The social and ecological influence of Neonicotinoids (NEOs) usage in agriculture sector is progressively higher. There are seven NEOs insecticides widely used for the insects control. Among the NEOs, thiacloprid (THD) was extensively used for insect control during crop cultivation. This study targets to analyse the contamination levels of NEOs in agricultural soil and identify photo-biodegradation of THD degradation using pure isolates and mixed consortium. The photo degradation (PD), biodegradation (BD) and photo-biodegradation (PBD) of THD were compared. The corn field agricultural soils were polluted by four NEOs, among them THD had greater contamination level (surface soil: 3901.2 ± 0.04 μg/g) and (sub-surface soil: 3988.6 ± 0.05 μg/g). Three soil free enriched bacterial strains following Bacillus atrophaeus (PB-2), Priestia megaterium (PB-3) (formerly known as Bacillus megaterium), and Peribacillus simplex (PB-4) (formerly known as Bacillus simplex) were identified by microbiological and molecular 16s rRNA gene sequencing. The PD, BD and PBD of THD were conducted and degradation rate was detected by instrument UPLC-MS-MS. The PBD process with blue-LEDs showed better THD degradation efficiency than PD and BD, where the specific THD degradation rate was 85 ± 0.2%, 87 ± 0.5%, and 89 ± 0.3%, respectively for PB-2, PB-3 and PB-4. Then, the photo-biodegradation performance is greater at 150, 175, 200 rpm, pH 7.0–9.0, and temperature 30–35 °C. After the PBD system deliver four intermediate metabolites, the THD degradation process maybe through nitro reduction, hydroxylation and oxidative cleavage pathway.

Toxicity of pesticides towards microorganisms can have a major impact on ecosystem function. Nevertheless, some microorganisms are able to respond quickly to this stress by degrading these molecules. The edaphic Bacillus megaterium strain Mes11 can degrade the herbicide mesotrione. In order to gain insight into the cellular response involved, the intracellular proteome of Mes11 exposed to mesotrione was analyzed using the two-dimensional differential in-gel electrophoresis (2D-DIGE) approach coupled with mass spectrometry. The results showed an average of 1820 protein spots being detected. The gel profile analyses revealed 32 protein spots whose abundance is modified after treatment with mesotrione. Twenty spots could be identified, leading to 17 non redundant proteins, mainly involved in stress, metabolic and storage mechanisms. These findings clarify the pathways used by B. megaterium strain Mes11 to resist and adapt to the presence of mesotrione.

Phytoextraction using Celosia argentea Linn. can potentially decontaminate Cd-contaminated soils. However, most earlier studies have been conducted at laboratory scale and for a relatively short remediation period. To evaluate the phytoextraction efficiency of C. argentea combined with different soil amendments (ammonium chloride, Bacillus megaterium, and citric acid), an 18-month field experiment was carried out in a farmland soil contaminated with 3.68 mg kg⁻¹ Cd by mine tailings in southern China. Soil Cd concentrations were decreased by 6.34 ± 0.73% after the three harvestings (with no amendments), which was 2.27 times that of the no-planting control (p < 0.05). Application of ammonium chloride, B. megaterium, and citric acid increased the overall Cd reduction rate in soil by 40.5%, 46.1%, and 105%, respectively. The application of citric acid decreased total Cd in soil by up to 16.9% in the rhizosphere soil and 13.0% in the bulk soil. The highest annual shoot biomass yield and Cd extraction amount reached 8.79 t ha⁻¹ and 273 g ha⁻¹. Acid-soluble Cd fraction in the rhizosphere was significantly lower compared to that in the bulk soil (p < 0.05), which indicates that mobile Cd in the rhizosphere was taken up by the roots vastly. C. argentea phytoextraction also improved soil metabolic functions by increasing the activities of soil enzymes (urease, invertase, phosphatase, and catalase). These findings demonstrate that Cd phytoextraction using C. argentea with the application of soil amendments can greatly improve the quality of Cd-contaminated soils.

The air pollutant ozone (O₃) is a phytotoxic oxidative stressor, leading to visible foliar injury and plant growth decline. Plant growth-promoting bacteria (PGPB) are emerging as an eco-friendly tool for improving plant growth under stress. In order to test PGPB as a tool for alleviating O₃ stress in plants, an O₃ sensitive genotype (Phaseolus vulgaris L. cv S156) was inoculated with native (rhizobacterial; B1 and B2) and non-native PGPB (Bacillus megaterium and B. amylolequefaciens) and exposed to realistic O₃ exposure (ambient, AA with AOT40 = 0.53 ppm per hour, and twice ambient ozone concentration, 2XAA, AOT40 = 1.84 ppm per hour). The promoting effect was assessed by quantifying visible foliar O₃ injury (PII), chlorophyll a fluorescence (Fv/Fm), contents of hydrogen peroxide (H₂O₂), malondialdehyde (MDA) and nitric oxide (NO), ethylene emission, 1-aminocyclo-propane-1-carboxylate (ACC) deaminase enzyme activity, above- and below-ground biomass. BM, BA and B1 showed higher ACC deaminase enzyme activity and Fv/Fm, while ethylene emission, PII, H₂O₂, MDA and NO contents were lower in the BM, BA and B1 plants than in the B2 and non-inoculated plants under 2XAA. Only BA increased above- and below-ground biomass under AA and 2XAA. We conclude that PGPB are able to ameliorate O₃ stress through induction of systemic resistance; the level of bacterial ACC deaminase is one of the good markers for identifying effective strains and may be tested as an agricultural practice for improving crop yield under O₃ pollution.

