Since Michael Cressé Potter, a British mycologist, noticed in 1911 that brewer's yeast could produce energy, the harnessing of microbial energy has been a long-standing interest of scientists.
E.Coli as an Electricity Generator
However, the efficiency of budding and tiny bioreactors has been seen to be too low in terms of practicality. There is also another issue regarding the pickiness of microbes in choosing which substrates to digest for electricity generation.
Now, researchers from the Swiss Federal Institute of Technology Lausanne (EPFL) were able to bioengineer Escherichia Coli, or E. coli, to produce electricity from wastewater sources. Interestingly, these endeavors have surpassed other recently bioengineered strains.
Chemical engineer Ardemis Boghossian, who is the study's senior author, explains that there are certain exotic microbes that are natural electricity producers; they may only do so when specific chemicals are present.
As E. coli could grow from various sources, the researchers were enabled to generate electricity in different environments, including that of wastewater.
To boost the bacteria's capacity to produce energy, the scientists modified the bacteria's genome to include certain instructions pertaining to the protein complex that can be found within Shewanella oneidensis, which is one of the most well-known bacteria for generating energy. S. oneidensis is capable of producing an electron flow when it decreases metals to pick up toxic metals.
The team incorporated the components of the electricity-generating pathways of S. oneidensis to E. coli. By doing so, the scientists were able to boost its electroactivity by two-fold in comparison to strains that were previously bioengineered, as they only included a certain part of S. oneidensis' pathway.
It is important to note, however, that these procedures were performed in one chamber and under laboratory conditions. The challenge lies in whether the technology could potentially work in an industrial setup.
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Generating Energy From Brewery Wastewater
Earlier research has discovered that algae can play a role in the treatment of brewery wastewater. Breweries require water processing before disposal, as this water holds a heady mix of starches, sugars, yeast, and alcohols that may facilitate microbial blooms if left untreated.
The team then tried out their E. coli technology in a wastewater sample that was taken from a local brewery in Lausanne. The modified bacteria then gobbled up the waters in more than 50 hours.
Boghossian explains that the bioengineered bacteria exponentially flourished as they fed off the waste. S. oneidensis, on the other hand, was unable to take in the effluent.
Such findings suggest that the bioengineered E. coli could be more suitable for the treatment of commercial wastewaters despite its lower potential to generate energy compared to S. oneidensis.
The appetite of E. coli for chemical substrates also means that this bioengineered bacteria could also adapt to other waste feedstocks or streams.
However, the scientists need to further see if the engineered E. coli is capable of processing massive volumes.
Nevertheless, if the efficiency of the system is seen, it may lead to significant energy conservation. Boghossian explains that rather than adding energy to the system for organic waste processing, energy can be produced while organic waste is being processed, as seen in the study. This means that the system is hitting two birds with one stone.
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