Nanozyme-mediated ratiometric fluorescence hydrogel for on-site detection of sulfite in food.

In this work, a ratiometric fluorescence hydrogel nanosensor was developed by integrating a composite consisting of o-phenylenediamine (OPD), manganese dioxide nanoflakes (MnO2 NFs), and N-doped carbon dots (N-CDs) into an agarose hydrogel for sulfite detection. MnO2 NFs demonstrated intense oxidase-like activity, facilitating the conversion of non-fluorescent OPD into yellow-emissive 2,3-diaminophenazine (DAP). As a result, a significant emission peak belongs to DAP, alongside the fluorescence quenching of N-CDs through FRET. Upon interaction with sulfite, MnO2 NFs lost their oxidase-like function. This process decreased the fluorescence of DAP and restored the blue fluorescence of N-CDs, producing a typical ratiometric response, ranging from 3 nM âˆ¼ 400 µM, with a detection limit (LOD) of 3.79 nM. Employing a smartphone, the fluorescence color change demonstrated by the hydrogel sensor was translated into quantitative data (LOD: 8.44 nM). This hydrogel sensor offers an affordable, portable, and user-friendly solution for sulfite detection and food safety monitoring.

Insight into the Efficient Selective Reduction of Cr(VI) in Sulfite/UV Process under Near-Neutral Conditions: The Critical Role of In Situ-Generated Sulfite Radical.

Efficient removal of contaminants in complex water matrices under mild conditions is highly desirable but still challenging. In this study, we unraveled the overlooked but crucial role of sulfite radical (SO3·-) in the efficient selective reduction of toxic Cr(VI) under near-neutral conditions. Fast removal of Cr(VI) at around pH 7 in sulfite/UV was found to be attributable to high reactivity of SO3·- toward HCrO4- (∼5.3 × 106 M-1 s-1). Furthermore, SO3·- was fast generated in situ via one-electron oxidation of S(IV) by transient reactive protonated Cr(V) and Cr(IV) intermediates. Therefore, the specific reactivity of SO3·- and its in situ generation together resulted in the surprisingly positive effect of nitrate and the efficient reduction of Cr(VI) in authentic surface water and industrial wastewater. A mathematical model was developed to simulate Cr(VI) removal in the process, and thus quantitatively demonstrated the roles of reactive species, i.e., SO3·- contributed to ∼93% of Cr(VI) reduction in surface water. Overall, this study provides an insight into the pivotal role of SO3·- in Cr(VI) reduction, and underscores its significance in selective reduction and detoxification of contaminants.

Improvement of egg yolk powder properties through ultrasound coupled sodium sulfite pretreatment assisted enzymatic hydrolysis and underlying mechanism.

Egg yolk is an excellent protein source for the production of bioactive peptides. However, the recent method need to remove lipid first which involves wastage and pollution of organic reagents. Therefore, the process of directly using oily yolk powder to prepare egg yolk peptides has attracted much attention. This study developed a one-step process to simultaneously extract oil and hydrolyze proteins based on an ultrasound coupled sodium sulfite pretreatment (UCSSP) assisted enzymatic hydrolysis for egg yolk powder. Results showed that UCSSP increased the oil extraction rate from zero to 75 % with 59.35 g/L of soluble protein and 33.99 g/L of peptide. Further analysis of the underlying mechanism demonstrated that ultrasound pre-treatment could change the secondary structure of EYP while sodium sulfite pre-treatment softened the protein and induced more hydrophobic groups exposed, thus inducing more lipoprotein released for hydrolysis. In addition, the proportion of peptides ranging from 180 Da to 3000 Da in the UCSSP group increased from 31.19 % before to 79.74 %, which was 31.27 % and 6.16 % higher than that of UP and SP. Furthermore, the obtained peptides showed obvious activities in uric acid-lowering, anti-obesity and antioxidant with 56.24 % inhibition in XOD activity and close antioxidant activity to vitamin C, implying it a potential health product.

The distribution of beneficial mutational effects between two sister yeast species poorly explains natural outcomes of vineyard adaptation.

