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Cultivation-dependent assessment, diversity, and ecology of haloalkaliphilic bacteria in arid saline systems of southern Tunisia.

El Hidri D, Guesmi A, Najjari A, Cherif H, Ettoumi B, Hamdi C, Boudabous A, Cherif A - Biomed Res Int (2013)

Bottom Line: Three gram-positive isolates showing between 95 and 96% of 16S rRNA sequence homology with Bacillus saliphilus could represent new species or genus.Activity tests showed that gram-positive bacteria were mostly active, particularly for protease, lipase, DNase, and amylase production.Our overall results demonstrate the huge phenotypic and phylogenetic diversity of haloalkaliphiles in saline systems of southern Tunisia which represent a valuable source of new lineages and metabolites.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Microorganisms and Active Biomolecules, Faculty of Sciences of Tunis, University of Tunis El Manar, 2092 Tunis, Tunisia ; LR Biotechnology and Bio-Geo Resources Valorization, Higher Institute for Biotechnology, Biotechpole Sidi Thabet, University of Manouba, 2020 Ariana, Tunisia.

ABSTRACT
Haloalkaliphiles are polyextremophiles adapted to grow at high salt concentrations and alkaline pH values. In this work, we isolated 122 haloalkaliphilic bacteria upon enrichments of 23 samples from 5 distinct saline systems of southern Tunisia, growing optimally in media with 10% salt and at pH 10. The collection was classified into 44 groups based on the amplification of the 16S-23S rRNA internal transcribed spacers (ITS-PCR). Phylogenetic analysis and sequencing of the 16S rRNA genes allowed the identification of 13 genera and 20 distinct species. Three gram-positive isolates showing between 95 and 96% of 16S rRNA sequence homology with Bacillus saliphilus could represent new species or genus. Beside the difference in bacterial diversity between the studied sites, several species ecological niches correlations were demonstrated such as Oceanobacillus in salt crust, Nesterenkonia in sand, and Salinicoccus in the rhizosphere of the desert plant Salicornia. The collection was further evaluated for the production of extracellular enzymes. Activity tests showed that gram-positive bacteria were mostly active, particularly for protease, lipase, DNase, and amylase production. Our overall results demonstrate the huge phenotypic and phylogenetic diversity of haloalkaliphiles in saline systems of southern Tunisia which represent a valuable source of new lineages and metabolites.

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Geographic distribution of haloalkaliphilic bacteria isolated from natural saline systems of southern Tunisian Sahara.
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Related In: Results  -  Collection


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fig3: Geographic distribution of haloalkaliphilic bacteria isolated from natural saline systems of southern Tunisian Sahara.

Mentions: Arid environment and saline systems in southern Tunisia are characterized by unstable climatic conditions, due to the periodic flooding by the subsurface ground water associated with high salt during dry phases. These specific conditions make such environment fascinating ecosystems to study the diversity and the ecological adaptations of thriving microorganisms. In the current study, cultivation approach showed a particular distribution of haloalkaliphilic bacteria according to their sampling origin (Table 1, Figure 3). The general distribution of the genera was very similar in Ksar Ghilane, Sabkhet Ennaouel, and Chott el Djerid with low bacterial diversity and the dominance of Halomonas and Nesterenkonia species (Figure 3). Beside the specific occurrence of Nesterenkonia species in these stations, Bacillus saliphilus and Halobacillus profundi were exclusively isolated from Ksar Ghilane and Chott el Djerid, respectively.


Cultivation-dependent assessment, diversity, and ecology of haloalkaliphilic bacteria in arid saline systems of southern Tunisia.

El Hidri D, Guesmi A, Najjari A, Cherif H, Ettoumi B, Hamdi C, Boudabous A, Cherif A - Biomed Res Int (2013)

Geographic distribution of haloalkaliphilic bacteria isolated from natural saline systems of southern Tunisian Sahara.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3842069&req=5

fig3: Geographic distribution of haloalkaliphilic bacteria isolated from natural saline systems of southern Tunisian Sahara.
Mentions: Arid environment and saline systems in southern Tunisia are characterized by unstable climatic conditions, due to the periodic flooding by the subsurface ground water associated with high salt during dry phases. These specific conditions make such environment fascinating ecosystems to study the diversity and the ecological adaptations of thriving microorganisms. In the current study, cultivation approach showed a particular distribution of haloalkaliphilic bacteria according to their sampling origin (Table 1, Figure 3). The general distribution of the genera was very similar in Ksar Ghilane, Sabkhet Ennaouel, and Chott el Djerid with low bacterial diversity and the dominance of Halomonas and Nesterenkonia species (Figure 3). Beside the specific occurrence of Nesterenkonia species in these stations, Bacillus saliphilus and Halobacillus profundi were exclusively isolated from Ksar Ghilane and Chott el Djerid, respectively.

Bottom Line: Three gram-positive isolates showing between 95 and 96% of 16S rRNA sequence homology with Bacillus saliphilus could represent new species or genus.Activity tests showed that gram-positive bacteria were mostly active, particularly for protease, lipase, DNase, and amylase production.Our overall results demonstrate the huge phenotypic and phylogenetic diversity of haloalkaliphiles in saline systems of southern Tunisia which represent a valuable source of new lineages and metabolites.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Microorganisms and Active Biomolecules, Faculty of Sciences of Tunis, University of Tunis El Manar, 2092 Tunis, Tunisia ; LR Biotechnology and Bio-Geo Resources Valorization, Higher Institute for Biotechnology, Biotechpole Sidi Thabet, University of Manouba, 2020 Ariana, Tunisia.

ABSTRACT
Haloalkaliphiles are polyextremophiles adapted to grow at high salt concentrations and alkaline pH values. In this work, we isolated 122 haloalkaliphilic bacteria upon enrichments of 23 samples from 5 distinct saline systems of southern Tunisia, growing optimally in media with 10% salt and at pH 10. The collection was classified into 44 groups based on the amplification of the 16S-23S rRNA internal transcribed spacers (ITS-PCR). Phylogenetic analysis and sequencing of the 16S rRNA genes allowed the identification of 13 genera and 20 distinct species. Three gram-positive isolates showing between 95 and 96% of 16S rRNA sequence homology with Bacillus saliphilus could represent new species or genus. Beside the difference in bacterial diversity between the studied sites, several species ecological niches correlations were demonstrated such as Oceanobacillus in salt crust, Nesterenkonia in sand, and Salinicoccus in the rhizosphere of the desert plant Salicornia. The collection was further evaluated for the production of extracellular enzymes. Activity tests showed that gram-positive bacteria were mostly active, particularly for protease, lipase, DNase, and amylase production. Our overall results demonstrate the huge phenotypic and phylogenetic diversity of haloalkaliphiles in saline systems of southern Tunisia which represent a valuable source of new lineages and metabolites.

Show MeSH
Related in: MedlinePlus