Assessing three industrially produced fungi for the bioremediation of diclofenac.

Diclofenac is an emerging pollutant: toxic, persistent, and bioaccumulative, present in several environmental niches in a concentration of parts per million. This pharmaceutical's biological removal was reported with various fungal species, showing promissory results. This work aimed at diclofenac removal by individually challenging the fungal species Pleurotus ostreatus, Aspergillus niger, and Penicillium roquefortii but triying to lower the biosorption nature of cell walls by NaCl addition. P. ostreatus removed 100% of the initial diclofenac concentration, whereas A. niger and P. roqueforti removed 74% and 32%, respectively. In all three cases, biosorption by polar interactions was negligible. We demonstrated that stressful environments, such as mineral media, force the fungus to take advantage of its metabolic tools to survive, hence showing higher removal capacity when limiting growth conditions. Bioremediation is an excellent alternative to give residual fungal biomass a secondary use.

Diclofenac removal by the microalgae species Chlorella vulgaris, Nannochloropsis oculata, Scenedesmus acutus, and Scenedesmus obliquus.

In this work, we evaluated the removal efficiency of diclofenac by Chlorella vulgaris OW-01, Nannochloropsis oculata CCAP 849/7, Scenedesmus acutus UTEX 72, and Scenedesmus obliquus CCAP 276/2. Each microalga was grown in media with different concentrations (50 and 100% of the original formulation) of carbon, nitrogen, and phosphorus, to evaluate their effect on the removal of diclofenac. We also evaluated the photodegradation of diclofenac under the same conditions. The diclofenac removed from the media ranged from 59 to 92%, obtaining the highest removal with S. obliquus. The diclofenac adsorbed on the cell walls ranged from 12.2 to 26.5%, obtaining the highest adsorption with S. obliquus. The diclofenac degraded by light ranged from 15 to 28%. The nutrient deficit showed no influence on the removal of diclofenac in any of the microalgae under study. These results indicate that S. obliquus is the best alternative for the bioremediation of diclofenac. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-022-03268-2.

Increased removal of cadmium by Chlamydomonas reinhardtii modified with a synthetic gene for γ-glutamylcysteine synthetase.

Bioremediation with genetically modified microalgae is becoming an alternative to remove metalloids and metals such as cadmium, a contaminant produced in industrial processes and found in domestic waste. Its removal is important in several countries including Mexico, where the San Luis Potosi region has elevated levels of it. We generated a construct with a synthetic gene for γ-glutamylcysteine synthetase and employed it in the chloroplast transformation of Chlamydomonas reinhardtii. In dose-response kinetics with media containing from 1 to 20 mg/L of cadmium, both the transplastomic clone and the wild-type strain grew similarly, but the former removed up to 32% more cadmium. While the growth of both decreased with higher concentrations of cadmium, the transplastomic clone removed 20 ± 9% more than the wild-type strain. Compared to the wild-type strain, in the transplastomic clone the activity of glutathione S-transferase and the intracellular glutathione increased up to 2.1 and 1.9 times, respectively, in media with 2.5 and 10 mg/mL of cadmium. While 20 mg/L of cadmium inhibited the growth of both, the transplastomic clone gradually duplicated. These results confirm the expression of the synthetic gene gshA in the transformed strain as revealed in its increased removal uptake and metabolic response.

Inhibition of polyamine oxidase activity affects tumor development during the maize-Ustilago maydis interaction.

Ustilago maydis is a biotrophic plant pathogenic fungus that leads to tumor development in the aerial tissues of its host, Zea mays. These tumors are the result of cell hypertrophy and hyperplasia, and are accompanied by the reprograming of primary and secondary metabolism of infected plants. Up to now, little is known regarding key plant actors and their role in tumor development during the interaction with U. maydis. Polyamines are small aliphatic amines that regulate plant growth, development and stress responses. In a previous study, we found substantial increases of polyamine levels in tumors. In the present work, we describe the maize polyamine oxidase (PAO) gene family, its contribution to hydrogen peroxide (H2O2) production and its possible role in tumor development induced by U. maydis. Histochemical analysis revealed that chlorotic lesions and maize tumors induced by U. maydis accumulate H2O2 to significant levels. Maize plants inoculated with U. maydis and treated with the PAO inhibitor 1,8-diaminooctane exhibit a notable reduction of H2O2 accumulation in infected tissues and a significant drop in PAO activity. This treatment also reduced disease symptoms in infected plants. Finally, among six maize PAO genes only the ZmPAO1, which encodes an extracellular enzyme, is up-regulated in tumors. Our data suggest that H2O2 produced through PA catabolism by ZmPAO1 plays an important role in tumor development during the maize-U. maydis interaction.

Removal and accumulation of As, Cd and Cr by Typha latifolia.

The removal from the solution and the accumulation of As, Cd and Cr by Typha latifolia was studied. Small plants of T. latifolia, collected from a non-contaminated site, were exposed to individual concentrations of As, Cd and Cr for 10 days. The ability of T. latifolia for the removal of toxic elements ranged from 23% to 54% for As, 43%-55% for Cd and 28%-73% for Cr. The accumulation of toxic elements in T. latifolia occurred mainly in the roots. The results suggest that T. latifolia can be considered as an interesting alternative for treating aquatic effluents polluted with toxic trace elements.

Removal and accumulation of cadmium and lead by Typha latifolia exposed to single and mixed metal solutions.

We investigated the effect of Cd and Pb on the growth of the aquatic macrophyte Typha latifolia; the removal from the solution and the accumulation of these elements by the plant were also studied. Thus, small plants of T. latifolia, collected from a noncontaminated site, were exposed for 10 days to Cd and Pb, in a single solution or in mixture solutions, at two concentrations of the metals (5 and 7.5 mg/L). Our results showed that T. latifolia removed effectively Cd and Pb from solutions and was able to accumulate these metals in the roots and, to a lesser extent, in the leaves. Our findings suggested a synergistic effect of Cd and Pb with respect to the toxicity to T. latifolia. Additionally, Cd diminished the Pb absorption by T. latifolia. Our results confirmed, using scanning electron microscopy, the internalization of Cd and Pb in T. latifolia.

Expression of Escherichia coli heat-labile enterotoxin b subunit (LTB) in carrot (Daucus carota L.).

We expressed the B subunit of enterotoxigenic Escherichia coli heat-labile enterotoxin (LTB) encoded by a synthetic codon-optimized gene in carrot. An Agrobacterium-mediated transformation method was used. Thirty independent transgenic lines were regenerated via somatic embryogenesis after 6 months in culture and were transferred to a greenhouse. GM1-ELISA assay was used to assess LTB protein content in mature taproots. Some transgenic lines expressed LTB up to 0.3% of the total soluble protein, which is tenfold higher than the expression levels reported earlier using the native bacterial gene in plants. Immunological assay confirmed proper assembly of the pentameric complex and in vitro activity of the recombinant LTB protein, suggesting that it can be functional in prevention of diarrhea.