Genetic Control of Cyanobacterial Cell Size for Harvesting
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Solution Overview
Problem
The high costs associated with cultivating and processing cyanobacteria for biofuel and chemical production are due to expensive processes like mixing cultures, recovering cell biomass, and lysing cells, which account for up to 40% of operating costs, mainly due to the intrinsic properties of cyanobacterial cells that complicate harvesting and processing.
Innovation Solution
Modulating the expression of genes such as MinC, MinD, MinE, Cdv3, and FtsZ to control cellular division and morphology, resulting in hyper-elongated cells that are more easily harvested and lysed, reducing the costs of cell mixing, separation, and processing by altering the sedimentation rate and susceptibility to physical strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If cyanobacterial cells are kept small and buoyant during growth, then mixing costs are minimized, but harvesting becomes difficult requiring expensive centrifugation or filtration
Solution Approach 1:
The patent applies dynamic control of cell size by modulating the expression of cell division control genes (minC, minD, minE, cdv3, ftsZ) at different cultivation stages. During growth phase, cells are maintained at normal small sizes for efficient mixing. At harvest phase, gene expression is modulated to produce hyper-elongated large cells that settle rapidly by gravity, eliminating the need for expensive centrifugation or filtration equipment.
Solution Approach 2:
The invention changes the physical parameter of cell size from small (during growth) to large (at harvest) through genetic modulation. This parameter change transforms the sedimentation properties of cells, enabling them to transition from requiring expensive mechanical separation to enabling simple gravity-based settling, thereby resolving the contradiction between mixing efficiency and harvesting ease.
2Productivity
If cyanobacterial cells are made large for easier harvesting, then sedimentation rate increases, but cell lysis becomes more difficult requiring more energy
Solution Approach 1:
The patent modulates the expression of cell division control genes to produce cells with specific morphological characteristics - hyper-elongated shape with increased surface area to volume ratio. This parameter change enables cells to sediment rapidly for efficient harvesting while maintaining structural properties that facilitate easy lysis through mild physical strain, resolving the contradiction between harvesting efficiency and lysis energy requirements.
3Reliability
If standard cell division control is maintained, then cells divide normally, but harvesting and processing costs remain high
Solution Approach 1:
The patent implements periodic control of cell division genes at different cultivation stages. During the growth phase, standard cell division control is maintained for reliable cell proliferation. At the harvest phase, expression of minC, minD, minE, cdv3, or ftsZ is modulated to halt division and produce large hyper-elongated cells that settle rapidly. This periodic action maintains reliability during growth while enabling ease of manufacture during harvesting.
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 modified cyanobacterial strains exhibit improved harvestability and processing efficiency, leading to reduced energy expenditure and increased product yield, thereby lowering operational costs and enhancing the economic viability of cyanobacterial bioproduction.
Implementation Method 1
Hyper-elongated cells exhibit increased rates of sedimentation under low centrifugal forces or by gravity-assisted settling.
Implementation Method 2
Hyper-elongated cells exhibit increased rates of sedimentation under low centrifugal forces or by gravity-assisted settling.
Implementation Method 3
hyper-elongated cells are also more susceptible to lysis through the application of mild physical strain.
Data Source
AI summary
Described herein are mutant cyanobacterial cell populations that have a smaller mean cell length than wild type cyanobacterial cell populations of the same species.