In situ Search for Extraterrestrial Life: A microbial fuel cell-based Sensor for the detection of Photosynthetic Metabolism

FIGUEREDO, F.; CORTÓN, E.; ABREVAYA, X.C.

ASTROBIOLOGY

MARY ANN LIEBERT INC

Lugar: New York; Año: 2015 vol. 15 p. 1 - 11

1531-1074

Microbial fuel cells (MFCs) are bioelectrochemical systems (BES) capable of harvesting electrons from redoxreactions involved in metabolism. In a previous work, we used chemoorganoheterotrophic microorganismsfrom the three domains of life?Bacteria, Archaea, and Eukarya?to demonstrate that these BES could beapplied to the in situ detection of extraterrestrial life. Since metabolism can be considered a common signatureof life ´as we know it´ we extended in this study the ability to use MFCs as sensors for photolithoautotrophicmetabolisms. To achieve this goal, two different photosynthetic microorganisms were used: the microalgaeParachlorella kessleri and the cyanobacterium Nostoc sp. MFCs were loaded with nonsterilized samples,sterilized samples, or sterilized culture medium of both microorganisms. Electric potential measurements wererecorded for each group in single experiments or in continuum during light-dark cycles, and power and currentdensities were calculated. Our results indicate that the highest power and current density values were achievedwhen metabolically active microorganisms were present in the anode of the MFC. Moreover, when continuousmeasurements were performed during light-dark cycles, it was possible to see a positive response to light.Therefore, these BES could be used not only to detect chemoorganoheterotrophic metabolisms but alsophotolithoautotrophic metabolisms, in particular those involving oxygenic photosynthesis. Additionally, thepositive response to light when using these BES could be employed to distinguish photosynthetic from nonphotosyntheticmicroorganisms in a sample.