department of Botany and Microbiology, Faculty of Science, Minia University, Minia City- 61519, Egypt.

⁴Department of Natural and Microbial Products Chemistry, Division of Pharmaceutical and Drug Industries Research, National Research Centre, Dokki, Cairo, Egypt.

⁵Pharmaceutical Technology Department, National Research Centre, Dokki, Cairo, Egypt.

Corresponding Author E-mail: m_helal2007rm@yahoo.com

DOI : http://dx.doi.org/10.13005/bbra/2113

ABSTRACT: In recent years, significant progress has been done to discover a novel microbial exopolysaccharides that possess novel and highly functional properties. During our screening program for curdlan producing bacteria, 35 bacterial strains were isolated from 15 sandy soils collected from Rafha governorate, Northern Border region, Saudi Arabia. Among them isolate, NBR-10 was selected for its promising ability for curdlan production. The selected isolate was identified based on 16S rDNA gene sequencing (Genbank accession number KT957624.1) as Paenibacillus sp. For enhancing the curdlan yield produced by Paenibacillus sp. NBR-10, different culture conditions and medium compositions were optimized. It was found that, the maximum yield was obtained at 35 °C, initial pH 7 after 48 h of incubation. Also different carbon and nitrogen sources were used to improve the curdlan yield, it was indicated that sucrose and yeast extract were the best carbon and nitrogen sources respectively. Generally, optimization of the different parameters was approximately duplicated the curdlan yield from 2.34 g/l to 4.82 g/l. The precipitated curdlan dissolved in 2M NaOH exhibited high affinity to gel formation. Analysis of FT-IR, ¹H NMR and ¹³C NMR spectra proved that the produced polymer by Paenibacillus sp. NBR-10 has β-(1-3)-D-glucan (curdlan) structure.

KEYWORDS: Curdlan; Paenibacillus sp.; Optimization; Characterization

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