Search Results (23)

Petroleum-contaminated soil is an increasingly severe environmental issue. The integration of phytoremediation and microbial remediation can effectively mitigate their individual limitations and enhance remediation efficiency. In this study, four newly isolated bacterial strains (including Cytobacillus and Rhodococcus) that exhibited preferential degradation of distinct petroleum components were combined with the rhamnolipid-producing strain Pseudomonas aeruginosa SL-1. The immobilization of this petroleum-degrading microbial consortium was performed by biochar adsorption and sodium alginate embedding, subsequently optimized using response surface methodology (0.75 g·L⁻¹ of biochar, 40 g·L⁻¹ of sodium alginate, and 40 g·L⁻¹ of calcium chloride). The results showed that the highest petroleum degradation rate (97.1%) of immobilized bacterial consortium was achieved at 72 h at a petroleum concentration of 5.0 g·L⁻¹. When combined with Sudan grass for soil bioremediation, the degradation rate reached 72.8% after 120 d for soil containing 5.0 g·kg⁻¹ of petroleum, higher than the results for the treatments with only immobilized bacterial consortium (53.0%) or Sudan grass (49.2%). Furthermore, significant improvements were observed for soil pH; nitrogen, phosphorus, and potassium contents; and urease, dehydrogenase, and catalase activities. Composite treatment also significantly increased the diversity and richness of the soil bacterial community and regulated its structure, function, and network composition. This study offers theoretical insights and potential practical applications for the enhanced bioremediation of petroleum-contaminated soils. Full article

The bioavailability of heavy metals is profoundly influenced by their interactions with active soil components (microorganisms, organic matter, and iron minerals). However, the effects of urease-producing bacteria combined with organo-Fe hydroxide coprecipitates (OFCs) on Cd accumulation in wheat, as well as the mechanisms underlying these effects, remain unclear. In this study, pot experiments integrated with high-throughput sequencing were employed to investigate the impacts of the urease-producing bacterial strain TJ6, ferrihydrite (Fh), and OFCs on Cd enrichment in wheat grains, alongside the underlying soil–microbial mechanisms. The results demonstrate that the strain TJ6-Fh/OFC consortium significantly (p < 0.05) reduced (50.1–66.7%) the bioavailable Cd content in rhizosphere soil while increasing residual Cd fractions, thereby decreasing (77.4%) Cd accumulation in grains. The combined amendments elevated rhizosphere pH (7.35), iron oxide content, and electrical conductivity while reducing (14.5–21.1%) dissolved organic carbon levels. These changes enhanced soil-colloid-mediated Cd immobilization and reduced Cd mobility. Notably, the NH₄⁺ content and NH₄⁺/NO₃⁻ ratio were significantly (p < 0.05) increased, attributed to the ureolytic activity of TJ6, which concurrently alkalinized the soil and inhibited Cd uptake via competitive ion channel interactions. Furthermore, the relative abundance of functional bacterial taxa (Proteobacteria, Gemmatimonadota, Enterobacter, Rhodanobacter, Massilia, Nocardioides, and Arthrobacter) was markedly increased in the rhizosphere soil. These microbes exhibited enhanced abilities to produce extracellular polymeric substances, induce phosphate precipitation, facilitate biosorption, and promote nutrient (C/N) cycling, synergizing with the amendments to immobilize Cd. This study for the first time analyzed the effect and soil science mechanism of urease-producing bacteria combined with OFCs in blocking wheat’s absorption of Cd. Moreover, this study provides foundational insights and a practical framework for the remediation of Cd-contaminated wheat fields through microbial–organic–mineral collaborative strategies. Full article

