Journal of Food, Agriculture and Environment

Comparative molecular characterization of halotolerant bacteria from some Saudi sebkhas

Author(s):

Mohammad A. Khiyami ^{1 *}, Essam J. Alyamani ¹, Ehab A. Serour ^{1, 2}

Recieved Date: 2013-10-02, Accepted Date: 2014-01-08

Abstract:

This study was conducted for the identification and molecular characterization of some halotolerant bacteria isolated from selected Saudi sebkhas (Tarut Island at Dammam, Farasan Island and Al-Oshazia Sebkha at Qassim). Isolated colonies were identified using highly sophisticated 2^nd generation DNA sequencing machines. The total number of isolates was 9, 9 and 10 in Taraut, Farasan and Al-Oshazia samples, respectively. The most frequent genus was Bacillus from which 7, 5 and 3 isolates were detected in Tarut, Farasan and Al-Oshazia samples, respectively. A high growth rate was observed at low salt concentration, while high salt concentrations reduced bacterial growth. Al-Oshazia Sebkha contained some bacterial isolates at 15% salinity as compared to Tarut and Farasan Islands, which did not contain the same amount of bacterial flora at the same salinity level. All isolates varied in their growth at pH 7.3 and 8.8, on which Salinivibrio costicola showed the highest growth rate. The estimation of bacterial genetic relationships was determined using DNA sequencing, phylogenetic trees, and bioinformatics techniques. Tarut isolates were arranged in two main clusters. The first cluster comprised of four bacterial species and the second included four bacterial species. Farasan isolates were arranged in two main clusters. The first cluster contained seven bacterial species (in two subgroups) and the second had two bacterial species: Vibrio natriegens and V. rotiferianus. Al-Oshazia isolates were also arranged in two main clusters. The first cluster had six bacterial species and the second included four bacterial species. The inter- and intra-specific analysis of the sequences showed that most bacterial species of Saudi sebkhas exhibit a homogeneous sequence, indicative of a low level of polymorphism, which is congruent with the reduced variability found in these bacterial species from other islands. The inter- and intra-specific variation suggests that DNA sequencing had the potential to aid in the quick identification and classification of halophilic bacterial isolates in Islands. The reproducibility generated by this technique may lead to the development of specific molecular markers for the characterization of these microbes. To conclude, the results indicated that Saudi Islands have a huge number of bacteria. The scarce knowledge of these microorganism calls for intense studies to understand the genetic regulation and thereby metabolic engineering of these fascinating microorganisms for new and improved biotechnological processes. Further studies are needed concerning potentiality, characterization, expression and regulation of the genes coding for halophilic tolerance. Genetic engineering, together with whole genome sequence data, would enable targeted manipulation for improved production of valuable products of biotechnological interest.

Keywords:

Saudi sebkhas, DNA sequencing, halotolerant bacteria

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Journal: Journal of Food, Agriculture and Environment
Year: 2014
Volume: 12
Issue: 1
Category: Environment
Pages: 441-446

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