Biology alum helps characterize new bacterial species

Fabiola Aviles, one of our former Biology majors, is the lead author on an article describing the discovery of a new bacterial species. The species was isolated from the San Elijo Lagoon near San Diego, where I took some samples while attending a science conference in 2019. After returning back to the lab, one of the samples gave bright yellow colonies on the plates. Fabiola extracted its DNA and sequenced the genome of this bacterium to find out its identity and characteristics.

Fabiola Aviles running the Illumina Miniseq sequencer at the BU labs.

At first glance we didn’t think we had anything unique there, because it looked like other soil bacteria, however Fabiola insisted on including it in her thesis project at BU, which made us look a little closer at the genome, and we were surprised to find it was a rather unique species.

As it turns out, the bacterium has the ability to decompose chitin (which is the hard outer shell of lobsters, shrimp and crabs, and insects), and cellulose, but can also feed on an unusual sugar called fucose. Therefore, the species was named Cellulosimicrobium fucosivorans (which literally means ‘fucose eating’ microbe). Fucose is found in insect and mammalian guts, but also in plant and algal polysaccharides. The ability to metabolize fucose gives certain bacteria in the gut flora a competitive advantage for colonization and invasion, making them pathogenic. Little is known about the ability to metabolize this sugar in nature.

Cellulosimicrobium fucosivorans cultivated on fucose and glucose.

It turned out to be even more surprising when we found out that the ability to feed on fucose was linked to the yellow color of the bacteria. Without the fucose, the bacteria are a pale white-pink color, but produce yellow carotenoids when fucose is present. These carotenoids are known to protect species from UV radiation damage from the sun (kind of like an internal sunscreen).

If you think about the environment this bacterium lives in, this starts making sense. There is plenty of algal and plant material, and if a bacterium can take the advantage of feeding on a component that others don’t use (for example fucose), then it has a competitive advantage. In addition, the coastal lagoons in San Diego gets lots of sun exposure and producing your own sun protection (carotenoids) seems a necessity for survival. So, this species turns out to be well adapted to living in the coastal sunny lagoon area.

The findings and a full detailed description were recently published in Archives of Microbiology and can be accessed here: https://rdcu.be/cmTYq

This is not Fabiola’s first scientific achievement. During her undergraduate studies at BU she also published a genome paper on Thiorhodococcus bacteria and recently completed a metagenomic study of the Piñones Lagoon in her home state of Puerto Rico. Fabiola plans to continue her studies in the field of marine biology, and these publications will undoubtedly help her in building out a successful scientific career.

This is project is a perfect example of how it is important to have an understanding of the different scientific disciplines, like microbiology, biochemistry, genomics, evolution, and bring them together to make unique discoveries.

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