Microbial Markers Profile in Anaerobic Mars Analogue Environments Using the LDChip (Life Detector Chip) Antibody Microarray Core of the SOLID (Signs of Life Detector) Platform.

L García-Descalzo ,Nicolas Walter,Petra Rettberg,Charles S Cockell,Christine Moissl-Eichinger,Patricia Cabezas,Elke Rabbow,Andreas Riedo,Maria Bohmeier,Ricardo Amils,Vı́ctor Parro ,Kristina Beblo‐Vranesevic ,E Monaghan ,Miriam García‐Villadangos ,P Ehrenfreund ,V Marteinsson ,F Gaboyer ,Francès Westall ,P Vannier ,A Perras ,M Malki ,Felipe Gómez

doi:10.3390/microorganisms7090365

Abstract

One of the main objectives for astrobiology is to unravel and explore the habitability of environments beyond Earth, paying special attention to Mars. If the combined environmental stress factors on Mars are compatible with life or if they were less harsh in the past, to investigate the traces of past or present life is critical to understand its potential habitability. Essential for this research is the characterization of Mars analogue environments on Earth through the development of techniques for biomarker detection in them. Biosensing techniques based on fluorescence sandwich microarray immunoassays (FSMI) have shown to be a powerful tool to detect biosignatures and depict the microbial profiles of different environments. In this study, we described the microbial biomarker profile of five anoxic Mars analogues sites using the Life Detector Chip (LDChip), an antibody microarray for multiple microbial marker detection. Furthermore, we contributed to new targets by developing a new 26-polyclonal antibodies microarray using crude extracts from anaerobic sampling sites, halophilic microorganisms, and anaerobic isolates obtained in the framework of the European Mars Analogues for Space Exploration (MASE) project. The new subset of antibodies was characterized and implemented into a microarray platform (MASE-Chip) for microbial marker searching in salty and anaerobic environments.

Highlights

Searching for life or potential habitable conditions beyond Earth is a central objective in Astrobiology [1,2,3]
There are data indicating the possibility of water on the present Mars at the equator where low-albedo features form and grow during the warmer months and disappear in the cold seasons, causing so-called recurring slope lineae (RSL), which could be explained by the existence of liquid brines near the surface; this is still an open question [13]
In the framework of MASE (Mars Analogues for Space Exploration), a European Seventh Framework Programme, FP7-funded project, we investigated several anoxic Mars analogues sites, including (i) cold sulfidic springs, (ii) an acidic lake environment, (iii) a hypersaline subsurface environment, and (iv) rock glacier sites in order to obtain a collection of different anoxic samples that were subjected to a set of investigations

Summary

Introduction

Searching for life or potential habitable conditions beyond Earth is a central objective in Astrobiology [1,2,3]. Geochemical data from Martian meteorites and planetary exploration instruments such as the high oxidant (iron-rich smectite clays, iron oxides, and magnesium sulfate) composition of the surface [24,25,26,27] and the cold desiccated radiation-bathed surface of the planet indicate that habitable conditions are most likely restricted to the subsurface rather than on the surface [8,28], where biota, which may have inhabited Mars in the past, were forced to retreat and might still persist today [7] This retreat could have induced microbial life, if it ever occurred, likely to be more abundant in protective niches far from radiation, desiccation (in brines) and lack of oxygen. The new LDChip proposed here (MASE-Chip) consists of 26-polyclonal antibodies against the mentioned halophiles and MASE anaerobic isolates

Mars Analogues Selection and Sampling

Building a Microarray from MASE Sites and Salty Environments

Testing and Validating the New Antibodies and MASE-Chip

Biomarker Profiles of MASE Sites

MASE-Chip