Title Page
Contents
Abstract 8
Abbreviations 10
1. Introduction 11
2. Materials and Methods 14
2.1. Strain and culture medium 14
2.2. Optimization of culture conditions 15
2.3. Batch and fed-batch biodegradation in bioreactor 16
2.3.1. Batch biodegradation 19
2.3.2. Fed-batch biodegradation 19
2.4. Biomass concentrations 20
2.5. Measurement of reducing sugar 21
2.6. Antioxidant activities of biodegraded SSW 23
2.6.1. DPPH radical scavenging assay 23
2.6.2. ABTS radical cation decolorization assay 24
2.6.3. Reducing power assay 25
2.7. Thin Layer Chromatography (TLC) 25
2.8. Determination of DNA damage inhibition 26
3. Results and discussion 28
3.1. Batch biodegradation 28
3.1.1. Biomass concentration (g/L) 29
3.1.2. pH 31
3.1.3. Production of reducing sugar 33
3.1.4. Antioxidant activity 36
3.2. Fed-batch biodegradation 45
3.2.1. Biomass concentration (g/L) 45
3.2.2. pH 46
3.2.3. Production of reducing sugar 47
3.2.4. Antioxidant activity 48
3.3. Thin Layer Chromatography (TLC) 51
3.4. DNA damages inhibition activity 53
4. Conclusion 55
6. References 58
Fig. 1. Biodegradation of SSW in a 3.8. L (maximum working volume of 3 L) Winpact... 18
Fig. 2. Standard curve created according to the modified method of Imoto and Yagishita... 22
Fig. 3. Growth kinetics of Bacillus cereus EW5 with time in batch and fed-batch... 30
Fig. 4. Changes in pH with time in batch and fed-batch biodegradation of SSW by... 32
Fig. 5. Determination of reducing sugar of culture supernatant collected during... 34
Fig. 6. Production of reducing sugar with time in batch and fed-batch biodegradation of... 35
Fig. 7. Determination of DPPH free radical scavenging activity of the culture supernatant... 37
Fig. 8. DPPH free radical scavenging activity of the supernatant with time in batch and... 38
Fig. 9. Determination of ABTS radical scavenging activity of the culture supernatant... 40
Fig. 10. ABTS radical scavenging activity of the supernatant with time in batch and fed-... 41
Fig. 11. Determination of reducing power of the culture supernatant collected during... 43
Fig. 12. Reducing power of the supernatant with time in batch and fed-batch... 44
Fig. 13. TLC analysis of supernatant and identification of bioactive compounds produced... 52
Fig. 14. DNA damage inhibition activity of the culture supernatant of degraded SSW... 54