The vertical distribution of phototrophic and non-phototrophic microorganisms was examined in 2 saltern evaporation ponds with salinities of 156 and 206 g l super(-1). The biogeochemistry of these 2 ...ponds was examined using microsensors for oxygen, pH and sulfide. These measurements showed that net rates of oxygen production/consumption were significantly higher at a salinity of 156 than at 206 g l super(-1). The distribution of phototrophic microorganisms was studied by microscopy, which revealed several differences between the 2 crusts. The relative amounts of Bacteria, Archaea, sulfate reducers and methanogens were studied by real-time quantitative PCR amplification of genes for 16S rRNA, dissimilatory sulfite reductase (DSR), and methyl coenzyme M reductase (MCR). Sulfate reducers and methanogens were detected only in the deepest part of the phototrophic zone and below. Sulfate reducers were most abundant in the zone just below the phototrophic layer, where the DSR gene copy number was ~1.5% that of the 16S rRNA gene copy number. Methanogens were much less abundant than sulfate reducers, and the number of MCR gene copies never exceeded 0.1% of the number of 16S rRNA gene copies. Methanogens were less abundant at a salinity of 206 than at 156 g l super(-1). Inter-pond and vertical variations in the composition of methanogenic and sulfate reducing communities were further characterized by DGGE analysis. The detected sulfate reducers were affiliated with 4 different phylogenetic groups that included members of the Desulfovibrionales, relatives of Desulfotomaculum, and 2 deeply branching groups with no close cultured relatives. The detected phylotypes were distributed in a distinct pattern in the crust according to both biogeochemical regimes and salinity. Methanogens were all affiliated with the known halophilic genera Methanohalophilus and Methanohalobium.
The effect of temperature, light and nutrient composition on morphological traits was determined in seven nostocacean cyanobacteria
(Anabaena planctonica, A. sphaerica
var.
conoidea, A. spiroides, ...Aphanizomenon gracile, Nostoc
sp.,
Scytonema
sp., and
Tolypothrix
sp.). Their morphological variability was high but only some of the features showed changes reflecting varied growth conditions. The frequency of heterocyst occurrence decreased with increasing nitrogen concentration. Within the range studied, the effect of temperature on heterocyst frequency of
Tolypothrix
sp. and planktonic
Anabaena
strains could be fitted by a normal curve with a clear optimum while linear correlation was found in
Aphanizomenon gracile
. T-and S-type branching was observed in both
Scytonema
sp. and
Tolypothrix
sp. strains. T-type branching was found to be markedly dependent on nitrogen concentration. The abundance of necridic cells of
Tolypothrix
sp. increased linearly with temperature and light intensity. Regularity of trichome coiling of
A. spiroides
depended on culture medium, suggesting that nutrient composition may be the main controlling factor. In contrast, the effect of the experimental conditions on the dimensions of vegetative cells and heterocysts was weak. Their variability was markedly higher within each experimental treatment than between treatments.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The planktonic and benthic microbial communities in 8 hypersaline evaporation ponds of the Israel Salt Company in Eilat, Israel, with salinities ranging from 58 to 329 g l super(-1) (total dissolved ...salt), were studied using fluorescence emission spectroscopy and kinetic fluorometry. With increasing salinity, the anoxygenic phototrophic bacteria (containing bacteriochlorophyll a, bchl a) formed a significant and increasing fraction of the planktonic phototrophic biomass. While the bchl a/chl a molar ratio was 0.01 at the lowest salinity, it reached almost 1 at the higher salinities. In the benthic communities, emission spectroscopy revealed depth-dependent changes in the photophysiology of benthic oxygenic phototrophs, and spatial variability in the abundance of several groups of anoxygenic photosynthetic bacteria (green bacteria containing chlorosomes and purple bacteria containing LH1). In general, the emission signal of the benthic oxygenic phototrophs (diatoms and Cyanobacteria) was dominated by photosystem I (detected in some cases down to 5 cm of sediment depth). The signal of photosystem II and phycobilisomes was several times weaker and was observed mostly in the surface layers. The spectroscopic data of microbial communities were complemented by microscopic characterization.
Two cyanobacterial strains were isolated in 2004 from different localities in the Czech Republic. Field morphology of the strain 04-26 (Jesenice reservoir) matched with the species description of ...Anabaena crassa (Lemm.) Kom.-Legn. et Cronb. 1992, whereas the strain 04-28 (Hodějovický fishpond) was identified as A. circinalis Rabenh. ex Born. et Flah. 1888. Both these strains, exposed to various experimental conditions (temperature, light intensity, nitrogen and phosphorus concentration), displayed highly similar morphologies and spanned the morphological variability of both of the above-mentioned species. Significant relationships between environmental conditions (temperature, phosphorus) and morphological characteristics (vegetative cell and heterocyte dimensions, trichome coiling parameters) have been recorded for the first time within the genus Anabaena. The strains studied differed in their temperature and light growth optima and in secondary metabolite contents. However, both were identical (100% similarity) in their 16S rRNA gene sequence and showed 99.9–100% similarity to the published 16S rRNA sequences of A. circinalis strains from northern Europe.
The species-specific production of extracellular phosphatases in phytoplankton of a subtropical polymictic lake was investigated from March to May 2004. Phosphatase activity was detected directly at ...the site of enzyme action using the enzyme-labelled fluorescence (ELF) technique. Size fractionation of bulk phosphatase activity (PA), concentrations of soluble reactive phosphorus (SRP), chlorophyll a, and phytoplankton composition were determined in parallel. Phosphatase-positive cells were present in every phytoplankton sample; labelled cells were detected in 33 algal taxa, including many chlorophytes, dinoflagellates and some diatoms, but never among cyanobacteria. We recorded an unusual dinoflagellate bloom (Peridiniopsis sp.), of which ∼25% of the cells were phosphatase-positive. Several populations were partly phosphatase-positive whenever present, while some other species never showed any activity. The production of extracellular phosphatases was not primarily regulated by ambient P concentrations; algae produced these enzymes even if SRP concentrations were high. Moreover, heterotrophic nanoflagellates most probably contributed to the pool of particle-bound PA in some samples.
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BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Morphological variability as a consequence of variable combinations of nutrient concentration, light intensity, temperature, and water movement was studied in seven monoclonal populations of ...planktonic coccoid genus Chroococcus isolated from phytoplankton, metaphyton and periphyton from different localities in the Czech and Slovak Republic and other countries. Width of the cells, formation of mucilage and formation of cellular packets were used to test changes in morphology. A 16SrRNA gene analysis was carried out altogether on ten strains formerly assigned to different species of the genus Chroococcus in the Culture Collections CCALA Trebon (www.cas.ccala.cz) and HBI AS CR in Ceske Budejovice, including those under detailed study. The sequences formed four distinct phylogenetic groups. Two of them showed no affiliation to the genus Chroococcus. However, two other groups situated distantly in the phylogenetic tree proved a polyphyletic character of the genus Chroococcus sensu auct. Apart from the group of typical species of the genus Chroococcus, the group of planktonic species could be distinguished, represented by Chroococcus limneticus (Limnococcus). All the sequences will be available in the GenBank.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
A case is presented of a 70-year-old man treated for 3 months for necrotizing pancreatitis with multiorgan failure. The autopsy revealed enterococcal endocarditis affecting all eleven valvular cusps ...of the four heart valves.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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