Doctoral dissertation

Understanding of microbial community dynamics is important for efficient biological hydrogen production

Onyine Jeneth Okonkwo
Synthetic co-cultures or bioaugmentation can be used to enhance thermophilic dark fermentation to obtain high yields of renewable hydrogen.

Currently, majority of the global energy consumption is derived from fossil fuels. This has important impacts on energy security as fossil fuels are depleting non-renewable resources. Furthermore, carbon dioxide emissions from energy production are believed to contribute to global warming. Thus, there is an increasing need to find renewable energy sources that have lower carbon footprint compared to fossil fuels.

Hydrogen is considered as an environmentally friendly fuel. It can be produced from renewable feedstocks and has the highest energy content among all known fuels. Hydrogen can be biologically produced from organic materials through a process called dark fermentation, but commercialization of the process is hindered by low yields and instability of hydrogen production. Therefore, further process optimization is needed to maintain a more stable process and enhance the hydrogen yield.

In her doctoral dissertation, MSc Onyinye Jeneth Okonkwo used microbial strategies, bioaugmentation and synthetic co-cultures of known hydrogen producing microorganisms, to enhance dark fermentative hydrogen production. In addition, molecular biology methods were used to increase the understanding of the microbial community dynamics especially during stress conditions.  

Onyinye's results demonstrated that synthetic co-cultures of carefully selected microorganisms enabled the highest hydrogen yields. Furthermore, bioaugmentation was shown to be an efficient strategy to enhance hydrogen production especially during and after temperature fluctuations. Real-time qPCR method developed in the study to measure HydA gene of Thermotoga neapolitana was successfully used to monitor the dynamics of this microorganism in synthetic co-cultures and mixed cultures. The use of molecular methods such as qPCR and high-throughput sequencing also helped to understand the role of different microorganisms in the microbial consortia and improved the understanding of the microbial community dynamics during stress conditions.

Public defense of a doctoral dissertation on Thursday, 12th of December

MSc Onyinye Jeneth Okonkwo’s dissertation in the field of environmental engineering entitled Enhancement of thermophilic dark fermentative hydrogen production and the use of molecular biology methods for bioprocess monitoring will be publicly examined in University of Paris-Est Marne-la-Vallée, France on Thursday, 12th of December 2019 at 13h30. The opponents will be Assoc. Prof. Gopalakrishnan Kumar from Stravanger University (Norway), Asst. Prof. Maria Alcina Pereira from University of Minho (Portugal) and Assoc. Prof. Cristiano Varrone from Aalborg University (Denmark). The thesis was supervised by Ass. Prof. Aino-Maija Lakaniemi from the Faculty of Engineering and Natural Sciences, Tampere University.

Onyinye Jeneth Okonkwo’s doctoral research has been conducted in the framework of the Advanced Biological Waste to Energy Technologies (ABWET) Innovative Training Network (ITN) European Joint Degree Programme. ABWET has four partner organizations: University of Cassino and Southern Lazio (Italy, coordinator), Université Paris-Est (France), IHE Delft (the Netherlands) and Tampere University of Technology (Finland). The Examination Committee of Onyinye Jeneth Okonkwo’s doctoral dissertation includes one representative from each partner organization.

Onyinye Jeneth Okonkwo comes from Nigeria and works as a researcher in the Bio and Circular Economy research group at Tampere University.

The dissertation is available in the faculty of Engineering and Natural Sciences (Konetalo building K2222A) at Tampere University and by request from the address: suvi.ikonen [at] tuni.fi