Bacillus Fermentation Feed Rate Shift for Protein Yield
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Solution Overview
Problem
Current large-scale industrial fermentation processes for producing proteins using Bacillus host cells face challenges in maximizing protein yield, particularly in optimizing carbon source feeding rates and temperatures to enhance protein expression and secretion.
Innovation Solution
A method involving a two-phase cultivation strategy where Bacillus host cells are initially cultivated with a carbon source at increasing rates followed by a phase with a constant or decreasing carbon source feed rate, accompanied by a temperature shift from the first to the second cultivation phase, to optimize protein production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carbon source is fed at high constant rate throughout cultivation, then biomass growth is maintained, but protein yield per carbon source decreases
Solution Approach 1:
The patent applies dynamic feeding strategy by transitioning from exponential feed rate (first phase) to constant or decreasing feed rate (second phase). This dynamic adjustment optimizes carbon source utilization at different cultivation stages, achieving up to 400% increase in protein yield per carbon source compared to constant high-rate feeding
Solution Approach 2:
The cultivation process is divided into two distinct phases with different feeding strategies: Phase 1 uses exponential feeding for rapid biomass accumulation, while Phase 2 uses constant or decreasing feeding for optimized protein production. This segmentation allows each phase to be optimized independently for its specific objective
2Productivity
If temperature is kept constant throughout cultivation, then process control is simple, but protein expression efficiency is suboptimal
Solution Approach 1:
The patent implements dynamic temperature control by maintaining a first temperature during Phase 1 and shifting to a second temperature during Phase 2. This temperature transition optimizes protein expression efficiency while using standard bioreactor temperature control capabilities, avoiding excessive system complexity
Solution Approach 2:
The temperature shift is timed to occur at the transition between Phase 1 and Phase 2, preparing the culture conditions in advance for optimal protein expression. This preliminary adjustment ensures that when the culture enters the protein production phase, the temperature is already optimized
Data Source
AI summary
The present invention relates to the field of industrial fermentation. In particular, it relates to method for cultivating a Bacillus host cell comprising the steps of (a) inoculating a fermentation medium with a Bacillus host cell comprising an expression construct for a gene encoding a protein of interest, cultivating for a first cultivation phase the Bacillus host cell in said fermentation medium under conditions conducive for the growth of the Bacillus host cell and the expression of the protein of interest, wherein the cultivation of the Bacillus host cell comprises the addition of at least one feed solution and wherein the at least one feed solution provides a carbon source at increasing rates, and (c) cultivating for a second cultivation phase the Bacillus host cell culture obtained in step (b) under conditions conducive for the growth of the Bacillus host cell and the expression of the protein of interest, wherein the cultivation comprises the addition of at least one feed solution and wherein the at least one feed solution provides a carbon source at a constant rate, at decreasing rates or at rates increasing less than the rates in step (b), wherein said constant rate or the starting rate of said decreasing rates or the starting rate of said rates increasing less than the rates in step (b) is below the maximum rate of the first cultivation phase. Further contemplated is a Bacillus host cell culture obtainable by said method.