Camino García-Balboa

Sorption and desorption of Cd, Cu and Pb using biomass from an eutrophized habitat in monometallic and bimetallic systems

This work examines the sorption capacity of a natural biomass collected from an irrigation pond. The biomass mainly consisted of a mixture of chlorophyte algae with caducipholic plants. Biosorption experiments were performed in monometallic and bimetallic solutions containing different metals commonly found in industrial effluents (Cd, Cu and Pb). The biosorption process was slightly slower in the binary system comparing with monometallic system which was related to competition phenomena between metal cations in solution. The biosorbent behaviour was quantified by the sorption isotherms fitting the experimental data to mathematical models. In monometallic systems, the Langmuir model showed a better fit with the following sorption order: Cu ~ Pb > Cd; and biomass-metal affinity order: Pb > Cd ~ Cu. In bimetallic systems, the binary-type Langmuir model was used and the sorption order obtained was: Pb ~ Cu > Cd. In addition, the effectiveness of the biomass was investigated in several sorption-desorption cycles using HCl and NaHCO(3). The recovery of metal was higher with HCl than with NaHCO(3), though the sorption uptake of the biomass was sensitively affected by the former desorption agent in subsequent sorption cycles.

Adaptation of microalgae to lindane: A new approach for bioremediation

Lindane is especially worrisome because its persistence in aquatic ecosystems, tendency to bioaccumulation and toxicity. We studied the adaptation of freshwater cyanobacteria and microalgae to resist lindane using an experimental model to distinguish if lindane-resistant cells had their origin in random spontaneous pre-selective mutations (which occur prior to the lindane exposure), or if lindane-resistant cells arose by a mechanism of physiological acclimation during the exposure to the selective agent. Although further research is needed to determine the different mechanisms contributing to the bio-elimination of lindane, this study, however, provides an approach to the bioremediation abilities of the lindane-resistant cells. Wild type strains of the experimental organisms were exposed to increasing lindane levels to estimate lethal concentrations. Growth of wild-type cells was completely inhibited at 5mg/L concentration of lindane. However, after further incubation in lindane for several weeks, occasionally the growth of rare lindane-resistant cells was found. A fluctuation analysis demonstrated that lindane-resistant cells arise only by rare spontaneous mutations that occur randomly prior to exposure to lindane (lindane-resistance did not occur as a result of physiological mechanisms). The rate of mutation from lindane sensitivity to resistance was between 1.48 × 10(-5) and 2.35 × 10(-7) mutations per cell per generation. Lindane-resistant mutants exhibited a diminished fitness in the absence of lindane, but only these variants were able to grow at lindane concentrations higher than 5mg/L (until concentrations as high as 40 mg/L). Lindane-resistant mutants may be maintained in uncontaminated waters as the result of a balance between new resistant mutants arising from spontaneous mutation and resistant cells eliminated by natural selection waters via clone selection. The lindane-resistant cells were also used to test the potential of microalgae to remove lindane. Three concentrations (4, 15 and 40 mg/L) were chosen as a model. In these exposures the lindane-resistant cells showed a great capacity to remove lindane (until 99% lindane was eliminated). Apparently, bioremediation based on lindane-resistant cells could be a great opportunity for cleaning up of lindane- and other chlorinated organics-polluted habitats.

Effects of adaptation, chance, and history on the evolution of the toxic dinoflagellate Alexandrium minutum under selection of increased temperature and acidification

The roles of adaptation, chance, and history on evolution of the toxic dinoflagellate Alexandrium minutum Halim, under selective conditions simulating global change, have been addressed. Two toxic strains (AL1V and AL2V), previously acclimated for two years at pH 8.0 and 20°C, were transferred to selective conditions: pH 7.5 to simulate acidification and 25°C. Cultures under selective conditions were propagated until growth rate and toxin cell quota achieved an invariant mean value at 720 days (ca. 250 and ca. 180 generations for strains AL1V and AL2V, respectively). Historical contingencies strongly constrained the evolution of growth rate and toxin cell quota, but the forces involved in the evolution were not the same for both traits. Growth rate was 1.5–1.6 times higher than the one measured in ancestral conditions. Genetic adaptation explained two-thirds of total adaptation while one-third was a consequence of physiological adaptation. On the other hand, the evolution of toxin cell quota showed a pattern attributable to neutral mutations because the final variances were significantly higher than those measured at the start of the experiment. It has been hypothesized that harmful algal blooms will increase under the future scenario of global change. Although this study might be considered an oversimplification of the reality, it can be hypothesized that toxic blooms will increase but no predictions can be advanced about toxicity.

