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A group of researchers has identified a multispecific bacterial community that could increase the efficiency of hydrogen generation through microbial metabolism. The proposed hydrogen system achieved a more than double production rate compared to typical biological hydrogen production technologies.
A team of researchers from the University of Córdoba, in Spain, has identified a natural multi-species bacterial community that could be used with microalgae for the commercialization of hydrogen produced through microbial metabolism (bioH2).
Biological production of bioH2 involves growing living organisms such as bacteria, cyanobacteria and algae that release H2. This technology allows H2 to be produced at low temperatures, between 23 ºC and 30 ºC, and at atmospheric pressure, which could be integrated with wastewater treatment.
“The main limitation of bio-H2 production lies in its low production rate, which makes it commercially inefficient and expensive,” Neda Fakhimi, co-author of the research, explained to pv magazine . However, by integrating this technology with other applications such as waste management - such as wastewater treatment - and the valorization of biomass, including the production of biofertilizers, feed, food, etc., it can get closer to industrialization." .
The research group specified that the identified bacterial community comes from a contaminated culture of the microalgae Chlamydomonas reinhardtii , which can expand the balance of the community itself by avoiding common problems such as excessive bacterial growth.
“Compared to other studies, we have doubled the hydrogen production rate, in addition to having lengthened hydrogen production. In other jobs, academics ran the system for 10-15 days, no more,” Fakhimi stated. “The industrial-scale production of H2 from the biological activity of microorganisms has not yet been publicly proposed.”
The proposed hydrogen system works better than previous ones because the bacterial consortium has unique characteristics when co-cultured with Chlamydomonas . The bacteria Microbacterium forte sp. nov. It is the novelty of the system, since it uses and creates nutrients that help regulate co-culture.
“In algal-bacterial consortia, bacteria usually dominate the entire culture, which negatively affects the viability of the algae, which are the only producers of bio-H2 in our system. The relationship, based on nutrient dependence, in which each member contributes to the growth of the others, can regulate the community to prevent a single member from dominating the crop. This ensures a cohesive system for bio-H2 production,” says Fakhimi.
Fakhimi explained, for example, that Microbacterium forte sp. nov. It cannot synthesize biotin and thiamine, necessary for growth. It also cannot use sulfate as a source of sulfur (S), so it needs reduced forms of S such as cysteine ??and methionine. The alga provides the mentioned essential nutrients to Microbacterium forte sp. nov. , while the bacteria provides ammonium and acetic acid, which favor the growth of the algae and the production of H2.
The team discovered that among the bacterial community, Microbacterium forte sp. nov. was solely responsible for the improvement in hydrogen production. The other two bacteria contribute to maintaining the health of the algae.
“When incubated in a medium containing mannitol and yeast extract, the natural bacterial community composed of Bacillus cereus and two new bacteria – Microbacterium forte sp. nov. and Stenotrophomonas goyi sp. nov. – can promote and maintain hydrogen production by algae,” the researchers say.
Conventional research in this field typically emphasizes axenic cultures, which are individual cultures, while the new work investigates cocultures of algae and bacteria. Coculture technology is developing, but cocultures often face problems such as acidification of the medium, nutrient competition, and overgrowth of one of the partners.
The academics presented their findings in the study “ Chlamydomonas reinhardtii and Microbacterium forte sp. nov., a mutualistic association that favors sustainable hydrogen production ” ( Chlamydomonas reinhardtii and Microbacterium forte sp. nov. ), recently published in Science of The Total Environment . According to them, this work opens the door to the production of photohydrogen concomitant with the generation of algal biomass using nutrients not suitable for the growth of mixotrophic algae. |