Domesticated strains of Saccharomyces cerevisiae have adapted to resist copper and sulfite, two chemical stressors commonly used in winemaking. S. paradoxus has not adapted to these chemicals despite being consistently present in sympatry with S. cerevisiae in vineyards. This contrast could be driven by a number of factors including niche differences or differential access to resistance mutations between species. In this study, we used a comparative mutagenesis approach to test whether S. paradoxus is mutationally constrained with respect to acquiring greater copper and sulfite resistance. For both species, we assayed the rate, effect size, and pleiotropic costs of resistance mutations and sequenced a subset of 150 mutants. We found that the distributions of mutational effects displayed by the two species were similar and poorly explained the natural pattern. We also found that chromosome VIII aneuploidy and loss of function mutations in PMA1 confer copper resistance in both species, whereas loss of function mutations in REG1 were only a viable route to copper resistance in S. cerevisiae. We also observed a de novo duplication of the CUP1 gene in S. paradoxus but not in S. cerevisiae. For sulfite, loss of function mutations in RTS1 and KSP1 confer resistance in both species, but mutations in RTS1 have larger effects in S. paradoxus. Our results show that even when available mutations are largely similar, species can differ in the adaptive paths available to them. They also demonstrate that assays of the distribution of mutational effects may lack predictive insight concerning adaptive outcomes.

Dataset on the decolorization of Naphthol Green B using a UV/sulfite system: Optimization by response surface methodology.

Naphthol Green B (NGB) is a synthetic azo dye widely used in various industries, including textiles and leathers. NGB poses significant environmental and ecological concerns when released into natural water systems. This paper investigates the decolorization of NGB using UV/sulfite system. The % decolorization of NGB was optimized using 32 Full Factorial Design (FFD), and the ANOVA results show that the model has a good fit for the data (R2 = 99.54 %, R2 (adj) = 98.76 %) and the significant factors contributing to the % decolorization are A, B, A2, and B2 where A = mM sulfite and B = pH. The model predicted ≥100 % decolorization with the optimum conditions 12 mM sulfite and pH 10. An actual experiment was conducted to verify the response, resulting in 96.2 % decolorization which is in good agreement with the model.

Source elimination of antibiotic resistance risk in aquaculture water by VUV/sulfite pretreatment.

Antibiotic resistance risk in the aquaculture industry is increasing with the excessive consumption of antibiotics. Although various efficient technologies for the degradation of antibiotics are available, the potential risk from antibiotic resistance in treated waters is often overlooked. This study compared the risks of antibiotic resistance in anaerobic sludge fed with pretreated florfenicol (FLO) containing wastewater after four UV or vacuum UV (VUV)-driven ((V)UV-driven) pretreatments, and established the VUV/sulfite recirculating water system to validate the effect of controlling the antibiotic resistance risk in the actual aquaculture water. Metagenomics sequencing revealed that a remarkable decrease in the abundance of antibiotic resistance genes (ARGs) was observed in four different pretreated groups, and results among the four pretreated groups were sorted in descending order based on ARG abundance: UV > VUV > UV/sulfite > VUV/sulfite. The low abundance of ARGs from VUV/sulfite group was close to that in the CK group (wastewater without FLO and without any pretreatments), which was 0.41 copies/cell. From the perspective of the temporal changes in the relative abundance of floR, the abundance in VUV/sulfite group remained lower than 11.67 ± 0.73 during the cultivation time. Additionally, microbial diversity analysis found that Proteobacteria and Firmicutes were major carriers of ARGs. Two species from Burkholderiaceae and Rhodocyclales were identified as potential co-hosts to spread by the correlation analysis of the abundances between floR or intI1 and the top 50 genera. Finally, the abundances of ARGs and MGEs in the VUV/sulfite recirculating water system with actual aquaculture water were reduced by 39.15% and 46.04%, respectively, compared to that in the blank group without any pretreatment. This study verified that VUV/sulfite pretreatment system could effectively control the antibiotic resistance risk of ARGs proliferation and transfer in aquaculture water. Furthermore, the study demonstrated that the reduction of antibiotic antibacterial activity plays an important role in the source control of resistance risk.

Phylogeny and evolution of dissimilatory sulfite reduction in prokaryotes.

