What you give, I take

SynCell News • June 30, 2020

The bacterial and human world have an intriguing and extremely complex relationship that goes back to our most primitive origin. Most aspects of our behavior, biology and interactions are related, in one way or another, to our bacterial companions. Therefore, it seems unavoidable to think of both species trying to get profit out of the other. At the end, except for some cases, we both live in symbiosis.

Our behavior, biology and interactions are related to our bacterial companions

When scientists realized that bacteria were able to produce nanomaterials as a by-product of their own survival, we found that this behavior might be a useful material for us. Soon enough, the scientific community discovered that, after purification and isolation, these bacterial-produced nanomaterials could be used for a purpose. Biosensors, electronics, catalysts, antibacterial agents or anticancer materials were quickly reported as based on bacteria-mediated nanomaterials [Iravani 2014], [Gahlawat and Choudhury 2019]. The list goes on and on.

Consequently, researchers started to isolate and use bacteria as biofactories. Since these unicellular organisms are relative easy to handle, cultivate and manipulate, this was not an impossible task [Lee 1996]. With the help of special conditions or bioreactors, most early studies were focused on the production of gold nanoparticles (AuNPs) by Bacillus subtilis or Pseudomonas aeruginosa, among others. Researchers found that bacterial cells can be incubated with a gold chloride (AuCl3) solution, resulting in the formation of AuNPs of around 5–200 nm in diameter [Lee 1996] [Beveridge and Murray 1980] [Karthikeyan and Beveridge 2002] [Kashefi, Tor, Nevin and Lovley 2001] [Lengke and Southam 2006] [Konishi et al. 2007].

 Using bacterial cells silver ions, which are highly toxic, can be reduced and converted into silver nanoparticles with no harm.

Later, it was discovered that different bacteria show different degrees of resistance to metallic ions present in their environment. Starting from this premise, many other metallic nanostructures have been produced using bacterial cells. Interestingly, silver ions (Ag+), which are known to be highly toxic to most microbial cells, can also be reduced and converted into silver nanoparticles (AgNPs) with no harm to the hosts [Slawson, Van Dyke, Lee, and Trevors 1992] [M. Singh, S. Singh, Prasad, and Gambhir 2008].

Besides, many other metallic nanomaterials were synthesized using bacteria and photosynthetic cyanobacteria, including cobalt (Co) [Srivastava and Constanti 2012], copper (Cu) [Singh, Patil, Anand, Milani, and Gade 2010] or mercury (Hg) [Park, Lee, Heo, and Seo 2010]. On the other hand, magnetic nanostructures, such as iron nanoparticles (FeNPs), have also been produced as suitable agents for biomedical applications [Revati and Pandey 2011].

Such is the beauty of nature, that bacteria are able to produce not only monometallic formulations, but also bimetallic nanoparticles [Tuo et al. 2017], quantum dots [Bao et al. 2010] or even magnetic nanostructures that can be used to target tumors [Lee, Purdon, Chu, and Westervelt 2004], and probably many other formulations that we are not even aware of.

At SynCell Biotechnology, we are devoted to understand and analyze the routes of microbial synthesis of nanoparticles, especially focused on chalcogen elements, with the aim to develop novel routes for the production of a new generation of antimicrobial and biomedical agents.