Gene fusion and functional diversification of P450 genes facilitate thermophilic fungal adaptation to temperature change.

Thermomyces dupontii harbors two P450 paralogs (P450S and P450L) in the gene cluster for the biosynthesis of prenylated indole alkaloids (PIAs) and correponding iron chelators with P450L assigned as one protein containing a CYP like domain fused with a FAD-binding domain-containing oxidoreductase. Genetic manipulation and metabolic profile analysis indicated both P450S and P450L were involved in transforming simple PIAs to their corresponding iron chelators. Moreover, P450S is responsible for bolstering simple PIAs to complex PIAs, and P450L for reinforcing conjugating unsaturated systems in complex PIAs. Chemical investigation led to isolation and characterization of novel complex PIA metabolites with more oxidations. P450L also contributed to forming the third iron-chelating core in iron chelators. A series of iron bioassays and infrastructure analysis revealed that lack of these P450 genes caused strongly elevated Fe3+ levels but attenuated Fe2+ levels, together with abnormal mitochondria in mycelia and lipid droplets and vacuoles in conidia. Phenotype analysis revealed that P450S and P450L facilitated fungal colony pigments, conidial formation and germination via bolstering conidiophores and cell walls in response to temperature reduction.

Three new Melanogaster species (Boletales, Paxillaceae) from southwestern China based on morphological and molecular evidence.

Three newly discovered Melanogaster species, namely M.cyaneus, M.diqingensis, and M.truncatisporus, are introduced and illustrated based on both morphological and molecular data from Sichuan and Yunnan provinces in China. A multigene phylogenetic analysis (nrITS, nrLSU, and rpb2) was performed mainly to verify the placement of the new species in Melanogaster. A second, nrITS-only phylogenetic analysis comprising more Melanogaster species for which only ITS sequences were available, was used to infer the relationship between the new species and as many known Melanogaster species as possible. Specimens of M.cyaneus, M.diqingensis, and M.truncatisporus formed three independent clades in a phylogenetic tree inferred from the ITS data set. The robust support from ITS for these clades and genetic similarity with other species being lower than 93.2% suggest that these three species are indeed distinct from the other Melanogaster species in the phylogeny. Morphologically, M.cyaneus is characterized by its blue or bluish gleba, light brown to yellowish brown peridium, and subglobose to globose basidiospores, 6.2-15 × 4.6-9.0 µm. Melanogasterdiqingensis is distinguished from other Melanogaster species by its pale yellow to brown-yellow peridium and obovate to subglobose basidiospores, 3.0-5.1 × 2.0-4.0 µm. Melanogastertruncatisporus is diagnosed by its subglobose to globose or irregularly elongate-pyriform basidiomata, pale yellow to deeply orange-yellow peridium, and subglobose to globose or pyriform, truncate basidiospores. Additionally, infrageneric classification based on the number of peridium layers, the average thickness of the peridium, and the average length and width of basidiospores was tested with M.cyaneus, M.diqingensis, and M.truncatisporus. Orthogonal partial least squares discriminant (OPLS-DA) analysis placed the three new species within the Melanogaster, Rivulares, and Variegati sections, respectively. However, the morphologically circumscribed sections were not monophyletic in the phylogenetic tree. Therefore, the current infrageneric classification should be abandoned.

New species and new records of Laccaria (Agaricales, Basidiomycota) from Northern Thailand.

Two new species Laccariapseudoalba and L.subroseoalbescens are described and illustrated, based on morphological characteristics and molecular phylogenetic analysis. Two new records, Laccariaumbilicata and L.yunnanensis from Thailand, are also reported. Laccariasubroseoalbescens is characterized by small basidiomata, stipe equal with an enlarged base, and nearly subclavate, pale pink to light orange. Laccariapseudoalba is characterized by pale orange to orange white pileus, has umbo when young on the pileus, and fistulose stipe of the pale to pastel red color. Phylogenetic analysis based on sequence data from rDNA internal transcribed spacer ITS1-5.8S-ITS2 rDNA (ITS), nuc 28S rDNA (28S), RNA polymerase II subunit 2 (rpb2), and translation elongation factor 1-α (tef1-α) are provided as further evidence. Molecular analysis confirms the phylogenetic positions of the two new species and two new records. The differences in characteristics of these two new species and closely related species are discussed herein.

Thermophilic fungus uses anthraquinones to modulate ferrous excretion, sterol-mediated endocytosis, and iron storage in response to cold stress.

