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Production & characterization of a unique dextran from an indigenous Leuconostoc mesenteroides CMG713.

ABSTRACT: On the basis of high enzyme activity a newly isolated strain of L. mesenteroides CMG713 was selected for dextran production. For maximum yield of dextran, effects of various parameters such as pH, temperature, sucrose concentration and incubation period were studied. L. mesenteroides CMG713 produced maximum dextran after 20 hours of incubation at 30 masculineC with 15% sucrose at pH 7.0. The molecular mass distribution of dextran produced by this strain showed that its molecular mass was about 2.0 million Da. Dextran analysis by (13)C-NMR spectrometry showed no signals corresponding to any other linkages except alpha-(1-->6) glycosidic linkage in the main chain, which has not been reported before. Physico-chemical properties of this unique dextran were also studied. These optimised conditions could be used for the commercial production of this unique high molecular weight dextran, which have significant industrial perspectives.

SUBMITTER: Sarwat F

PROVIDER: S-EPMC2567811 | biostudies-literature | 2008

REPOSITORIES: biostudies-literature

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Production & characterization of a unique dextran from an indigenous Leuconostoc mesenteroides CMG713.

Sarwat Farwa F Ul Qader Shah Ali SA Aman Afsheen A Ahmed Nuzhat N

International journal of biological sciences 20081015 6

On the basis of high enzyme activity a newly isolated strain of L. mesenteroides CMG713 was selected for dextran production. For maximum yield of dextran, effects of various parameters such as pH, temperature, sucrose concentration and incubation period were studied. L. mesenteroides CMG713 produced maximum dextran after 20 hours of incubation at 30 masculineC with 15% sucrose at pH 7.0. The molecular mass distribution of dextran produced by this strain showed that its molecular mass was about 2 ...[more]

PMID: 18953402

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Project description:During nonventilated storage of carrots, CO2 gradually accumulates to high levels and causes modifications in the carrot's microbiome toward dominance of Lactobacillales and Enterobacteriales The lactic acid bacterium Leuconostoc mesenteroides secretes a slimy exudate over the surface of the carrots. The objective of this study was to characterize the slime components and the potential cause for its secretion under high CO2 levels. A proteomic analysis of the exudate revealed bacterial glucosyltransferases as the main proteins, specifically, dextransucrase. A chemical analysis of the exudate revealed high levels of dextran and several simple sugars. The exudate volume and dextran amount were significantly higher when L. mesenteroides was incubated under high CO2 levels than when incubated in an aerated environment. The treatment of carrot medium plates with commercial dextransucrase or exudate protein extract resulted in similar sugar profiles and dextran production. Transcriptome analysis demonstrated that dextran production is related to the upregulation of the L. mesenteroides dextransucrase-encoding genes dsrD and dsrT during the first 4 to 8?h of exposure to high CO2 levels compared to aerated conditions. A phylogenetic analysis of L. mesenteroides YL48 dsrD revealed a high similarity to other dsr genes harbored by different Leuconostoc species. The ecological benefit of dextran production under elevated CO2 requires further investigation. However, this study implies an overlooked role of CO2 in the physiology and fitness of L. mesenteroides in stored carrots, and perhaps in other food items, during storage under nonventilated conditions.IMPORTANCE The bacterium Leuconostoc mesenteroides is known to cause spoilage of different types of foods by secreting a slimy fluid that damages the quality and appearance of the produce. Here, we identified a potential mechanism by which high levels of CO2 affect the spoilage caused by this bacterium by upregulating dextran synthesis genes. These results have broader implications for the study of the physiology, degradation ability, and potential biotechnological applications of Leuconostoc.

Dataset Information

Production & characterization of a unique dextran from an indigenous Leuconostoc mesenteroides CMG713.

Publications

Production & characterization of a unique dextran from an indigenous Leuconostoc mesenteroides CMG713.

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