Bacillus Sporulation via Fed-Batch C/N Ratio Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for culturing Bacillus bacteria face challenges in achieving high concentrations of spores and metabolites due to limitations in oxygenation and substrate concentration, leading to inhibited sporulation and prolonged culture times, especially when using high sugar concentrations.
Innovation Solution
A fed-batch culture method is employed, where a medium with a sugar concentration between 50.1 g/L and 100 g/L is used initially, and a fed-batch medium with a C/N ratio of 5.5 to 13.5 is added, containing a sugar-source raw material and a nitrogen-containing compound, to maintain optimal growth conditions and prevent substrate inhibition, while heat-sterilizing the components to avoid Maillard reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the concentration of nutritional substrates in media is increased to obtain higher concentration of spores or metabolites, then the bacterial cell concentration and metabolites increase in proportion, but the culture system becomes unable to adequately oxygenate due to increased oxygen demand, leading to poor growth and longer culture time
Solution Approach 1:
The patent employs fed-batch culture where substrate concentration is dynamically adjusted during the culture process. Initially, high concentration substrates are provided to promote rapid growth, then substrate addition is controlled or stopped to maintain oxygen availability, and finally substrate is replenished to extend the production phase. This dynamic adjustment resolves the contradiction between substrate concentration and oxygen demand.
Solution Approach 2:
The patent uses a two-stage approach where bacterial growth is first promoted under conditions of adequate oxygen supply, and then substrate is added to induce metabolite production. This preliminary action of establishing proper oxygenation before substrate addition prevents the oxygen demand problem while still achieving high metabolite concentrations.
2Quantity of substance
If glucose concentration in medium is increased above 20 g/L to improve growth, then bacterial cell concentration increases, but sporulation is inhibited
Solution Approach 1:
The patent implements periodic substrate addition during fed-batch culture. Substrate is added in intervals rather than continuously, allowing periods of high cell growth followed by periods where substrate limitation triggers sporulation. This periodic action resolves the contradiction between maintaining high cell concentration and enabling sporulation.
Solution Approach 2:
The patent first allows bacterial cells to grow to high concentrations under adequate substrate and oxygen conditions, then subsequently adds substrate under controlled conditions to induce sporulation. This preliminary growth phase followed by controlled substrate addition ensures both high cell concentration and successful sporulation.
3Productivity
If fed-batch culture is used to obtain high concentrations of spores and metabolites, then productivity improves, but the culture time extends to as long as 60 hours when sugar concentration is lowered and materials are fed at low levels
Solution Approach 1:
The patent uses dynamic substrate addition strategies where the rate and timing of substrate feeding are optimized to maintain high growth rates throughout the culture process. This prevents culture time extension while still achieving high productivity through fed-batch operation.
Solution Approach 2:
The patent optimizes multiple parameters including substrate concentration, C/N ratio, and feeding timing to achieve high productivity within reduced culture time. By changing these parameters strategically, the patent avoids the 60-hour culture time while maintaining improved productivity over batch culture.
4Reliability
If chemically pure compounds are used in complete synthetic medium to culture Bacillus bacteria, then controlled culture conditions are achieved, but huge cost is required to obtain spores through large-scale culturing
Solution Approach 1:
The patent changes the composition parameters of the culture medium by replacing chemically pure compounds with inexpensive raw materials such as sugar-source raw materials and nitrogen-containing compounds from food production residues. This parameter change maintains controllable culture conditions while dramatically reducing production costs for large-scale spore production.
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 approach allows for high bacterial concentrations and efficient production of spores and metabolites, such as cyclic lipopeptides, by maintaining optimal oxygen levels and substrate availability, thereby overcoming previous limitations in sporulation rates and culture duration.
Implementation Method 1
a fed-batch medium which contains a sugar or a sugar-source raw material and a nitrogen-containing compound
Implementation Method 2
heat-sterilizing the components to avoid Maillard reactions
Data Source
AI summary
An objective of the present invention is to provide a culturing method, by which Bacillus bacterial spores can be efficiently produced. The present invention provides a method for producing Bacillus bacterial spores, comprising culturing Bacillus bacteria in a liquid medium containing a sugar or a sugar-source raw material at a concentration between 50.1 g/L and 100 g/L at the start of culture, and then in the course of the culture, feeding a fed-batch medium containing a sugar or a sugar-source raw material and a nitrogen-containing compound, and having the weight ratio (C/N ratio) of carbon atoms to nitrogen atoms ranging from 5.5 to 13.5 to the liquid medium.