Ureolytic Lysinibacillus sp. exhibiting Calcium Carbonate Precipitation with Effective Lead (Pb) Removal

Scaling EPS yield and bio-carrier application of Bacillus paralicheniformis UB08 for rapid lead remediation

The most potent strain, Bacillus paralicheniformis UB08 (TISTR 10842), displayed an extraordinary nominal Pb tolerance, with a minimum bactericidal concentration exceeding 9,000 ppm, and alginate bead encapsulation enables rapid and complete Pb removal, offering a promising solution for heavy metal treatment based on physical adsorption and potential biological synergies.

Ureolytic Rhizobacteria for Cadmium Remediation: Contribution of Bioadsorption and Bioaccumulation During Microbially Induced Carbonate Precipitation in Liquid Medium Assays

Microbially induced carbonate precipitation (MICP) is a recognized bioremediation strategy for mitigating toxic metal pollution; however, the relative contributions of bioprecipitation, biosorption, and bioaccumulation to cadmium (Cd) removal during MICP remain underexplored. This study assessed Cd immobilization by six rhizosphere ureolytic bacterial strains from different genera in liquid medium and quantified the metal distributed among the bioprecipitated, biosorbed, and bioaccumulated fractions. Minimum inhibitory concentration assays showed Cd tolerance ranging from 90 to 300 mg L−1. The strains presented total Cd removal efficiencies of 64.9%–99.8% within 120 h. Notably, Cd removal occurs mainly under 48 h. Biosorption assays revealed substantially lower Cd removal compared with bioprecipitation experiments. Comparative analysis of Cd bioprecipitation and biosorption assays, combined with sequential extraction, demonstrated that bioadsorption plays a significant role in the removal of Cd via MICP. Precipitates characterization further confirmed coprecipitation of Cd with vaterite, a calcium carbonate polymorph. These findings elucidate an important role of biosorption in Cd immobilization during MICP, highlighting the need to evaluate removal mechanisms when assessing bacterial MICP potential, as different mechanisms can lead to distinct long‐term stability outcomes.

Integrated nitrate bioremediation and microbial risk mitigation using Bacillus pacificus

Screening and molecular characterization of an indigenous antibiotic and heavy metal-resistant Aeromonas hydrophila with bioremediation potential

Heavy metal contamination arising from municipal, industrial, and biomedical waste disposal has emerged as a major environmental concern, contributing not only to ecosystem degradation but also to the co-selection and dissemination of antimicrobial resistance among environmental microorganisms. The present study aimed to isolate, characterize, and molecularly identify an antibiotic- and heavy metal-resistant (AHMR) bacterium from contaminated solid waste disposal sites in West Bengal, India, and to evaluate its potential for bioremediation of heavy metal-polluted environments. Soil samples collected from hospital, industrial, and municipal waste disposal sites were screened on nutrient agar supplemented with nickel (Ni), lead (Pb), and cadmium (Cd) (50 µg mL⁻¹), resulting in the recovery of seven morphologically distinct bacterial isolates. Antibiotic susceptibility profiling using the Kirby–Bauer disc diffusion method identified isolate S23 as the most resistant strain, exhibiting a multidrug resistance (MDR) index of 0.8 with resistance to gentamicin, tetracycline, penicillin, and amphotericin B. Heavy metal tolerance assays demonstrated a minimum inhibitory concentration (MIC) of approximately 100 µg mL⁻¹ for all three metals, with nickel producing the strongest inhibitory effect on bacterial growth. Physiological and biochemical characterization revealed that isolate S23 was a mesophilic, halotolerant, catalase-positive bacterium capable of utilizing multiple carbohydrates, including glucose and sucrose. Growth kinetics further demonstrated its ability to maintain sustained proliferation under heavy metal stress, indicating a high degree of environmental adaptability. Molecular identification based on 16S rRNA gene sequencing confirmed the isolate as Aeromonas hydrophila. The concurrent occurrence of multidrug antibiotic resistance and heavy metal tolerance supports the hypothesis of co-selection of resistance determinants in contaminated environments. Furthermore, the remarkable metal tolerance exhibited by A. hydrophila suggests its potential application in the bioremediation of heavy metal-contaminated soils and wastewater through mechanisms such as biosorption, bioaccumulation, and biotransformation. Overall, this study highlights the ecological significance of environmental A. hydrophila as a resilient microorganism with promising applications in sustainable remediation strategies while emphasizing the environmental role of polluted habitats as reservoirs for multidrug-resistant bacteria

Bioremediation and heavy metal recovery from e-waste through enrichment and identification of effective bacterial isolates

Results support the hypothesis that SNBT005 actively facilitates metal recovery and reveal some localized pitting and surface degradation of the PCB matrix as the result of microbial activity.

Restaurant wastewater as a sustainable medium for ureolytic bacteria in biocementation

Restaurant wastewater (RWW) represents an abundant yet largely unexplored nutrient source for enriching ureolytic microbial consortia applicable to microbial-induced calcite precipitation (MICP). This study characterised RWW collected from a food-service establishment in Johor, Malaysia (COD 1,341 mg/L; BOD 837 mg/L; pH 6.8), and systematically evaluated its capacity to support indigenous ureolytic bacterial enrichment across three media formulations: yeast extract-based (Medium-1), nutrient broth-based (Medium-2), and brown sugar-based (Medium-3). Medium-1 delivered the strongest performance, achieving OD600 = 1.29 ± 0.06, urease activity = 17.42 ± 1.19 mM urea hydrolysed min− 1, and CaCO3 precipitation = 2.81 ± 0.17 g/L. Optimal bioactivity was recorded at pH 8 and 30 °C, conditions closely aligned with the tropical collection environment. 16 S rRNA amplicon sequencing (DADA2 pipeline; SILVA nr v138.1) yielded 101,869 quality-filtered reads across 116 amplicon sequence variants (ASVs; Shannon H = 2.79), identifying a co-dominant community of Firmicutes (50.83%) and Proteobacteria (48.36%), with Sporosarcina (6.09%), Bacillus (3.35%), Lysinibacillus (2.63%), and Raoultella (34.39%) as principal ureolytic contributors. Soil biocementation trials returned a mean surface strength of 423.3 ± 21.6 psi and a CaCO3 content of 16.64 ± 1.72%. Heavy metal immobilisation efficiencies reached 99.60% for Cd2+, 81.87% for Ni2+, 42.47% for Cr3+, and 22.47% for Cu2+ at 10 mg/L. XRD, FTIR, TGA, and DSC collectively confirmed a thermally stable, mineralogically pure biogenic calcite (> 96.7% residue at 894 °C). Collectively, these findings establish RWW-enriched consortia as functionally capable, cost-effective biocatalysts for sustainable MICP, in support of circular economy objectives within tropical urban contexts.