Dyes are widely used across various industries, and their incomplete fixation to fibers contaminates water. These compounds and their degradation products may be toxic, mutagenic, or carcinogenic, highlighting the need for efficient bioremediation strategies. This study reports the isolation of soil-derived Bacillus strains capable of decolorizing multiple azo dyes within a few days. Three strains, designated C7.1, L6, and L7, exhibited the highest decolorization rates under static conditions. Whole-genome analysis indicated that strains C7.1 and L7 are affiliated with the Bacillus cereus sensu lato group, whereas L6 is closely related to Bacillus velezensis. Genes encoding azoreductases, key enzymes responsible for the reductive cleavage of the azo chromophore, were identified in all strains, suggesting their central role in dye degradation. Additionally, B. velezensis (strain L6) has sequences encoding spore coat CotA laccase and DyP-type peroxidase, enzymes implicated in the biodegradation of other xenobiotic compounds. Cytotoxicity assays using Vero cells demonstrated that, after seven days of cultivation in media containing azo dye Methyl Orange, cell viability increased after treatment with strains C7.1 and L6. These findings suggest that the selected Bacillus isolates are promising candidates for bioremediation of dye-contaminated effluents and warrant further investigation to elucidate the metabolites and enzymatic pathways involved.

Bacteria are ubiquitous in nature, and the majority of them are contaminating and pathogenic in nature. These are the diversified organisms with an ability to grow in a wide range of conditions and environments. Glycerol is a polyol compound, a major constituent of soaps. A novel isolate was observed in contamination on glycerol-based soap by growing on it. The current study focused on isolating the organism, followed by screening tests, along with microbial identification by 16S rRNA sequencing and taxonomical classification. The isolate was isolated from the contaminated glycerin-based soap by primary screening with glycerol degradation using MB1 + 3% glycerol agar plates, where it showed the ability to degrade/utilise glycerol as its sole carbon source. The isolate was further studied by growing them under elevated glycerol concentrations like 3%, 6%, and 10% at varying pH from 6 to 10. This strain showed significant glycerol-degrading activity, which is evident from its rapid growth at pH 9 even after 6.5 days of incubation with an absorbance value of 8.01 ± 0.18 at 600 nm. Later, molecular characterization was performed by 16SrRNA sequencing and phylogenetic tree construction. This analysis unravels the identity of the organism as Ralstonia picketti, and the isolate was named as TS1, in an arbitrary manner. This study concludes that Ralstonia picketti TS1, isolate identified, is having a potential of glycerol degradation in glycerol-based soap.

Bisphenol A (BPA) is an endocrine disruptor. It is used to produce polycarbonate plastic and epoxy resins. It is a significant water contaminant that profoundly impacts ecosystems and human health, necessitating its removal from aquatic environments. Two oxidoreductases, Laccase and Versatile Peroxidase (VP) were selected to explore their potential for BPA degradation. Enzymatic degradation offers several advantages over microbial and chemical degradation, as it is substrate-specific, effective, and safe. It is effective and time saving to use computational methods to elucidate the interactions and stability of enzyme-xenobiotic complexes. In the current study, we employed molecular docking, MD simulations, binding free energy calculations, principal component analysis, free energy landscape, and DFT analysis approaches to investigate the possible non-covalent interactions and their life span. The study revealed that both Laccase and VP exhibit the ability to degrade BPA. Laccase exhibited minimal conformational changes upon BPA binding, while VP undergoes a noticeable opening to accommodate the pollutant. VP exhibited a higher affinity for BPA than Laccase, as evidenced by their respective binding energies. In vitro studies are warranted to validate the results. Further analysis indicated that amino acid residues such as Ala and Val were crucial in binding BPA to both enzymes. The outcomes can be used to engineer and design efficient enzymes to degrade BPA.

Soil contamination with potentially toxic elements (PTEs) such as lead (Pb) and cadmium (Cd) poses a significant threat to food security, ecosystem stability, and public health, particularly in urban and peri-urban environments. Despite increasing interest in phytoremediation, limited attention has been given to ornamental species with dual ecological and esthetic value. This study aimed to evaluate the capacity of Tagetes erecta (marigold), inoculated with arbuscular mycorrhizal fungi (AMF), to tolerate and accumulate Pb and Cd under controlled conditions. A greenhouse factorial experiment was conducted using five concentrations of Pb (0–200 mg/kg) and Cd (0–52.2 mg/kg) with and without Rhizophagus irregularis inoculation. AMF inoculation significantly improved biomass production and altered metal uptake patterns under PTE stress, suggesting modulation of physiological tolerance mechanisms. Key variables measured included shoot and root biomass, chlorophyll content, metal accumulation, and translocation/bioaccumulation factors. AMF inoculation significantly increased shoot dry weight by up to 43% under Pb200 and Cd52.2 treatments (p < 0.05), while reducing shoot Cd concentration by 41% at moderate contamination levels. Root colonization ranged from 80% to 94% in inoculated plants. Translocation factor for Pb reached 2.11 in AMF-treated plants, indicating enhanced mobility. These findings demonstrate that T. erecta–AMF symbiosis promotes biomass retention and selective metal uptake under PTE stress, suggesting a role in phytostabilization rather than active phytoextraction in ornamental settings for moderately contaminated soils.

