Endophytic and endolichenic fungal diversity in maritime Antarctica based on cultured material and their evolutionary position among Dikarya

Fungal endophytes comprise one of the most ubiquitous groups of plant symbionts. They live asymptomatically within vascular plants, bryophytes and also in close association with algal photobionts inside lichen thalli. While endophytic diversity in land plants has been well studied, their diversity in lichens and bryophytes are poorly understood. Here, we compare the endolichenic and endophytic fungal communities isolated from lichens and bryophytes in the Barton Peninsula, King George Island, Antarctica. A total of 93 fungal isolates were collected from lichens and bryophytes. In order to determine their identities and evolutionary relationships, DNA sequences of the nuclear internal transcribed spacer (ITS), nuclear ribosomal small subunit (nuSSU), nuclear large subunit (nuLSU), and mitochondrial SSU (mtSSU) rDNA were obtained and protein coding markers of the two largest subunit of RNA polymerase II (RPB1 and RPB2) were generated. Multilocus phylogenetic analyses revealed that most of the fungal isolates were distributed in the following six classes in the phylum Ascomycota: Dothideomycetes, Eurotiomycetes, Lecanoromycetes, Leotiomycetes, Pezizomycetes and Sordariomycetes. For the first time we report the presence of subphylum Mortierellomycotina that may belong to an undescribed order in endophytic fungi. Taken together, our results imply that lichens and bryophytes provide similar niches and harbour a selection of these fungi, indicating generalists within the framework of evolutionary adaptation.

Characterisation of heavy metal tolerance and biosorption capacity of bacterium strain CPB4 (Bacillus spp.)

A heavy metal resistant bacterium Bacillus spp. strain CPB4 was isolated from heavy metal contaminated soil in Korea and further characterised. The CPB4 strain showed a high capacity for uptake of heavy metal Pb (Pb > Cd > Cu > Ni > Co > Mn > Cr > Zn) both in single and in mixed heavy metal solution. Optimal conditions for heavy metal uptakes of CPB4 strain were 20-40 degrees C culture temperature, 5-7 pH and 24 h pre-culture times. TEM showed that large amounts of the electron-dense granules (heavy metal complexes) were found mainly on the cell wall and cell membrane. Furthermore, more than 90% of adsorbed heavy metals were distributed both in cell wall and in cell membrane fractions. The amount of heavy metal uptake was remarkably decreased by reducing the crude protein contents when cells were treated by alkali solutions. Therefore, this study showed one of the possible examples for useful bioremediation.

Relating the microscopic and macroscopic response of a polymeric fluid in a shearing flow

The microscopic and macroscopic response of a polymer solution in start-up shear flow was investigated using fluorescence microscopy of single molecules, bulk viscosity measurements, and Brownian dynamics simulations. An overshoot in viscosity was observed upon flow inception and understood via the observed molecular extension and by simulation findings. Increasing the polymer concentration up to six times the overlap concentration ( C(*)) has no effect on the character of the dynamics of individual molecules.