MICROBIAL DIVERSITY IN GYPSUM MATS UTILIZING MICROSCOPY AND DNA ANALYSIS

Microbial mats collected from Museo del Sale saltern (salinity 25%, water depth 0.46 m, temperature 24ºC), Trapani, Italy were studied to determine microbial diversity using microscopy and DNA sequencing. The top layer of the mat is yellowish with euhedral gypsum crystals (1-5 mm), followed by a thin green layer, a purple layer, and black sulfidic mud at the base. The microscopy was completed using a Zeiss Axio Imager A1 microscope equipped with oil immersion objective. Images were taken using Zen 2012 Blue Edition software. Unicellular and filamentous Cyanobacteria, brine shrimp, and diatoms were observed in the green and purple layers; no microorganisms were found in the black sulfidic mud.

Bacterial DNA from the mats were extracted and lysed applying ASL Buffer and the DNA was purified using Maxwell 16 DNA Purification kit. A region of 16S rRNA of Bacteria was amplified using a primer set; that data was used to construct a phylogenetic tree. The most common bacteria sequenced in extracts from the mat belonged to the phyla Bacteriodetes, Firmicutes, and Proteobacteria. DNA sequence analysis aided microorganism identification: Spirochaetes, a filamentous bacterium, was identified by microscopy and DNA analysis. The microbial community from Museo del Sale saltern may be an analog for ancient saline environments on Earth and Mars.