Cold-adapted Microorganisms

Isao Yumoto (ed.)Publisher: Caister Academic Press, 2013. ISBN: 978-1-908230-26-3, 226 pages

Fungal species associated with fruit and vegetables transported to the J.G. Mendel station and the influence of UV-C treatment on their fungal community

The aim of this study was to investigate the fungal community associated with fruits and vegetables transported into the Antarctic region and observe qualitative changes of their surface mycobiota after UV-C treatment. This measure is used to prevent the post-harvest diseases of stored fruits and vegetables and reduce the risk of introducing non-native species to the Antarctic environment. In total, 82 strains of filamentous fungi were isolated from the surfaces of 64 pieces of fresh fruits and vegetables before and after their UV-C treatment. They were assigned to the genera Penicillium, Fusarium, Mucor, Cladosporium, and Acremonium. After the UV-C treatment of the examined fruits and vegetables, spores of the genera Fusarium, Cladosporium and Acremonium were not detected, while spores of the genera Penicillium and Mucor were more resistant and stayed viable after the treatment. Penicillium strains prevailed in the examined samples. Their introduction to the Antarctic environment could represent a potential risk for endemic autochthonous organisms

Influence of heating parameters on flow stress curves of low-alloy Mn-Ti-B steel

Influence of the initial grain size on hot deformation behavior of the low-alloy Mn-Ti-B steel was investigated. The uniaxial compression tests were performed in range of the deformation temperatures of 900-1200 degrees C and strain rates of 0.1-10 s(-1). One set of samples was heated directly to the deformation temperature, which corresponded to the initial austenitic grain size of 19-56 mu m; the other set of samples was uniformly preheated at the temperature of 1200 degrees C. Whereas the values of activation energy, peak stress and steady-state stress values practically did not depend on the initial austenitic grain size, the peak strain values of coarser-grained structure significantly increase mainly at high values of the Zener-Hollomon parameter. This confirms the negative effect of the large size of the initial grain on the dynamic recrystallization kinetics, which can be explained by the reduction in nucleation density.Web of Science6341792178

First evidence of high-molecular-weight bacteriocin (tailocin) produced by Antarctic Pseudomonas spp.

Cold-adapted soil ecosystems represent dynamic communities varying in a structure, microbial abundance and metabolic activity. To antagonize competitors, soil bacteria produce a variety of inhibitory agents. We tested production of antimicrobials in Pseudomonas spp. isolated in James Ross Island, Antarctica, and performed transmission electron microscopic analyses of selected high-molecular-weight bacteriocin particles. The dimensions of R-tailocins produced by Pseudomonas sp. P2422 were 168 ± 2.0nm (length) and 16 ± 0.8nm (width) thus representing one of the largest tailocins secreted by Pseudomonas spp. To our knowledge, this is the first evidence of tailocin production by bacteria originated from polar regions

Isolation of human pathogen Escherichia albertii from faeces of seals (Leptonychotes weddelli) in James Ross Island, Antarctica

A set of nine gram-negative fermenting rods biochemically identified as Escherichia coli was isolated from faeces of seals. These bacteria were characterized by phenotypic classification, 16S rDNA sequence analyses, automated ribotyping, study of whole-cell protein profiles by SDS-PAGE and finally by bacteriocin production. The results of our polyphasic taxonomic study supported the recognition of P4652, P4653 and P4740 isolates as true members of Escherichia albertii species – probably a major enteric human pathogen. To our best knowledge, this is the first evidence showing that E. albertii produces bacteriocin, colicin D. Obtained data unambiguously showed incon-venience of commercial identification systems to distinguish both Escherichia species due to missing data of E. albertii in the commercial databases. The results of Escherichia isolates taxonomy suggest seals as a novel source of human and animal pathogen,E. albertii in the Antarctic region

Free-Living Enterobacterium Pragia fontium 24613: Complete Genome Sequence and Metabolic Profiling

