Resistance of Cyanobacterial Fouling on Architectural Paint Films to Cleaning by Water Jet

Mortar panels painted with three different white acrylic coatings were exposed to the environment in urban (So Paulo) and rural (Pirassununga) sites in Brazil for 7 years. After this time, all panels were almost equally discoloured, and paint detachment was observed to only a small degree. The biofilms were composed mainly of cyanobacteria and filamentous fungi, principal genera being Gloeocapsa and Chroococcidiopsis of the cyanobacteria, and Cladosporium and Alternaria of the fungi. Two of the three paints in Pirassununga became covered by a pink film that contained red-encapsulated Gloeocapsa and clay particles. The third, an 800% elastomeric matt formulation, became discoloured with a grey, only slightly pink, film, although the same cyanobacteria were present. The levels of paint detachments from all films in both locations were low, with rating range of 0-1 of a maximum 5 (100% detachment). After high-pressure water jetting, paint detachments increased at both locations, up to 2 in Pirassununga and 3 in So Paulo. Discoloration decreased; L*A*B* analysis of surface discoloration showed that Delta E (alteration in colour from the original paint film) changed from 28-39 before cleaning to 13-16 afterwards. The pink coloration was not entirely removed from Pirassununga samples, suggesting that cyanobacterial cells are difficult to detach, and microscopic analysis of the biofilms confirmed that Gloeocapsa was still present as the principal contaminant on all surfaces, with Chroococcidiopsis being present as the second most common. Almost no fungi were detected after water jet application.

Petrographic approach to the study of organic microfossils from the Irati Subgroup (Permian, Parana Basin, Brazil)

Early diagenetic chert, infrequently exploited in Phanerozoic micropaleontology, was examined for organic-walled microfossils in petrographic thin sections of silicified dolostones from diverse levels and localities of the Assistencia Formation (Permian, Parana Basin) in the state of Sao Paulo, Brazil. In contrast to previous palynological studies of this formation, the use of thin sections allowed direct observation in three dimensions of common palynomorphs, as well as benthic microbial mats preserved in situ in various stages of their life cycles and degradation. As in palynological residues from the more wellknown shale of this formation, the chert contains wind-dispersed pollen grains and phytoclasts derived from terrestrial sources and planktonic cryptarchs (unornamented coccoidal unicellular or colonial palynomorphs). However, only in the chert is it possible to see much more delicate microfossils, such as abundant cyanobacteria of the in situ benthic microbiota as well as chlorophycean microalgae of the microphytoplankton. Post-depositional processes affecting the formation have destroyed all but the most resistant organic remains in the other lithologies, such that only rare, degraded pollen grains are seen in the unsilicified dolostone of the formation, and in the shale the vast majority of microfossils have been compacted to flattened disks. On the other hand, early silicification not only preserved organic remains at an incipient stage of decomposition but also impeded significant further degradation due to compaction, recrystallization, and oxidation. Thus, the petrographic study of such chert can complement traditional palynological investigations in Phanerozoic rocks by furnishing hitherto unavailable information, especially with regard to benthic organic microfossils and fragile organic-walled phytoplankton normally absent from organic residues. (C) 2011 Elsevier Ltd. All rights reserved.

Cadmium and Chromium Toxicity to Pseudokirchneriella subcapitata and Microcystis aeruginosa

The toxicity of cadmium and chromium to Pseudokirchneriella subcapitata and Microcystis aeruginosa was evaluated through algal growth rate during 96h exposure bioassays. Free metal ion concentrations were obtained using MINEQL(+) 4.61 and used for IC50 determination. Metal accumulations by the microorganisms were determined and they were found to be dependent on the concentration of Cd2+ and Cr6+. IC50 for P. subcapitata were 0.60 mu mol L-1 free Cd2+ and 20 mu mol L-1 free Cr6+, while the IC50 values for M. aeruginosa were 0.01 mu mol L-1 Cd2+ and 11.07 mu mol L-1 Cr6+. P. subcapitata accumulated higher metal concentrations (0.001 - 0.05 mu mol Cd mg(-1) dry wt. and 0.001 - 0.04 mu mol Cr mg(-1) dry wt) than the cyanobacteria (0.001 - 0.01 mu mol Cd mg(-1) dry wt and 0.001 - 0.02 mu mol Cr mg(-1) dry wt). Cadmium was more toxic than chromium to both the microorganisms.