To date, there are no real physiological mechanisms for iron excretion in eukaryote, and no physiological "actuator" that can control all the three fundamental biologic processes of absorption, storage, and excretion. Here, we observed that the accumulation of anthraquinones by Thermomyces dupontii under cold stress can achieve this process. Through mutation analysis, we found that mutant ΔAn deficiency in anthraquinones accumulated ferrous and total free iron due to adopting a rare lifestyle with no endocytosis but accumulation of membrane-derived vesicles. Anthraquinone complement indicated that the vesicles in ΔAn could coat the extrinsic anthraquinone-induced granules to prevent contact with the fungal interiors. Detailed chemical investigation on ΔAn led to characterization of a rare oxygen-free ergosterene with unstable nature in air as the major membrane steroid in ΔAn, suggesting hypoxia inner in ΔAn cells, consistent with dramatically low oxygen-consuming rates in ΔAn. A series of physiological and metabolic analyses indicated anthraquinones were involved in exporting ferrous and promoting formation of oxygen-containing metabolites, including ergosterols for endocytosis and iron chelators for iron storage. Moreover, we found that both the anticancer agent mitoxantrone with well-known-cardiotoxicity side effect and the major terpenoid-derived polycyclic aromatics from Danshen for treating cardiovascular disease showed potent ferrous transporting capabilities in human cancer cells. Our findings provide a novel insight into the underlying mechanisms of polycyclic aromatics in nature and pharmacology, and offer a new strategy for developing potential therapeutics and agents for membrane transport, iron homestasis, and anticold.

Hybrid Local and Charge-Transfer Material with Ultralong Room Temperature Phosphorescence for Efficient Organic Afterglow Light-Emitting Diodes.

Organic ultralong room temperature phosphorescence (OURTP) materials capable of combining various emission behaviors for diversified optoelectronic properties and applications have recently gained a vigorous development, but it remains a forbidden challenge in designing OURTP molecules with hybrid local and charge-transfer (HLCT) feature, possibly due to the elevated difficulties in simultaneously meeting the stringent requirements of both HLCT and OURTP emitters. Here, through introducing multiple heteroatoms into one-dimensional fused ring of coumarin with moderate charge transfer perturbation in donor-π-acceptor architecture, we demonstrate a HLCT-featured OURTP molecule showing both promoted fluorescence with a quantum yield of 77% in solution and long-lived OURTP with a lifetime of 251 ms in conventional host material used in electroluminescent device. Thus, efficient OURTP organic light-emitting diodes (OLEDs) were fabricated, exhibiting bright electroluminescence with an exciton utilization efficiency of 85% and yellow OURTP lasting over 2 s for afterglow. Impressively, the HLCT OURTP-OLEDs can be further optimized to reach an unprecedented total external quantum efficiency (EQE) of ~12% and OURTP EQE up to 3.11%, representing the highest performance among the reported OURTP-OLEDs. These impressive results highlight the significance to fuse HLCT and OURTP together in enriching OURTP materials and improving the afterglow OLED performances.

Three New Species of Tuber Discovered in Alpine Fir Forests in Yunnan, China.

Three new species of Tuber, T. albicavum, T. laojunshanense, and T. umbilicicavatum belonging to the Puberulum phylogroup, are described based on specimens collected in alpine Abies forests at 3600-4000 m, Northwest Yunnan, China. T. albicavum is distinguished by its ascomata with a single chamber of 0.5-1.8 cm diameter, with an apical opening of 0.2-0.6 cm in diameter, and light golden-brown alveolate reticulate ascospores up to 30 µm in length; T. laojunshanense is characterized by having ascomata with a slightly tomentose surface, sometimes with a white navel, a relatively thick peridium, up to 280 µm, and yellow-brown spores with alveolate reticulate ornamentation, up to 34 µm in length; T. umbilicicavatum is characterized by smooth ascomata with a distinct white navel, a relatively thin peridium, up to 110 µm, and golden or golden-brown alveolate reticulate ascospores, up to 40 µm in length. The molecular analysis of the internal transcribed spacer region also supports that these three new species differ from previously described Tuber species.

Alterations in captive Alexandrine parakeet (Palaeornis eupatria) gut microbiome and metabolome in response to dietary change.