This study investigates the impact of agitation speed on the ability of Penicillium chrysogenum to remove four different dyes: Everzol Black B (EBB), Basic Yellow (BY), Reactive Red (RR), and Acid Blue 62 (AB62). The results revealed that each dye achieved its maximum removal efficiency at different time points. For instance, AB62 reached 94.6% removal efficiency by day six, while RR and BY attained maximum removal rates of 88.7% and 89.4%, respectively, by day eight. EBB also showed a removal efficiency of 84.1% on day eight. These findings highlight the potential of Penicillium species in bioremediation applications. To validate these results, high-performance liquid chromatography (HPLC) was employed to analyze the of the dye degradation. The HPLC profiles, which compared the retention times and peak intensities of treated and untreated samples, confirmed significant dye degradation. This was evidenced by the disappearance of original peaks and the emergence of new peaks, indicating structural breakdown. For example, the disappearance of the 472 nm peak and the appearance of a 136 nm peak for EBB suggested substantial molecular changes. Similarly, for AB62, degradation was indicated by the removal of peaks at 472, 361, 329, and 279 nm, along with the appearance of a new peak at 136 nm, suggesting the formation of lower-mass fragments. The patterns of peak removal and formation for BY and RR further supported the successful breakdown of complex dye molecules into simpler forms. These results not only validate the efficacy of Penicillium chrysogenum in dye degradation but also underscore the utility of HPLC in monitoring biotransformation processes.

The accumulation of heavy metals in terrestrial and aquatic environments engenders significant detrimental effects on ecological systems and the health of biotic organisms. Bioremediation utilizing bacterial agents represents a highly effective and ecologically sustainable strategy for mitigating heavy metal contamination. In the present investigation, soils subjected to pollution and tainted with petroleum derivatives were scrutinized, leading to the isolation and identification of two predominant bacterial strains. Through the examination of the 16S ribosomal RNA gene region, the isolated bacterial strains were identified as Kocuria rosea and Mesobacillus persicus. The efficacy of the isolated strains in bioremediation was assessed under varying concentrations of Pb(II), revealing that both strains exhibited substantial potential in diminishing Pb(II) solubility and associated toxicity. Notably, the Kocuria rosea PH1 strain demonstrated superior bioremediation capabilities compared to the Mesobacillus persicus DH1 strain. The most pronounced percentage of bioremediation was recorded at a Pb(II) concentration of 50 mg/L; however, at a higher concentration of 250 mg/L of Pb(II), the bioremediation efficacy of the strains was found to be 44% for Kocuria rosea PH1 and 38% for Mesobacillus persicus DH1. The sedimentation of the bacteria was analyzed via Scanning Electron Microscopy (SEM). The findings indicated that Pb(II) was adhered to the exterior of bacterial cells. A detailed examination of the compounds present on the bacterial cell surfaces revealed that the quantity of Pb(II) on the surface of Mesobacillus persicus DH1 cells was 3.83%, while that on Kocuria rosea PH1 cells was 1.83%. Intriguingly, the phosphorus content in the Mesobacillus persicus DH1 strain was observed to be threefold greater than that in the Kocuria rosea PH1 strain. Collectively, the results elucidate that Kocuria rosea PH1 and Mesobacillus persicus DH1, as novel bioremediation agents, possess significant potential for the remediation of Pb(II) from contaminated environments.

Sulfate-containing wastewater treatment is important for decreasing industrial pollution. This study investigated the operation of upflow anaerobic sludge blanket (UASB) in removing sulfate at high loading rates under light and dark environments, respectively. Then, sulfate reducing bacteria (SRB) and photosynthetic bacteria (PSB) were isolated from reactors and cultivated at different oxygen and illumination conditions to explore their sulfate removal performance. In UASB systems, photoreactors maintained approximately 60% sulfate removal at a COD concentration of 10,000 mg/L, whereas non-photoreactors exhibited a near-complete loss of sulfate removal under the same conditions due to sulfide toxicity. SRB survived in both aerobic and anaerobic environments; however, exposure to light slightly inhibited sulfate removal with a reduction of 7.72%. Besides, PSB exhibited 20% faster growth under anaerobic conditions. Natural light further enhanced sulfide removal efficiency, achieving 50% removal at 300 mg/L sulfide, compared to less than 40% under compact fluorescent light. Batch inoculation of domesticated SRB and PSB into photoreactors resulted in sulfate removal efficiencies of 85.14% and 91.10%, respectively, which is significantly higher than the corresponding 72.55% and 63.48% achieved in non-photoreactors. This study not only provided a clean pathway to sulfate removal but also helped fully understand the properties of sulfate removal via SRB and PSB, providing a precondition for their practical application.

