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Team:Hong Kong HKU/project/cargo
Polyphosphate Kinase
The enhanced biological phosphorous removal process is necessarily dependent on the ability of sludge microorganism (PAOs) to take up phosphate and to store it intracellularly in the form of polyP. For polyP formation to occur, phosphate must first be transported into the microbial cell and subsequently converted into ATP before incorporation in the polyP polymer. To improve the efficiency of the whole process, there are two steps we can work on:
(1) Phosphate transport system: increase phosphate uptake by engineering biological phosphate transport system.
(2) PolyP synthesis: engineer microbes to favour the formation of PolyP over the hydrolysis of PolyP, so that higher cell PolyP concentration and longer PolyP chain can be achieved.
Phosphate transport system
There are two major phosphate transport system in bacterial cells:
A. The inorganic phosphate transport system (Pit) is constitutively expressed and has a relatively low specificity for phosphate. Pit transport neutral metal phosphates, each in symport with a proton.
B. The phosphate-specific transport system (Pst) transport both H2PO4- and HPO42-, but not neutral metal phosphates. Unlike constitutively expressed Pit system, Pst system is phosphate-starvation inducible.
More future research on microbial polyP metabolism in the EBPR process is needed to investigate how phosphate transport system activities affect polyP production. Clarification of the mechanism by which in-fluent phosphate is converted into ATP and used as substrate for polyP synthesis. Due to the much unknown details and limit of time, we choose to focus on the enhancement of PolyP synthesis efficiency inside bacteria.
PolyP synthesis
Polyphosphate kinase 1 (PPK1) is the most extensively studied polyp-synthesizing enzyme and has been detected in a wide range of prokaryotes. It catalyzes the transfer of the terminal phosphate of ATP to an active-site histidine residue, the initial step in the processive synthesis of a long PolyP chain. The reaction is reversible but favors synthesis.
The enhanced biological phosphorous removal process is necessarily dependent on the ability of sludge microorganism (PAOs) to take up phosphate and to store it intracellularly in the form of polyP. For polyP formation to occur, phosphate must first be transported into the microbial cell and subsequently converted into ATP before incorporation in the polyP polymer. To improve the efficiency of the whole process, there are two steps we can work on:
(1) Phosphate transport system: increase phosphate uptake by engineering biological phosphate transport system.
(2) PolyP synthesis: engineer microbes to favour the formation of PolyP over the hydrolysis of PolyP, so that higher cell PolyP concentration and longer PolyP chain can be achieved.
Phosphate transport system
There are two major phosphate transport system in bacterial cells:
A. The inorganic phosphate transport system (Pit) is constitutively expressed and has a relatively low specificity for phosphate. Pit transport neutral metal phosphates, each in symport with a proton.
B. The phosphate-specific transport system (Pst) transport both H2PO4- and HPO42-, but not neutral metal phosphates. Unlike constitutively expressed Pit system, Pst system is phosphate-starvation inducible.
More future research on microbial polyP metabolism in the EBPR process is needed to investigate how phosphate transport system activities affect polyP production. Clarification of the mechanism by which in-fluent phosphate is converted into ATP and used as substrate for polyP synthesis. Due to the much unknown details and limit of time, we choose to focus on the enhancement of PolyP synthesis efficiency inside bacteria.
PolyP synthesis
Polyphosphate kinase 1 (PPK1) is the most extensively studied polyp-synthesizing enzyme and has been detected in a wide range of prokaryotes. It catalyzes the transfer of the terminal phosphate of ATP to an active-site histidine residue, the initial step in the processive synthesis of a long PolyP chain. The reaction is reversible but favors synthesis.
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