Simple Devices for Concentration of Microbial Life: Experiments in Haughton

Introduction: The Detection of Microbial Life: If we are to find extant life on another planet, it is most likely to be extremely simple in nature, the equivalent of microbial life on Earth. Accordingly, strategies to detect extant life are focused on analyses for biological signatures in the soil zone. This was attempted in the Viking labeled release experiment on Mars, and more recently has involved development of a range of approaches including high-resolution mass spectrometry, Raman spectroscopy, and molecular probes [1]. These techniques follow an ‘instant gratification’ approach. We suggest that there is also a value in longer-term experiments, that attempt to concentrate microbial life before making an analysis. By concentrating any ambient microbes, the chance of detecting them will be greater. In some mission scenarios for Mars, deployment of a concentration mechanism for several months is quite feasible. Encouraging Concentration of Microbial Life: The concentration of microbial life is most likely to be achieved by providing something that they want. This could include an energy source, chemical nutrients, or liquid water. Simple deployment of a nutrient plate might be enough, but has not been attempted. Provision of light energy and moisture could be achieved in a single simple device, using a pair of transparent plates sufficiently close together to allow water to be held between them due to capillary action. Light is a universal energy source, and photosynthesis is probably a widespread response [2], so using a device that provides light has a chance of attracting any microbial life available. Materials can be transparent to various wavelength ranges of light, so harmful ultra-violet irradiation can be excluded. Experiments in Haughton Impact Structure: We trialled devices of this type in the Haughton Impact Structure, Canadian High Arctic. Pairs of sterilized glass microscope slides were deployed, bound by a paper clip (Fig. 1). A second clip is anchored in the soil and wedges the two slides apart at one end to allow formation of a water film. The insertion of single glass slides in soil is an established technique for sampling of microbial matter in the subsurface [3]. The slides deployed at Haughton were used in a novel manner to attract microbial matter by providing an environment offering high levels of sunlight. This was inspired by the natural colonization of transparent rocks [4] and minerals [5] in the crater by cyanobacteria, most specifically by Gloeocapsa [4].