The phenylurea herbicide diuron is persistent in soil, water and groundwater and is considered to be a highly toxic molecule. The principal product of its biodegradation, 3,4-dichloroaniline, exhibits greater toxicity than diuron and is persistent in the environment. Five diuron degrading microbial consortia (C1C5), isolated from different agricultural soils, were investigated for diuron mineralization activity. The C2 consortium was able to mineralize 81.6% of the diuron in solution, while consortium C3 was only able to mineralize 22.9%. Isolated consortia were also tested in soil slurries and in all cases, except consortium C4, DT50 (the time required for the diuron concentration to decline to half of its initial value) was drastically reduced, from 700 days (non-inoculated control) to 546, 351, and 171 days for the consortia C5, C2, and C1, respectively. In order to test the effectiveness of the isolated consortium C1 in a more realistic scenario, soil diuron mineralization assays were performed under static conditions (40% of the soil water-holding capacity). A significant enhancement of diuron mineralization was observed after C1 inoculation, with 23.2% of the herbicide being mineralized in comparison to 13.1% for the control experiment. Hydroxypropyl-β-cyclodextrin, a biodegradable organic enhancer of pollutant bioavailability, used in combination with C1 bioaugmentation in static conditions, resulted in a significant decrease in the DT50 (214 days; 881 days, control experiment). To the best of our knowledge, this is the first report of the use of soil-isolated microbial consortia in combination with cyclodextrins proposed as a bioremediation technique for pesticide contaminated soils.

A PAHs-contaminated industrial soil was analyzed using PCR amplification of the gene 16S ribosomal RNA for the detection and identification of different isolated bacterial strains potentially capable of degrading PAHs. Novel degrader strains were isolated and identified as Achromobacter xylosoxidans 2BC8 and Stenotrophomonas maltophilia JR62, which were able to degrade PYR in solution, achieving a mineralization rate of about 1% day^–1. A. xylosoxidans was also able to mineralize PYR in slurry systems using three selected soils, and the total extent of mineralization (once a plateau was reached) increased 4.5, 21, and 57.5% for soils LT, TM and CR, respectively, regarding the mineralization observed in the absence of the bacterial degrader. Soil TM contaminated with PYR was aged for 80 days and total extent of mineralization was reduced (from 46 to 35% after 180 days), and the acclimation period increased (from 49 to 79 days). Hydroxypropyl-ß-cyclodextrin (HPBCD) was used as a bioavailability enhancer of PYR in this aged soil, provoking a significant decrease in the acclimation period (from 79 to 54 days) due to an increase in PYR bioavailable fraction just from the beginning of the assay. However, a similar global extension of mineralization was obtained. A. xylosoxidans was then added together with HPBCD to this aged TM soil contaminated with PYR, and the total extent of mineralization decreased to 25% after 180 days, possibly due to the competitive effect of endogenous microbiota and the higher concentration of PYR in the soil solution provoked by the addition of HPBCD, which could have a toxic effect on the A. xylosoxidans strain.

The phenylurea herbicides are persistent in soil and water, making necessary the de-velopment of techniques for their removal from the environment. To identify new options in this regard, bacterial strains were isolated from a soil historically managed with pesticides. Ochrobactrum anthropi CD3 showed the ability to remove completely herbicides such as diuron, linuron, chlorotoluron and fluometuron from aqueous solution, and up to 89% of isoproturon. In the case of diuron and linuron, their main metabolite, 3,4-dichloroaniline (3,4-DCA), which has a higher toxicity than the parent compounds, was formed, but remained in solution without further degradation. O. anthropi CD3 was also tested for bioremediation of two different agricultural soils artificially contaminated with diuron, employing bioremediation techniques: (i) biostimulation, using a nutrient solution (NS), (ii) bioaugmentation, using O. anthropi CD3, and iii) bioavailability enhancement using 2-hydroxypropyl-β-cyclodextrin (HPBCD). When bioaugmentation and HPBCD were jointly applied, 50% of the diuron initially added to the soil was biodegraded in a range from 4.7 to 0.7 d. Also, 3,4-DCA was degraded in soil after the strain was inoculated. At the end of the soil biodegradation assay an ecotoxicity test confirmed that after inoculating O. anthropi CD3 the toxicity was drastically reduced.