Biosorption of Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II) using different residual biomass

The sorption behaviour of a biomass sample collected in an irrigation pond has been investigated. The biomass sample was selected from several ones collected in different eutrophised habitats of the Community of Madrid (Spain). The selection was made based on its effectiveness in the recovery of heavy metals from aqueous solution. The biomass sample selected was mainly composed of several Chlorophyta algae species and deciduous plants, and was tested to evaluate its behaviour in the biosorption of Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II), metals commonly found in industrial effluents. Preliminary studies were started in monometallic systems to determine the optimum values of pH, biomass concentration and sorption kinetics. The quantification of the sorption process was accomplished with sorption isotherms by fitting the experimental data to two mathematical models. The Langmuir model gave the best fit. Copper and lead were adsorbed in higher proportions, followed by nickel and zinc and, finally, cadmium. The metals more easily adsorbed in monometallic systems were also preferentially adsorbed in bimetallic systems. FTIR and acid-base titration were the analytical techniques used to establish sorption mechanisms, and carboxylic groups were identified as the main functional groups involved in the process.

Algal Biosorption and Biosorbents

Algae belong to the kingdom Protista which contains all the Eucaryotes organisms that cannot be classified within other eucaryotic kingdoms: Fungi, Animalia or Plantae. They are autotrophic organisms that carry out an oxygenic photosynthesis. Maybe the most well-known use of algae since ancient times is in food, especially in the Asian coast. In addition, the phycocolloid industry uses algae as raw material in the manufacture of a wide variety of additive products in the cosmetic, pharmaceutical and food industries. Lately algae have been proposed for the treatment of wastewaters due to their high heavy metal sorption capacity. Although, traditionally they have been used in less extent than other biomass, algae have important advantages such as: high efficiency metal removal, non-toxic chemical sludge and low cost. The main kinds of algae (green, red and brown) have constituents (cellulose, carrageenan and alginate, respectively) that provide binding sites such as: hydroxyl, carboxyl, amino and sulfhydryl, which are responsible for the selectivity of these biomass for heavy metals. In this way, Fucus spiralis, a brown alga very common in the Galician coast, has been proved very selective in the sorption of copper versus other heavy metals. Like for other types of biomass, one way to improve its biosorbent capacity is by pre-treatment with different reagents.

Iron Speciation in Dissimilatory Fe(III)-reducing Cultures

A protocol has been developed for determination of iron distribution and speciation in the solid and liquid phases of dissimilatory Fe(III)-reducing bacteria cultures. Sampling methods and sample processing have been improved. Three different extraction conditions have been tested for iron measurement: hydrochloric acid, ammonium oxalate and hydroxylamine hydrochloride. Separate collection of samples for liquid and solids analysis was tested, providing the best insight into Fe distribution. One sample was taken from the aqueous phase after solid settlement in vials to determine the concentration of dissolved iron species; the other was taken from agitated flasks, in which iron was extracted from solids prior to the analysis. Extraction with HCl 1Mfor 24 h proved the least labor-intensive procedure, with extraction efficiency adequate for our purposes. The extractant properties of HCl, less aggressive than the others, dissolved only the bio-available fraction of Fe(III).

Rapid adaptation of some phytoplankton species to osmium as a result of spontaneous mutations

To understand the vulnerability of individual species to anthropogenic contamination, it is important to evaluate the different abilities of phytoplankton to respond to environmental changes induced by pollution. The ability of a species to adapt, rather than its initial tolerance, is the basis for survival under rapidly increasing levels of anthropogenic contamination. High doses of osmium (Os) cause massive destruction of diverse phytoplankton groups. In this study, we found that the coastal chlorophyte Tetraselmis suecica and the continental chlorophyte Dictyosphaerium chlorelloides were able to adapt to a lethal dose of Os. In these species, Os-resistant cells arose as a result of rare spontaneous mutations (at rates of approximately 10−6 mutants per cell division) that occurred before exposure to Os. The mutants remained in the microalgal populations by means of mutation–selection balance. The huge size of phytoplankton populations ensures that there are always enough Os-resistant mutants to guarantee the survival of the population under Os pollution. In contrast, we observed that neither a haptophyte species from open ocean regions nor a cyanobacterium from continental freshwater were able to adapt to the lethal Os dose. Adaptation of phytoplankton to Os contamination is relevant because industrial activities are leading to a rapid increase in Os pollution worldwide.

