Identification and characterization of Antarctic bacteria capable of oxidizing manganese

Dr. Vanesa Amarelle, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE)

Since 2007, one of the research lines of the Department of Biochemistry and Microbial Genomics (BIOGEM) is focused on the identification and characterization of bacterial enzymes with possible biotechnological application. Since 2011, in the framework of a project funded by the Uruguayan Antarctic Institute (IAU), we started working with Antarctic bacterial communities, focusing also on the identification of functions with potential biotechnological application. In the work we have done we have found that bacteria living in Antarctica fulfill a variety of interesting functions from the applied point of view.

Cold environments are the habitat of microorganisms specially adapted to live in these conditions, called psychrophilic microorganisms. These microorganisms usually present different physiological adaptations that allow them to carry out their vital functions at low temperatures, with the production of psychrophilic enzymes being one of the main mechanisms. Although psychrophilic enzymes are able to perform metabolic processes at low or very low temperatures, their optimum temperature is usually located at moderate temperatures making it possible to apply at room temperature. Due to this property, the psychophilic enzymes are an interesting alternative and of great impact in the biotechnological development since they can be used in processes that do not require energy in the form of heat, which is very expensive at industrial level. For these reasons, the cold environments and the microorganisms that inhabit it constitute an attractive resource for the identification of new enzymes with potential biotechnological application.

The study of Antarctic bacteria allows us to generate new knowledge and learn much more of this wonderful microscopic world. While it is interesting to know in depth who are present and what functions they perform in these environments, this time we focus our work on a particular group of bacteria: manganese oxidizing bacteria (BOM). These bacteria with the ability to oxidize Mn (II) to Mn (III) -Mn (IV) generating manganese oxides (MnOx). The interesting thing about the MnOx from the biotechnological point of view is its high reactivity, which allows them to sequester heavy metals (Pb, Zn, Co, Ni, As and Cr) by their adsorption. On the other hand, the MnOx are capable of transforming polluting organic compounds such as antibacterial agents, phenols, anilines and pesticides. These qualities make MnOx and BOM an interesting input with various industrial applications, for example in the field of bioremediation. Another interesting aspect of the BOM is that very little is known about the reason for this phenomenon (Mn oxidation) and the mechanisms involved, so that the generation of new knowledge will generate a contribution in this area.

Our objective is to identify and characterize Antarctic cultivable bacteria capable of oxidizing Mn considering its possible biotechnological application. Our strategy is to generate a collection of bacterial isolates and to identify, through growth in the presence of MnCl2, those isolates that form a brown-red precipitate characteristic of Mn oxidation. Isolates capable of oxidizing manganese will be characterized and the enzyme responsible for the activity will be identified, so that it can be incorporated into a bacterium frequently used in the laboratory and in industry. This will allow us to generate a bacterium with biotechnological application. The potential of these BOMs or their enzymes in bioremediation.