Lead oxalates in some Chinese leafy vegetable cultivation: their biomineralization and remediation by oxalate degrading Streptomyces sp.

Heavy metal contamination is a global threat with far-reaching effects for both human health and the environment. Biological agents, such as plants and microorganisms, provide uncomplicated and eco-friendly ways of removing toxic metals; thus, they are regarded as successful and alternative tools. In this study, we evaluated the ability of Streptomyces NJ10 (SN10), an oxalotrophic bacterium with outstanding oxalate metabolizing potential, to convert toxic lead oxalate (PbOx) into lead carbonate (PbCO3). SN10 was therefore used to determine the reduction of toxicity of Chinese leafy vegetables grown in the presence of PbOx in the soil. When compared to control, SN10 treated pots showed improved plant growth characters, i.e. shoot length (5.85 ± 0.56 cm), average leaf area (5.5 ± 0.44 cm2) and root length (7.2 ± 0.45 cm), as established by the plant growth attributes and the results obtained are statistically significant (at P ≤ 0.05) (for a period of 30 days). Furthermore, X-ray diffraction (XRD) and Scanning Electronic Microscopy-Energy-Dispersive X-ray Spectroscopy (SEM-EDS) studies revealed that PbOx was successfully transformed into a less toxic, water-insoluble precipitate of Pb-bearing carbonate, Phosgenite. The results provided a new idea for the biotransformation and toxicity mitigation of Pb contamination in soil. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-022-03353-6.

The formation of fungus-serpentine aggregation and its immobilization of lead(II) under acidic conditions.

Serpentine has weak immobilization capacity for Pb(II), especially under acidic conditions. In order to improve its application potential, a new biological modification method was adopted, i.e., the serpentine powder was weathered by Aspergillus niger and the fungus-serpentine aggregation (FSA) formed was investigated for its Pb(II) immobilization potential and underlying mechanism. Batch adsorption of Pb(II) by FSA closely followed the Langmuir model, while the maximum adsorption capacity of FSA (370.37 mg/g) was significantly higher than fungal mycelium (31.85 mg/g) and serpentine (8.92 mg/g). The adsorption process can be accurately simulated by pseudo-second-order kinetic model. Our data revealed the loading of organic matter is closely related to the adsorption of FSA, and the stronger immobilization capacity was mainly related to its modified porous organic-inorganic composite structure with extensive exchangeable ions. Moreover, FSA is an economical bio-material with excellent Pb(II) adsorption (pH = 1-8) along with significantly lower desorption efficiency (pH = 3-8), especially under acidic conditions. These findings provide a new perspective to explore the usage of fungus-minerals aggregation on heavy metals immobilization in acidic environments. Key Points • Co-culture of Aspergillus niger and serpentine produced a porous composite material like fungus-serpentine aggregation. • Fungus-serpentine aggregation has a surprisingly higher adsorption capacity of Pb(II) and significantly lower desorption efficiency under acidic conditions. • The loading of organic matter is closely related to the adsorption of FSA.

Aspergillus and Fusarium control in the early stages of Arachis hypogaea (groundnut crop) by plant growth-promoting rhizobacteria (PGPR) consortium.

In this study, we have attempted to develop a plant growth promoting rhizobacteria (PGPR) consortia against early-stage diseases in Arachis hypogaea (Groundnut crop) plantation of Andhra Pradesh, India. The dominant PGPRs were selected by considering the various plant growth and protection qualities, followed by characterisation and grouping based on compatibility to form a consortium of PGPRs [Group-1 includes EX-1 (Acinetobacter baumannii stain HAMBI 1846); EX-3 (Pseudomonas aeruginosa strain A1K319); EX-5 (Bacillus subterraneus strain CF1.9); KNL-1 (Bacillus subtilis strain JMP-B); CTR-4 (Enterobacter cloacae strain VITKJ1); ANT-4 (Bacillus subtilis strain SBMP4) and Group-2 includes EX-4 (Pseudomonas otitidis strain SLC8); KDP-4 (Pseudomonas aeruginosa strain Kasamber 11); NLR-4 (Bacillus species ADMK68); ANT-6 (Bacillus subtilis subsp. inaquosorum strain KCTC 13429)]. In addition to resistance to early stage pathogens, in both in vitro and pot experiments the PGPR consortium showed significantly higher germination rate and root induction (Aspergillus niger; A. flavus; Fusarium oxysporum) when compared to control and fertilizer treated groups. In addition, Group 2 was more successful in stimulating and protecting plant growth among the two groups of PGPRs developed. The PGPR consortia developed showed multiple plant growth characteristics, including phosphate solubilization, production of HCN and Indole acetic acid along with broad antagonism against the tested phytopathogens.