Sulfate is the second most common nonmetallic ion in modern oceans, as its concentration dramatically increased alongside tectonic activity and atmospheric oxidation in the Proterozoic. Microbial sulfate/sulfite metabolism, involving organic carbon or hydrogen oxidation, is linked to sulfur and carbon biogeochemical cycles. However, the coevolution of microbial sulfate/sulfite metabolism and Earth's history remains unclear. Here, we conducted a comprehensive phylogenetic analysis to explore the evolutionary history of the dissimilatory sulfite reduction (Dsr) pathway. The phylogenies of the Dsr-related genes presented similar branching patterns but also some incongruencies, indicating the complex origin and evolution of Dsr. Among these genes, dsrAB is the hallmark of sulfur-metabolizing prokaryotes. Our detailed analyses suggested that the evolution of dsrAB was shaped by vertical inheritance and multiple horizontal gene transfer events and that selection pressure varied across distinct lineages. Dated phylogenetic trees indicated that key evolutionary events of dissimilatory sulfur-metabolizing prokaryotes were related to the Great Oxygenation Event (2.4-2.0 Ga) and several geological events in the "Boring Billion" (1.8-0.8 Ga), including the fragmentation of the Columbia supercontinent (approximately 1.6 Ga), the rapid increase in marine sulfate (1.3-1.2 Ga), and the Neoproterozoic glaciation event (approximately 1.0 Ga). We also proposed that the voluminous iron formations (approximately 1.88 Ga) might have induced the metabolic innovation of iron reduction. In summary, our study provides new insights into Dsr evolution and a systematic view of the coevolution of dissimilatory sulfur-metabolizing prokaryotes and the Earth's environment.

Unveiling the role of artificial intelligence in tetracycline antibiotics removal using UV/sulfite/phenol advanced reduction process.

UV/sulfite-based advanced reduction processes (ARP) have attracted increasing attention due to their high capability for removing a wide range of pollutants. Therefore, developing UV/sulfite ARP systems with assisted Artificial Intelligence (AI) models is considered an efficient strategy for sustainable pollutant removal. The present study delves into modeling and optimizing photodegradation of tetracycline (TC) antibiotics under UV/sulfite/рhenol reԁuсtion рroсess (UV/SPAP) using integrаteԁ Artifiсiаl Neurаl Networks (ANN), Suррort Veсtor Regression (SVR), аnԁ Genetiс Algorithm (GA). The сonсentrаtions of рhenol (X1) аnԁ sulfite (X2), рH (X3), reасtion time (X4), аnԁ TC сonсentrаtion (X5) in our exрerimentаl setuр were varied, аnԁ use the generаteԁ ԁаtа to trаin AI moԁels. The findings revealed that the AI-optimized performance is very effective in predicting and optimizing the removal of TC, thereby providing a sustainable water treatment approach. In general, SVR performed better based on scaling coefficients and ANN using different criteria indicated that X4 and X5 parameters were statistically significant. Oрtimаl rаnges for X1, X2, X3, X4, аnԁ X5 аre ԁetermineԁ to be 6.34, 3, 8.45, 80.13, аnԁ 1, resрeсtively. This аррroасh highlights the imрortаnсe of integrаting AI аnԁ ARP for sustаinаble environmentаl mаnаgement.

Salivary-secreted vitellogenin suppresses H2O2 burst of plants facilitating Recilia dorsalis leafhopper feeding.

