Waste-eating bacteria produce hydrogen
Professor Matti Karp’s research group is growing bacteria under a number of different environmental conditions and developing genetically engineered bacterial strains to maximize the production of hydrogen.
A research group led by Professor Matti Karp is looking at ways to turn wastewater generated in the pulp and paper industry into a sustainable source of hydrogen.
Certain bacteria are capable of producing hydrogen as a by-product of their natural metabolic processes.
“The biological production of hydrogen resembles the process of brewing beer, whereby microbes convert sugar into alcohol,” describes Matti Karp, a professor of biotechnology in the Department of Chemistry and Bioengineering at Tampere University of Technology (TUT).
The bacteria under investigation feast on a diet of industrial effluent from pulp and paper mills and crude glycerol derived from biodiesel production. They include thermophiles that live in hot springs and halophiles that are abundant in salt-saturated lakes.
The research group is, among others, cultivating a strain of bacteria that grows optimally at 67 degrees Celsius and another that thrives in brine with a salt concentration of 15 per cent. The high temperature and salt content prevent the growth of other microbes that would consume the produced hydrogen.
Collaboration between dry lab and wet lab
The study of bacterial strains and production processes brings together researchers whose expertise lies in molecular biotechnology, systems biology or bioprocess engineering.
The members of Karp’s research group maintain close collaboration with their colleagues in the Department of Signal Processing, which houses a “dry lab” for developing, among others, computational models of the functions of bacterial genes. The models enable the researchers who work in the “wet lab” operated by the Department of Chemistry and Bioengineering to determine the optimal conditions for bacterial growth and the necessary genetic modifications to improve the yield of hydrogen.
The group has an international partnership with the University of Delhi South Campus, where researchers have developed biological methods for the detoxification of lignocellulose using enzymes produced by moulds. Toxic compounds must be removed from industrial wastewater before feeding it to bacteria.
Effective system for hydrogen production
The research is already showing promising results. For example, the bacteria that flourish in a salty environment are capable of converting hydrogen ions, which are present in the sugars they eat, into hydrogen gas with an efficiency of nearly 100 per cent. The problem is that they multiply too slowly, whereas the heat-loving bacteria reproduce every ten minutes.
“Thermophilic bacteria reach their maximum growth rate in seven hours, all the while converting 97 per cent of the hydrogen ions found in their food into hydrogen gas,” says Matti Karp.