Oxalate Carbonate Pathway-Conversion and Fixation of Soil Carbon-A Potential Scenario for Sustainability.

It is still an important aspect of global climate research to explore a low-cost method that can effectively reduce the increase of CO2 concentration in the global atmosphere. Oxalotrophic bacterial communities exist in agricultural or forest soil with ubiquitous oxalate as the only carbon and energy source. When soil oxalate is oxidized and degraded, carbonate is formed along with it. This process is called the oxalate carbonate pathway (OCP), which can increase soil inorganic carbon sink and soil organic matter content. This soil carbon sink is a natural CO2 trapping system and an important alternative if it is properly managed for artificial sequestration/storage. As the main driver of OCP, the oxalate degrading bacteria are affected by many factors during the oxalate conversion process. Understanding this process and the synergy of oxalogenic plants, saprophytic decomposers, and oxalotrophic bacteria in agricultural or forest soil is critical to exploiting this natural carbon capture process. This article aims to provide a broader perspective of OCP in CO2 sequestration, biomineralization, and elemental cycling.

Heavy Metal Detoxification by Different Bacillus Species Isolated from Solar Salterns.

The biosorption mechanism is an alternative for chemical precipitation and ultrafiltration which have been employed to treat heavy metal contamination with a limited success. In the present study, three species of Bacillus which were isolated from solar salterns were screened for their detoxification potential of the heavy metals, lead, chromium, and copper, by biosorption. Biosorption potential of each isolate was determined by Atomic Absorption Spectroscopy (AAS), Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), and Energy Dispersive Spectroscopy (EDS) as the amount of metal present in the medium after the treatment with the isolates. Bacterial isolates, Bacillus licheniformis NSPA5, Bacillus cereus NSPA8, and Bacillus subtilis NSPA13, showed significant level of lead biosorption with maximum of 87-90% by Bacillus cereus NSPA8. The biosorption of copper and chromium was relatively low in comparison with lead. With the obtained results, we have concluded that the bacterial isolates are potential agents to treat metal contamination in more efficient and ecofriendly manner.

Video analysis of the biomechanics of a bicycle accident resulting in significant facial fractures.

INTRODUCTION: This study aimed to use video analysis techniques to determine the velocity, impact force, angle of impact, and impulse to fracture involved in a video-recorded bicycle accident resulting in facial fractures. Computed tomographic images of the resulting facial injury are presented for correlation with data and calculations. To our knowledge, such an analysis of an actual recorded trauma has not been reported in the literature. MATERIALS AND METHODS: A video recording of the accident was split into frames and analyzed using an image editing program. Measurements of velocity and angle of impact were obtained from this analysis, and the force of impact and impulse were calculated using the inverse dynamic method with connected rigid body segments. These results were then correlated with the actual fracture pattern found on computed tomographic imaging of the subject's face. RESULTS: There was an impact velocity of 6.25 m/s, impact angles of 14 and 6.3 degrees of neck extension and axial rotation, respectively, an impact force of 1910.4 N, and an impulse to fracture of 47.8 Ns. These physical parameters resulted in clinically significant bilateral mid-facial Le Fort II and III pattern fractures. DISCUSSION: These data confer further understanding of the biomechanics of bicycle-related accidents by correlating an actual clinical outcome with the kinematic and dynamic parameters involved in the accident itself and yielding a concrete evidence of the velocity, force, and impulse necessary to cause clinically significant facial trauma. These findings can aid in the design of protective equipment for bicycle riders to help avoid this type of injury.