Growth, respiratory activity and chlorpyrifos biodegradation in cultures of Azotobacter vinelandii ATCC 12837

This study aimed to evaluate the growth, respiratory activity, and biodegradation of chlorpyrifos in cultures of Azotobacter vinelandii ATCC 12837. A strategy based on the modification of culture media and aeration conditions was carried out to increase the cell concentration of A. vinelandii , in order to favor and determine its tolerance to chlorpyrifos and its degradation ability. The culture in shaken flasks, using sucrose as a carbon source, significantly improved the growth compared to media with mannitol. When the strain was cultivated under oxygen-limited (5.5, 11.25 mmol L- 1 h- 1 ) and no-oxygen-limited conditions (22 mmol L -1 h -1 ), the growth parameters were not affected. In cultures in a liquid medium with chlorpyrifos, the bacteria tolerated a high pesticide concentration (500 ppm) and the growth parameters were improved even under conditions with a reduced carbon source (sucrose 2 g L -1 ). The strain degraded 99.6 % of chlorpyrifos at 60 h of cultivation, in co-metabolism with sucrose; notably, A. vinelandii ATCC 12837 reduced by 50% the initial pesticide concentration in only 6 h (DT 50 ).

Hydroxylamine Accelerates the Cycle of Fe(III)/Fe(II)-Cu(II)/Cu(I) to Enhance the Ability of Fe-Cu Bimetallic System to Activate Peroxymonosulfate to Degrade AO7

In this study, a new type of iron/copper bimetallic combined with hydroxylamine (HA) activated peroxymonosulfate (PMS) was constructed to treat organic pollutants. Selecting the azo dye AO7 as the representative of organic pollutants, the new system can achieve nearly 100% degradation of AO7 within 5 minutes. The Fe(Ⅲ)/Cu(Ⅱ)/HA/PMS system mainly generates SO4·- to achieve the degradation of AO7 in acidic environment, while neutral and alkaline environments rely on ·OH. The presence of hydroxylamine accelerates the cycle of Fe(Ⅲ)/Fe(Ⅱ) and Cu(Ⅱ)/Cu(Ⅰ) in the system, and enhances the degradation ability of the system for organic pollutants. The addition of trace Cu(Ⅱ) (1 μM) enhances the ability of a single Fe(Ⅲ)/HA/PMS system to degrade AO7 in neutral and alkaline environments without causing secondary copper pollution. The common inorganic anions Cl- and NO3- in water have almost no effect on the degradation of AO7 in the system. The constructed Fe(Ⅲ)/Cu(Ⅱ)/HA/PMS system is an efficient and clean organic pollutant wastewater treatment process, which has very promising application prospects.

Growth, respiratory activity and chlorpyrifos biodegradation in cultures of Azotobacter vinelandii ATCC 12837

This study aimed to evaluate the growth, respiratory activity, and biodegradation of chlorpyrifos in cultures of Azotobacter vinelandii ATCC 12837. A strategy based on the modification of culture media and aeration conditions was carried out to increase the cell concentration of A. vinelandii, in order to favor and determine its tolerance to chlorpyrifos and its degradation ability. The culture in shaken flasks, using sucrose as a carbon source, significantly improved the growth compared to media with mannitol. When the strain was cultivated under oxygen-limited (5.5, 11.25 mmol L−1 h−1) and no-oxygen-limited conditions (22 mmol L−1 h−1), the growth parameters were not affected. In cultures in a liquid medium with chlorpyrifos, the bacteria tolerated a high pesticide concentration (500 ppm) and the growth parameters were improved even under conditions with a reduced carbon source (sucrose 2 g L−1). The strain degraded 99.6% of chlorpyrifos at 60 h of cultivation, in co-metabolism with sucrose; notably, A. vinelandii ATCC 12837 reduced by 50% the initial pesticide concentration in only 6 h (DT50). Graphical Abstract

Oxidative Degradation of Hazardous Benzene Derivatives by Ferrate(VI): Effect of Initial pH, Molar Ratio and Temperature

Two of the most hazardous benzene derivatives (HBD) that have polluted the aquatic environment are bromobenzene and chlorobenzene. Ferrate can degrade various pollutants quickly and efficiently without producing harmful byproducts. This study aims to determine the ability of ferrate to degrade harmful contaminants such as bromobenzene and chlorobenzene. A series of batch experiments were carried out, including for the molar ratio, initial pH solution, and temperature. The study was conducted at an initial pH of 3.6 to 9.6, a molar ratio of 2 to 8 and a temperature of 15 to 55 °C. The study will also examine the differences in functional groups in these pollutants. As a result of the experiments, the optimum conditions to oxidize HBD in a batch reactor was found to have an initial pH of 7.0, a molar ratio of 8, and a temperature of 45 °C, with a 10 min reaction time. Ferrate has a degradation ability against chlorobenzene greater than bromobenzene. The functional cluster in pollutants also significantly affects the degradation ability of ferrate. The results of the degradation experiment showed that ferrate(VI) could effectively oxidize hazardous benzene derivatives in a solution.