Surfactant can reduce the interfacial tension in liquid–gas system and may probably improve the rate and/or extent of dissolution. This study was conducted to evaluate the effect of three different surfactants (viz., sodium dodecyl sulfate (SDS), Triton X-100, and cetyltrimethylammonium chloride (CTAC)) on CO₂biomineralization by two ureolytic microorganism—Sporosarcina pasteurii and Bacillus megaterium. In S. pasteurii-mediated biomineralization, headspace CO₂content (2.5 mM) was decreased by 40, 52, and 68 % in the presence of SDS, Triton X-100 or CTAC, respectively within the first 8 h of incubation. CO₂removal with B. megaterium in the presence of Triton X-100 (64 %) and CTAC (56 %) was better in comparison to control without surfactant (48 %). However, appreciable CO₂depletion was not observed with SDS, which was just 4 %. On other hand, headspace CO₂loss in the presence of CTAC with B. megaterium did not get biomineralized, as no calcium carbonate was detected. Crystalline phase and morphology of CaCO₃precipitate also varied between ionic and nonionic surfactants. The result suggests that the effect of surfactant on CO₂capture and biomineralization can be largely different, depending on the surfactant and concerned microbial species involved.

Microbial remediation, especially the application of probiotics, has recently gained popularity in improving water quality and maintaining aquatic animal health. The efficacy and mechanism of mixed Bacillus for improvement of water quality and its effects on aquatic microbial community structure remain unknown. To elucidate these issues, we applied two groups of mixed Bacillus (Bacillus megaterium and Bacillus subtilis (A0 + BS) and Bacillus megaterium and Bacillus coagulans (A0 + BC)) to the aquaculture system of Crucian carp. Our results showed that the improvement effect of mixed Bacillus A0 + BS on water quality was better than that of A0 + BC, and the NH₄⁺-N, NO₂⁻-N, NO₃⁻-N, and total phosphorus (TP) concentrations were reduced by 46.3%, 76.3%, 35.6%, and 80.3%, respectively. In addition, both groups of mixed Bacillus increased the diversity of the bacterial community and decreased the diversity of the fungal community. Microbial community analysis showed that mixed Bacillus A0 + BS increased the relative abundance of bacteria related with nitrogen and phosphorus removal, such as Proteobacteria, Actinobacteria, Comamonas, and Stenotrophomonas, but decreased the relative abundance of pathogenic bacteria (Acinetobacter and Pseudomonas) and fungi (Epicoccum and Fusarium). Redundancy analysis showed that NH₄⁺-N, NO₂⁻-N, and TP were the primary environmental factors affecting the microbial community in aquaculture water. PICRUST analysis indicated that all functional pathways in the A0 + BS group were richer than those in other groups. These results indicated that mixed Bacillus A0 + BS addition produced good results in reducing nitrogenous and phosphorus compounds and shaped a favorable microbial community structure to further improve water quality.

The integrated management of water resources is a requirement for environmental preservation and economic development, with the removal of nutrients being one of the main drawbacks. In this work, the efficiency of a bacterial consortium (Ecobacter WP) made up of eight bacterial strains of the genus Bacillus subtilis, Bacillus licheniformis, Bacillus megaterium, Bacillus cereus, Arthrobacter sp., Acinetobacter paraffineus, Corynebacterium sp., and Streptomyces globisporus was evaluated in the removal of nitrogen compounds in domestic wastewater in a plug flow system, in the extended aeration and bioaugmentation (FLAEBI). To promote the nitrification and denitrification processes, three doses were tested to establish the optimal concentration of the bacterial consortium on a laboratory scale and its subsequent application in an outdoor wastewater treatment plant (WWTP). The evaluation period was 15 days for each treatment in the laboratory and WWTP. The parameters monitored both at laboratory and outdoor were pH, temperature, dissolved oxygen, chemical oxygen demand (COD), biochemical oxygen demand (BOD₅), ammonium, nitrites, and nitrates. The results indicated that the optimal concentration of the consortium was 30 mg L⁻¹, with a removal of 92% of nitrate at the laboratory and 62% outdoor. Such a difference is attributed to the different operation residence times and the volume that caused different concentration gradients. The consortium studied can be used to promote nitrification and denitrification processes that intervene in the removal of nitrogenous compounds in plants with similar operating conditions, without investment in restructuring or design modification of the WWTP.

