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Gram staining, morphological and physiological characterization of the isolates having a zone of clearance with iodine solution_
| Sample | Gram stain | Morphology under light microscope | Colony color | Colony morphology | Growth on α-amylase agar |
|---|---|---|---|---|---|
| M1 | + | Bacillus | white | filamentous | ++++ |
| M2 | + | Bacillus | white | irregular | +++ |
| WL | + | Bacillus | white | irregular | ++++ |
| M12 | + | Bacillus | creamy | circular | ++ |
| M13 | + | Bacillus | creamy | circular | ++++ |
| L5 | − | Bacillus | white | circular | ++ |
| L6 | + | Bacillus | white | circular | ++ |
| L8 | + | Bacillus | creamy | irregular | +++ |
| L15 | + | Bacillus | creamy | circular | ++ |
Flow sheet of the Bacillus cereus WL purification_
| Purification steps | Total activity (U) | Total proteina (mg) | Specific activity (U/mg) | Activity recovery (%) | Purification factor |
|---|---|---|---|---|---|
| Crude enzyme | 180 | 0.817 | 220 | − | 1 |
| Participate by amm. sulfate (80%) | 90 | 0.225 | 400 | 50 | 1.8 |
| Sephacryl S-200 | 45 | 0.055 | 818.18 | 25 | 3.7 |
Screening of α-amylase activity (U/ml) using starch nitrate medium and selecting of WL as a potent isolate for further study_
| Isolate code | α-amylase activity (U/ml) |
|---|---|
| M1 | 511.08 ± 0.12 |
| M2 | 572.10 ± 0.14 |
| WL | 579.12 ± 0.18 |
| M12 | 509.98 ± 0.04 |
| M13 | 499.99 ± 0.02 |
| L5 | 568.12 ± 0.18 |
| L6 | 539.08 ± 0.12 |
| L8 | 568.12 ± 0.12 |
| L15 | 539.08 ± 0.14 |
Physiological characters of the selected bacterial Bacillus cereus WL_
| Character | WL Strain |
|---|---|
| Temperature range | 35–60°C |
| Optimum temperature | 45°C |
| pH range | 4–8 |
| Optimal pH | 6 |
| Catalase | + |
| Oxidase | + |