Obtainment of Lignocellulose Degradation Microbial Community: The Effect of Acid-Base Combination After Restrictive Enrichment

Acid-base combination is used in some cases expecially after restricted enrichment, and has created many lignocellulose-degrading communities. While how it worked is not well understood. In this study, compost was used as inoculum source. Induced community structure changes were analyzed with high throughput sequencing to elucidate the formation processes and determine the mechanisms of acid-base combination. We found that after restricted enrichment, retaining primarily bacteria not only included that could decompose and utilize lignocellulose, such as Clostridium and Pseudomonas, but also synergistic microbiota such as Pseudoxanomonas and Alkalobacillaceae. When the proportion of these two types of bacteria was not balanced, the degradation ability of the microbial community was low or pH changes of it did not compound regular changes , which maybe lead to the failure of restricted enrichment. Microbial communities were re-constituted by acid-base combination, whereby the degrading and synergistic strains were adjusted to a more appropriate proportion. Acid-base combination fixed the instability of microbial communities caused by randomness of restrictive screening enrichment. In this study, the mechanism of acid-base combination was analyzed, which enriched the theoretical system of restricted culture, and provided an effective and controllable technical method for obtaining high-quality lignocellulose-degrading microbial community resources.

Biomineralization Induced by Cells of Sporosarcina pasteurii: Mechanisms, Applications and Challenges

Biomineralization has emerged as a novel and eco-friendly technology for artificial mineral formation utilizing the metabolism of organisms. Due to its highly efficient urea degradation ability, Sporosarcina pasteurii (S. pasteurii) is arguably the most widely investigated organism in ureolytic biomineralization studies, with wide potential application in construction and environmental protection. In emerging, large-scale commercial engineering applications, attention was also paid to practical challenges and issues. In this review, we summarize the features of S. pasteurii cells contributing to the biomineralization reaction, aiming to reveal the mechanism of artificial mineral formation catalyzed by bacterial cells. Progress in the application of this technology in construction and environmental protection is discussed separately. Furthermore, the urgent challenges and issues in large-scale application are also discussed, along with potential solutions. We aim to offer new ideas to researchers working on the mechanisms, applications and challenges of biomineralization.

Foot-and-Mouth Disease Virus 3C Protease Antagonizes Interferon Signaling and C142T Substitution Attenuates the FMD Virus

3C protease (3Cpro), a chymotrypsin-like cysteine protease encoded by the foot-and-mouth disease virus (FMDV), plays an essential role in processing the FMDV P1 polyprotein into individual viral capsid proteins in FMDV replication. Previously, it has been shown that 3Cpro is involved in the blockage of the host type-I interferon (IFN) responses by FMDV. However, the underlying mechanisms are poorly understood. Here, we demonstrated that the protease activity of 3Cpro contributed to the degradation of RIG-I and MDA5, key cytosolic sensors of the type-I IFN signaling cascade in proteasome, lysosome and caspase-independent manner. And also, we examined the degradation ability on RIG-I and MDA5 of wild-type FMDV 3Cpro and FMDV 3Cpro C142T mutant which is known to significantly alter the enzymatic activity of 3Cpro. The results showed that the FMDV 3Cpro C142T mutant dramatically reduce the degradation of RIG-I and MDA5 due to weakened protease activity. Thus, the protease activity of FMDV 3Cpro governs its RIG-I and MDA5 degradation ability and subsequent negative regulation of the type-I IFN signaling. Importantly, FMD viruses harboring 3Cpro C142T mutant showed the moderate attenuation of FMDV in a pig model. In conclusion, our results indicate that a novel mechanism evolved by FMDV 3Cpro to counteract host type-I IFN responses and a rational approach to virus attenuation that could be utilized for future vaccine development.

Synergistic PAHs biodegradation by a mixed bacterial community: Based on a multisubstrate enrichment approach

Polycyclic aromatic hydrocarbons (PAHs) are highly hard-biodegradable compounds. Therefore, in this work, a multisubstrate enrichment approach was proposed to develop a bacterial community named MBF from activated sludge of coking wastewater plant capable of degrading mixed-PAHs consisting of phenanthrene and pyrene (50 mg/L of each) by 98.8% and 73.3% within 5 days, respectively. The bacterial community could maintain its degradation ability to mixed PAHs relatively under temperatures (20°C–35°C), pH values (5.0–9.0), and salinities (0–10 g/L NaCl). Additionally, the bacterial community MBF degraded 58.9%, 79.9%, and 80.7% of mixed PAHs in the presence of catechol, salicylic acid, and phthalic acid, respectively within 5 days. High-throughput sequencing of 16S rRNA gene amplicon analysis showed that the bacterial community MBF was dominated by Pseudomonas in most treatments, and Burkholderia was predominant under both acidic condition and high salt concentrations. Furthermore, the composition of microbial communities of the bacterial community was significantly different with/without addition of pathway intermediate metabolites after biodegradation of mixed PAHs, revealing the metabolic burden may be distributed between members of this bacterial community. Those results demonstrate that the biodegradation ability of MBF could be maintained with the bacterial community structure altering when facing environmental variations or changes in composition of target contaminants.

Recent Development and Application of TiO2 Nanotubes Photocatalytic Activity for Degradation Synthetic Dyes – A Review

Synthetic dyes waste from textile industries, produce of the problematic pollutants in wastewater. TiO2 based photocatalysis are materials that exhibit excellent absorption behavior for organic compounds in wastewater due it properties including nontoxicity, high photocatalysis degradation ability, and chemical stabilities. However, several challenges exist regarding TiO2 nanotubes pure applications for dyes degradation such as poor affinity, high band gap energy, and difficulty of recovery and easy to recombination so it would decrease effectiveness of the photocatalysis process. Therefore, more design and optimization testing need to be conducted on the treatment conditions in order to reach higher removal efficiencies with lower costs. The modified physical properties by adding metal dopant, nonmetal, and sensitizer significantly enhanced photocatalysis activity. These parameters, which affect photocatalysis activity on degrade dyes waste pollutants, are discussed in the current review. As a result, the photocatalysis becomes more expected, and encourages to further research development. Keywords: TiO2, nanotubes, degradation, synthetic, dyes