The hydrothermal carbonization (HTC) of biomass presents a sustainable approach for waste management and production of value-added materials such as hydrochar, which holds promise as an adsorbent and support matrix for bacterial immobilization applied, e.g., for bioremediation processes of sites contaminated with phthalate ester plasticizers such as diethyl phthalate (DEP). In the present study, hydrochar was synthesized from vine shoots (VSs) biomass employing the following parameters during the HTC process: 260 °C for 30 min with a 1:10 (w/v) biomass-to-water ratio. The resulting vine shoots hydrochar (VSs-HC) was characterized for porosity, elemental composition, and structural properties using Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDX), and Raman spectroscopy. Elemental analysis confirmed the presence of key elements in the VSs structure, elements essential for char formation during the HTC process. The VSs-HC exhibited a macroporous structure (>0.5 μm), facilitating diethyl phthalate (DEP) adsorption, bacterial adhesion, and biofilm formation. Adsorption studies showed that the VSs-HC achieved a 90% removal rate for 4 mM DEP within the first hour of contact. Furthermore, VS-HC was tested as a support matrix for a bacterial consortium (Pseudomonas spp. and Microbacterium sp.) known to degrade DEP. The immobilized bacterial consortium on VSs-HC demonstrated enhanced tolerance to DEP toxicity, degrading 76% of 8 mM DEP within 24 h, compared with 14% by planktonic cultures. This study highlights VSs-HC’s potential as a sustainable and cost-effective material for environmental bioremediation, offering enhanced bacterial cell viability, improved biofilm formation, and efficient plasticizer removal. These findings provide a pathway for mitigating environmental pollution through scalable and low-cost solutions. Full article

Slow decomposition rates of cereal crop residues can lead to agronomic challenges, such as nutrient immobilization, delayed soil warming, and increased pest pressures. In this regard, microbial inoculation with efficient strains offers a viable and eco-friendly solution to accelerating the decomposition process of crop residues. However, this solution often focuses mostly on selecting microorganisms based on the appropriate enzymic capabilities and neglects the metabolic versatility required to utilize both structural and non-structural components of residues. Therefore, this study aimed to address these limitations by assessing the metabolic profiles of five previously identified cellulolytic bacterial strains, including Bacillus pumilus 1G17, Micromonospora chalcea 1G49, Bacillus mobilis 5G17, Streptomyces canus 1TG5, and Streptomyces achromogenes 3TG21 using Biolog Phenotype Microarray analysis. Moreover, this study evaluated the impact of wheat straw inoculation with single strains and a bacterial consortium on soil organic carbon and nitrogen content in a pot experiment. Results revealed that, beyond the core subset of 12 carbon sources, the strains exhibited diverse metabolic capacities in utilizing 106 carbon sources. All strains demonstrated effective straw biomass degradation compared to the negative control, with significant differences detected only in oil seed rape straw biodegradation estimations. Furthermore, wheat straw inoculated with a bacterial consortium showed a significant increase in soil organic carbon content after 180 days in the pot experiment. Overall, these findings underscore the critical role of metabolic profiling in gaining a deeper understanding of microbial capabilities and addressing the complexities of residue composition and environmental variability. Full article

This study investigates the potential of microbial-induced calcium carbonate precipitation (MICP) for soil stabilization and heavy metal immobilization, utilizing landfill leachate-derived ureolytic consortium. Experimental conditions identified yeast extract-based media as most effective for bacterial growth, urease activity, and calcite formation compared to nutrient broth and brown sugar media. Optimal MICP conditions, at pH 8–9 and 30 °C, supported the most efficient biomineralization. The process facilitated the removal of Cd²⁺ (99.10%) and Ni²⁺ (78.33%) while producing stable calcite crystals that enhanced soil strength. Thermal analyses (thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC)) confirmed the successful production of CaCO₃ and its role in improving soil stability. DSC analysis revealed endothermic and exothermic peaks, including a significant exothermic peak at 444 °C, corresponding to the thermal decomposition of CaCO₃ into CO₂ and CaO, confirming calcite formation. TGA results showed steady weight loss, consistent with the breakdown of CaCO₃, supporting the formation of stable carbonates. The MICP treatment significantly increased soil strength, with the highest surface strength observed at 440 psi, correlating with the highest CaCO₃ content (18.83%). These findings underscore the effectiveness of MICP in soil stabilization, pollutant removal, and improving geotechnical properties. Full article

