Differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to determine morphological, structural and surface changes (biodegradation) on thermo-oxidized (80°C, 15 days) low-density polyethylene (TO-LDPE) incubated with Aspergillus niger and Penicillium pinophilum fungi, with and without ethanol as cosubstrate for 31 months. TO-LDPE mineralization by fungi was also evaluated. Significantly morphological and structural final changes on biologically treated TO-LDPE samples were observed. Decreases to three units on crystallinity and crystalline lamellar thickness (0.4 -1.8 Å), and increases in small-crystals content (up to 3.2%) and mean crystallite size (8.4 -14 Å) were registered. An oxidation decrease (almost twice) on samples without ethanol with respect to the control was observed, while in those with ethanol it was increased (up to 2.5 times). Double bond index increased more than twice from 21 to 31 months. The higher TO-LDPE changes and fungi-LDPE interaction was observed in samples with ethanol, suggesting that ethanol favors the TO-LDPE biodegradation, at least in case of P. pinophilum, probably by means of a cometabolic process. Mineralization of 0.50 % and 0.57 % for A. niger, and of 0.64 % and 0.37 % for P. pinophilum were obtained, for samples with and without ethanol, respectively. A model to explain morphological and structural changes on biologically treated TO-LDPE is also proposed.

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Phytoremediation offers a cheap, efficient and environmentally friendly option for cleaning sites contaminated with toxic elements. However, there is a need to find new plant species for phytoremediation and to understand the mechanisms involved in processes such as tolerance, accumulation, exclusion and metabolism of toxic metals in plants. Thereby, in this study, the ability of Acacia farnesiana (L.) Willd to tolerate and accumulate lead was analyzed. Seedlings grown in vitro with 250 and 500 mg Pb 2+ L −1 showed an increase in their growth, achieving tolerance indexes close to 100%. In seedlings exposed to 1,000 mg Pb 2+ L −1 , growth was strongly inhibited, finding an effective concentration 50% (EC 50 ) from 720 to 766 mg Pb 2+ L −1 . A. farnesiana accumulated ≥80% of the Pb 2+ in roots (up to 51,928 mgkg −1 of air-dried tissue) in seedlings exposed to 1,000 mg Pb 2+ L −1 , with high bioconcentration (>8.5) and low translocation (≤0.03) factors. These results indicate the suitability of A. farnesiana for lead-phytostabilization purposes. Lead concentrations below 500 mgL −1 had no significant effect on lipid peroxidation and enhanced the glutathione content, suggesting that the ability of A. farnesiana to withstand the Pb-induced oxidative stress could be related to glutathione metabolism.

The genus Aspergillus is ubiquitous in nature and includes various species extensively exploited industrially due to their ability to produce and secrete a variety of enzymes and metabolites. Most processes are performed in submerged fermentation (SmF); however, solid-state fermentation (SSF) offers several advantages, including lower catabolite repression and substrate inhibition and higher productivity and stability of the enzymes produced. This study aimed to explain the improved metabolic behavior of A. brasiliensis ATCC9642 in SSF at high glucose concentrations through a proteomic approach. Online respirometric analysis provided reproducible samples for secretomic studies when the maximum CO production rate occurred, ensuring consistent physiological states. Extracellular extracts from SSF cultures were treated by SDS-PAGE, digested with trypsin, and analyzed by LC-MS/MS. Of 531 sequences identified, 207 proteins were analyzed. Twenty-five were identified as the most abundant unregulated proteins; 87 were found to be up-regulated and 95 were down-regulated with increasing glucose concentration. Of the regulated proteins, 120 were enzymes, most involved in the metabolism of carbohydrates (51), amino acids (23), and nucleotides (9). This study shows the high protein secretory activity of A. brasiliensis under SSF conditions. High glucose concentration favors catabolic activities, while some stress-related proteins and those involved in proteolysis are down-regulated.