The removal of chlorpyrifos (CLP) from the environment is a matter of general interest, because it is one of the most widely used insecticides in the world but presents a high toxicity and persistence in the environment. Biological strategies are considered as a good option to remediate different environmental compartments. Assisted natural attenuation was used to find the ability of different kinds of soils to mineralise CLP. In this way, two soils showed the capacity to degrade CLP (R and LL up to 47.3% and 61.4% after 100 d, respectively). Thus, two CLP-degrading strains, Bacillus megaterium CCLP1 and Bacillus safensis CCLP2 were isolated from them, showing the capacity to degrade up to 99.1 and 98.9% of CLP in a solution with an initial concentration of 10 mg L⁻¹ after 60 d. Different strategies were considered for increasing the effectiveness of soil bioremediation: (i) biostimulation, using a nutrients solution (NS); (ii) bioaugmentation, using B. megaterium CCLP1 or B. safensis CCLP2; (iii) bioavailability enhancement, using randomly methylated β-cyclodextrin (RAMEB), a biodegradable compound. When bioaugmentation and RAMEB were jointly inoculated and applied, the best biodegradation results were achieved (around 70%). At the end of the biodegradation assay, a toxicity test was used to check the final state of the bioremediated soil, observing that when the degrading strains studied were individually inoculated into the soil, the toxicity was reduced to undetectable levels.

Ibuprofen (IBU) is a significant contaminant frequently found in wastewater treatment plants due to its widespread use and limited removal during treatment processes. This leads to its discharge into the environment, causing considerable environmental concerns. The use of microorganisms has recently been recognized as a sustainable method for mitigating IBU contamination in wastewater. In this study, new bacteria capable of growing in a solid medium with IBU as the only carbon source and removing IBU from a liquid medium were isolated from environmental samples, including soil, marine, mine, and olive mill wastewater. Four bacterial strains, namely Klebsiella pneumoniae TIBU2.1, Klebsiella variicola LOIBU1.1, Pseudomonas aeruginosa LOIBU1.2, and Mycolicibacterium aubagnense HPB1.1, were identified through 16S rRNA gene sequencing. These strains demonstrated significant IBU removal efficiencies, ranging from 60 to 100% within 14 days, starting from an initial IBU concentration of 5 mg per litre. These bacteria have not been previously reported in the literature as IBU degraders, making this work a valuable contribution to further studies in the field of bioremediation in environments contaminated by IBU. Based on the IBU removal results, the most promising bacteria, K. pneumoniae TIBU2.1 and M. aubagnense HPB1.1, were selected for an in silico analysis to identify genes potentially involved in IBU biodegradation. Interestingly, in the tests with TIBU2.1, a peak of IBU transformation product(s) was detected by high‐performance liquid chromatography, while in the tests with HPB1.1, it was not detected. The emerging peak was analysed by liquid chromatography–mass spectrometry, indicating the presence of possible conjugates between intermediates of IBU biodegradation. The proteins encoded on their whole‐genome sequences were aligned with proteins involved in an IBU‐degrading pathway reported in bacteria with respective catabolic genes. The analysis indicated that strain HPB1.1 possesses genes encoding proteins similar to most enzymes reported associated with the IBU metabolic pathways used as reference bacteria, while strain TIBU2.1 has genes encoding proteins similar to enzymes involved in both the upper and the lower part of that pathway. Notably, in the tests with the strain having more candidate genes encoding IBU‐catabolic enzymes, no IBU transformation products were detected, while in the tests with the strain having fewer of these genes, detection occurred.