Exopolysaccharide production byVolcaniella eurihalina

Quesada, Emilia; Béjar, Victoria; Calvo, C.

doi:10.1007/bf01929910

Cited by 100 publications

(63 citation statements)

References 11 publications

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“…at 32 uC in MY complex medium supplemented with 7.5 % w/v sea salts. The EPSs were isolated using the method described in previous publications (Quesada et al, 1993(Quesada et al, , 1994. Briefly, the culture was centrifuged and the supernatant precipitated with cold ethanol before being ultracentrifuged, dialysed against distilled water and lyophilized.…”

Section: Methodsmentioning

confidence: 99%

Genetic and phenotypic analysis of the GacS/GacA system in the moderate halophile Halomonas anticariensis

2013

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A multisensory, hybrid histidine kinase (HK) and a response regulator (RR), which together may well constitute a two-component regulatory system (TCS), have been located in Halomonas anticariensis FP35 T by transposon mutagenesis. This TCS is homologous to the GacS/GacA system described for many Gram-negative bacteria. An analysis of crude N-acylhomoserine lactone (AHL) extracts from cultures of FP35gacS and FP35gacA mutants showed that they produced lower quantities of AHLs than the wild-type strain. In addition, RT-PCR analysis revealed a considerable decrease in the expression of the quorum-sensing (QS) genes hanR and hanI compared with the wild-type strain. This result indicates that the GacS/GacA TCS exerts a positive effect upon the QS HanR/HanI system and suggests its integral involvement in the intercellular communication strategies of this bacterium. We have also demonstrated the influence of GacS and GacA upon exopolysaccharide production and biofilm formation, in which this regulatory machinery appears to play a key role in an overall system that co-ordinates gene expression and behaviour in H. anticariensis FP35 T in response to environmental conditions.

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Section: Methodsmentioning

confidence: 99%

Genetic and phenotypic analysis of the GacS/GacA system in the moderate halophile Halomonas anticariensis

2013

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“…Mutagenesis in any one or more than one gene sequences might lead to constitutive expression of genes required for EPS production and thereby enhance the synthesis and accumulation of the EPS (Tang et al, 1991). Chemical mutagenesis in H. xianhensis remarkably increased the amount of EPS from 7.05 to 12.98 g L −1 , an amount much higher (4.9 g L −1 ) than that of the reported species of the genus Halomonas (Quesada et al, 1993;Arias et al, 2003;Mata et al, 2006). As against this, the EPS production of natural isolates of H. eurihalina ranged from 1.6-2.8 g L −1 (Bejar et al, 1998;Quesada et al, 1993).…”

Section: Discussionmentioning

confidence: 94%

“…KJ933394), a moderately halophilic EPS producing bacterium isolated from multi-pond solar salterns of Surala, Odisha, India reported from this laboratory was used throughout the present study of strain improvement by chemical mutagenesis and was maintained on agar slopes of MY medium (Quesada et al, 1993 …”

Section: Bacterial Strain and Cultural Conditionsmentioning

confidence: 99%

Chemical Mutagenesis for Improvement of Production of a Biologically Active Extracellular Polymeric Substance by <i>Halomonas xianhensis</i> SUR308

Biswas¹,

Paul²

2016

American Journal of Microbiology

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A moderately halophilic bacterium, Halomonas xianhensis SUR308 (Genbank Accession No. KJ933394) isolated from solar saltern of Surala, Odisha, India was found to produce significant amount of a biologically active extracellular polymeric substances (EPS). Under optimized cultural conditions, the strain was able to produce 7.05 g L −1 of EPS after 8 days of incubation under shake culture. To enhance the EPS production efficiency, the isolate SUR308 was subjected to chemical mutagenesis following the use of hydroxylamine (HA), acridine orange (AO) and ethyl methanesulfonate (EMS). Evaluation of the toxicity of these mutagens indicated that EMS was comparatively toxic but effective for mutagenesis. Mutagenic treatments have resulted in the isolation of 58 amoxycillin resistant morphologically distinct phenotypes. Three of these mutant phenotypes (EM3, EM13 and HM6) were capable of producing 12.98, 11.97 and 11.21 g L −1 of EPS respectively in malt extract-yeast extract medium supplemented with casein hydrolysate with significant reduction of incubation period. Compared to wild type strain, mutant strains were found to produce 1.6-1.8 fold more EPS. However, the physico-chemical nature of the EPS derived from the mutants remained unaltered when compared with that of the wild type strain. These findings, therefore, have more impact on production economy of EPS for biotechnological applications.

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“…This can be addressed by chemical modification [30]. EPS from Halomonas maura and H. eurihalina has immunomodulating activity [31][32][33][34]. H. stenophila produced EPS having antitumor activity [35].…”

Section: Introductionmentioning

confidence: 99%

Production and Characterization of Exopolysaccharide From Marine Moderately Halophilic Bacterium Halomonas Smyrnensis SVD Iii

Deshmukh

Kanekar²,

Bhadekar

2017

Int J Pharm Pharm Sci

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Objective: To study 1) Optimization of nutritional and environmental parameters to enhance the yield of EPS by Halomonas smyrnensis SVD III isolated from seawater, West Coast of Maharashtra, India and 2) Purification and characterization of the EPS produced. Methods:The isolate was grown in Sehgal and Gibbons (SG) medium broth supplemented with 3% glucose, at 37 °C, 120 rpm for 7 d. Optimization of different parameters was carried out with one factor at a time approach. EPS was isolated from cell-free supernatant of the culture broth by centrifugation and precipitation using chilled ethanol, after removal of proteins by trichloroacetic acid (TCA) treatment. Characterization of the purified EPS was carried out with respect to fourier-transform infrared (FTIR) spectrum, 1 H nuclear magnetic resonance (NMR) spectrum and mass spectrometry (MS) analysis.Results: Two-fold increase in the yield of EPS (23 g/l) by the selected isolate was obtained by using culture conditions as 10% inoculum size having cell density of 10 7 cells/ml, pH 6, incubation temperature 45 °C, 3% carbohydrate, 0.5% yeast extract as nitrogen source, 20% salt concentration and 7 d of incubation period. Characterization of the purified EPS suggested the presence of dominated glycosidic linkages and heptasaccharide nature of the molecule. As the present strain is halophilic, 20% NaCl was found to be optimum. Conclusion:Optimization studies resulted in two-fold increase in the yield of EPS which is of heptasaccharide nature.

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Exopolysaccharide production byVolcaniella eurihalina

Cited by 100 publications

References 11 publications

Genetic and phenotypic analysis of the GacS/GacA system in the moderate halophile Halomonas anticariensis

Genetic and phenotypic analysis of the GacS/GacA system in the moderate halophile Halomonas anticariensis

Chemical Mutagenesis for Improvement of Production of a Biologically Active Extracellular Polymeric Substance by <i>Halomonas xianhensis</i> SUR308

Production and Characterization of Exopolysaccharide From Marine Moderately Halophilic Bacterium Halomonas Smyrnensis SVD Iii

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