Muhammad Faisal Siddiqui

Mining soils often suffer from low biodiversity, poor organic matter, and environmental disturbances, which hinder seed germination and plant growth. This study utilized composting and phytocapping approaches to reclaim Fe tailing soil at field scale through addition of different organic residues and Sesbania sesban plant. The improvement of soil quality parameters including pH, soil organic matter (SOM), electrical conductivity (EC), cation exchange capacity (CEC), total N, total P, total microbial count, organically bound Fe, total Fe in soil, and in different parts of the plant were analyzed for 90 days. Organically bound iron was analyzed through Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and microbial community dynamics through 16S rRNA genome sequencing. All treatments showed highly significant difference (p < 0.05) in the pH values compared to C, while within treatments negligible changes in the pH was observed. In case of SOM, organically and plant treated samples showed significant increase as compared to C sample, similarly N, P content, EC, CEC and microbial count, total Fe and organically bound Fe were also significantly increased. The shift of microbial community from lithotrophs to organotrophs was observed compared to control which showed higher abundance of chemolithotrophs. It is concluded that the addition of organic matter enhanced the iron tailing properties along with iron mineralization, while S. sesban has further improved this process and uptake iron efficiently. These findings suggest treatment strategies applicable not only to iron mining sites but also to other extraction sites, including Cu and Pb.

Streptococcus mutans, the primary cause of dental caries, relies on its ability to create and sustain a biofilm (dental plaque) for survival and pathogenicity in the oral cavity. This study was focused on the antimicrobial biofilm formation control and biofilm dispersal potential of Coumaric acid (CA) against Streptococcus mutans on the dentin surface. The biofilm was analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) viability assay, microtiter plate assay, production of extracellular polymeric substances (EPSs), florescence microscopy (surface coverage and biomass μm²) and three-dimensional (3D) surface plots. It was observed that CA at 0.01 mg/mL reduced bacterial growth by 5.51%, whereases at 1 mg/mL, a significant (p < 0.05) reduction (98.37%) was observed. However, at 1 mg/mL of CA, a 95.48% biofilm formation reduction was achieved, while a 73.45% biofilm dispersal (after 24 h. treatment) was achieved against the preformed biofilm. The MTT assay showed that at 1 mg/mL of CA, the viability of bacteria in the biofilm was markedly (p < 0.05) reduced to 73.44%. Moreover, polysaccharide (EPS) was reduced to 24.80 μg/mL and protein (EPS) to 41.47 μg/mL. ImageJ software (version 1.54 g) was used to process florescence images, and it was observed that the biofilm mass was reduced to 213 (μm²); the surface coverage was reduced to 0.079%. Furthermore, the 3D surface plots showed that the untreated biofilm was highly dense, with more fibril-like projections. Additionally, molecular docking predicted a possible interaction pattern of CA (ligand) with the receptor Competence Stimulating Peptide (UA159sp, PDB ID: 2I2J). Our findings suggest that CA has antibacterial and biofilm control efficacy against S. mutans associated with dental plaque under tested conditions.

Objectives: Antibiotics are valuable therapeutics. However, the unwarranted and excessive use of these antimicrobials in food animals and the consequent contamination of the environment have been associated with the emergence and spread of antimicrobial resistance. Continuous surveillance and monitoring of antimicrobial resistance among E. coli isolates is recommended, not only for bovine health but also for public health. This study aims to assess the antimicrobial resistance profile, virulence potential, and genetic characterization of fecal E. coli isolates from healthy cows. Methodology: The in vitro, phenotypic antibiotic resistance of isolates was measured via the Kirby–Bauer disc-diffusion method against twenty-seven antibiotics. The β-lactamase enzymatic activities of the strains were also investigated. For the assessment of virulence potential, fecal E. coli isolates were subjected to several in vitro pathogenicity assays, including biofilm formation ability, blood hemolysis, complement resistance, and growth in human urine. Phylogroup determination and virulence-associated genes were detected via multiplex PCR. Results: In vitro antibiotic resistance profiling showed that 186/200 (93%) of the isolates were multidrug-resistant (MDR), with the highest resistance against penicillin, tetracycline, fluoroquinolone, and macrolide classes of antibiotics. Of particular concern was the phenotypic resistance to colistin in 52/200 isolates (26%), though 16% of the total isolates harbored mcr1, the genetic determinant of colistin. Despite the scarce use of fluoroquinolone, cephalosporin, and carbapenem in the agricultural sector, resistance to these classes was evident due to the presence of extended-spectrum β-lactamase (ESBL) in 41% of E. coli isolates. The β-lactamase genotyping of E. coli isolates showed that 47% of isolates harbored either blaCTX or blaTEM. Approximately 32% of isolates were resistant to serum complement, and their growth in human urine was evident in 18% of isolates, indicating a possible infection of these isolates in high nitrogenous condition. Phylogrouping showed that the most prevalent phylogenetic group among fecal E. coli isolates was phylogroup B1 (57%), followed by phylogroups A (33%), D (6%), and B2 (4%). The most prevalent virulence-associated genes in fecal E. coli were fimH, iss and tatT. Results showed that ten isolates (5%) harbored the stx1 gene, the genetic marker of enterohemorrhagic E. coli. This study provides insights into the antibiotic resistance and virulence profiling of the fecal E. coli isolates from healthy cows. These results emphasize the need for imposing regulations on the proper use of antibiotics and growth promoters in food-producing animals.

Finding new biological ways to control biofouling of the membrane in reverse osmosis (RO) is an important substitute for synthetic chemicals in the water industry. Here, the study was focused on the antimicrobial, biofilm formation, and biofilm dispersal potential of rhamnolipids (RLs) (biosurfactants). The MTT assay was also carried out to evaluate the effect of RLs on biofilm viability. Biofilm was qualitatively and quantitatively assessed by crystal violet assay, light microscopy, fluorescence microscopy (bacterial biomass (µm²), surface coverage (%)), and extracellular polymeric substances (EPSs). It was exhibited that RLs can reduce bacterial growth. The higher concentrations (≥100 mg/L) markedly reduced bacterial growth and biofilm formation, while RLs exhibited substantial dispersal effects (89.10% reduction) on preformed biofilms. Further, RLs exhibited 79.24% biomass reduction while polysaccharide was reduced to 60.55 µg/mL (p < 0.05) and protein to 4.67 µg/mL (p < 0.05). Light microscopy revealed biofilm reduction, which was confirmed using fluorescence microscopy. Microscopic images were processed with BioImageL software. It was revealed that biomass surface coverage was reduced to 1.1% at 1000 mg/L of RLs and that 43,245 µm² of biomass was present for control, while biomass was reduced to 493 µm² at 1000 mg/L of RLs. Thus, these data suggest that RLs have antimicrobial, biofilm control, and dispersal potential against membrane biofouling.