Engineered Microalgae PSR1 Overexpression for Rapid Phosphate Uptake
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Solution Overview
Problem
Existing biological phosphorus removal systems, such as those based on polyphosphate accumulating organisms (PAOs), are limited in efficiency and capacity for phosphate uptake and accumulation, necessitating improved methods for sustainable and efficient phosphate recovery from wastewater.
Innovation Solution
Development of recombinant microalgal strains with overexpression of the PSR1 gene and underexpression or knockout of the PTC1 gene to enhance phosphate uptake and accumulation, utilizing genetic modifications to modulate phosphate homeostasis and signaling, leading to increased phosphate removal and accumulation capacities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional biological phosphorus removal systems are used, then phosphate removal can be achieved, but the efficiency and capacity for phosphate uptake and accumulation are limited
Solution Approach 1:
The patent applies parameter changes by genetically modifying the microalgal strains to alter key physiological parameters: overexpressing PSR1 (a master regulator of phosphate starvation response) to enhance phosphate uptake signaling, and knocking out PTC1 (a tonoplast phosphate transporter) to prevent phosphate efflux from vacuoles. These genetic parameter changes transform the microalgae into high-capacity phosphate accumulators capable of removing 30 mg/L phosphate in 2 days, representing a 3.5-fold improvement in removal efficiency compared to wild-type strains.
2Productivity
If phosphate uptake is enhanced, then phosphate removal efficiency improves, but the time required for phosphate removal decreases from 7 days to 2 days
Solution Approach 1:
The patent implements preliminary action by pre-engineering the microalgal strains with enhanced phosphate starvation response mechanisms before deployment. The PSR1 overexpression and PTC1 knockout modifications are established in advance, enabling the microalgae to immediately exhibit high-rate phosphate uptake behavior when introduced to wastewater, eliminating the need for prolonged acclimation periods and achieving rapid 2-day removal compared to 7 days for conventional systems.
3Quantity of substance
If genetic modifications are made to enhance phosphate accumulation, then phosphate uptake capacity increases, but the complexity of the system increases
Solution Approach 1:
The patent applies the extraction principle by specifically removing (knocking out) the single problematic PTC1 gene that causes phosphate efflux from vacuoles, while simultaneously overexpressing the single master regulator PSR1 that controls phosphate starvation response. This targeted extraction and enhancement of specific genetic elements, rather than complex multi-gene modifications, achieves high phosphate accumulation (68 mg/g DW) with relatively simple genetic engineering approaches.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The engineered microalgal strains demonstrate significantly enhanced phosphate removal efficiency, capable of removing up to 30 mg/L of phosphate from wastewater in 2 days compared to wild-type strains taking 7 days, with increased total phosphate and polyphosphate content, and can accumulate up to 68 mg/g DW, demonstrating improved phosphate uptake and utilization.
Implementation Method 1
overexpression of a PSR1 gene... over-expression of PSR1 triggers phosphate starvation signalling
Implementation Method 2
loss-of-function of a tonoplast-located P transporter-Phosphate Transporter C1 (CrPTC1)... caused excess polyP accumulation
Implementation Method 3
excess polyP accumulation in acidocalcisomes... high P and vacuolar polyP accumulation in cells
Data Source
AI summary
The invention provides a recombinant microalgal strain comprising in its genome a first modification which causes overexpression of a PSR1 gene, and optionally a further modification which reduces or eliminates expression from an endogenous PTC1 gene. The strains of the invention have utility in promoting phosphate uptake, for example from wastewater, with the microalgae then being useful as fertilisers.