BACKGROUND: Vitellogenin (Vg), known as the yolk protein precursor for oocyte development in female insects, can be secreted to plant host from salivary glands of hemipterans, including rice leafhopper Recilia dorsalis. The aim of this study was to investigate the function of salivary-secreted Vg of R. dorsalis (RdVg) in rice host. We propose that RdVg possibly regulates the rice defense against insects, benefiting R. dorsalis feeding. RESULTS: RdVg was released into rice phloem along with saliva during R. dorsalis feeding. Knocking down RdVg increased the level of H2O2 and improved H2O2 metabolism in rice plants, making it difficult for R. dorsalis to feed. The transient expression or overexpression of the lipoprotein N-terminal domain of RdVg (RdVg2) significantly reduced hydrogen peroxide (H2O2) metabolism in plants. This suggests that salivary-secreted RdVg acts as an effector suppressing the H2O2 burst in rice plants, and RdVg2 is the key domain. RdVg2 could interact with rice sulfite oxidase (OsSO), which catalyzes the oxidation of SO3 2- and produces H2O2. Exposure of rice plants to R. dorsalis, overexpression of RdVg2 or knocking out OsSO reduced OsSO accumulation and SO3 2- oxidation, benefiting R. dorsalis feeding. However overexpression of OsSO increased SO3 2- oxidation and H2O2 metabolism, inhibiting R. dorsalis feeding. CONCLUSION: RdVg inhibits H2O2 generation via suppressing OsSO accumulation, ultimately benefiting R. dorsalis feeding. These findings identify RdVg as an effector that suppresses plant defense to insects, and provide insights into the function of salivary-secreted Vg in other Hemiptera insects. © 2024 Society of Chemical Industry.

Evolutionary history and origins of Dsr-mediated sulfur oxidation.

Microorganisms play vital roles in sulfur cycling through the oxidation of elemental sulfur and reduction of sulfite. These metabolisms are catalyzed by dissimilatory sulfite reductases (Dsr) functioning in either the reductive or reverse, oxidative direction. Dsr-mediated sulfite reduction is an ancient metabolism proposed to have fueled energy metabolism in some of Earth's earliest microorganisms, whereas sulfur oxidation is believed to have evolved later in association with the widespread availability of oxygen on Earth. Organisms are generally believed to carry out either the reductive or oxidative pathway, yet organisms from diverse phyla have been discovered with gene combinations that implicate them in both pathways. A comprehensive investigation into the metabolisms of these phyla regarding Dsr is currently lacking. Here, we selected one of these phyla, the metabolically versatile candidate phylum SAR324, to study the ecology and evolution of Dsr-mediated metabolism. We confirmed that diverse SAR324 encode genes associated with reductive Dsr, oxidative Dsr, or both. Comparative analyses with other Dsr-encoding bacterial and archaeal phyla revealed that organisms encoding both reductive and oxidative Dsr proteins are constrained to a few phyla. Further, DsrAB sequences from genomes belonging to these phyla are phylogenetically positioned at the interface between well-defined oxidative and reductive bacterial clades. The phylogenetic context and dsr gene content in these organisms points to an evolutionary transition event that ultimately gave way to oxidative Dsr-mediated metabolism. Together, this research suggests that SAR324 and other phyla with mixed dsr gene content are associated with the evolution and origins of Dsr-mediated sulfur oxidation.

Sorption/desorption and degradation of long- and short-chain PFAS by anion exchange resin and UV/sulfite system.

A combined sorption/desorption and UV/sulfite degradation process was investigated for achieving efficient elimination of PFAS from water. Two gel-type resins, Purolite A532E and A600, and one macroporous resin, Purolite A860, were firstly tested for the sorption of individual PFPrA, PFHxA, PFOA, PFOS, and GenX at different concentrations. Sorption data and density functional theory (DFT) calculations revealed that electrostatic interactions predominated for short-chain PFAS sorption and hydrophobic interactions played a more significant role for long-chain PFAS than for short-chain PFAS. A600 and A860 were selected for desorption tests with 0.025% NaOH, 5% NaCl, and 5% NH4Cl solution with or without 20% ethanol (EtOH) due to their high sorption capacity for all target PFAS. The mixture of 5% NH4Cl and 20% EtOH as the desorption solution typically showed the highest desorption efficiency. PFOS was the most resistant for desorption but its desorption could be enhanced by stronger mixing conditions (in 5% NaCl + 20% EtOH). Direct degradation of studied PFAS in the desorption solution (0.025% NaOH, 5% NaCl, and 5% NH4Cl) by UV/sulfite achieved 97.6-100% degradation and 46.6-86.1% defluorination. EtOH hindered degradation and thus should be separated from the water before UV/sulfite degradation.

Preparation of Fe/Co bimetallic oxide loaded hydrophobic & catalytic bifunctional membrane and its catalytic performance in sulfite oxidation.