This study was aimed at studying the effect of heavy metals and arsenic on the survival and biofilm formation of some saprotrophic microorganisms: Bacillus megaterium var. phosphaticum, Bacillus mucilaginosus, Pectobacterium carotovorum, and Escherichia coli. As a source of heavy metals and arsenic, we used aqueous solutions of NaAsO₂, Cd(CH₃COO)₂, and Pb(NO₃)₂ (2.5, 25, 250 mg L⁻¹). The cultures in the liquid medium had different resistance to the toxicants under study: B. megaterium > B. mucilaginosus > P. carotovorum > E. coli. The toxicity of the tested solutions of heavy metals and arsenic for microorganisms can be arranged (decreasing toxicity) as follows: cadmium acetate > lead nitrate > sodium metaarsenite. These experiments revealed some regularities related to the mechanisms of toxic effect of As, Pb, and Cd solutions on the formation of biofilms of soil bacteria, changes in bacterial cellular forms, and their survival. Bacillus megaterium strain was the most resistant to high As concentrations and was able to influence the formation of highly structured colonies of bacterial cells with the honeycomb-like structure. The immobilization of heavy metals can be achieved due to their binding into strong compounds with the matrix substances of biofilms and polymeric organic compounds formed during the sporulation of rhizobacteria. It can increase the resistance of bacteria to high concentrations of heavy metals and arsenic. The results obtained can be of great practical importance in the development of biotechnologies related to soil bioremediation, in the field of nanotechnology, crop production, and medicine.

The processes of wind erosion of fertile soil, dune movement in sand deserts, dust storms in arid and semi-arid regions, as well as the emission and dispersion of agricultural or industrial dusts create a lot of problems and dangers for human life, environment, and infrastructure. Conventional ways to suppress dust emission to the atmosphere are agricultural fixation in the case of fertile soil surface and application of chemical agents to immobilize dust particulates onto the surface of soil, desert sand, country roads, or mining areas. However, these methods are often too expensive to be applied for large-scale suppression of sand dust. Chemical methods of dust suppression are often environmentally unfriendly due to the release of toxic reagents in water, air, and soil. This paper examines, for the first time, the microbially mediated aggregation of fine sand particles to suppress the emission of sand dust and its chemical and bacteriological pollutants. The bioaggregation reagent was a solution of calcium chloride and urea sprayed over the sand surface, which was preliminarily treated with the suspension of urease-producing bacteria. Quantity of calcium used for sand dust suppression was 15.6 g of Ca/m2. After the biotreatment of fine sand, the release of sand dust and its artificial pollutants to the atmosphere decreased in comparison with control by 99.8 % for dust, 92.7 % for phenantherene, 94.4 % for led nitrate, and 99.8 % for bacterial cells of Bacillus megaterium. This immobilization of dust and dust pollutants was due to the bioaggregation of fine sand particles. The sizes of 90 % of the sand dust particles increased from 29 μm in control to 181 μm after bioaggregation. Bioaggregation treatment of the soil surface could be a useful method to prevent the dispersion of dust and dust-associated chemical and bacteriological pollutants in water, air, and soil. © 2013 Springer Science+Business Media Dordrecht.

Excess Cd and Pb in agricultural soils enter the food chain and adversely affect all organisms. Therefore, it is important to find an eco-friendly way to reduce heavy metal accumulation in vegetables. We used urea agar plates to isolate urease-producing bacteria from the rhizosphere soil of lettuce in Cd- and Pb-contaminated farmland and investigated their ability to produce urease and immobilize heavy metals. The effects of these strains on the biomass, quality, and Cd and Pb accumulation of lettuce were also studied. The results showed that two urease-producing bacteria, Enterobacter bugandensis TJ6 and Bacillus megaterium HD8, were screened from the rhizosphere soil of lettuce. They had a high ability to produce urease (44.5 mS cm⁻¹ min⁻¹ OD₆₀₀⁻¹ and 54.2 mS cm⁻¹ min⁻¹ OD₆₀₀⁻¹, respectively) and IAA (303 mg L⁻¹ and 387 mg L⁻¹, respectively). Compared with the control, inoculation with strains TJ6 and HD8 reduced the Cd (75.3–85.8%) and Pb (74.8–87.2%) concentrations and increased the pH (from 6.92 to 8.13–8.53) in solution. A hydroponic experiment showed that the two strains increased the biomass (31.3–55.2%), improved the quality (28.6–52.6% for the soluble protein content and 34.8–88.4% for the vitamin C (Vc) content), and reduced the Cd (25.6–68.9%) and Pb (48.7–78.8%) contents of lettuce shoots (edible tissue). In addition, strain HD8 had a greater ability than strain TJ6 to reduce lettuce Cd and Pb uptake and water-soluble Cd and Pb levels in solution. These data show that the urease-producing bacteria protect lettuce against Cd and Pb toxicity by extracellular adsorption, Cd and Pb immobilization, and increased pH. The effects of heavy metal immobilization by the two strains can guarantee vegetable safety in situ for the bioremediation of heavy metal–polluted farmland.