Pragia fontium is one of the few species that belongs to the group of atypical hydrogen sulfide-producing enterobacteria. Unlike other members of this closely related group, P. fontium is not associated with any known host and has been reported as a free-living bacterium. Whole genome sequencing and metabolic fingerprinting confirmed the phylogenetic position of P. fontium inside the group of atypical H2S producers. Genomic data have revealed that P. fontium 24613 has limited pathogenic potential, although there are signs of genome decay. Although the lack of specific virulence factors and no association with a host species suggest a free-living style, the signs of genome decay suggest a process of adaptation to an as-yet-unknown host

Biodiversity of culturable procaryotes from the Hranice abyss and the role of microorganisms in carbonate speleothemes forming

Hranice Karst is situated in northeastern part of Moravia, Czech Republic, at the contact between two major geological units of the Bohemian Massif and Western Carpathians. This karst developed in combination of meteoric water and hydrothermal dissolution of deformed and tectonically stacked Devonian and Lower Carboniferous limestones. This karst, therefore, exceeds to considerable depths of several hundreds metres. In the 1977, unusually massive organic coatings high in microbial extracellular polymers, occurring together with biofilm structures, were discovered in the vertical caves of low hydrothermally active ‚Hranická propast (Hranice Abyss)‘, particularly on the cave walls in deep underwater environments. These mucilaginous formations may have been classified among ‚snottites‘, mucous-like coatings and stalactites. The present study provides the first insights into both the microbial diversity and morphological/structural variability of these extremophilic formations.Hranice Karst is situated in northeastern part of Moravia, Czech Republic, at the contact between two major geological units of the Bohemian Massif and Western Carpathians. This karst developed in combination of meteoric water and hydrothermal dissolution of deformed and tectonically stacked Devonian and Lower Carboniferous limestones. This karst, therefore, exceeds to considerable depths of several hundreds metres. In the 1977, unusually massive organic coatings high in microbial extracellular polymers, occurring together with biofilm structures, were discovered in the vertical caves of low hydrothermally active ‚Hranická propast (Hranice Abyss)‘, particularly on the cave walls in deep underwater environments. These mucilaginous formations may have been classified among ‚snottites‘, mucous-like coatings and stalactites. The present study provides the first insights into both the microbial diversity and morphological/structural variability of these extremophilic formations

Synthesis and effect of hierarchically structured Ag-ZnO hybrid on the surface antibacterial activity of a propylene-based elastomer blends

In this study, a hybrid Ag-ZnO nanostructured micro-filler was synthesized by the drop technique for used in plastic and medical industry. Furthermore, new antibacterial polymer nanocomposites comprising particles of Ag-ZnO up to 5 wt % and a blend of a thermoplastic polyolefin elastomer (TPO) with polypropylene were prepared using twin screw micro-compounder. The morphology and crystalline-phase structure of the hybrid Ag-ZnO nanostructured microparticles obtained was characterized by scanning electron microscopy and powder X-ray diffractometry. The specific surface area of this filler was investigated by means of nitrogen sorption via the Brunauer-Emmet-Teller method. A scanning electron microscope was used to conduct a morphological study of the polymer nanocomposites. Mechanical and electrical testing showed no adverse effects on the function of the polymer nanocomposites either due to the filler utilized or the given processing conditions, in comparison with the neat polymer matrix. The surface antibacterial activity of the compounded polymer nanocomposites was assessed against Escherichia coli ATCC 8739 and Staphylococcus aureus ATCC 6538P, according to ISO 22196:2007 (E). All the materials at virtually every filler-loading level were seen to be efficient against both species of bacteria. © 2018 by the authors.Ministry of Education, Youth and Sports of the Czech Republic-Program NPU I [LO1504]; European Regional Development Fund (ERDF); national budget of the Czech Republic [CZ.1.05/2.1.00/19.0409]; TBU in Zlin [IGA/CPS/2017/007