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Biotechnology and Applied Biochemistry (2001) 34, (93–97) (Printed in Great Britain)

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Production of dextran from sucrose by a newly isolated strain of Leuconostoc mesenteroides (PCSIR-3) with reference to L. mesenteroides NRRL B-512F

Shah Ali Ul-Qader¹, Lubna Iqbal, Husan Afroz Rizvi and Rabia Zuberi

Pharma & Fine Chemical Research Centre, P.C.S.I.R. Laboratories Complex, Karachi, Pakistan

Key words: dextransucrase, fermentation, polymers.

Abbreviation used: DSU, dextransucrase units.

¹To whom correspondence should be addressed (e-mail madar01@yahoo.com).

A newly isolated strain of Leuconostoc mesenteroides (PCSIR-3) produced a different dextran compared with that of L. mesenteroides NRRL B-512F. Different media compositions used for dextran production showed that media containing CaCl₂ produced dextran in higher quantities compared with other media. The viscosity of the dextran produced in different media varied in nature. Dextran from media 1 and 2 was of higher molecular mass compared with that from media 3, 4 and 5. Dextran production is also effected by the sucrose concentration in the media. The higher the initial concentration of sucrose, the higher is the yield of dextran produced per unit volume; however, the percentage conversion of sucrose into dextran decreases. A continuous drop in pH was associated with growth and dextran production. The yield of dextran increases during the growth phase and maximum yield was obtained at the end of the exponential phase. Dextran produced by L. mesenteroides PCSIR-3 is quite different from the dextran produced by NRRL B-512F. Maximum dextran production from L. mesenteroides PCSIR-3 occurs in 18 h compared with 12 h for NRRL B-512F.

Received 20 March 2001/5 July 2001; accepted 11 July 2001

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