| Author | Huang, Tan Swee |
| Call Number | AIT Thesis no.EV-00-19 |
| Subject(s) | Sewage--Purification--Heavy metals removal
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science |
| Publisher | Asian Institute of Technology |
| Abstract | The objectives of this study were to isolate the metal binding proteins (MBPs) from activated sludge cultures acclimated with inducer metal (i.e., copper), and to examine the metal binding properties as well as the feasibility of isolated MBPs in removing heavy metal other than inducer metal. Copper (Cu2+) was used as an inducer to trigger the production of metal binding proteineceous extracellular biopolymers in aerobic mixed microbial cultures. Two different copper concentrations were added into non-selective growth mediums, namely L culture (contained 0.5mM Cu2+) and H culture (contained 2.5mM Cu2+), culture with no copper addition was referred as C culture and was used for comparison purposes. Crude membrane proteins were extracted from the cultures and incubated with 2.5mM metal solutions composed of either Cd2+ or Cu2+ alone, or in combination of both ions, to test the metal binding capacities of extracted proteins. The crude proteins were fractionated according to their molecular weight via size exclusion chromatography, followed by metal and protein analysis in each fraction collected. Identification of metal binding proteins was done by calculating the metal content in each protein fraction and the binding capacities were expressed in terms of mg of metal /g of protein and mo! of metal /mo! of protein. Nine metal-binding proteins (MBPs) were isolated in this study. The molecular weight of isolated MBPs ranging from l.3k- 103.lk dalton (Da). Copper (Cu) uptakes of these isolated MBPs ranging from 0.24- 666.90 mg Cu/g protein whilst cadmium (Cd) uptakes varied within 0.03- 940.0S mg Cd/g protein. Three low molecular weight isolated MBPs, namely LS, HS and H6, were considered as Cu-induced MBPs since they only existed in acclimated cultures where copper was present. The molecular weight of LS, HS and H6 was 2.7kDa, 2.1 kDa and 1.3 kDa, respectively. Each isolated protein exhibited different metals binding capacities. In general, metal uptakes capacities were higher in MBPs obtained from acclimated cultures and in low molecular weight MBPs. The highest Cu-binding capacity of 666.60 mg Cu/g protein was derived from protein HS when incubated in binary metal solution containing equimolar of Cu2 + and Cd2+; whereas protein LS showed best Cd-binding capacity of 940.0S mg Cd/g protein while incubated with 2.5mM of Cd2 + alone. A decrease of metal binding capacities was observed when higher metal concentrations were used for incubation in single metal system. In most of the cases, binding capacities of MBPs dropped below value before incubation, suggesting that denaturation of proteins might take place under such circumstances. The increase of metal-binding capacity of acclimated cultures explore the potential applications of using this simple acclimatization tecnique to improve the treatment efficiency of biological systems in terms of metal removal, as well as developing new biosorbent from isolated MBPs for heavy metal removal and recovery. However, further investigations on the economic and other factors are necessary before any firm conclusion can be retrieved. |
| Year | 2000 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering and Management (EV) |
| Chairperson(s) | Fukushi, Kensuke |
| Examination Committee(s) | Muttamara, Samorn;Preeda Parkpian |
| Scholarship Donor(s) | Asian Institute of Technology (Paitial Scholarship) |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2000 |