This work describes the development of an electrochemical biosensor method based on bacterial consortia to determine antioxidant capacity. The bacterial consortium used is a combination of bacteria from the genera Bacillus and Pseudomonas which can produce the enzymes tyrosinase and laccase. The consortium bacteria were immobilized on the surface of the screen-printed carbon electrode (SPCE) to form a biofilm. Biofilms were selected based on the highest current response evaluated electrochemically using cyclic voltammetry analysis techniques. Optimum consortium biofilm conditions were obtained in a phosphate buffer solution of pH 7, and biofilm formation occurred on day 7. This work produces analytical performance with a coefficient of determination (R²) of 0.9924. The limit of detection (LOD) and limit of quantification (LOQ) values are 0.5 µM and 10 µM, respectively. The biosensor showed a stable response until the 10th week. This biosensor was used to measure the antioxidant capacity of five extracts, and the results were confirmed using a standard method, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. The highest antioxidant capacity is guava extract and the lowest is tempuyung extract. Thus, the development of this biosensor method can be used as an alternative for measuring antioxidant capacity. Full article

The production of biogas is achieved during anaerobic digestion (AD) using organic matter as a substrate. In Mediterranean countries, a promising substrate is lignocellulose biomass of perennial grass Miscanthus x giganteus, due to its potentially high biogas yields, which could be comparable to maize silage. During AD, bacteria convert biomass into more minor compounds, which are further converted to methane by methanogenic archaea. The selection of appropriate microbes for the degradation of the substrate is crucial, and the enhancement of this step lies in the immobilization of microbes on biocarriers. Described here, a microbial consortium, de novo isolated and conditioned to degrade the Mischantus biomass, was immobilized onto several natural biocarriers: natural zeolitized tuff, ZeoSand^® (Velebit Agro, Zagreb, Croatia), perlite, and corncob. There was no statistically significant difference in the number of immobilized bacteria across the different materials. Therefore, all proved to be suitable for the immobilization of the consortium. In the consortium, five bacterial species with different shares in the consortium were identified: Enterobacter cloacae, Klebsiella pneumoniae, Enterobacter asburiae, Leclercia adecarboxylata, and Exiguobacterium indicum. After immobilization on each carrier, the share of each species changed when compared to starting conditions, and the most dominant species was E. cloacae (71–90%), while the share for other species ranged from 2 to 23%. The share of E. indicum was 14% at the start. However, it diminished to less than 1% because it was overgrown during the competition with other bacterial species, not due to an inability to immobilize. Full article

The amalgamation of mineral and targeted bacterial preparations represents a new generation of agricultural technology. Inoculation with combined preparations of microorganisms is more effective than inoculation with a single microorganism in stimulating plant growth by providing a more balanced diet for various crops. In this work, the effect of inoculation of 20 consortium variants on the yield indicators of three crops (wheat, buckwheat, corn) and the soil microbiome in the open field was investigated. The soil microbiome was defined by 16S rRNA sequences through NGS. The species richness of the soil microbial community (alpha diversity) was similar for all studied samples. A beta-diversity analysis revealed that the microbial diversity of three soil samples (C.bw, F.bw and Soil.bw) differed significantly from all others. At the phylum level, the number of Acidobacteriota and Firmicutes in these samples was increased. For the combination “Consortium C (Rothia endophytic GMG9 and Azotobacter chroococcum GMG39)—buckwheat”, a systemic positive improvement in all growth and yield indicators was observed. The soil of the site where buckwheat grew, inoculated by Consortium C, contained significantly more available phosphorus than all other soil samples. Such results can be explained both by the direct action of a consortium of phosphate-immobilizing and nitrogen-fixing bacteria and acidification of the medium due to an increase in phylum Acidobacteriota bacteria in the soil. Full article

Xanthan is an extracellular heteropolysaccharide produced by the bacteria Xanthomonas campestris. Due to its unique properties, the polysaccharide and its derivatives are widely used in many industries, from food to biomedicine and oil production, that demands an efficient xanthan depolymerization method to adapt this polysaccharide for various applications. Unlike the known chemical approaches, biological methods are considered to be more environmentally friendly and less energy intensive. In laboratory conditions, we have isolated a bacterial community capable of reducing the xanthan viscosity. Identification of the individual isolates in the microbial community and their testing resulted in the consortium LE-C1, consisting of two microorganisms Paenibacillus phytohabitans KG5 and Cellulosimicrobium cellulans KG3. The specific activities of the overall xanthanase and auxiliary enzymes that may be involved in the xanthan depolymerization were as follows: xanthanase, 19.6 ± 0.6 U/g; β-glucosidase, 3.4 ± 0.1 U/g; α-mannosidase, 68.0 ± 2.0 U/g; β-mannosidase, 0.40 ± 0.01 U/g; endo-glucanase, 4.0 ± 0.1 U/g; and xanthan lyase, 2.20 ± 0.07 U/mg. In order to increase the efficiency of xanthan biodegradation, the LE-C1 whole cells were immobilized in a poly(vinyl alcohol) cryogel. The resulting regenerative biocatalyst was able to complete xanthan depolymerization within 40 cycles without loss of activity or degradation of the matrix. Full article

