Laser-Induced Fluorescence Emission (L.I.F.E.):In SituNondestructive Detection of Microbial Life in the Ice Covers of Antarctic Lakes

Abstract

Laser-induced fluorescence emission (L.I.F.E.) images were obtained in situ following 532 nm excitation of cryoconite assemblages in the ice covers of annual and perennially frozen Antarctic lakes during the 2008 Tawani International Expedition to Schirmacher Oasis and Lake Untersee in Dronning Maud Land, Antarctica. Laser targeting of a single millimeter-scale cryoconite results in multiple neighboring excitation events secondary to ice/air interface reflection and refraction in the bubbles surrounding the primary target. Laser excitation at 532 nm of cyanobacteria-dominated assemblages produced red and infrared autofluorescence activity attributed to the presence of phycoerythrin photosynthetic pigments. The method avoids destruction of individual target organisms and does not require the disruption of either the structure of the microbial community or the surrounding ice matrix. L.I.F.E. survey strategies described may be of interest for orbital monitoring of photosynthetic primary productivity in polar and alpine glaciers, ice sheets, snow, and lake ice of Earth's cryosphere. The findings open up the possibility of searching from either a rover or from orbit for signs of life in the polar regions of Mars and the frozen regions of exoplanets in neighboring star systems.

A frozen asset: The potential of flow cytometry in constraining the glacial biome

“…Autofluorescence signals from unstained populations may prove informative of sub‐population dynamics . As previously summarized , fluorescence emission is potentially the most sensitive photonic probe in the absence of sample preparation and/or destruction: polycyclic aromatic hydrocarbons (PAHs) can be observed using deep UV (<250 nm) excitation, longer wavelength UV (∼375 nm) cedes fluorescence in the visible wavelengths from microorganism metabolites (e.g., flavin adenine dinucleotide), and visible spectrum excitation yields fluorescence in the red to NIR (>500 nm) range for a variety of microbial pigments (e.g., phycobiliproteins and chlorophylls). This analytical potential is aided by the diminished natural autofluorescence of inorganic, mineral particles .…”

Fluorescence Characterization of Clinically-Important Bacteria

“…Other prior applications of fluorescence techniques include assessing the presence of organic compounds or pollutants in the environment [16–18], identifying potentially pathogenic or toxic microorganisms in environmental water or food preparation [19–22], and detecting trace concentrations of microorganisms in glacial [23] and Antarctic ice [24], Antarctic sandstone [25], and the Atacama desert [26]. …”

Proposed mission for in-situ detection of microorganisms in Low Earth Orbit

“…Ultraviolet light induced fluorescence is a common method of identifying organic compounds, and has been proposed as an in-situ method of detecting microbial life [32][33][34][35][36]. We propose a block of silica aerogel measuring 3.5" X 3.5" and 1.5" thick with one edge being illuminated by a linear array of UV light emitting diodes (LED).…”