Screening and analysis of radioresistant fungi isolated from the Namib Desert

SCK•CEN Mentor

Janssen Paul, pjanssen@sckcen.be, +32 (0)14 33 21 29

Expert group

Microbiology

Short project description

The Namib Desert is the oldest desert in the world and has been in existence for some 55 million years, remaining unchanged in its present form for the last 2 million years. This desert covers over 130,000km2 in the South West parts of Africa and It is generally regarded as one of most inhospitable places on earth, with only 8-25 mm rainfall per year and soaring soil surface temperatures of up to 60-65 oC. Areas close to the coast have considerably moderate temperatures year round. Much of the biodiversity in the Namib Desert is higly depended on the fog that regularly (about 120 d/yr) is blown inland from the cooler sea coast region. In the absence of this fog, hyperarid conditions and the unrelenting bombardment of the desert surface by solar UV radiation have led to discrete adaptations for plant and animal species as well as for microbes and microbial communities.The presence and distribution of uranium, driven by extensive mining in some areas of the desert, is an additional factor Namib organisms have to reckon with. The Desert Research Foundation Namibia has established the Gobabeb Training and Research Center (http://www.gobabebtrc.org) located 120 km by road south-east of Walvis Bay. Gobabeb conducts research in a wide variety of fields ranging from archaeology and anthropology to climate and ecology in its broadest sense to geology, geomorphology and desert conservation and restoration. One of the activities Gobabeb supports are the yearly expeditions into the Namib Desert under the joint banners of the University of Pretoria Center for Microbial Ecology and Genomics (CMEG), the University of the Western Cape Institute for Microbial Biotechnology and Metagenomics (IMBM), and the University of Cape Town Viromics Group. Their typical field program includes the collection of microorganisms from desert-plant rhizospheres, rocks, and soils.

Objective

A collection of 48 yeast isolates were obtained from various locations in the Namib Desert during the April 2017 Gobabeb Expedition. So far, five of those could be identified by ITS sequencing at CMEG as Aureobasidium pullulans, Cryptococcus albidus var. kuetzingii, Cystobasidium minutum, Coniochaeta polymorpha, and Coniochaeta hoffmanni. All isolates will be screened for radioresistance in the RITA facility at different doses in the range of 100 - 14,400 Gy using 6- or 12-well plates. Post-irradiation growth will then be monitored. Survival curves may also be established by CFU counts of serial dilutions. Radioresistant strains surviving the highest dose will be further investigated in BRIGITTE at doses up to 27 kGy. If none of the strains survive above 100 Gy, the experiment might be repeated at LNK at doses in the range of 5 - 100 Gy. Based on the combined outcome of these experiments, selected strains will be irradiated at the appropriate sub-lethal dose, and cells will be snap froozen and send by express courier to CMEG for transcriptomic and proteomic analyses (RNAseq, LC-MS). The expected time frame will be about 3 weeks, starting in the second halve of May 2018.

The minimum diploma level of the candidate needs to be

Academic bachelor

The candidate needs to have a background in

Biology