The effects of the presence of perfluorocarbons (PFC) with a gas transport function in media with different phototrophic microorganisms on their growth rates and the accumulation of their biomass when using free and immobilized cells as inoculums were investigated. The significant increase in the average rate of biomass accumulation as well as levels of biomass accumulation in the presence of various PFCs were established for Chlorella vulgaris cells. When 1 g/L glycerol was introduced into the growth medium with PFCs and C. vulgaris cells, the increase in the rate of biomass accumulation was 9–32%. The maximum intracellular ATP concentrations corresponded to the combination of microalgae (Chlorella vulgaris) with bacterial cells (Pseudomonas esterophilus and Rhodoccus ruber) obtained with a mass ratio of 25:1. It provided for the formation of a consortium, which was able to accumulate the maximum amount of microalgae biomass for 3 days in the medium with PFCs and organophosphorus pesticide. The obtained data allow, on the one hand, predicting the growth of microalgae under environmental conditions in media with PFC pollution and, on the other hand, developing approaches to regulation of phototrophic microorganisms’ growth in order to obtain and use their high biomass yields for various purposes. Full article

Microbial biodegradation is considered as one of the most effective strategies for the remediation of soil contaminated with polycyclic aromatic hydrocarbons (PAHs). To improve the degradation efficiency of PAHs, PAH-degrading consortia combined with strengthening remediation strategies was used in this study. The PAH biodegrading performance of seven bacterial consortia constructed by different ratios of Mycobacterium gilvum MI, Mycobacterium sp. ZL7 and Rhodococcus rhodochrous Q3 was evaluated in an aqueous system containing phenanthrene, pyrene, benzo[a]pyrene and benzo[b]fluoranthene. Bacterial consortium H6 (Q3:ZL7:MI = 1:2:2) performed a high degrading efficiency of 59% in 8 days. The H6 was subsequently screened to explore its potential ability and performance to degrade aged PAHs in soils from a coking plant and the effects of strengthening strategies on the aged PAH degradation, including the addition of glucose or sodium dodecyl benzene sulfonate (SDBS) individually or as a mixture along immobilization of the inoculant on biochar. The highest degradation efficiencies, which were 15% and 60% for low-molecular-weight (LMW) PAHs and high-molecular-weight (HMW) PAHs, respectively, were observed in the treatment using immobilized microbial consortium H6 combined with the addition of glucose and SDBS after 24 days incubation. This study provides new insights and guidance for future remediation of aged PAH contaminated soils. Full article

This work provides the basis for implementing a continuous treatment system using a bacterial consortium for wastewater containing a pesticide mixture of iprodione (IPR) and chlorpyrifos (CHL). Two bacterial strains (Achromobacter spanius C1 and Pseudomonas rhodesiae C4) isolated from the biomixture of a biopurification system were able to efficiently remove pesticides IPR and CHL at different concentrations (10 to 100 mg L⁻¹) from the liquid medium as individual strains and free consortium. The half-life time (T_1/2) for IPR and CHL was determined for individual strains and a free bacterial consortium. However, when the free bacterial consortium was used, a lower T_1/2 was obtained, especially for CHL. Based on these results, an immobilized bacterial consortium was formulated with each bacterial strain encapsulated individually in alginate beads. Then, different inoculum concentrations (5, 10, and 15% w/v) of the immobilized consortium were evaluated in batch experiments for IPR and CHL removal. The inoculum concentration of 15% w/v demonstrated the highest pesticide removal. Using this inoculum concentration, the packed-bed bioreactor with an immobilized bacterial consortium was operated in continuous mode at different flow rates (30, 60, and 90 mL h⁻¹) at a pesticide concentration of 50 mg L⁻¹ each. The performance in the bioreactor demonstrated that it is possible to efficiently remove a pesticide mixture of IPR and CHL in a continuous system. The metabolites 3,5-dichloroaniline (3,5-DCA) and 3,5,6-trichloro-2-pyridinol (TCP) were produced, and a slight accumulation of TCP was observed. The bioreactor was influenced by TCP accumulation but was able to recover performance quickly. Finally, after 60 days of operation, the removal efficiency was 96% for IPR and 82% for CHL. The findings of this study demonstrate that it is possible to remove IPR and CHL from pesticide-containing wastewater in a continuous system. Full article

