Gabriela Angeles-De Paz

The application of pyrolysis is being extended to inorganic residues like plastics, which are considered an abundant residue nowadays. However, the sorbent capacity of plastic-derived char and its capacity to host biofilm formation that may be applied in bioremediation processes are unexplored. This study aimed to evaluate the char produced by pyrolysis of nonrecyclable post-consumer plastics to develop biofilm formation and its application in a real agrochemical effluent. The experimental design was set up in two phases: (i) adherence ability was measured with Ochrobactrum anthropi AD2 (with known adherence capacity) at optimal growth conditions on nonactivated or washed char, char activated with Na2CO3, and char activated with KOH; and (ii) biofilm formation ability in a real and polluted agrochemical wastewater on the surface of activated chars. The obtained results showed that O. anthropi AD2 biofilms were markedly influenced by the structural and surface characteristics of char, with the activated chars being more successful than nonactivated char. In the second phase, Na2CO3-activated char was the most efficient in the removal of copper, and it showed significantly higher microbial enumeration compared to KOH. The biofilm was composed of members of the Pseudomonas genus. This study suggests the potential of co-systems of biofilm-char as biotreatment of heavy metal-polluted wastewater.

Polyether ether ketones (PEEK) and polydimethylsiloxanes (PDMS) are widely used biomaterials; however, their susceptibility to microbial colonization remains a limitation in clinical applications. This study comparatively evaluated biofilm formation by Candida albicans and Nakaseomyces glabratus on PEEK and PDMS and characterized the effect of TiO₂/ZrO₂-based coatings applied to PEEK. Biofilm development was analyzed during adhesion, maturation, and dispersion using biomass quantification, metabolic activity assays, and scanning electron microscopy. Surface modifications were also evaluated. Both species formed a biofilm on the biomaterials, with a significantly higher biomass on the control, followed by PEEK and PDMS. TiO₂/ZrO₂-based coating affected biofilm maturation, with coating B as the one producing the greatest reduction in biofilm development. These findings suggest that surface modifications, such as hydrophobicity, using TiO₂/ZrO₂ coatings may influence fungal biofilm reduction and improve the antimicrobial performance of biomedical materials.

Untreated sewage sludge (SS) and misused stabilization technologies have contributed to great contamination and the accumulation of various pollutants in agricultural soils. Regarding micro-pollutants’ degradation, scalable and effective technologies are still scarce. Although many attempts at composting adaptations have been discussed, only a few have been tested individually under outdoor conditions. To investigate different composting methods (bioaugmentation and semipermeable cover) for the removal of micro-pollutants frequently found in SS, we performed a set of on-site experiments. Windrows of SS and olive pruning were used as the compostable material and were subjected to (i) bioaugmentation with the fungus Penicillium oxalicum, (ii) covered composting, (iii) covered and bioaugmented composting, and (iv) a conventional composting pile, which was included as a control. The entire experiment lasted 99 days. Bioaugmentation without cover increased the phosphorus content, favored a reduction in heavy metal content, and was the only treatment that reduced carbamazepine at the end of the process. Moreover, the inoculation of P. oxalicum under semipermeable cover increased the richness, diversity, and dominance of specific microbial taxa and total bacterial abundance. The four mature composts obtained met the standards required to be classified in the B fertilizer category, showing that we reduced most of the micro-pollutants, and passed the germination test.

A significant concentration of pharmaceuticals has been detected within composted sewage sludge. Their uncomplete removal and lack of monitoring during composting neglects their potentially toxic effects when used as a soil organic amendment. Previously, we successfully implemented a bioaugmentation–composting system focused on toxicity and pharmaceuticals’ concentration reduction. This method, however, comprised a long inoculant-acclimatization period, making it an unprofitable technology. Hence, this work aimed to explore a shorter and yet effective composting process by simultaneously implementing the inoculation of a native microbial consortium and the fungus Penicillium oxalicum XD 3.1 in composting piles of sewage sludge and olive prunings. All the piles were subjected to frequent inoculation, windrow turning, and monitoring of the physicochemical and biological parameters. Additionally, both the bioaugmentation stability and pharmaceuticals degradation were evaluated through different analysis and removal rates calculations. One hundred days earlier than previous attempts, both bioaugmentation treatments achieved adequate composting conditions, maintained core native populations while improving the degrading microbial diversity, and achieved around 70–72% of pharmaceutical remotion. Nevertheless, only Penicillium inoculation produced favorable toxicity results ideal for organic amendments (acute microtoxicity and phytotoxicity). Thus, a shorter but equally stable and effective degrading bioaugmentation–composting with P. oxalicum was achieved here.

We present the complete genome of the halotolerant strain Bacillus paralicheniformis HAS-1.

Microorganisms showed unique mechanisms to resist and detoxify harmful metals in response to pollution. This study shows the relationship between presence of heavy metals and plant growth regulator compounds. Additionally, the responses of Rhodotorula mucilaginosa YR29 isolated from the rhizosphere of Prosopis sp. growing in a polluted mine jal in Mexico are presented. This research carries out a phenotypic characterization of R. mucilaginosa to identify response mechanisms to metals and confirm its potential as a bioremediation agent. Firstly, Plant Growth-Promoting (PGP) compounds were assayed using the Chrome Azurol S (CAS) medium and the Salkowski method. In addition, to clarify its heavy metal tolerance mechanisms, several techniques were performed, such as optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) supplemented with assorted detectors. Scanning transmission electron microscopy (STEM) was used for elementary mapping of the cell. Finally, yeast viability after all treatments was confirmed by confocal laser scanning microscopy (CLSM). The results have suggested that R. mucilaginosa could be a PGP yeast capable of triggering Pb²⁺ biosorption (representing 22.93% of the total cell surface area, the heavy metal is encapsulated between the cell wall and the microcapsule), and Pb²⁺ bioaccumulation (representing 11% of the total weight located in the vacuole). Based on these results, R. mucilaginosa as a bioremediation agent and its wide range of useful mechanisms for ecological purposes are highlighted.

One of the most challenging environmental threats of the last two decades is the effects of emerging pollutants (EPs) such as pharmaceutical compounds or industrial additives. Diclofenac and bisphenol A have regularly been found in wastewater treatment plants, and in soils and water bodies because of their extensive usage and their recalcitrant nature. Due to the fact of this adversity, fungal communities play an important role in being able to safely degrade EPs. In this work, we obtained a sewage sludge sample to study both the culturable and non-culturable microorganisms through DNA extraction and massive sequencing using Illumina MiSeq techniques, with the goal of finding degraders adapted to polluted environments. Afterward, degradation experiments on diclofenac and bisphenol A were performed with the best fungal degraders. The analysis of bacterial diversity showed that Dethiosulfovibrionaceae, Comamonadaceae, and Isosphaeraceae were the most abundant families. A predominance of Ascomycota fungi in the culturable and non-culturable population was also detected. Species such as Talaromyces gossypii, Syncephalastrum monosporum, Aspergillus tabacinus, and Talaromyces verruculosus had remarkable degradation rates, up to 80% of diclofenac and bisphenol A was fully degraded. These results highlight the importance of characterizing autochthonous microorganisms and the possibility of selecting native fungal microorganisms to develop tailored biotransformation technologies for EPs.