Isolation and Characterization of Microorganisms from Extreme Aquatic Habitats and Their Relevance for Space Biology

Abstract

Extreme habitats on earth are still widely unexplored, which holds the percentage of unidentified microorganisms very low. In the following, the description of two microorganisms of extreme aquatic habitats, and further investigation about their resistances and therefore relevance to space is described. One organism, namely HP23, was sampled in a high-altitude lake in the Atacama Desert, showing high salinity. The other organism, namely R23, was sampled in the geyser Andernach in a colder environment. Both microorganisms were identified via 16S rRNA sequencing and compared to their closest relatives, according to the sequencing results. HP23 showed the highest 16S rRNA sequence similarity to the bacteria Roseovarius tibetensis and Roseovarius nitratireducens, with 97.53 % and below, which indicates a potentially new species. R23 showed 16S rRNA sequence similarity with the bacteria Arundinibacter roseus, Rhabdobacter roseus, and Dyadobacter koreensis, with 95.07 % and below, which indicated a potentially new genus. Both Bacteria were characterized, including 16S rRNA analysis, favorable growth conditions, enzyme activities, fatty acids, and polar lipids, to compare the results to the already described relatives. Additionally, the bacteria were tested upon motility, photosynthesis activity, and pigment production, to give a better characterization of the newly isolated microorganism. Further experiments were conducted for both isolates, being stress tests, to test their resistances upon diverse extreme conditions, like desiccation, irradiation, and perchlorate presence. Those two isolates are presenting the main part of the thesis. Since the samples were taken in aqueous environments, the sampled Atacama lake, Laguna Verde, was tested upon the presence of Cyanobacteria, which resulted in a variety of those as well. The cyanobacteria were cultivated and partly identified upon 16S rRNA analysis, and their pigment production was examined. The obtained results underlie the project “MultiKulti” funded by BMBF, which aims the cultivation of yet unknown microorganisms. Further on, the possible application of the isolates in diverse fields of biology should be explored.