Industrial effluents contaminated with lead (Pb) pose a critical threat to ecosystems, human health, and aquatic life. While extensive research has focused on chemical and phytoremediation techniques, microbial remediation remains a cost-effective yet underexplored alternative – particularly concerning the role of gram-positive bacteria. This study investigates the involvement of gram-positive bacterial strains in the bioremediation of Pb from industrial effluents discharged by Berger Paints Pvt. Ltd., Hooghly, West Bengal. Pb concentrations in a total of 6 surface water samples collected during December at 0 km intervals up to 5 km from the discharge point were quantified using Atomic Absorption Spectroscopy (AAS), revealing significantly elevated Pb levels (p < 0.05) near the source. Microbial strains isolated from these samples were characterized through gram and endospore staining, followed by comprehensive physicochemical and biochemical profiling, including pH, temperature, and salt tolerance assessments, as well as IMViC, motility, catalase, oxidase, urease, TSI, EMB, MacConkey agar, and carbohydrate utilization tests. Four distinct gram-positive cocci strains were consistently isolated, exhibiting optimal growth at 35 ± 1 °C, pH 5–9 ± 1, and 0–4 ± 0.5% NaCl. These isolates demonstrated strong biochemical activity and variable resistance to Pb, with Minimum Inhibitory Concentration (MIC) values ranging from 1.20 to 4.80 ppm. The consistent identification of gram-positive strains suggests a potential role for peptidoglycan and teichoic acid components in biofilm-mediated Pb remediation. These findings underscore the significance of indigenous gram-positive bacteria in heavy metal bioremediation, particularly in Pb-contaminated industrial effluents. However, the lack of 16S rRNA sequencing and detailed analysis of metal-resistance genes remains a limitation. Future studies incorporating molecular identification and genetic profiling along with analysis of varying seasonal samples will provide deeper insights into the mechanisms and enzymatic evidence of microbial Pb remediation and validate the applicability of these strains in biotechnological interventions for environmental management.

The research examined the biological degradation of distributed yellow 4 G dye at various concentrations using four kinds of fungal cells. The research identified two fungal species, Morchella esculenta and Trametes versicolor, exhibiting the best biological removal rates by analyzing their laccase and MnP enzyme activities, together with the biological removal of dyestuff by free fungal cells. Free fungal cells removed the dye with efficiencies ranging from approximately 60% to 85.86% over 120 h, depending on the dye concentration. Immobilized fungal cells, using a calcium alginate-PVA matrix, achieved higher degradation rates, reaching up to 96.24%, compared to 92.47% for free-cell consortia. These results showed that immobilized cells were more suitable for the biological removal of dispersed yellow 4 G dyestuffs. The study demonstrated that dye concentration significantly affected degradation efficiency and highlighted the critical roles of laccase and MnP enzymes in the process. Overall, immobilized fungal cells were found to be more effective for the biological removal of dispersed yellow 4 G dye. The study also varied the concentration of dye to investigate its effect on the performance of the fungal cells.

Chromium, a hazardous and carcinogenic substance, is widely used in multiple industries. Its global presence is increasing, posing a significant risk to living organisms can be addressed with bioremediation. The current research examined the effects of chromate stress on exopolysaccharide (EPS) production capabilities of indigenous Cr (VI) resistant bacterial strains AKR2, UT25, LM3, UT8, NY2 and LM8. These strains demonstrated a marked increase in EPS production when cultured in Luria-Bertani (LB) broth under Cr (VI) stress (1500 µg/mL). The total protein and carbohydrate content of extracted EPS significantly elevated in response to Cr (VI) exposure. Characterization of extracted EPS through Fourier transform infrared spectroscopy (FTIR) revealed a highly intricate composition in all strains. Optimization of EPS production revealed 37 °C and pH 7 optimized physiological conditions through a one-variable-at-a-time strategy. Most strains showed enhanced exopolymer production with yeast extract and glucose as the sole source of nitrogen and carbon in presence of Cr (VI) stress (1000 µg/mL). Scanning electron microscopy (SEM) images of EPS from chromate treated strains indicated a dense assembly of cells enveloped by an EPS matrix. Transmission electron microscopy (TEM) of strain UT25 illustrated the role of EPS in remediation of Cr (VI).