Cylindrospermopsis raciborskii exudate-Cu complexes: impact on copper dynamics and bioavailability in an aquatic food chain

The increasing contamination of aquatic environments motivates studies on the interactions among natural dissolved organic matter, metals, and the biota. This investigation focused on the organic exudates of the toxic cyanobacteria Cylindrospermopsis raciborskii as a Cu carrier through a three-level aquatic trophic chain (bacteria, protozoa, and copepod). The effects of bacteria activity and growth on the metal-organic complexes were evaluated through changes in free Cu2+ ions, total dissolved, and total particulate Cu. To be sure that the added copper would be complexed to the exudates, its complexing properties were previously determined. The cyanobacteria exudate-Cu complexes were furnished to bacteria that were further used as a food source to the protozoan Paramercium caudatum. This was then furnished as food to the copepod Mesocyclops sp. The results showed that, in general, the cyanobacterial exudates decreased Cu bioavailability and toxicity to the first trophic level (bacteria), but because the heterotrophic bacteria accumulated Cu, they were responsible for the transference for the otherwise low availability metal form. Both the bacteria and protozoan organisms accumulated Cu, but no metal accumulation was detected in the copepods.

Emergy analysis of oil production from microalgae

The use of microalgae and cyanobacteria for the production of biofuels and other raw materials is considered a very promising sustainable technology due to the high areal productivity, potential for CO2 fixation and use of non-arable land. The production of oil by microalgae in a large scale plant was studied using emergy analysis. The joint transformity calculated for the base scenario was 1.32E + 5 sej/J, the oil transformity was 3.51E + 5 sej/J, the emergy yield ratio (EYR) was 1.09 and environmental loading ratio was 11.10 and the emergy sustainability index (ESI) was 0.10, highlighting some of the key challenges for the technology such as high energy consumption during harvesting, raw material consumption and high capital and operation costs. Alternatives scenarios and the sensitivity to process improvements were also assessed, helping prioritize further research based on sustainability impact. (C) 2012 Elsevier Ltd. All rights reserved.

Dynamics of phytoplankton associations in three reservoirs in northeastern Brazil assessed using Reynolds' theory

The aim of the present study was to evaluate the influence of seasonality on the behavior of phytoplankton associations in eutrophic reservoirs with different depths in northeastern Brazil. Five collections were carried out at each of the reservoirs at two depths (0.1 m and near the sediment) at three-month intervals in each season (dry and rainy). The phytoplankton samples were preserved in Lugol's solution and quantified under an inverted microscope for the determination of density values, which were subsequently converted to biomass values based on cellular biovolume and classified in phytoplankton associations. The following abiotic variables were analyzed: water temperature, dissolved oxygen, pH, turbidity, water transparency, total phosphorus, total dissolved phosphorus, orthophosphate and total nitrogen. The data were investigated using canonical correspondence analysis. The influence of seasonality on the dynamics of the phytoplankton community was lesser in the deeper reservoirs. Depth affected the behavior of the algal associations. Variation in light availability was a determinant of changes in the phytoplankton structure. Urosolenia and Anabaena associations were more abundant in shallow ecosystems with a larger eutrophic zone, whereas the Microcystis association was more related to deep ecosystems with adequate availability of nutrients. The distribution of Cyclotella, Geitlerinema, Planktothrix, Pseudanabaena and Cylindrospermopsis associations was different from that seen in subtropical regions and the substitution of these associations was related to a reduction in the eutrophic zone rather than the mixture zone. Published by Elsevier GmbH.

Effects of photobioreactor configuration, nitrogen source and light intensity on the fed-batch cultivation of Arthrospira (Spirulina) platensis. Bioenergetic aspects

Bioenergetic analysis may be applied in order to predict microbial growth yields, based on the Gibbs energy dissipation and mass conservation principles of the overall growth reaction. The bioenergetics of the photoautotrophic growth of the cyanobacterium Arthrospira (Spirulina) platensis was investigated in different bioreactor configurations (tubular photobioreactor and open ponds) using different nitrogen sources (nitrate and urea) and under different light intensity conditions to determine the best growing conditions in terms of Gibbs energy dissipation, number of photons to sustain cell growth and phototrophic energy yields distribution in relation to the ATP and NADPH formation, and release of heat. Although an increase in the light intensity increased the Gibbs energy dissipated for cell growth and maintenance with both nitrogen sources, it did not exert any appreciable influence on the moles of photons absorbed by the system to produce one C-mol biomass. On the other hand, both bioenergetic parameters were higher in cultures with nitrate than with urea, likely because of the higher energy requirements needed to reduce the former nitrogen source to ammonia. They appreciably increased also when open ponds were substituted by the tubular photobioreactor, where a more efficient light distribution ensured a remarkably higher cell mass concentration. The estimated percentages of the energy absorbed by the cell showed that, compared with nitrate, the use of urea as nitrogen source allowed the system to address higher energy fractions to ATP production and light fixation by the photosynthetic apparatus, as well as a lower fraction released as heat. The best energy yields values on Gibbs energy necessary for cell growth and maintenance were achieved in up to 4-5 days of cultivation, indicating that it would be the optimum range to maintain cell growth. Thanks to this better bioenergetic situation, urea appears to be a quite promising low-cost, alternative nitrogen source for Arthrospira platensis cultures in photobioreactors. (C) 2011 Elsevier Ltd. All rights reserved.

