title: Ecophysiological properties of cultivable heterotrophic bacteria and yeasts dominating in phytocenoses of Galindez Island, maritime Antarctica.
abstract: Antarctic plants are stable specific microenvironments for microbial colonization that are still less explored. In this study, we investigated cultivable heterotrophic bacteria and yeasts dominating in plant samples collected from different terrestrial biotopes near Ukrainian Antarctic Base on Galindez Island, maritime Antarctica. Phylogenetic analysis revealed affiliation of the bacterial isolates to genera Pseudomonas, Stenotrophomonas, Brevundimonas, Sporosarcina, Dermacoccus, Microbacterium, Rothia and Frondihabitans, and the yeast isolates to genera Rhodosporidium, Cryptococcus, Leucosporidiella, Candida and Exophiala. Some ecophysiological properties of isolated strains were determined that are important in response to different stresses such as psychro- and halotolerance, UV-resistance and production of hydrolytic enzymes. The majority of isolates (88 %) was found to be psychrotolerant; all are halotolerant. Significant differences in survival subsequent to UV-C radiation were observed among the isolates, as measured by culturable counts. For the bacterial isolates, lethal doses in the range 80-600 J m⁻² were determined, and for the yeast isolates--in the range 300-1,000 J m⁻². Dermacoccus profundi U9 and Candida davisiana U6 were found as most UV resistant among the bacterial and yeast isolates, respectively. Producers of caseinase, gelatinase, β-glucosidase, and cellulase were detected. To the best of our knowledge, this is the first report on isolation of UV resistant strain D. profundi, and Frondihabitans strain from Antarctica, and on detection of cellulase activity in Antarctic yeast strain C. davisiana. The results obtained contribute to clarifying adaptation strategies of Antarctic microbiota and its possible role in functional stability of Antarctic biocenoses. Stress tolerant strains were detected that are valuable for ecological and applied studies.
authors.affiliation: Departments of General and Applied Microbiology, The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Str., Bl. 26, 1113, Sofia, Bulgaria, evaston@yahoo.com.
authors.forename: Evgenia
authors.initials: E
authors.lastname: Vasileva-Tonkova
authors.forename: Victoria
authors.initials: V
authors.lastname: Romanovskaya
authors.forename: Galina
authors.initials: G
authors.lastname: Gladka
authors.forename: Dilnora
authors.initials: D
authors.lastname: Gouliamova
authors.forename: Iva
authors.initials: I
authors.lastname: Tomova
authors.forename: Margarita
authors.initials: M
authors.lastname: Stoilova-Disheva
authors.forename: Oleksandr
authors.initials: O
authors.lastname: Tashyrev
mesh_terms: D000864:Antarctic Regions; D001419:Bacteria / Q000145:classification / Q000254:growth & development* / Q000302:isolation & purification; D018407:Bacterial Physiological Phenomena; D015373:Bacterial Typing Techniques; D058448:Biota; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D005658:Fungi / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification / Q000502:physiology*; D020459:Genes, rRNA; D016533:Mycological Typing Techniques; D010802:Phylogeny; D010944:Plants / Q000382:microbiology*; D012329:RNA, Bacterial / Q000235:genetics; D012331:RNA, Fungal / Q000235:genetics; D012335:RNA, Ribosomal / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013312:Stress, Physiological
chemical_list: D004275:DNA, Ribosomal; D012329:RNA, Bacterial; D012331:RNA, Fungal; D012335:RNA, Ribosomal; D012336:RNA, Ribosomal, 16S; C065096:RNA, ribosomal, 26S