The Alexandrine parakeet (Palaeornis eupatria), also known as the Alexandrine parrot, is a critically endangered species in the world and a national second class protected animal. Current knowledge on gut microbiome and metabolome of captive Alexandrine parrots is limited. In the current study, we characterized the effect of dietary change with pellet feeding on the gut microbiome and metaboliome in Alexandrine parrots using 16S gene sequencing and liquid chromatography with tandem mass spectrometry (LC-MS/MS). Total of 12 Alexandrine parrots were used in a cross-over study with each period for 10 days. The results showed that dietary change with pellet feeding did not affect alpha indices of gut microbiota. Cyanobacteria, Firmicutes and Proteobacteria were the predominant bacterial phyla in the gut of Alexandrine parrot with Cynobacteria being the highest. Change of diet significantly increased the relative abundance of Actinobacteria and decreased Spirochaetota. The relative abundance of Fusobacteriota tended to increase with pellet feeding. No treatment effects were observed between the control and pellet feeding groups at the genus level. Based on the annotation results from Clusters of Orthologous Genes (COG) database, dietary change with pellet feeding significantly increased the relative abundance of genes coding for extracellular structures and lipid transport and metabolism. Metabolomics analysis combined with enrichment analysis revealed that dietary change altered the concentrations of gut metabolites as well as the metabolic pattern, and significantly affected the concentrations of fecal metabolites involved in isoflavonoid biosynthesis, flavonoid biosynthesis, nucleotide metabolism etc. In summary, dietary changes with pellet feeding affected the gut microbial composition and metabolites to some extent. The relevance of current findings to Alexandrine parrots' health and potential zoonosis need further exploring.

Two new species of Ganoderma (Ganodermataceae, Basidiomycota) from Southwest China.

Ganoderma is a large and diverse genus containing fungi that cause white rot to infect a number of plant families. This study describes G.phyllanthicola and G.suae as new species from Southwest China, based on morphological and molecular evidence. Ganodermaphyllanthicola is characterized by dark brown to purplish black pileus surface with dense concentric furrows, pale yellow margin, irregular pileipellis cells, small pores (5-7 per mm) and ellipsoid to sub-globose basidiospores (8.5-10.0 × 6.0-7.5 µm). Ganodermasuae is characterized by reddish brown to oxblood red pileus surface and lead gray to greyish-white pore surface, heterogeneous context, wavy margin and almond-shaped to narrow ellipsoid basidiospores (8.0-10.5 × 5.0-7.0 µm). The phylogeny of Ganoderma is reconstructed with multi-gene sequences: the internal transcribed spacer region (ITS), the large subunit (nrLSU), translation elongation factor 1-α gene (TEF-1α) and the second subunit of RNA polymerase II (RPB2). The results show that G.suae and G.phyllanthicola formed two distinct line-ages within Ganoderma. Descriptions, illustrations and phylogenetic analyses results of the two new species are presented.

Liquid-Phase Adsorption Behavior of ß-D-Glucooligosaccharides When Using Activated Carbon for Separation, and the Antioxidant Stress Activity of Purified Fractions.

The adsorption characteristics of ß-glucooligosaccharides on activated carbon and the purification were systematically investigated. The maximum adsorption capacity of activated carbon reached 0.419 g/g in the optimal conditions. The adsorption behavior was described to be monolayer, spontaneous, and exothermic based on several models' fitting results. Five fractions with different degrees of polymerization (DPs) and structures of ß-glucooligosaccharides were obtained by gradient ethanol elution. 10E mainly contained disaccharides with dp2a (G1→6G) and dp2b (G1→3G). 20E possessed trisaccharides with dp3a (G1→6G1→3G) and dp3b (G1→3G1→3G). 30E mainly consisted of dp3a and dp4a (G1→3G1→3(G1→6)G), dp4b (G1→6G1→3G1→3G), and dp4c (G1→3G1→3G1→3G). In addition to tetrasaccharides, 40E and 50E also contained pentasaccharides and hexasaccharides with ß-(1→3)-linked or ß-(1→6)-linked glucose residues. All fractions could inhibit the accumulation of intracellular reactive oxygen species (ROS) in H2O2-induced Caco-2 cells, and they could improve oxidative stress damage by increasing the activity of superoxide dismutase (SOD) and reduced glutathione (GSH), which were related to their DPs and structures. 50E with high DPs showed better anti-oxidative stress activity.

Enhanced performance of thermally activated delayed fluorescent light emitting diodes by optimized host polarity.