Sulfite oxidation is critical for the stable operation of desulfurization process and the treatment & recovery of desulfurization by-products. The Fe and Co oxides modified super hydrophobic layer was prepared on tubular ceramic membranes using hydrothermal synthesis and surface modifications to realize the combination of the membrane catalysis and membrane aeration. These two oxides were approximately two-layer distributed on the membrane surface, among which the Fe2O3 located in the bottom layer and the Co3O4 located in the upper layer. The catalytic rate of the bifunctional membrane was about 5.8 times than that of the original ceramic membrane, which was decreased with the increasing of Fe/Co ratio and declined after an initial rise with the increase of urea and cetyltrimethylammonium bromide. The conjoint effect of Fe and Co could improve the catalytic performance and reduce the dissolution loss of catalyzer. The oxidation rate tended to be constant after a 15 % decrease in 7 times experiments.

Photo-reductive decomposition of perfluorooctane sulfonate (PFOS) and its common alternatives by UV/VUV/sulfite process: Mechanism, kinetic modeling, and water matrix effects.

The present study investigated the photo-reduction of perfluorooctane sulfonate (PFOS) and its alternatives, focusing on decomposition mechanisms, active species involvement, the influence of background water constituents, and kinetic model development. The decomposition and defluorination rates followed the order of PFOS > PFHxS > 6:2 FTSA > PFBS, with shorter chains and CH2 linkers enhancing the resistance of PFOS alternatives against the attack of hydrated electrons (eaq-). Two primary pathways were identified during the photodegradation of PFAS: (i) H/F exchange at CF bonds with the lowest bond dissociation energies (BDEs) and (ii) functional group cleavage followed by short-chain PFCAs formation, with OH playing a crucial role in transforming intermediates. Adding iodide and elevated temperatures demonstrated a synergistic effect on PFBS decomposition and defluorination, with high temperatures promoting functional group cleavage as the preferred defluorination pathway. The study examined the impact of background water constituents in different aqueous environments, from surface waters to wastewater streams and ion-exchange brine concentrates. Chloride exhibited a concentration-based dual impact on the UV/VUV/sulfite process: promotive effects at low dosages (1-10 mM) by acting as a secondary eaq- mediator, and adverse effects at high dosages (20-500 mM) due to the scavenging effect of generated chlorine radicals (Cl). High ionic strength adversely affected eaq- quantum efficiency. Additionally, bicarbonate and natural organic matter (NOM) had opposing effects on PFOS photo-reduction, primarily through eaq- scavenging and pH alteration. Kinetic modeling revealed reaction rate constants of the studied PFAS with eaq- ranging from 1.8 × 106 to 1.3 × 109 M-1 s-1, corroborating the concentration profiles of active species and highlighting the reductive nature of sulfite-mediated processes.

Rapid Oxidative Dissolution of Zerovalent Iron Induced by Sulfite for Efficient Removal of Arsenate and Arsenite: Selective Formation of Scorodite.

In this study, we proposed a moderate oxidation strategy for accelerating the oxidative dissolution of zerovalent iron (ZVI) using sulfite (S(IV)), thereby improving the removal of As(V) and As(III). Results revealed that, in the presence of 2.0 mM S(IV), both As(V) and As(III) were selectively converted into scorodite at pH0 3.0-7.0, while As(III) oxidation and As(V) immobilization were impressed over pH0 8.0-10.0. Batch experiments, radical quenching experiments, and electron spin resonance (ESR) measurements demonstrated that ZVI initially boosted S(IV) activation to generate SO4•-, •OH, and protons, and in turn, ZVI was further oxidized more intensely by these radicals than by oxygen. Concurrently, substantial protons derived from S(IV) oxidation neutralized hydroxyls produced by ZVI oxidation, maintaining an acidic environment conducive to the generation of scorodite rather than iron (hydr)oxides. Characterizations of X-ray diffraction (XRD), Raman, attenuated total reflectance-Fourier transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure (XAFS), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM) confirmed that scorodite was formed in situ and then exfoliated from the surface of ZVI, and approximately 75% of ZVI could still be recovered, which contributed to efficient As removal in successive runs and real As-polluted wastewater. The application of S(IV) achieved a balance among ZVI reactivity improvement, As(V)/As(III) removal, and raw material consumption, making it a promising approach for addressing arsenic contamination in wastewater treatment.

