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The study was conducted as following:
Normalized Difference Vegetation Index (NDVI)
Drainage Pattern Extraction using DEM
In situ sample collection for selenite reducing bacteria isolation and enumeration from six different locations (1,2,3,4,5 and 6)
Isolation and enumeration of selenite reducing bacteria from different samples ( sediment, water and mangrove leaves) within six locations
Identification of selenite reducing bacteria
Factors influencing selenite reducing bacterial growth
Environmental growth parameters affecting selenite bio-reduction
Location detection of elemental selenium by SEM and TEM)
16S r RNA identification of selected isolates.
Correlation analysis of studied parameters
The results can be summarized in the following:
1. By using remote sensing techniques the six study areas were classified as following; two areas as control, two as mangrove and two as mangrove exposed to flash flood.
2. The pink and red colonies in the presence of sodium selenite, indicating the reduction of selenite into red elemental selenium.
3. There is a significant difference in bacterial counts within six locations.
4. NDVI results and change detection data of mangroves area showed that there is an increase at both study areas (location 3 and 4) clearly.
5. Drainage pattern showing that there are different drains that pour directly in mangrove stands in both study areas especially in South Safaga stand which connected with main drain.
6. Se concentrations in location 3 greater than location 4.
7. There is a positive correlation between bacterial counts in different samples under the same condition.
8. Most of the isolated colonies were circular, smooth, and convex. Pigmentation ranged from dark, faint red and orange, All sixteen strains were gram negative, rods. There is a variable ability in carbohydrate fermentation. All isolates were negative for casein hydrolysis and positive for nitrate reduction. Some were positive for blood hemolysis and gelatin production.
9. The majority of bacterial strains were classified as halotolerant and moderate halophiles, alkalophiles and mesophiles.
10. Most of isolates showed lower reduction at lower selenite concentration while higher reduction observed at higher concentrations.
11. At pH 3, all strains showed less selenite reduction but at a higher pH, more selenite reduction was observed with all strains.
12. The selenium content in biomass was 0.96 and 0.91 ppm of selenium of dry weight of biomass of strains 2 and strains 3, respectively.
13. The heat map analysis shows that, the red and blue colors indicate high and low correlation between parameters and isolates.
14. The PCA determines the relationship between the various parameters according to their effect on the isolates.
15. The correlation network demonstrates the statistical structure of the factors effects on each other.
16. TEM and SEM micrographs of Cobetia amphilecti and Vibrio alginolyticus indicate the presence of spherical selenium particales outside and inside the cells.
17. 16 S rRNA analysis of the two selected isolates affiliated to (Cobetia amphilecti and Vibrio alginolyticus) with accession numbers of MN099349 and MN099350 respectively .