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Calle Catedrático Agustín
Escardino, 9, 46980,
Paterna, València, Spain

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Success cases

Bioprospecting the solar panel microbiome

At DARWIN, we have conducted various bioprospecting studies focused on the microbiome inhabiting the surfaces of solar panels. This extreme environment is characterized by high levels of solar irradiation, desiccation, and temperature fluctuations, leading to the adaptation of microorganisms living there. One way to survive the effects of radiation is through the accumulation of pigments, particularly carotenoids, which are very interesting due to their high commercial value and antioxidant capacity.

 

Problem

 

Reactive Oxygen Species (ROS) are metabolites generated at high levels under stress conditions that can be harmful for the cells. Microbial communities living in extreme environments, such as solar panels, are continuously exposed to sunlight radiation. To cope with this stress, the microorganisms develop different strategies, including efficient DNA repair systems, pigments production, and protection against oxidative stress.

 

For this reason, solar panels surfaces are good candidates for the search of novel antioxidant microorganisms. Although the taxonomic and functional composition of these communities has been studied previously, the process of microbial colonization remain unclear.

 

Solution

 

At DARWIN, we isolated 68 microorganisms (the vast majority pigmented) belonging to 20 different microbial genera from the dry and highly irradiated surface of solar panels located at the University of Valencia. From this collection, a total of 14 isolates were selected (excluding pathogens or opportunistic pathogens) to perform oxidative stress tests in Caenorhabditis elegans, a nematode often used as a model organism due to its small size and simplicity, short life cycle, and low economic cost. Additionally, it feeds on microorganisms, which means it can be administered our selected pigmented strains.

 

DARWIN also monitored the microbial colonization process for 24 months by conducting weekly measurements of photovoltaic efficiency, high-throughput sequencing of the 16S rRNA gene, and studying the effect of antimicrobial compounds on the microbial biocenosis composition. This was the first long-term study of the solar panel colonization process, and our results revealed that species richness and biodiversity exhibit seasonal fluctuations and that there is a trend towards an increase in specialized taxa (adapted to solar panels) and a decrease in generalist taxa.

 

Completion Year: 2020

 

Success

 

High-throughput in vivo assays using Caenorhabditis elegans as an experimental model demonstrated the high antioxidant and UV protection properties of the bacterial isolates rich in carotenoids. The results suggest that solar panels harbor a microbial community that includes strains with potential applications as antioxidants.

 

A total of 10 out of the 14 isolates demonstrated protection of C. elegans against oxidative stress, providing between 57-78% survival compared to worms fed a control diet, which had an average survival of 37%. These isolates also protected C. elegans against UV radiation, and an analysis of the carotenoids contained in these microorganisms revealed the presence of colorless carotenoids, such as phytoene and phytofluene, as well as colored carotenoids, such as β-cryptoxanthin, adonirubin, canthaxanthin, astaxanthin, and β-carotene.

 

These results reveal the high antioxidant capacity of microorganisms inhabiting the surface of solar panels and their biotechnological potential due to the production of commercially valuable carotenoids for cosmetic and personal care applications. The results of monitoring microbial colonization of solar panels also show that these are extreme environments that select for a particular microbial community.

 

Papers