Biochar loaded with ferrihydrite and Bacillus pseudomycoides enhances remediation of co-existed Cd(II) and As(III) in solution

Bioremediation is one of the effective ways for heavy metal remediation. Iron-modified biochar (F@BC) loaded with Bacillus pseudomycoides (BF@BC) was synthesized to remove the coexistence of cadmium (Cd) and arsenic (As) in solutions. The results showed that B. pseudomycoides significantly increased the removal rate of Cd(II) by enhancing the specific surface area and Si-containing functional groups of biochar (BC). The surface of F@BC was enriched with Fe-containing functional groups, significantly improving As(III) adsorption. The combination of ferrihydrite and strains on BF@BC enhanced the removal of Cd(II) and As(III). It also promoted the oxidation of As(III) by producing an abundance of hydroxyl radicals (·OH). The maximum saturated adsorption capacity of BF@BC for Cd(II) and As(III) increased by 52.47% and 2.99 folds compared with BC, respectively. This study suggests that biochar loaded with Fe and bacteria could be sustainable for the remediation of the coexistence of Cd(II) and As(III) in solutions.

Synergistic approach for enhanced production of polyhydroxybutyrate by Bacillus pseudomycoides SAS-B1: Effective utilization of glycerol and acrylic acid through fed-batch fermentation and its environmental impact assessment

The continual rise in the consumption of petroleum-based synthetic polymers raised a significant environmental concern. Bacillus pseudomycoides SAS-B1 is a gram-positive rod-shaped halophilic bacterium capable of accumulating Polyhydroxybutyrate (PHB)-an intracellular biodegradable polymer. In the present study, the optimal conditions for cell cultivation in the seed media were developed. The optimal factors included a preservation age of 14 to 21 days (with 105 to 106 cells/mL), inoculum size of 0.1 % (w/v), 1 % (w/v) glucose, and growth temperature of 30 °C. The cells were then cultivated in a two-stage fermentation process utilizing glycerol and Corn Steep Liquor (CSL) as carbon and nitrogen sources, respectively. PHB yield was effectively increased from 2.01 to 9.21 g/L through intermittent feeding of glycerol and CSL, along with acrylic acid. FTIR, TGA, DSC, and XRD characterization studies were employed to enumerate the recovered PHB and determine its physicochemical properties. Additionally, the study assessed the cradle-to-gate Life Cycle Assessment (LCA) of PHB production, considering net CO2 generation and covering all major environmental impact categories. The production of 1000 kg of PHB resulted in lower stratospheric ozone depletion and comparatively reduced carbon dioxide emissions (2022.7 kg CO2 eq.) and terrestrial ecotoxicity (9.54 kg 1,4-DCB eq.) than typical petrochemical polymers.

In-silico analysis of a halophilic bacterial isolate-Bacillus pseudomycoides SAS-B1 and its polyhydroxybutyrate production through fed-batch approach under differential salt conditions

Polyhydroxybutyrate (PHB) is a natural biopolymer and a viable substitute for petroleum-derived polymers that possess immense potential for diverse applications. In the present study, PHB was produced by a halophilic bacteria identified as Bacillus pseudomycoides SAS-B1 by 16S rRNA gene sequencing. The bacterial genome was evaluated through complete genome sequencing, which elucidated a 5,338,308 bp genome with 34.88 % of G + C content and 5660 genes. Other genome attributes were analyzed such as functional profiling, gene ontology, and metabolic pathways. Genes involved in PHB biochemical pathway were identified such as phaA, phaB, and phaC. Furthermore, sodium-dependent transporters and other ATP-binding genes were identified in the genome that may be involved in sodium uptake during saline conditions. The PHB production by B. pseudomycoides SAS-B1 was examined under differential salt conditions. The PHB yield was increased from 3.14 ± 0.02 g/L to 6.12 ± 0.04 g/L when salinity was increased upto 20 g/L with intermittent feeding of glucose and corn steep liquor. FTIR, NMR, and GC-MS studies elucidated the presence of desired functional groups, molecular structure, and monomeric compositions of PHB respectively. Further, TGA revealed the thermal stability of the recovered PHB upto (220-230) °C and has a crystallinity index of upto 33 ± 0.5 % as confirmed by XRD analysis.