Degradation of [D-Leu]-Microcystin-LR by solar heterogeneous photocatalysis (TiO2)

The present study investigates the use of solar heterogeneous photocatalyis (TiO2) for the destruction of [D-Leu]-Microcystin-LR, powerful toxin of widespread occurrence within cyanobacteria blooms. We extracted [D-Leu]-Microcystin-LR from a culture of Microcystis spp. and used a flat plate glass reactor coated with TiO2 (Degussa, P25) for the degradation studies. The irradiance was measured during the experiments with the aid of a spectroradiometer. After the degradation experiments, toxin concentrations were determined by HPLC and mineralization by TOC analyses. Acute and chronic toxicities were, quantified using mice and phosphatase inhibition in vitro assays, respectively. According to the performed experiments, 150 min were necessary to reduce the toxin concentration to the WHO's guideline for drinking water (from 10 to 1 mu g L-1) and to mineralize 90% of the initial carbon content. Another important finding is that solar heterogeneous photocatalysis was a destructive process indeed, not only for the toxin, but also for the other extract components and degradation products generated. Moreover, toxicity tests using mice have shown that the acute effect caused by the initial sample was removed. However, tests using the phosphatase enzyme indicated that it may be formed products capable of inducing chronic effects on mammals. The performed experiments indicate the feasibility of using solar heterogeneous photocatalysis for treating contaminated water with [D-Leu]-Microcystin-LR, not only due to its destruction, but also to the significant removal of organic matter and acute toxicity that can be achieved. (C) 2012 Elsevier Ltd. All rights reserved.

Biomonitoring of Microcystin and Aflatoxin Co-Occurrence in Aquaculture Using Immunohistochemistry and Genotoxicity Assays

This work investigated the effects of co-occurring aflatoxin B-1 (AFB(1)) and microcystin (MC) in aquaculture, using immunohistochemistry and genotoxicity methods. Tilapia (Oreochromis niloticus) were exposed to AFB(1) by intraperitoneal and MC (cell extract of Microcystis aeruginosa) by intraperitoneal and immersion routes. The interaction of MC-AFB(1) was evaluated co-exposing the intraperitoneal doses. Blood samples were collected after 8, 24, and 48h to analyze the micronucleus frequency and comet score. The interaction of MC-AFB(1) showed a synergic mutagenic response by higher micronucleus frequency of co-exposed group. A slight genotoxic synergism was also observed in the comet score. Immunohistochemistry detected MC in al lthe fish liver tissues exposed to MC by intraperitoneal route, and only the immersed group with the highest dose of MC showed a positive response. Although MC was non-detectable in the edible muscle, the combination of immunohistochemistry with genotoxicity assay was an attractive biomonitoring tool in aquaculture, where the animals were frequently exposed to co-occurring synergic hazards.

The Carmaphycins: New Proteasome Inhibitors Exhibiting an alpha,beta-Epoxyketone Warhead from a Marine Cyanobacterium

Two new peptidic proteasome inhibitors were isolated as trace components from a Curacao collection of the marine cyanobacterium Symploca sp. Carmaphycin A (1) and carmaphycin B (2) feature a leucine-derived a,beta-epoxyketone warhead directly connected to either methionine sulfoxide or methionine sulfone. Their structures were elucidated on the basis of extensive NMR and MS analyses and confirmed by total synthesis, which in turn provided more material for further biological evaluations. Pure carmaphycins A and B were found to inhibit the beta 5 subunit (chymotrypsin-like activity) of the S. cerevisiae 20S proteasome in the low nanomolar range. Additionally, they exhibited strong cytotoxicity to lung and colon cancer cell lines, as well as exquisite antiproliferative effects in the NCI60 cell-line panel. These assay results as well as initial structural biology studies suggest a distinctive binding mode for these new inhibitors.

