Influence of pH and calcium on the growth, polysaccharide production and symbiotic association of Sinorhizobium meliloti SEMIA 116 with alfalfa roots

Delavechia, Carolina; Hampp, Eugenio; Fabra, Adriana; Castro, Stella

doi:10.1007/s00374-003-0627-0

Cited by 6 publications

(2 citation statements)

References 28 publications

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“…This was observed for S. meliloti strains grown under acidic conditions at low Ca 2+ concentrations. Under these conditions, the limitation of Ca 2+ in the culture medium drastically reduced the production of EPS by the strains (Dilworth et al, 1999;Delavechia et al, 2003).…”

Section: Exopolysaccharides In the Process Of Rhizobia Adaptation To mentioning

confidence: 99%

Exopolysaccharides produced by the symbiotic nitrogen-fixing bacteria of leguminosae

Bomfeti

Florentino

Guimarães³

et al. 2011

Rev. Bras. Ciênc. Solo

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SUMMARYThe process of biological nitrogen fixation (BNF), performed by symbiotic nitrogen fixing bacteria with legume species, commonly known as α and β rhizobia, provides high sustainability for the ecosystems. Its management as a biotechnology is well succeeded for improving crop yields. A remarkable example of this success is the inoculation of Brazilian soybeans with Bradyrhizobium strains. Rhizobia produce a wide diversity of chemical structures of exopolysaccharides (EPS). Although the role of EPS is relatively well studied in the process of BNF, their economic and environmental potential is not yet explored. These EPS are mostly species-specific heteropolysaccharides, which can vary according to the composition of sugars, their linkages in a single subunit, the repeating unit size and the degree of polymerization. Studies have showed that the EPS produced by rhizobia play an important role in the invasion process, infection threads formation, bacteroid and nodule development and plant defense response. These EPS also confer protection to these bacteria when exposed to environmental stresses. In general, strains of rhizobia that produce greater amounts of EPS are more tolerant to adverse conditions when compared with strains that produce less. Moreover, it is known that the EPS produced by microorganisms are widely used in various industrial activities. These compounds, also called biopolymers, provide a valid alternative for the commonly used in food industry through the development of products with identical properties or with better rheological characteristics, which can be used for new applications. The microbial EPS are also able to increase the adhesion of soil particles favoring the mechanical stability of aggregates, increasing levels of water retention and air flows in this environment. Due to the importance of EPS, in this review we discuss the role of these compounds in the process of BNF, in the adaptation of rhizobia to environmental stresses and in the process of soil aggregation. The possible applications of these biopolymers in industry are also discussed.Index terms: Exopolysaccharides, nodules, environmental stress, soil aggregation, rhizobia. RESUMO: EXOPOLISSACARÍDEOS PRODUZIDOS POR BACTÉRIAS FIXADORAS DE NITROGÊNIO SIMBIÓTICAS DE LEGUMINOSAE O processo de fixação biológica de nitrogênio (FBN), realizado por bactérias fixadoras de

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Section: Exopolysaccharides In the Process Of Rhizobia Adaptation To mentioning

confidence: 99%

Exopolysaccharides produced by the symbiotic nitrogen-fixing bacteria of leguminosae

Bomfeti

Florentino

Guimarães³

et al. 2011

Rev. Bras. Ciênc. Solo

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“…Published studies have shown that supplementation of the culture medium with calcium (Delavechia et al, 2003;Macció et al, 2002;Watkin et al, 1997) or magnesium (Piddington et al, 2000) prevented the pH-dependent inhibition of bacterial growth. We therefore supplemented both TSB and TSB 1 %G culture media with calcium (Ca 2+ ) and magnesium (Mg 2+ ), and evaluated their effect on the reported glucose-dependent cell dormancy.…”

Section: Effect Of Calcium and Magnesium On The Glucoseinduced Cell Dmentioning

confidence: 99%

Staphylococcus epidermidis biofilms with higher proportions of dormant bacteria induce a lower activation of murine macrophages

Cerca

Andrade

França

et al. 2011

Journal of Medical Microbiology

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Staphylococcus epidermidis is an opportunistic pathogen and, due to its ability to establish biofilms, is a leading causative agent of indwelling medical device-associated infection. The presence of high amounts of dormant bacteria is a hallmark of biofilms, making them more tolerant to antimicrobials and to the host immune response. We observed that S. epidermidis biofilms grown in excess glucose accumulated high amounts of viable but non-culturable (VBNC) bacteria, as assessed by their low ratio of culturable bacteria over the number of viable bacteria. This effect, which was a consequence of the accumulation of acidic compounds due to glucose metabolism, was counteracted by high extracellular levels of calcium and magnesium added to the culture medium allowing modulation of the proportions of VBNC bacteria within S. epidermidis biofilms. Using bacterial inocula obtained from biofilms with high and low proportions of VBNC bacteria, their stimulatory effect on murine macrophages was evaluated in vitro and in vivo. The inoculum enriched in VBNC bacteria induced in vitro a lower production of tumour necrosis factor alpha, interleukin-1 and interleukin-6 by bone-marrow-derived murine macrophages and, in vivo, a lower stimulatory effect on peritoneal macrophages, assessed by increased surface expression of Gr1 and major histocompatibility complex class II molecules. Overall, these results show that environmental conditions, such as pH and extracellular levels of calcium and magnesium, can induce dormancy in S. epidermidis biofilms. Moreover, they show that bacterial suspensions enriched in dormant cells are less inflammatory, suggesting that dormancy can contribute to the immune evasion of biofilms.

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Bacterial Exo-Polysaccharides: A Biological Tool for the Reclamation of Salt-Affected Soils

Ashraf

Hasnain

Berge

2012

Developments in Soil Salinity Assessment and Reclamation

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Influence of pH and calcium on the growth, polysaccharide production and symbiotic association of Sinorhizobium meliloti SEMIA 116 with alfalfa roots

Cited by 6 publications

References 28 publications

Exopolysaccharides produced by the symbiotic nitrogen-fixing bacteria of leguminosae

Exopolysaccharides produced by the symbiotic nitrogen-fixing bacteria of leguminosae

Staphylococcus epidermidis biofilms with higher proportions of dormant bacteria induce a lower activation of murine macrophages

Bacterial Exo-Polysaccharides: A Biological Tool for the Reclamation of Salt-Affected Soils

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