Antibiotic contamination of water is an emerging global issue with severe implications for both public health and the environment. Ciprofloxacin (CIP) is a synthetic fluoroquinolone antibiotic, which is broadly used in human and veterinary medicines around the world to treat various bacterial infections. The presence of CIP in the aquatic environment poses serious health problems to human beings and other living entities. Floating treatment wetland (FTW) is a low-cost and eco-friendly wastewater remediation technology. In the current study, the Canna indica. (Indian shot) was vegetated in a floatable mat to develop FTWs. A consortium of three bacterial strains, Acinetobacter lwoffii ACRH76, Bacillus pumulis C2A1, and Acinetobacter sp. HN3, was immobilized on iron oxide nanoparticles (Fe₃O₄-NPs) and augmented in the FTWs for the remediation of CIP-contaminated (100 mg/L) water. The augmentation of bacteria (immobilized or free) in the FTWs significantly enhanced the removal of CIP from water. The maximum reduction in CIP (98%), chemical oxygen demand (COD; 90%), biochemical oxygen demand (BOD; 93%) and total organic carbon (TOC; 95%) was observed in FTWs that had Fe₃O_4-NP supported bacteria. This study reveals that FTWs have a great potential to remove the CIP from contaminated water, albeit its CIP removal efficiency was substantially enhanced by augmentation with Fe₃O₄-NPs supported bacteria. Full article

The unwanted occurrence of antibiotics in the environment is an emerging concern of non-target toxicity and antimicrobial resistance. Floating treatment wetland (FTW) is a low-cost and ecofriendly wastewater remediation strategy; however, the effect of immobilized bacteria on its efficacy during the remediation of ciprofloxacin (CIP)-contaminated water has not been documented. In this study, Phragmites australis was planted to develop FTW, and it was augmented with a bacterial consortium (Acinetobacter lwoffii ACRH76, Bacillus pumulis C2A1, and Acinetobacter sp. HN3), with and without immobilization for the remediation of CIP-contaminated (100 mg L⁻¹) water. The augmentation of bacteria (immobilized or in suspension) in the FTWs significantly increased the elimination of CIP from the water. Maximum removal of CIP (97%), COD (92%), BOD (93%), and TOC (90%) from the water was observed in the FTWs having immobilized bacteria. This research revealed that the FTWs have tremendous potential to remove the CIP from the water and its removal efficiency can be enhanced via immobilized bacterial augmentation strategies. Full article

This work was aimed at the development of an immobilized artificial consortium (IMAC) based on microorganisms belonging to the Gram-positive and Gram-negative bacterial cells capable of jointly carrying out the rapid and effective degradation of different organophosphorus pesticides (OPPs): paraoxon, parathion, methyl parathion, diazinon, chlorpyrifos, malathion, dimethoate, and demeton-S-methyl. A cryogel of poly(vinyl alcohol) was applied as a carrier for the IMAC. After a selection was made between several candidates of the genera Rhodococcus and Pseudomonas, the required combination of two cultures (P. esterophilus and R. ruber) was found. A further change in the ratio between the biomass of the cells inside the granules of IMAC, increasing the packing density of cells inside the same granules and decreasing the size of the granules with IMAC, gave a 225% improvement in the degradation activity of the cell combination. The increase in the velocity and the OPP degradation degree was 4.5 and 16 times greater than the individual P. esterophilus and R. ruber cells, respectively. Multiple uses of the obtained IMAC were demonstrated. The increase in IMAC lactonase activity confirmed the role of the cell quorum in the action efficiency of the synthetic biosystem. The co-inclusion of natural strains in a carrier during immobilization strengthened the IMAC activities without the genetic enhancement of the cells. Full article