The interaction between the intrinsic polarity of the host material and the TADF guest material affects charge injection and transport, exciton formation, charge recombination, and emission mechanisms. Therefore, understanding and controlling the interaction between the intrinsic polarity of the host material and the TADF guest material is very important to realize efficient TADF-OLED devices. This study investigated the molecular interaction between different polar host materials and a thermally activated delayed fluorescence material (DMAc-PPM). It has been found that interaction between the host and guest (π-π stacking interaction, multiple CH/π contacts) greatly influence the molecular transition dipole moment orientation of the guest. And the OLED devices based on the strong polar host (DPEPO) exhibited the highest EQEmax and lowest luminescence intensity, while devices using the weaker polar hosts mCP and CBP achieved higher luminance and lower EQEmax. Then, the strong polar host DPEPO was mixed with the weaker polar hosts CBP and mCP, respectively. The devices prepared based on the mixed-host DPEPO: mCP showed a 2.2 times improvement in EQEmax from 6.3% to 20.1% compared to the single-host mCP. The devices prepared based on the mixed-host DPEPO: CBP showed a 3.1 times improvement in luminance intensity from 1023 cd/m2 to 4236 cd/m2 compared to the single host of DPEPO. This suggests that optimizing the polarity of host materials has the potential to enhance the performance of solution prepared OLED devices.

Conductive Hydrogel Restores Electrical Conduction to Promote Neurological Recovery in a Rat Model.

Spinal cord injury (SCI), caused by significant physical trauma, as well as other pathological conditions, results in electrical signaling disruption and loss of bodily functional control below the injury site. Conductive biomaterials have been considered a promising approach for treating SCI, owing to their ability to restore electrical connections between intact spinal cord portions across the injury site. In this study, we evaluated the ability of a conductive hydrogel, poly-3-amino-4-methoxybenzoic acid-gelatin (PAMB-G), to restore electrical signaling and improve neuronal regeneration in a rat SCI model generated using the compression clip method. Gelatin or PAMB-G was injected at the SCI site, yielding three groups: Control (saline), Gelatin, and PAMB-G. During the 8-week study, PAMB-G, compared to Control, had significantly lower proinflammatory factor expression, such as for tumor necrosis factor -α (0.388 ± 0.276 for PAMB-G vs. 1.027 ± 0.431 for Control) and monocyte chemoattractant protein (MCP)-1 (0.443 ± 0.201 for PAMB-G vs. 1.662 ± 0.912 for Control). In addition, PAMB-G had lower astrocyte and microglia numbers (35.75 ± 4.349 and 40.75 ± 7.890, respectively) compared to Control (50.75 ± 6.5 and 64.75 ± 10.72) and Gelatin (48.75 ± 4.787 and 71.75 ± 7.411). PAMB-G-treated rats also had significantly greater preservation and regeneration of remaining intact neuronal tissue (0.523 ± 0.059% mean white matter in PAMB-G vs 0.377 ± 0.044% in Control and 0.385 ± 0.051% in Gelatin) caused by reduced apoptosis and increased neuronal growth-associated gene expression. All these processes stemmed from PAMB-G facilitating increased electrical signaling conduction, leading to locomotive functional improvements, in the form of increased Basso-Beattie-Bresnahan scores and steeper angles in the slope test (76.667 ± 5.164 for PAMB-G, vs. 59.167 ± 4.916 for Control and 58.333 ± 4.082 for Gelatin), as well as reduced gastrocnemius muscle atrophy (0.345 ± 0.085 for PAMB-G, vs. 0.244 ± 0.021 for Control and 0.210 ± 0.058 for Gelatin). In conclusion, PAMB-G injection post-SCI resulted in improved electrical signaling conduction, which contributed to lowered inflammation and apoptosis, increased neuronal growth, and greater bodily functional control, suggesting its potential as a viable treatment for SCI.

Mild steam treatment: Enhancing the rehydration performance of instant rice noodles by changing the physicochemical properties and gel structure of rice starch.

