Carrier Cell Plasmid Conjugation for Antibacterial Efficacy

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Solution Overview

Problem

Bacterial cells equipped with Resistance-Nodulation-Cell Division (RND) efflux pumps exhibit high resistance to antibiotics and are challenging to target due to their ability to expel a broad spectrum of antimicrobial agents, including fluoroquinolones, β-lactams, and biocides, making them difficult to kill, especially in biofilm formations.

Innovation Solution

A method involving carrier bacterial cells that conjugate with target cells, transferring a conjugative plasmid encoding an antibacterial agent toxic to the target cells, allowing the agent to be expressed and killing the target cells, even in the presence of RND efflux pumps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional antibiotics are used to treat bacterial cells with RND efflux pumps, then the antibiotics should kill the bacteria, but the RND efflux pumps expel the antibiotics and confer resistance

Engineering Contradiction:

Improveantibiotic killing efficacyVSAvoidefflux pump-mediated antibiotic resistance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent uses a conjugative plasmid as an intermediary vector to deliver antibacterial agents directly into the target bacterial cells. The plasmid-mediated conjugation system bypasses the efflux pump defense mechanism by transferring DNA encoding toxic proteins (such as listeriolysin O) directly from donor to recipient cells, allowing the toxic agent to be expressed inside the target cell where it can kill the bacteria despite the presence of RND efflux pumps.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the conventional chemical antibiotic mechanism with a biological toxin mechanism. Instead of relying on antibiotics that are pumped out by RND efflux systems, the invention uses plasmid-encoded toxic proteins (hemolysins, listeriolysins) that are expressed directly within the bacterial cell, substituting the chemical action of antibiotics with a biological killing mechanism that is not substrate for efflux pumps.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If carrier cells transfer plasmids to target cells, then antibacterial agents can be delivered to kill target cells, but the process requires direct cell-to-cell contact through conjugation

Engineering Contradiction:

Improvetarget cell killing efficacyVSAvoidconjugation process complexity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The conjugative plasmid system serves multiple functions simultaneously: it acts as the vector for DNA transfer, encodes the antibacterial toxic agent, and provides the machinery for cell-to-cell contact and DNA transfer. This multi-functionality consolidates several operations (vector delivery, gene expression, and killing) into a single unified system that operates through natural bacterial conjugation mechanisms.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If RND efflux pumps expel antibiotics, then bacteria show intrinsic resistance, but conjugative plasmid transfer can still deliver toxic agents to these resistant cells

Engineering Contradiction:

Improvemethod effectiveness against resistant bacteriaVSAvoidconventional antibiotic treatment failure

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent inverts the conventional approach by instead of trying to overcome efflux pump resistance with more antibiotics, it uses the bacterial conjugation system itself to deliver the killing agent. The plasmid is transferred from a donor cell to the resistant target cell, and the toxic agent is expressed within the target cell, effectively using the bacteria's own horizontal gene transfer capability against them.

Inventive Principle:

Principle #13The other way round (Inversion)

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

This method achieves high rates of target cell killing, with over 90% efficacy, even in biofilms, by effectively delivering antibacterial agents using conjugation, despite the presence of RND efflux pumps, and maintains bactericidal effects on surfaces.

Implementation Method 1

the carrier cell comprises a conjugative plasmid encoding an antibacterial-microbial agent that is toxic to target cells. A carrier bacterium is capable of conjugative transfer of plasmid DNA encoding the agent to a target cell.

Methodology Applied

Scientific EffectConjugation:

Data Source

PatentUS20240251800A1Antibacterial methods & cells

Publication Date: 2024.08.01 FOLIUM FOOD SCI LTD

AI summary

The invention relates to methods of killing bacterial target cells comprising Resistance-Nodulation-Cell Division (RND)-efflux pumps, as well as carrier cells useful for this purpose wherein the carrier cells comprise a conjugative plasmid encoding an antibacterial-microbial agent that is toxic to target cells. A carrier bacterium is capable of conjugative transfer of plasmid DNA encoding the agent to a target cell.