The Industrial Biotech Section Seminars are a series of monthly lectures from internal researchers covering all aspects of research related to industrial biotechnology.
For more information, contact Thea Jess Plesner, tjp@bce.au.dk
Speakers: Laura Munoz, Susmit Chakraborty & Timothé Philippon
Title: Relevance of H2 consumption characteristics for acetogenic and methanogenic bioelectrochemical CO2 reduction
Place: Gustav Wieds Vej 10C, 8000 Aarhus C, Building 3130, Room 303.
Acetogens and methanogens reduce carbon dioxide with H2 as electron donor to obtain energy. This autotrophic metabolism is of interest for CO2 valorization biotechnologies, such as gas fermentation and even more microbial electrosynthesis. Indeed, the ability of those microbes to rapidly consume H2 could enhance electrochemical H2 production, once put near an electrode performing proton reduction. This hypothesis could be important for bio-electrochemical applications if proven to be true. To test our hypothesis, we must first characterize differences in H2 consumption characteristics between available acetogenic and methanogenic strains. Understanding those differences will also aid optimal strain selection for microbial electrosynthesis.
First, we determined the H2 threshold, i.e. the H2 partial pressure at which acetogenesis or methanogenesis halts, for diverse acetogenic (1) and methanogenic strains and observed strong differences. The observed H2 thresholds suggest significant variations in bioenergetics, potentially influencing growth yields and kinetics as well.
Furthermore, we determined the H2 consumption kinetics of different acetogens over a wide range of H2 initial concentrations. Interestingly, we observed that their H2 consumption followed first-order kinetics at under-saturated H2 levels. Our results thus suggest that acetogenic conversion rates can be increased by increasing the H2 partial pressures. In addition, we found strong differences in the first-order H2 consumption coefficient. We hypothesize the kinetic differences can be in part related to different types of hydrogenases of the strains.
In addition, to predict the performance of these strains in bioelectrochemical reactors, we incorporated the H2 threshold and kinetic data into mathematical models. These models simulate the behaviour of the strains under various conditions, such as electric current input, providing useful insights to optimize H2 utilization rates and enhance process efficiency.
Overall, our comprehensive new understanding of H2 dynamics for these hydrogenotrophic strains will guide the selection of suitable biocatalysts for microbial electrosynthesis.
References
1 Munoz, L; Philips, J. No acetogen is equal: Strongly different H2 thresholds reflect diverse bioenergetics in acetogenic bacteria. Environ Microbiol 2023;25:2032–40.
Lecture by: Professor Dr.-Ing. habil. Selin Kara, Department of Biological and Chemical Engineering, Aarhus University, Denmark
Title: "Process intensification for enzymatic decarboxylations: Transitioning from lab to industrial scales”
Place: Gustav Wieds Vej 10C, 8000 Aarhus C, Building 3130, Room 303
The application of nature’s catalysts, “enzymes,” for the synthesis of chemicals is a crucial emerging field of industrial biotechnology to meet the current and future needs of our society for sustainable manufacturing of chemicals. Nature uses an elegant and efficient synthetic strategy: Coupling enzymes in multi-step pathways without intermediate isolation and purification steps with precise spatial control of catalysis. Inspired by nature, the design of multi-step biotransformations has been attracting significant attention within the biocatalysis community. The talk will introduce enzymatic decarboxylation reactions (in cascading systems), exploring the use of non-conventional media, enzyme immobilization, and different operational modes for enhancing the volumetric productivity of these biocatalytic applications.
Lecture by: Maria Florencia Bambace & Herald Wilson Ambrose
Title: "Reuterin-based biological treatment to mitigate methane emissions from pig slurry storage”
Place: Gustav Wieds Vej 10C, 8000 Aarhus C, Building 3130, Room 303.
Methane (CH4) accounts for more than 90% of farmgate greenhouse gas (GHG) emissions in pig farming, with 80% being produced during manure management. In intensive pig production, slurry is stored in manure pits under the barn floor for short term storage (1 to 6 weeks) and in outside storage tanks for longer storage periods. During this time, CH4 is emitted as a result of microbial degradation of organic substrates present in the pig feces, combined with the anaerobic conditions developed under the slurry surface, which promote the activity of methanogens. Acidification is considered a benchmark technology for mitigating CH4 emissions from stored slurry. However, there are several associated drawbacks such as safety issues in application, soil sensitivity to increased sulphur loads during land application, and inhibitory effects on biogas production. Other chemical additives raise further environmental concerns; hence the need for a biological alternative is highly sought for CH4 mitigation in slurry storage.
Biological treatments studied thus far, utilizing microbial or enzymatic additives have shown little to insignificant potential for CH4 mitigation in pig and cattle slurry storages. In this seminar talk, we will present and discuss the results of a successful biological treatment aimed at inhibiting methanogenic activity in slurry storages, conducted on a laboratory scale headspace emission setup. The biological additive involves the use of Limosilactobacillus reuteri, which in the presence of glycerol produces reuterin, a broad-spectrum antimicrobial agent. We assessed the impact of endogenously produced reuterin on CH4 emissions from pig slurry by initially introducing both L. reuteri and glycerol into the slurry, which was then stored for a period of 26 to 30 days, during which CH4 emissions were measured. We also optimized the dosage combination of L. reuteri and glycerol. Our results showed that endogenously produced reuterin reduced CH4 emissions by 74-90% compared to untreated slurry. The environmental and biological aspect of our study will be further discussed, highlighting this novel approach as a promising alternative to H2SO4 or chemical surfactant treatments for reducing methanogenic activity in pig slurry storages.
Lecture by: Nele Van Dessel, CEO from Ernest Pharmaceuticals (USA)
Title: "The use of Salmonella bacteria to treat cancer”
Place: Zoom, https://aarhusuniversity.zoom.us/j/62375855091
The microbial biotechnology course will host an online guest lecture on the use of Salmonella bacteria to treat cancer.
The guest speaker is Nele Van Dessel, CEO from Ernest Pharmaceuticals (USA), a small startup company, trying to bring this new and intriguing microbial biotechnology to the market.
