Adriani Pantazidou

Morphology and molecular evaluation of Iphinoe spelaeobios gen. nov., sp. nov. and Loriellopsis cavernicola gen. nov., sp. nov., two stigonematalean cyanobacteria from Greek and Spanish caves

Caves have generally been found to host phototrophic micro-organisms from various taxonomic groups, with cyanobacteria comprising an important group that have adapted to these stable and highly specific environments. A polyphasic study based on aspects of classical morphology and molecular data revealed two new monospecific genera from fresh material of Greek and Spanish caves. Both taxa are characterized by obligatory true branching (T-type, V-type and false branching), the presence of heterocysts, and reproduction by hormocysts and akinetes. They shared some similarities in their morphological characteristics as revealed by light, scanning electron and transmission electron microscopy, but phylogenetic analysis based on 16S rRNA gene sequences showed that the two phylotypes were different (89.8% similarity); this represents an example of shared morphology in genetically different strains of cave-adapted species. Phenotypic and genetic traits strongly support classification of the phylotypes as independent taxa in the order Stigonematales (the most differentiated and complicated group of cyanobacteria), family Loriellaceae Geitl 1925. Hence, the names Iphinoe spelaeobios Lamprinou and Pantazidou gen. nov., sp. nov. and Loriellopsis cavernicola Hernández-Mariné and Canals gen. nov., sp. nov. are proposed.

Euendolithic shell-boring cyanobacteria and chlorophytes from the saline lagoon Ahivadolimni on Milos Island, Greece

Samples of typical estuarine mollusc shells (Cerastoderma glauca, Abra ovata and Hydrobia acuta), differing in appearance, size and age, were collected from littoral habitats of a saline water lagoon (Ahivadolimni on Milos Island, Greece). Each shell sample was examined for the distribution, frequency and taxonomy of its shell-boring cyanobacteria and chlorophytes, and the associated attached (epizoic) diatoms. The euendolithic microflora was extracted using Perenys solution and observed by light microscopy (LM). The results of microbial penetration (traces of euendoliths) were examined by scanning electron microscopy (SEM) after a hypochlorite treatment. The three-dimensional patterns of microbial penetration (boring patterns) were investigated under SEM by applying the resin-casting technique for modern euendoliths. Of the five euendolithic cyanobacteria found, one (Cyanosaccus atticus) was established from Greek marine biotopes, three (Hyella caespitosa var. arbuscula, H. inconstans and H. reptans) are second records and new for Europe, whereas one cyanobacterium (Leptolyngbya terebrans = Plectonema terebrans) and the three euendolithic chlorophytes found (Phaeophila dendroides, Ostreobium quekettii and Gomontia polyriza) show a cosmopolitan distribution. A survey of the diatoms found as epizoic on the mollusc shells (30 taxa) shows that most of them are typical representatives of marine to brackish water of coasts and estuarine areas. A systematic account of all euendoliths found in the mollusc shells is given. The morphological variability of the cyanobacterium Hyella inconstans, and of the chlorophytes Ostreobium quekettii and Gomontia polyriza is presented, with extended taxonomic comments for the latter species. The susceptibility of molluscs to infestation, as well as the morphological variability, world distribution and penetration patterns of the euendoliths within the host mollusc shells are also discussed.

A polyphasic taxonomic approach in isolated strains of Cyanobacteria from thermal springs of Greece.

Strains of Cyanobacteria isolated from mats of 9 thermal springs of Greece have been studied for their taxonomic evaluation. A polyphasic taxonomic approach was employed which included: morphological observations by light microscopy and scanning electron microscopy, maximum parsimony, maximum likelihood and Bayesian analysis of 16S rDNA sequences, secondary structural comparisons of 16S-23S rRNA Internal Transcribed Spacer sequences, and finally environmental data. The 17 cyanobacterial isolates formed a diverse group that contained filamentous, coccoid and heterocytous strains. These included representatives of the polyphyletic genera of Synechococcus and Phormidium, and the orders Oscillatoriales, Spirulinales, Chroococcales and Nostocales. After analysis, at least 6 new taxa at the genus level provide new evidence in the taxonomy of Cyanobacteria and highlight the abundant diversity of thermal spring environments with many potential endemic species or ecotypes.

Distribution survey of Cyanobacteria in three Greek caves of Peloponnese

Caves and hypogean environments host various phototrophic microorganisms, with Cyanobacteria constituting the major group. The spatial and temporal distribution of Cyanobacteria (156 taxa in total) from three Greek caves, located in the limestone arc of Peloponnese and differing in morphology, was studied. The community patterns in different ecological niches were analyzed in relation to environmental parameters (Photosynthetically Active Radiation, Temperature, and Relative Humidity). Cyanobacterial communities were found to thrive in patchy biofilms and showed known protective strategies against desiccation and irradiation. The nMDS analysis of the cumulative seasonal samples per sampling site showed no general pattern of distribution, with a clear differentiation of cyanobacterial communities among the three caves. Only in the typical cave ‘Kastria’, cyanobacterial taxa showed growth habits in accordance with the gradient of light from entrance inwards.