Performance of an electronic tongue during monitoring 2-rnethylisoborneol and geosmin in water samples

2-Methylisoborneol (MIB) and geosmin (GSM) are sub products from algae decomposition and, depending on their concentration, can be toxic: otherwise, they give unpleasant taste and odor to water. For water treatment companies it is important to constantly monitor their presence in the distributed water and avoid further costumer complaints. Lower-cost and easy-to-read instrumentation would be very promising in this regard. In this study, we evaluate the potentiality of an electronic tongue (ET) system based on non-specific polymeric sensors and impedance measurements in monitoring MIB and GSM in water samples. Principal component analysis (PCA) applied to the generated data matrix indicated that this ET was capable to perform with remarkable reproducibility the discrimination of these two contaminants in either distilled or tap water, in concentrations as low as 25 ng L-1. Nonetheless, this analysis methodology was rather qualitative and laborious, and the outputs it provided were greatly subjective. Also, data analysis based on PCA severely restricts automation of the measuring system or its use by non-specialized operators. To circumvent these drawbacks, a fuzzy controller was designed to quantitatively perform sample classification while providing outputs in simpler data charts. For instance, the ET along with the referred fuzzy controller performed with a 100% hit rate the quantification of MIB and GSM samples in distilled and tap water. The hit rate could be read directly from the plot. The lower cost of these polymeric sensors allied to the especial features of the fuzzy controller (easiness on programming and numerical outputs) provided initial requirements for developing an automated ET system to monitor odorant species in water production and distribution. (C) 2012 Elsevier B.V. All rights reserved.

Taxonomic and Functional Microbial Signatures of the Endemic Marine Sponge Arenosclera brasiliensis

The endemic marine sponge Arenosclera brasiliensis (Porifera, Demospongiae, Haplosclerida) is a known source of secondary metabolites such as arenosclerins A-C. In the present study, we established the composition of the A. brasiliensis microbiome and the metabolic pathways associated with this community. We used 454 shotgun pyrosequencing to generate approximately 640,000 high-quality sponge-derived sequences (similar to 150 Mb). Clustering analysis including sponge, seawater and twenty-three other metagenomes derived from marine animal microbiomes shows that A. brasiliensis contains a specific microbiome. Fourteen bacterial phyla (including Proteobacteria, Cyanobacteria, Actinobacteria, Bacteroidetes, Firmicutes and Cloroflexi) were consistently found in the A. brasiliensis metagenomes. The A. brasiliensis microbiome is enriched for Betaproteobacteria (e.g., Burkholderia) and Gammaproteobacteria (e.g., Pseudomonas and Alteromonas) compared with the surrounding planktonic microbial communities. Functional analysis based on Rapid Annotation using Subsystem Technology (RAST) indicated that the A. brasiliensis microbiome is enriched for sequences associated with membrane transport and one-carbon metabolism. In addition, there was an overrepresentation of sequences associated with aerobic and anaerobic metabolism as well as the synthesis and degradation of secondary metabolites. This study represents the first analysis of sponge-associated microbial communities via shotgun pyrosequencing, a strategy commonly applied in similar analyses in other marine invertebrate hosts, such as corals and algae. We demonstrate that A. brasiliensis has a unique microbiome that is distinct from that of the surrounding planktonic microbes and from other marine organisms, indicating a species-specific microbiome.

Development of a high sensitive automatic setup for screening of microcystins in surface waters by employing a LED-based photometric detector

In this manuscript, an automatic setup for screening of microcystins in surface waters by employing photometric detection is described. Microcystins are toxins delivered by cyanobacteria within an aquatic environment, which have been considered strongly poisonous for humans. For that reason, the World Health Organization (WHO) has proposed a provisional guideline value for drinking water of 1 mu g L-1. In this work, we developed an automated equipment setup, which allows the screening of water for concentration of microcystins below 0.1 mu g V. The photometric method was based on the enzyme-linked immunosorbent assay (ELISA) and the analytical signal was monitored at 458 nm using a homemade LED-based photometer. The proposed system was employed for the detection of microcystins in rivers and lakes waters. Accuracy was assessed by processing samples using a reference method and applying the paired t-test between results. No significant difference at the 95% confidence level was observed. Other useful features including a linear response ranging from 0.05 up to 2.00 mu g L-1 (R-2 =0.999) and a detection limit of 0.03 mu g L-1 microcystins were achieved. (C) 2011 Elsevier B.V. All rights reserved.

Bioaccumulation Of Microcystins In Lettuce

The contamination of lettuce (Lactuca sativa L.) by water-borne crude extracts of the cyanobacterium microcystin-producing Microcystis aeruginosa (Kutzing) Kutzing was investigated. The aim of the study was to determine whether bioaccumulation of microcystins occurs in lettuce foliar tissue when sprayed with solutions containing microcystins at concentrations observed in aquatic systems (0.62 to 12.5 mu g center dot L-1). Microcystins were found in lettuce foliar tissues (8.31 to 177.8 mu g per Kg of fresh weight) at all concentrations of crude extracts. Spraying with water containing microcystins and cyanobacteria may contaminate lettuce at levels higher than the daily intake of microcystins recommended by the World Health Organization (WHO), underscoring the need to monitor such food exposure pathways by public authorities.