Production of succinic acid by Actinobacillus succinogenes in attached-growth bioreactors and dynamic modelling of biofilm formation
(2023) KMBM05 20231Applied Microbiology
- Abstract
- Actinobacillus succinogenes is a microorganism is a very efficient producer of succinic acid, a chemical with a wide range of industrial applications. The bacterium is prone to form biofilm, a flocculation of cells attached to a surface. In this study, the bioproduction of succinic acid using Actinobacillus succinigenes 130Z was performed in microplate, bottle, and bioreactor systems to gain new insight regarding the biofilm formation process. From microplate experiments the growth kinetics of both suspended and attached cells were characterized at different initial pH and concentration of yeast extract, indicating that biofilm formation is enhanced at lower pH. The maximum specific growth rate was determined to be between 0.178 h-1 and... (More)
- Actinobacillus succinogenes is a microorganism is a very efficient producer of succinic acid, a chemical with a wide range of industrial applications. The bacterium is prone to form biofilm, a flocculation of cells attached to a surface. In this study, the bioproduction of succinic acid using Actinobacillus succinigenes 130Z was performed in microplate, bottle, and bioreactor systems to gain new insight regarding the biofilm formation process. From microplate experiments the growth kinetics of both suspended and attached cells were characterized at different initial pH and concentration of yeast extract, indicating that biofilm formation is enhanced at lower pH. The maximum specific growth rate was determined to be between 0.178 h-1 and 0.413 h-1 for suspended cells and 0.063 h-1 and 0.089 h-1 for attached cells, depending on the initial conditions. During batch fermentation in glass bottles, Kaldnes K1 packing material was used as biofilm support material for comparison between fermentation without and with packing material. No significant difference was found regarding suspended cell growth, substrate consumption, and product formation. A difference was observed regarding the formation of biofilm as measurements indicated more rapid biofilm formation and elevated levels of biofilm on packing material compared to glass surfaces. The maximum specific growth rates when no packing material was present were 0.224 h-1 and 0.413 h-1 for 20 ml bottles and 100 ml bottles, respectively. With packing material these values were 0.209 h-1 and 0.427 h-1. Kinetic parameters calculated from the experiments were used to calibrate a kinetic model which well represented the experimental results. A bioreactor setup using a bubble column reactor was constructed and fermentations were performed in both batch and continuous operation. The bioreactor experiments were all contaminated at some time during the fermentation processes with limited results. Using data from a CSTR fermentation the model was validated which showed difficulties in predicting suspended and attached cell growth. (Less)
- Popular Abstract
- During this project a bacteria called Actinobacillus succinogenes was used production of succinic acid, a chemical that has several applications in the industry. The bacteria have the ability to form biofilm, a cluster of cells that have attached to a surface. This is interesting as the biofilm allow for higher cell concentration and can survive and produce succinic acid under hasher conditions. The process of biofilm formation is complex and is difficult to predict due to their unpredictability, slow growth, and difficult measurement techniques. This can cause problems during fermentations as good predictions are necessary to gain better control over the system. More research is therefore necessary regarding the kinetics of biofilm... (More)
- During this project a bacteria called Actinobacillus succinogenes was used production of succinic acid, a chemical that has several applications in the industry. The bacteria have the ability to form biofilm, a cluster of cells that have attached to a surface. This is interesting as the biofilm allow for higher cell concentration and can survive and produce succinic acid under hasher conditions. The process of biofilm formation is complex and is difficult to predict due to their unpredictability, slow growth, and difficult measurement techniques. This can cause problems during fermentations as good predictions are necessary to gain better control over the system. More research is therefore necessary regarding the kinetics of biofilm formation which is the focus of this study.
During the project different cultivation methods were utilized for characterization of cell growth, substrate consumption, and product formation. Biofilm was quantified using crystal violet, a dye commonly used for cell quantification. Biofilm formation was compared on both plastic packing material and glass surfaces in bottles to see if increased formation and better production of succinic acid is possible. A bioreactor setup was constructed to perform fermentations on a larger scale which is important before moving up to even larger scale to finally end with industrial production.
From the results, a mathematical model was produced for prediction of suspended cell growth, attached cell growth, substrate consumption, and product formation. The predictions of the model were compared to the experimental results which showed that it represented the data quite well for batch operation when no changes are made to the system.
The most valuable results from this study were the biofilm formation results which indicated that:
• Biofilm formation is dependent on the pH of the fermentation medium.
• Crystal violet staining can be used as a method for biofilm measurement.
• Attached cell growth occurs more slowly than suspended cell growth.
• Cells attach more rapid to surfaces on plastic packing material than glass surfaces.
More research can be done regarding the biofilm formation process, especially the influence of pH and more refined quantification methods. This could provide more insight in the phenomenon which could be used to improve the accuracy of the prediction model. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9125645
- author
- Östberg, Henrik LU
- supervisor
-
- Ed van Niel LU
- organization
- alternative title
- Tillverkning av bärnstenssyra av Actinobacillus succinogenes i adherenta bioreaktorer och dynamisk modellering av biofilmsformation
- course
- KMBM05 20231
- year
- 2023
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- Actinobacillus succinogenes, Succinic acid, Biofilm, Attached-growth bioreactor, Dynamic modelling, Cell cultivation, Applied microbiology
- language
- English
- id
- 9125645
- date added to LUP
- 2023-06-19 12:23:48
- date last changed
- 2023-06-19 12:23:48
@misc{9125645,
abstract = {{Actinobacillus succinogenes is a microorganism is a very efficient producer of succinic acid, a chemical with a wide range of industrial applications. The bacterium is prone to form biofilm, a flocculation of cells attached to a surface. In this study, the bioproduction of succinic acid using Actinobacillus succinigenes 130Z was performed in microplate, bottle, and bioreactor systems to gain new insight regarding the biofilm formation process. From microplate experiments the growth kinetics of both suspended and attached cells were characterized at different initial pH and concentration of yeast extract, indicating that biofilm formation is enhanced at lower pH. The maximum specific growth rate was determined to be between 0.178 h-1 and 0.413 h-1 for suspended cells and 0.063 h-1 and 0.089 h-1 for attached cells, depending on the initial conditions. During batch fermentation in glass bottles, Kaldnes K1 packing material was used as biofilm support material for comparison between fermentation without and with packing material. No significant difference was found regarding suspended cell growth, substrate consumption, and product formation. A difference was observed regarding the formation of biofilm as measurements indicated more rapid biofilm formation and elevated levels of biofilm on packing material compared to glass surfaces. The maximum specific growth rates when no packing material was present were 0.224 h-1 and 0.413 h-1 for 20 ml bottles and 100 ml bottles, respectively. With packing material these values were 0.209 h-1 and 0.427 h-1. Kinetic parameters calculated from the experiments were used to calibrate a kinetic model which well represented the experimental results. A bioreactor setup using a bubble column reactor was constructed and fermentations were performed in both batch and continuous operation. The bioreactor experiments were all contaminated at some time during the fermentation processes with limited results. Using data from a CSTR fermentation the model was validated which showed difficulties in predicting suspended and attached cell growth.}},
author = {{Östberg, Henrik}},
language = {{eng}},
note = {{Student Paper}},
title = {{Production of succinic acid by Actinobacillus succinogenes in attached-growth bioreactors and dynamic modelling of biofilm formation}},
year = {{2023}},
}