Isolation and structural elucidation of biologically active phospholipids from Scytonema julianum (cyanobacteria).

The role of platelet-activating factor (PAF) as a mediator appeared in rather primitive organisms like protozoans and was maintained in more evolved organisms. No reports exist for the presence of PAF or PAF analogues - or even compounds that exhibit PAF-like activity - in cyanobacteria, even though they belong to a a group of organisms at a low evolutionary level where the content of alkylacyl forms of ether lipids is expected to be high. In addition, cyanobacteria serve as a rich source of novel bioactive metabolites. In the present study the total lipids of a strain of Scytonema julianum, a filamentous cyanobacterium isolated from a Greek cave, were separated into neutral lipids and phospholipids, the latter being further fractionated by HPLC. Each phospholipid fraction was tested in vitro for its ability to inhibit PAF-, arachidonic acid- and ADP-induced washed-rabbit-platelet aggregation and/or to cause platelet aggregation. Two types of phospholipids causing platelet aggregation were detected and shown to be an acetylsphingomyelin and an acylacetylglycerol phosphoacetylated glycolipid. The existence of the sphingomyelin analogues is very important, since ceramides, cerebrosides and related lipids are intracellular second messengers. The identification of the phosphoglycoglycerolipid demonstrates a new type of lipid in cyanobacteria, namely one that exhibits a biological activity very similar to that of PAF. Its presence reinforces the concept that PAF is a member of a large family of lipid mediators, apparently having different physiological roles in prokaryotic and eukaryotic organisms. In addition, Scytonema julianum contains a phosphatidylcholine (C(16:0)/(18:2)), even though bacteria in general seldom contain choline-containing phosphoacylglycerols.

The show cave of Diros vs. wild caves of Peloponnese, Greece - distribution patterns of Cyanobacteria

*aamilli@biol.uoa.gr 2011). Under such conditions the oligotrophic nature of cave environments is expected to change through organic inputs that alter both the food web, and the abundance and distribution of cave organisms (Hoyos et al., 1998; Fernández-Cortés et al., 2006; Saiz-Jimenez et al., 2011; Saiz-Jimenez, 2012). Additionally, the artificial lighting system in the show caves affects the photosynthetic microflora in areas around the installed illumination equipment. The photosynthetic community thriving in proximity to artificial lighting is known as ‘Lampenflora’– a term introduced by Dobàt (1963) – and it was first studied in Austrian caves (Kyrle, 1923; Morton and Gams, 1925). Further research has shown that the growth and distribution of these floristic aggregations depend on abiotic factors such as light quality and intensity, temperature, relative humidity, as well as type and coherence of the underlying substratum (Roldán et INTRODUCTION

Phenotypic and Molecular Biological Characterization of Cyanobacteria from Marble Surfaces of Treated and Untreated Sites of Propylaea (Acropolis, Athens)

Cyanobacteria cause aesthetic damage to marble surfaces and in particular their endolithic mode of life contributes to the breakdown of rock crystalline structures. The aim of this work was to estimate, with both phenotypical and molecular approach, the composition of cyanobacterial communities on the Propylaea marbles of the Acropolis Monuments. The two selected sampling sites were treated and untreated with a commercial biocide in order to estimate its effect on the cyanobacterial diversity. Our study revealed that in both sampling sites were present 13 phenotypes and 10 phylotypes and that the cyanobacterial taxa were considerably lower in the treated site.

Cave Cyanobacteria showing antibacterial activity

Cave Cyanobacteria - thriving in an ‘extreme’ environment with interesting species biodiversity - are supposed to be a potential source of bioactive compounds. Lipid extracts from pure cultures of two recently established Cyanobacteria from Greek caves, Toxopsis calypsus and Phormidium melanochroun, were used for antibacterial screening against human pathogenic bacteria (reference and clinical isolates). Antimicrobial Susceptibility testing for both taxa was carried out using the disc-diffusion (Kirby Bauer) method, while preliminary data applying the standard broth microdilution method for the determination of the Minimal Inhibitory Concentration (MIC) are given only for T. calypsus. Antibacterial activity was demonstrated against the Gram-positive clinical and reference bacteria, mostly pronounced in enterococci; no activity was observed against the Gram-negative bacteria. The above screening is the first record of antibacterial activity from lipid extracts of cave Cyanobacteria enhancing the importance of cave microbiota and the necessity for cave conservation. cave Cyanobacteria; Toxopsis calypsus; Phormidium melanochroun; antimicrobial susceptibility screening