Jose Julio Ortega-Calvo

Chemical composition of Spirulina and eukaryotic algae food products marketed in Spain

ThreeSpirulina and five eukaryotic algal food products available in the Spanish market have been extensively studied. Results are given for their gross chemical composition (water content, crude protein, total carbohydrates, lipids, nucleic acids etc.) and contents of macrominerals, trace elements, fatty acids, amino acids and neutral sugars. The results are compared to those from other studies on natural or laboratory-produced populations. An overall nutritional and toxicological evaluation of these products is included.

From Bioavailability Science to Regulation of Organic Chemicals

The bioavailability of organic chemicals in soil and sediment is an important area of scientific investigation for environmental scientists, although this area of study remains only partially recognized by regulators and industries working in the environmental sector. Regulators have recently started to consider bioavailability within retrospective risk assessment frameworks for organic chemicals; by doing so, realistic decision-making with regard to polluted environments can be achieved, rather than relying on the traditional approach of using total-extractable concentrations. However, implementation remains difficult because scientific developments on bioavailability are not always translated into ready-to-use approaches for regulators. Similarly, bioavailability remains largely unexplored within prospective regulatory frameworks that address the approval and regulation of organic chemicals. This article discusses bioavailability concepts and methods, as well as possible pathways for the implementation of bioavailability into risk assessment and regulation; in addition, this article offers a simple, pragmatic and justifiable approach for use within retrospective and prospective risk assessment.

Pyrolysis/methylation: A method for structural elucidation of the chemical nature of aquatic humic substances

Abstract Pyrolysis has been used for the last ten years to study the chemical nature of humic substances. However, obtaining data is hampered by analytical limitations. One of these is that carboxylic acids other than fatty acids are not usually present amongst pyrolysis products. To overcome this problem, a novel method—pyrolysis/methylation—is applied. Simultaneous pyrolysis/derivatization with tetramethylammonium hydroxide protects the carboxyl groups by formation of methyl esters. At the same time, partial methylation of hydroxyl groups occurs. This method permits the identification of a suite of carboxyl-containing aromatic and aliphatic compounds, not previously observed in conventional pyrolysis, providing useful information on the biodegradation processes of plant materials leading to macromolecular humic substances.

Bioavailability of pollutants and chemotaxis

The exposure of bacteria to pollutants induces frequently chemoattraction or chemorepellent reactions. Recent research suggests that the capacity to degrade a toxic compound has co-evolved in some bacteria with the capacity to chemotactically react to it. There is an increasing amount of data which show that chemoattraction to biodegradable pollutants increases their bioavailability which translates into an enhancement of the biodegradation rate. Pollutant chemoreceptors so far identified are encoded on degradation or resistance plasmids. Genetic engineering of bacteria, such as the transfer of chemoreceptor genes, offers thus the possibility to optimize biodegradation processes.

Organic and inorganic compounds in limestone weathering crusts from cathedrals in Southern and Western Europe

This work was supported by the Commission of the European Community, Project STEP-CT90-0107.

Applications of analytical pyrolysis to the study of stony cultural properties

Abstract Pyrolysis-gas chromatography/mass spectrometry was used to study the organic compounds present in weathered building materials from historic buildings and monuments. Three very different materials were investigated: a black layer from a terracotta statue from the Pardon Gate, Cathedral of Seville, Spain; a green layer found beneath a black sulphated crust from the Cathedral of Seville; and a black coating covering the stones of the Old Church of Delft, The Netherlands. From a general pattern in which n -alkanes and polycyclic aromatic hydrocarbons were the main components of black sulphated crust (as exemplified by the layer covering the terracotta statue), biogenic inputs could be easily recognized by study of specific markers (as denoted the contribution of the cyanobacterium Phormidium sp. to the green layer). Also an odd input, as in the case of the tar constituting the black coating of the stones of the Dutch church, was readily segregated. The results obtained indicate that analytical pyrolysis may be used as a first approach for analysis of organic matter within mineral matrices in cultural properties.