The capability of Bacillus pseudomycoides from soil to remove Cu(II) in water and prevent it from entering plants

AIMS

Copper ion is widespread in wastewater and threatens the condition and human health. Micro-organisms have unique advantages to remove heavy-metal ions from water, but are rarely reported in the removal of copper ion. This aims to develop micro-organisms that can remove copper ion in water, characterize their properties and analyse their potential application in practice.

METHODS AND RESULTS

Sewage sludge was used as the source to isolate wild bacteria that can remove copper ion in water. The most efficient strain was screened out from 23 obtained isolates, identified as Bacillus pseudomycoides and coded as C6. The properties of C6 in the removal of copper ion in water were investigated in the aspects of reaction conditions, reaction groups, reaction dynamic and the application in oat planting. The reaction at pH 7 within 10 min yielded the highest removal rate of copper ion, 83%. The presence of lead ion in the reaction system could promote the removal rate of copper ion. Carboxyl groups and amidogen of C6 biomass were mainly involved in the removal of copper ion. The removal of copper ion was in accord with single-layer adsorption and Langmuir adsorption isotherm model. In application, C6 biomass reduced the copper content in the oat seedlings grown in copper ion containing water by more than seven times.

CONCLUSIONS

B. pseudomycoides C6 can efficiently remove copper ion in water and inhibit it from entering plants.

SIGNIFICANCE AND IMPACT OF STUDY

This is the first time to report the capability of B. pseudomycoides to remove copper ion in water, which is also more efficient than the currently reported chemical and biological methods.

Rapid immobilization of viable Bacillus pseudomycoides in polyvinyl alcohol/glutaraldehyde hydrogel for biological treatment of municipal wastewater

A new approach for easy synthesis of Bacillus pseudomycoides immobilized polyvinyl alcohol (PVA)/glutaraldehyde (GA) hydrogel for application in a wastewater treatment system is reported. Optimization studies revealed that GA/PVA mass ratio of 0.03 and acidic pH of 2 were required for hydrogel synthesis and eventually for bacterial cell immobilization. The synthesized crosslinked matrix possessed a pore size suitable for microbial cell entrapment while maintaining cell accessibility to external environment for bioremediation. Possible crosslinking and bacterial cell immobilization in the hydrogel were evidenced by FTIR, XRD, and SEM studies, respectively. Further, the extent of crosslinking of GA with PVA was investigated and confirmed by transmittance and permeability experiments. The viability and proliferation of hydrogel embedded cells (after 25 days) was confirmed by confocal fluorescence microscopy which also indicated that acidic pH of polymer solution did not affect the immobilized live cells. B. pseudomycoides immobilized hydrogel were demonstrated to be effective for treatment of municipal wastewater and reduced biochemical oxygen demand (BOD), chemical oxygen demand (COD), and protein content below the recommended levels. Overall, the results from this bench-scale work show that employing bacteria-embedded PVA/GA hydrogel for the treatment of municipal wastewater yield promising results which should be further explored in pilot/field-scale studies.

Isolation and Characterization of Spore-Forming Bacilli (SFB) from Shepherd's Purse (Capsella bursa-pastoris)

Shepherd's purse (Capsella bursa-pastoris), native to Europe, is commonly consumed fresh and sometimes inadequately washed before consumption in Korea. The objective of this study was to characterize isolates of spore-forming bacilli (SFB) in samples of fresh Shepherd's purse. Three genera were identified: Bacillus (9 species), Paenibacillus (3 species), and Brevibacillus (1 species). None of the genes of the hemolysin BL (HBL) and nonhemolytic enterotoxin (NHE) complexes, or of the emetic toxin, was detected in the 25 SFB isolates, except for 2 Bacillus pseudomycoides isolates, where all 3 genes of the HBL enterotoxin complex were detected. There were significant sequence variations between the 2 species (Bacillus cereus and B. pseudomycoides) in the 3 genes of the HBL enterotoxin complex. These findings may provide insights into the diverse characteristics of the B. pseudomycoides HBL enterotoxin complex. Antibiotic resistance was assessed using 8 antibiotics. Among the 25 SFB isolates, 11 showed resistance to antibiotics, of which 5 were multiresistant. Assessment of the spoilage potential showed that all 25 SFB isolates could produce enzymes that can cause spoilage of foods. In conclusion, our findings may serve as integrative information for food research and industrial sectors.