CO2-Enriched Air Fermentation for RTX-Toxin Yield
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Solution Overview
Problem
Current methods for producing RTX-toxins ApxI and ApxIII by culturing Actinobacillus pleuropneumoniae in a liquid medium are limited by low production yields, with previous attempts focusing on the stationary phase and not effectively utilizing carbon dioxide for enhanced production during the exponential growth phase.
Innovation Solution
Passing air with a carbon dioxide content above normal atmospheric levels through the medium during the exponential growth phase, combined with the use of a bicarbonate buffer and calcium borogluconate to enhance toxin production and prevent calcium precipitation, allows for increased yields and reduced production time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If air with normal atmospheric carbon dioxide levels is used during cultivation, then the cultivation process is simple and straightforward, but the production yield of RTX-toxins remains low
Solution Approach 1:
The patent applies parameter changes by modifying the carbon dioxide concentration in the air supply from normal atmospheric levels (0.04%) to enriched levels (5-10% v/v). This parameter change in the gas composition directly stimulates increased RTX-toxin production during the exponential growth phase, resolving the contradiction between simple air supply and low production yield
Solution Approach 2:
The patent implements preliminary action by enriching the air with carbon dioxide before it contacts the culture medium, and introducing it during the exponential growth phase. This preliminary preparation of the gas environment primed the bacterial culture for enhanced toxin production before the stationary phase begins, avoiding the need for complex mid-process interventions
2Productivity
If the cultivation is extended into the stationary phase to maximize toxin production, then the toxin yield increases, but the production time and associated costs increase
Solution Approach 1:
The patent applies preliminary action by introducing carbon dioxide-enriched air during the exponential growth phase, which primes the bacteria to produce toxins earlier and at higher rates. This preliminary stimulation shifts the production kinetics so that maximum toxin yield is achieved sooner, reducing the need for extended stationary phase cultivation
Solution Approach 2:
The patent implements periodic action by introducing carbon dioxide enrichment specifically during the exponential growth phase rather than continuously. This timed, periodic intervention optimizes toxin production during the most productive period while avoiding unnecessary extension of the overall cultivation time into the stationary phase
3Reliability
If calcium is added to the medium to support bacterial growth, then the growth requirements are met, but calcium precipitation occurs affecting medium stability
Solution Approach 1:
The patent applies the intermediary principle by introducing carbon dioxide as a mediator that indirectly addresses calcium stability. The carbon dioxide forms carbonic acid in the medium, which lowers the pH and prevents calcium precipitation without requiring complex chelating agents or buffer systems. This intermediary approach maintains medium stability while keeping the composition relatively simple
Solution Approach 2:
The patent uses parameter changes by allowing the pH of the medium to decrease through carbon dioxide dissolution, which shifts the chemical equilibrium and prevents calcium precipitation. This parameter change (pH reduction) provides a simple mechanism to maintain calcium solubility without adding complex stabilizing agents to the medium formulation
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 significantly increases the production of RTX-toxins ApxI and ApxIII, potentially doubling yields and reducing lipopolysaccharide levels, while maintaining pH stability and preventing calcium precipitation issues, thus improving the efficiency and economics of the fermentation process.
Implementation Method 1
passing air which has a carbon dioxide content above a normal atmospheric level through said medium during the production phase of the RTX-toxins
Implementation Method 2
combined with the use of a bicarbonate buffer and calcium borogluconate to enhance toxin production and prevent calcium precipitation
Data Source
AI summary
The current invention pertains to a method to produce RTX-toxins Apxl or Apxlll by culturing Actinobacillus pleuropneumoniae bacteria in a liquid culturing medium that supports growth of the bacteria, characterised in that air is passed through the medium, wherein the air has a carbon dioxide content above normal atmospheric level to increase RTX-toxin production during the production phase of the RTX-toxins.