Pharmacodynamic profiling in three patients with molybdenum cofactor deficiency type A reveals prolonged biological effects after withdrawal of cyclic pyranopterin monophosphate.

Molybdenum cofactor deficiency type A has successfully been treated in a small number of children with daily intravenous administration of cyclic pyranopterin monophosphate. Pharmacodynamic data for this novel treatment have not been published and alternative dosing intervals have not been explored. We monitored pharmacodynamic biomarkers of sulfite oxidase and xanthine oxidoreductase activity in three patients with MoCD-A for a period of 2 to 9 months after discontinuation of cPMP substitution. We found that the clinical and metabolic effects were sustained for longer than expected, over 7 days at least. Our data implicate a biological half-life of the molybdenum cofactor dependent enzyme activities of approximately 3 days and suggest the possibility that less frequent than once daily dosing intervals could be a safe alternative to current practice.

Molybdenum's Role as an Essential Element in Enzymes Catabolizing Redox Reactions: A Review.

Molybdenum (Mo) is an essential element for human life, acting as a cofactor in various enzymes crucial for metabolic homeostasis. This review provides a comprehensive insight into the latest advances in research on molybdenum-containing enzymes and their clinical significance. One of these enzymes is xanthine oxidase (XO), which plays a pivotal role in purine catabolism, generating reactive oxygen species (ROS) capable of inducing oxidative stress and subsequent organ dysfunction. Elevated XO activity is associated with liver pathologies such as non-alcoholic fatty liver disease (NAFLD) and hepatocellular carcinoma (HCC). Aldehyde oxidases (AOs) are also molybdenum-containing enzymes that, similar to XO, participate in drug metabolism, with notable roles in the oxidation of various substrates. However, beneath its apparent efficacy, AOs' inhibition may impact drug effectiveness and contribute to liver damage induced by hepatotoxins. Another notable molybdenum-enzyme is sulfite oxidase (SOX), which catalyzes the conversion of sulfite to sulfate, crucial for the degradation of sulfur-containing amino acids. Recent research highlights SOX's potential as a diagnostic marker for HCC, offering promising sensitivity and specificity in distinguishing cancerous lesions. The newest member of molybdenum-containing enzymes is mitochondrial amidoxime-reducing component (mARC), involved in drug metabolism and detoxification reactions. Emerging evidence suggests its involvement in liver pathologies such as HCC and NAFLD, indicating its potential as a therapeutic target. Overall, understanding the roles of molybdenum-containing enzymes in human physiology and disease pathology is essential for advancing diagnostic and therapeutic strategies for various health conditions, particularly those related to liver dysfunction. Further research into the molecular mechanisms underlying these enzymes' functions could lead to novel treatments and improved patient outcomes.

Iron (hydr)oxides-induced activation of sulfite for contaminants degradation: The critical role of structural Fe(III).

Iron-based sulfite (S(IV)) activation has emerged as a novel strategy to generate sulfate radicals (SO4•-) for contaminants degradation. However, numerous studies focused on dissolved iron-induced homogeneous activation processes while the potential of structural Fe(III) remains unclear. In this study, five iron (hydr)oxide soil minerals (FeOx) including ferrihydrite, schwertmannite, lepidocrocite, goethite and hematite, were successfully employed as sources of structural Fe(III) for S(IV) activation. Results showed that the catalytical ability of structural Fe(III) primarily depended on the crystallinity of FeOx instead of their specific surface area and particle size, with ferrihydrite and schwertmannite being the most active. Furthermore, in-situ ATR-FTIR spectroscopy and 2D-COS analysis revealed that HSO3- was initially adsorbed on FeO6 octahedrons of FeOx via monodentate inner-sphere complexation, ultimately oxidized into SO42- which was then re-adsorbed via outer-sphere complexation. During this process, strong oxidizing SO4•- and •OH were formed for pollutants degradation, confirmed by radical quenching experiments and electron spin resonance. Moreover, FeOx/S(IV) system exhibited superior applicability with respect to recycling test, real waters and twenty-six pollutants degradation. Eventually, plausible degradation pathways of three typical pollutants were proposed. This study highlights the feasibility of structural Fe(III)-containing soil minerals for S(IV) activation in wastewater treatment.

