الفهرس 
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Abstract
A number of microbes are capable of growing in diverse environments and producing secondary metabolites (extracellular polysaccharides, proteins and lipids) during their growth.
Bioflocculants have shown great potential to improve the quality of waste water treatment, productivities and are safe for both human and the environment compared to in-use chemical flocculants, which have been implicated in undesirable health conditions. However, high production cost and a complicated production process are limiting the use of bioflocculants. Optimization of culture medium conditions has been observed as a way of improving both production yield and flocculating efficiency.
Marine habitats, which support a rich biodiversity of marine bacteria, remain under explored for industrial utilization, yet they possess enormous potentials for screening novel bioflocculant-producing microorganisms. Due to their species diversity, marine microorganisms can produce a wide variety of metabolites with various structures.
1. In this study, twenty bacterial isolates were isolated from different marine water Egyptian habitats, including (Dahb, Ras Sudr, and ELSukhna) at red sea.
2. All isolated bacteria were screened for their ability to produce of exopolysaccharides (EPSs) by inoculation in aliquid production medium. After being incubated for 3 days at 37 oC, the precipitated exopolysaccharides were separated by centrifugation at 5000 rpm for 20 min, washed twice with acetone, and dehydrated by diethylether.
3. Bioflocculant activity for separated exopolysaccharides (EPSs) was determined using kaolin suspension (5,000 mgL−1) as test material.
4. Based on the highest productivity the most potent isolate were identified by studying its morphological, physiological and biochemical characteristics and microscopical studies.
5. To confirm the identity of the most potent isolate, (HS9) isolate was genetically identified using of 16S rDNA techniques. According to information from the gene bank it was identified and coded as Bacillus amyloliquefaciens strain MSH.
6. Optimization of medium components required for maximum exopolysaccharide production by a bacterial strain was evaluated in broth production medium as the synthesis and production of EPS are influenced by a variety of variables. As a result, by examining the effects of various factors on the production of EPSs by isolate (HS9), it was discovered that the maximum yield of EPS was (7.9 g/l) and cell dry was (4.1 g/l) when the incubation temperature was 40 °C after three days, RPM 120, pH 7, peptone as a nitrogen source, and sucrose (20 g/l) as a carbon source.
7. Bacillus amyloliquefaciens strain MSH was scaled up on liquid production medium, and the supernatant was used for precipitation of EPS with ethanol, yielding (5.8 g/l) of extract after being washed twice with acetone and dehydrated by diethylether.
8. Chemical analysis of the EPSHS9 fraction revealed that it contained sulfate (13.1%) and uronic acid (7.4%). The monosaccharide composition of this fraction is composed of glucose, rhaminose and arabinose with molar ratio 6.0: 3.0: 1.0, respectively. These indicate that this fraction is an acidic heteropolysaccharide.
9. The FTIR spectrum fraction exhibited a significant, broad characteristic peak at around at 3410.49 cm-1 region was attributed to the expansion vibration of O–H in the ingredient sugar residues. The EPS fraction also appears to have a particular band at 1629.55 cm-1, which is dominated by circle vibrations, The band at 1140.69 cm−1 indicated the SO= 3. Interfered with stretching vibration of C-O glycosidic bond vibration and the strap at 834.062 cm−1 suggested the β-pyranose.
10. Factors affecting flocculating activity of the purified EPSHS9 were studied and revealed that maximum flocculating rates were accomplished at bioflocculant concentration 1.0 mg/ml, EPSHS9 possessed the best flocculating activities (95.99%) according to its concentration at pH 8, the remaining flocculating activity was increased at temperatures range of 40 ˚C and NaCl cation could clearly improve the flocculating rate of the suspension of EPSHS9.