Engineered E. coli Membrane Proteins for Phage Resistance
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Solution Overview
Problem
Industrial fermentation processes face challenges with bacterial culture contamination due to bacteriophage infections, which are difficult to manage with existing strategies, and there is a need for improved bacterial strains that are resistant to phage attacks without compromising bioproduct production.
Innovation Solution
A genetically modified E. coli strain with reduced expression or mutation of endogenous membrane protein encoding genes provides phage resistance, specifically targeting a wide range of phage types without affecting bioproduct productivity or cell growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mixed starter cultures are used to minimize bacteriophage infection, then resistance to phage attack is improved, but strain distribution becomes unpredictable and strain dominance occurs leading to increased susceptibility
Solution Approach 1:
The invention extracts and eliminates the problematic variable component (strain distribution variability) by using a single defined strain instead of a mixed culture. The solution takes out the complexity of maintaining stable strain distributions in mixed cultures and replaces it with a controlled single-strain system that has engineered phage resistance through membrane protein modification.
Solution Approach 2:
The invention changes the genetic parameters of the bacterial strain by modifying membrane protein encoding genes (reducing expression or introducing mutations). This parameter change at the molecular level provides phage resistance without affecting the stability of the culture composition, as the resistance is built into the single strain's genetics rather than relying on mixed culture dynamics.
2Reliability
If strain rotation is used to limit phage development, then phage susceptibility is reduced, but the process becomes difficult and cumbersome to manage
Solution Approach 1:
The invention makes the bacterial strain self-sufficient for phage resistance by engineering the membrane proteins directly in the strain. Instead of requiring external management actions (rotation between different strains), the strain itself provides the resistance capability through its modified membrane proteins, eliminating the need for complex rotation protocols and strain tracking.
Solution Approach 2:
The invention performs preliminary action by pre-modifying the membrane protein encoding genes in the strain before fermentation begins. The genetic modifications (expression reduction or mutations) are established in advance, so the strain is already resistant to phage attack when used in production, eliminating the need for reactive strain rotation when phage problems arise.
3Reliability
If endogenous membrane protein encoding genes are deleted to achieve phage resistance, then phage susceptibility is reduced, but normal cell function may be hampered
Solution Approach 1:
The invention applies partial action by reducing the expression of membrane protein encoding genes rather than completely deleting them. This partial reduction is sufficient to confer phage resistance while maintaining enough membrane protein function to support normal cell growth and bioproduct production. The approach avoids the excessive action of complete deletion that would harm cell function.
Solution Approach 2:
The invention applies local quality by introducing specific mutations in the membrane protein encoding genes that target phage interaction sites while preserving other functional domains. This localized modification provides phage resistance at the molecular level without affecting the overall function of the membrane proteins needed for cell growth and metabolism.
Data Source
AI summary
Described is a method of producing bioproducts by fermentation with a genetically modified cell, as well as to the genetically modified cell used in the method. The cell is genetically modified to produce a bioproduct and is further genetically modified by reducing the expression of at least one endogenous membrane protein encoding gene and/or mutating the expression of the endogenous membrane protein.