001. González R, García-Balboa C, Rouco M, Lopez-Rodas V, Costas E. Genetica, Facultad de Veterinaria, Universidad Complutense, 28040, Madrid, Spain. Adaptation of microalgae to lindane: a new approach for bioremediation. Aquatic Toxicology, 2012, 109, 25 - 32.
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.
Keywords: Adaptation, Bioremediation, Lindane, Microalgae, Mutation.
002. Alguacil Mdel M, Torrecillas E, Hernández G, Roldán A. CSIC-Centro de Edafología y Biología Aplicada del Segura, Department of Soil and Water Conservation, Campus de Espinardo, Murcia, Spain. Changes in the diversity of soil arbuscular mycorrhizal fungi after cultivation for biofuel production in a guantanamo (cuba) tropical system. PLoS One. 2012, 7 (4). 1 - 8.
The arbuscular mycorrhizal fungi (AMF) are a key, integral component of the stability, sustainability and functioning of ecosystems. In this study, we characterised the AMF biodiversity in a native vegetation soil and in a soil cultivated with Jatropha curcas or Ricinus communis, in a tropical system in Guantanamo (Cuba), in order to verify if a change of land use to biofuel plant production had any effect on the AMF communities. We also asses whether some soil properties related with the soil fertility (total N, Organic C, microbial biomass C, aggregate stability percentage, pH and electrical conductivity) were changed with the cultivation of both crop species. The AM fungal small sub-unit (SSU) rRNA genes were subjected to PCR, cloning, sequencing and phylogenetic analyses. Twenty AM fungal sequence types were identified: 19 belong to the Glomeraceae and one to the Paraglomeraceae. Two AMF sequence types related to cultured AMF species (Glo G3 for Glomus sinuosum and Glo G6 for Glomus intraradices-G. fasciculatum-G. irregulare) did not occur in the soil cultivated with J. curcas and R. communis. The soil properties (total N, Organic C and microbial biomass C) were higher in the soil cultivated with the two plant species. The diversity of the AMF community decreased in the soil of both crops, with respect to the native vegetation soil, and varied significantly depending on the crop species planted. Thus, R. communis soil showed higher AMF diversity than J. curcas soil. In conclusion, R. communis could be more suitable for the long-term conservation and sustainable management of these tropical ecosytems.
Keywords: arbuscular mycorrhizal fungi, native vegetation soil, fungal small sub-unit, mycorrhizal fungi.