The Influence of Disimilatory Fe(III) Reducers on Iron Ore Dissolution

The biological reduction rate of Fe(III) was studied using dissimilatory ferric reducing bacterial cultures (FeRB) in an attempt to establish a biotechnological via for the metallurgical treatment of iron ores. Enrichment cultures of dissimilatory ferric reducers were obtained from samples collected from a flooded acidic open pit in an abandoned Pb and Zn sulphide mining site nearby La Unión (Murcia, Spain). Adapted cultures were able to reduce 3 g/L of soluble Fe(III) with 100 efficiency in 36 hours. The growth of mixed cultures was also tested in solids. Ferrihydrite and ammonium jarosite served as electron acceptors in cultures where lactate acted as electron donor. Bacterial growth was also positive in both cases. This result represents an effective alternative to the chemical reduction of ferric minerals that avoids extreme temperatures when pyrometallurgical reactors are used. In addition, three species of FeRB were isolated and identified as Serratia fonticola, Aeromonas hydrophila and Clostridium celerecrescens. One of them, Aeromonas hydrophila, results of particular interest and, at the present moment, is being studied in depth. The particular significance of Aeromonas hydrophila is related to the characteristics of its exhausted cultures, where ferrous iron remains solved at pH values next to 7. At the present moment, the identification and characterization of the Fe(II) soluble complex is being account.

Adaptation prevents the extinction of Chlamydomonas reinhardtii under toxic beryllium.

The current biodiversity crisis represents a historic challenge for natural communities: the environmental rate of change exceeds the population’s adaptation capability. Integrating both ecological and evolutionary responses is necessary to make reliable predictions regarding the loss of biodiversity. The race against extinction from an eco-evolutionary perspective is gaining importance in ecological risk assessment. Here, we performed a classical study of population dynamics—a fluctuation analysis—and evaluated the results from an adaption perspective. Fluctuation analysis, widely used with microorganisms, is an effective empirical procedure to study adaptation under strong selective pressure because it incorporates the factors that influence demographic, genetic and environmental changes. The adaptation of phytoplankton to beryllium (Be) is of interest because human activities are increasing the concentration of Be in freshwater reserves; therefore, predicting the effects of human-induced pollutants is necessary for proper risk assessment. The fluctuation analysis was performed with phytoplankton, specifically, the freshwater microalgae Chlamydomonas reinhardtii, under acute Be exposure. High doses of Be led to massive microalgae death; however, by conducting a fluctuation analysis experiment, we found that C. reinhardtii was able to adapt to 33 mg/l of Be due to pre-existing genetic variability. The rescuing adapting genotype presented a mutation rate of 9.61 × 10−6 and a frequency of 10.42 resistant cells per million wild-type cells. The genetic adaptation pathway that was experimentally obtained agreed with the theoretical models of evolutionary rescue (ER). Furthermore, the rescuing genotype presented phenotypic and physiologic differences from the wild-type genotype, was 25% smaller than the Be-resistant genotype and presented a lower fitness and quantum yield performance. The abrupt distinctions between the wild-type and the Be-resistant genotype suggest a pleiotropic effect mediated by an advantageous mutation; however, no sequencing confirmation was performed.

Evolutionary Control of Economic Strategy in Fishes: Giffen Behaviourcould be a Common Economic Strategy on the Earth?

The existence of Giffen behaviour (i.e. the opposite situation to the Law of Demand in which consumers respond to a rising price of a certain good by demanding more of it) associated with poor consumers is one of the major controversies in economics. However, economists rarely consider that nothing makes sense except in light of evolution. In this paper, we prove the existence of Giffen behaviour in animals that exhibit no intelligent reasoning. Sardines feed on phytoplankton, and zooplankton. If the amount of phytoplankton is greater than zooplankton, then Sardines fit the Law of Demand, but if the amount of phytoplankton is smaller, the Sardines apparently show Giffen behaviour. Evolutionary population genetics models show that Giffen behaviour has more adaptive value than follow the Law of Demand under resource scarcity. Since overwhelming animal species live in poverty, Giffen behaviour may be the common economic strategy on the Earth.