Flow cytometry discrimination between bacteria and clay–humic acid particles during growth‐linked biodegradation of phenanthrene by Pseudomonas aeruginosa 19SJ

Abstract Methods that quickly assess microbial density and aggregation in soil and sediments are needed in environmental microbiology. We report a flow cytometry method that uses the green and orange emission of the fluorochrome SYTO-13 to discriminate between bacteria and clay-humic acid particles. This approach distinguishes single or clustered bacteria, and clusters of bacteria and abiotic particles during the growth of the biosurfactant-producing strain Pseudomonas aeruginosa 19SJ on solid phenanthrene in the presence of humic acid-clay complexes.

Pyrolysis/methylation: A microanalytical method for investigating polar organic compounds in cultural properties

Abstract The organic compounds present in weathered surfaces of building stones were investigated using simultaneous pyrolysis/methylation. The method consists of the derivatization of the sample with the alkylating reagent tetramethylammonium hydroxide. Tetramethylammonium salts of organic acids can be converted to methyl ester and the corresponding byproduct in the pyrolysis unit. Hydroxyl groups are also methoxylated. The protection of functional groups permits direct and complete analysis of samples by pyrolysis. No time-consuming solvent extractions, concentrations, derivatizations, and other manipulations which imply the possibility of cross-contamination, are required. The data obtained by solvent extraction and subsequent gas chromatography-mass spectrometry analysis are similar to those obtained by pyrolysis/methylation, proving that this method is an analytical procedure of great sensitivity for investigating organic compounds in inorganic matrices.

Development of eukaryotic zoospores within polycyclic aromatic hydrocarbon (PAH)-polluted environments: A set of behaviors that are relevant for bioremediation

In this study, we assessed the development (formation, taxis and settlement) of eukaryotic zoospores under different regimes of exposure to polycyclic aromatic hydrocarbons (PAHs), which imitated environmental scenarios of pollution and bioremediation. With this aim, we used an oomycete, Pythium aphanidermatum, as a source of zoospores and two PAH-degrading bacteria (Mycobacterium gilvum VM552 and Pseudomonas putida G7). The oomycete and both bacteria were not antagonistic, and zoospore formation was diminished only in the presence of the highest bacterial cell density (10(8)-10(10) colony-forming units mL(-1)). A negative influence of PAHs on zoospore formation and taxis was observed when PAHs were exposed in combination with organic solutions and polar solvents. Co-exposure of PAHs with non-polar solvents [hexadecane (HD) and 2,2,4,4,6,8,8-heptamethylnonane (HMN)] did not affect zoospore settlement at the interfaces of the organic solvents and water. However, zoospores settled and created mycelial networks only at HD-water interfaces. Both bacteria diminished the toxic influence of PAHs on zoospore formation and taxis, and they did not interrupt zoospore settlement. The results suggest that zoospore development could be applicable for toxicity assessment of PAHs and enhancement of their bioavailability. Microbial interactions during both swimming modes and community formation at pollutant interfaces were revealed as major factors that have potential relevance to bioremediation.

Mobilization of Pollutant-Degrading Bacteria by Eukaryotic Zoospores

The controlled mobilization of pollutant-degrading bacteria has been identified as a promising strategy for improving bioremediation performance. We tested the hypothesis whether the mobilization of bacterial degraders may be achieved by the action of eukaryotic zoospores. We evaluated zoospores that are produced by the soil oomycete Pythium aphanidermatum as a biological vector, and, respectively, the polycyclic aromatic hydrocarbon (PAH)-degrading bacteria Mycobacterium gilvum VM552 and Pseudomonas putida G7, acting as representative nonflagellated and flagellated species. The mobilization assay was performed with a chemical-in-capillary method, in which zoospores mobilized bacterial cells only when they were exposed to a zoospore homing inducer (5% (v/v) ethanol), which caused the tactic response and settlement of zoospores. The mobilization was strongly linked to a lack of bacterial motility, because the nonflagellated cells from strain M. gilvum VM552 and slightly motile, stationary-phase cells from P. putida G7 were mobilized effectively, but the actively motile, exponentially grown cells of P. putida G7 were not mobilized. The computer-assisted analysis of cell motility in mixed suspensions showed that the swimming rate was enhanced by zoospores in stationary, but not in exponentially grown, cells of P. putida G7. It is hypothesized that the directional swimming of zoospores caused bacterial mobilization through the thrust force of their flagellar propulsion. Our results suggest that, by mobilizing pollutant-degrading bacteria, zoospores can act as ecological amplifiers for fungal and oomycete mycelial networks in soils, extending their potential in bioremediation scenarios.