Riboflavin overproduction from diverse feedstocks with engineeredCorynebacterium glutamicum.

Riboflavin overproduction byCorynebacterium glutamicumwas achieved by screening synthetic operons, enabling fine-tuned expression of the riboflavin biosynthetic genesribGCAH.The synthetic operons were designed by means of predicted translational initiation rates of each open reading frame, with the best-performing selection enabling riboflavin overproduction without negatively affecting cell growth. Overexpression of the fructose-1,6-bisphosphatase (fbp) and 5-phosphoribosyl 1-pyrophosphate aminotransferase (purF) encoding genes was then done to redirect the metabolic flux towards the riboflavin precursors. The resulting strain produced 8.3 g l-1of riboflavin in glucose-based fed-batch fermentations, which is the highest reported riboflavin titer withC. glutamicum. Further genetic engineering enabled both xylose and mannitol utilization byC. glutamicum, and we demonstrated riboflavin overproduction with the xylose-rich feedstocks rice husk hydrolysate and spent sulfite liquor, and the mannitol-rich feedstock brown seaweed hydrolysate. Remarkably, rice husk hydrolysate provided 30% higher riboflavin yields compared to glucose in the bioreactors.

Role of reactive manganese and oxygen species in the KMnO4/Na2SO3 process for purification of algal-rich water and membrane fouling alleviation.

Ultrafiltration (UF) is a highly efficient technique for algal-rich water purification, but it is heavily contaminated due to the complex water characteristics. To solve this problem, potassium permanganate (KMnO4) oxidation enhanced with sodium sulfite (Na2SO3) was proposed as a pretreatment means. The results showed that the end-normalized flux was elevated from 0.10 to 0.91, and the reversible fouling resistance was reduced by 99.95%. The membrane fouling mechanism also changed obviously, without the generation of cake filtration. Regarding the properties of algal-rich water, the zeta potential was decreased from -29.50 to -5.87 mV after KMnO4/Na2SO3 pretreatment, suggesting that the electrostatic repulsion was significantly reduced. Meanwhile, the fluorescent components in algal-rich water were significantly eliminated, and the removal of dissolved organic carbon was increased to 67.46%. In the KMnO4/Na2SO3 process, reactive manganese species (i.e., Mn(V), Mn(III) and MnO2) and reactive oxygen species (i.e., SO4•- and •OH) played major roles in purifying algal-rich water. Specifically, SO4•-, •OH, Mn(V) and Mn(III) could effectively oxidize algal pollutants. Simultaneously, the in-situ adsorption and coagulation of MnO2 could accelerate the formation of flocs by decreasing the electrostatic repulsion between cells, and protect the algal cells from being excessive oxidized. Overall, the KMnO4/Na2SO3 process showed significant potential for membrane fouling alleviation in purifying algal-rich water.

A fluorescent probe for detecting bisulfite/sulfite in lipid droplets and tracking the dynamics of lipid droplets.

Intracellular lipid droplets (LDs) are important organelles regulating intracellular redox processes. Endogenous bisulfite/sulfite (HSO3-/SO32-) is one of the metabolites of thiol metabolism. The variation in HSO3-/SO32- content around LDs is closely related to cellular homeostasis. However, there is currently no effective method to visualize and quantify the dynamic changes in HSO3-/SO32- content around LDs. In this work, a fluorescent probe MC-BEN utilizing a triphenylamine basic framework was developed to selectively recognize HSO3-/SO32- via a nucleophilic addition reaction. The probe exhibits excellent anti-interference capability, short response time, outstanding photostability, and a low fluorescence detection limit (6.1 µM) for HSO3-/SO32- recognition. More interesting, there is a trend of accelerated contact between LDs and lysosomes after MC-BEN targeting LDs and reacting with endogenous/exogenous HSO3-/SO32-, which may provide new ideas for the study of intracellular lysosomal lipophagy.