The "instant" quality of instant rice noodles is significantly affected by slow rehydration during cooking. This happens as a result of the native rice starch's low ability to gelatinize as well as the high shear and pressure utilized in industries during the widely used extrusion molding process. In order to address this issue, the rice flour was pretreated with mild steam (MS) technology. The results revealed that the rehydration qualities of the rice noodles that were extruded from the steam-treated flour significantly improved. There was a reduction of 25.5% in the rehydration time, from 443 to 330 s. The MS-treated rice starch's peak viscosity increased to 4503 from 4044 mPa/s. Decreases in gelatinization enthalpy (ΔH) and short-range ordering also suggest a reduction in difficulty in accomplishing starch gelatinization. Scanning electron microscopy studies showed particle aggregation increased as the treatment duration lasted longer. In conclusion, our findings indicate that we successfully addressed the issue of slow rehydration in instant rice noodles while presenting a novel approach for their manufacturing in the manufacturing sector.

Morphological and molecular analyses reveal two new species of Grifola (Polyporales) from Yunnan, China.

Species of Grifola are famous edible mushrooms and are deeply loved by consumers around the world. Most species of this genus have been described and recorded in Oceania, Europe and South America, with only Grifolafrondosa being recorded in Asia. In this study, two novel species of Grifola from southwestern China (Asia) are introduced. Macro and micromorphological characters are described. Grifolaedulissp. nov. present medium-size basidiomata with gray to gray-brown lobes upper surface, mostly tibiiform or narrowly clavate, rarely narrowly lageniform or ellipsoid chlamydospores, cuticle hyphae terminal segments slightly enlarged. Grifolasinensissp. nov. has white to grayish white lobes upper surface, mostly ellipsoid, rarely narrowly utriform chlamydospores, and broadly ellipsoid to ellipsoid basidiospores (4.6-7.9 × 3.0-5.9 µm). The two new species are supported by phylogenetic analyses of combined nuclear rDNA internal transcribed spacer ITS1-5.8S-ITS2 rDNA (ITS) and ß-tubulin (TUBB). Moreover, the genetic distance between TUBB sequences of those specimen from GenBank was 1.76-1.9%. Thus, the conspecificity relationship of our specimens remains uncertain, and further specimens are required to conclusively confirm its identity.

Rare NRPS Gene Cluster for Desferriferrichrome Biosynthesis Controls the Conflict between Trap Formation and Nematicidal Activity in Arthrobotrys oligospora.

The formation of the trapping device induced by nematodes has been assumed as an indicator for a switch from saprophytic to predacious lifestyles for nematode-trapping fungi. However, fungal nematocidal activity is not completely synonymous with fungal trap formation. We found that the predominant nematode-trapping fungus Arthrobotrys oligospora harbored a rare NRPS (Ao415) gene cluster that was mainly distributed in nematode-trapping fungi. The gene Ao415 putatively encodes a protein with a unique domain organization, distinct from other NRPSs in other fungi. Mutation of the two key biosynthetic genes Ao415 and Ao414 combined with nontarget metabolic analysis revealed that the Ao415 gene cluster was responsible for the biosynthesis of a hydroxamate siderophore, desferriferrichrome (1). Lack of desferriferrichrome (1) and its hydroxamate precursor (3) could lead to significantly increased Fe3+ content, which induced fungal trap formation without a nematode inducer. Furthermore, the addition of Fe3+ strongly improved fungal trap formation but deleteriously caused broken traps. The addition of 1 significantly attenuated trap formation but enhanced fungal nematicidal activity. Our findings indicate that iron is a key factor for trap formation and provide a new insight into the underlying mechanism of siderophores in nematode-trapping fungi.

Uterine Immunoprivileged Cells Restore Cardiac Function of Male Recipients After Myocardial Infarction.

It has been documented that the uterus plays a key cardio-protective role in pre-menopausal women, which is supported by uterine cell therapy, to preserve cardiac functioning post-myocardial infarction, being effective among females. However, whether such therapies would also be beneficial among males is still largely unknown. In this study, we aimed to fill in this gap in knowledge by examining the effects of transplanted uterine cells on infarcted male hearts. We identified, based on major histocompatibility complex class I (MHC-I) expression levels, 3 uterine reparative cell populations: MHC-I(neg), MHC-I(mix), and MHC-I(pos). In vitro, MHC-I(neg) cells showed higher levels of pro-angiogenic, pro-survival, and anti-inflammatory factors, compared to MHC-I(mix) and MHC-I(pos). Furthermore, when cocultured with allogeneic mixed leukocytes, MHC-I(neg) had lower cytotoxicity and leukocyte proliferation. In particular, CD8+ cytotoxic T cells significantly decreased, while CD4+CD25+ Tregs and CD4-CD8- double-negative T cells significantly increased when cocultured with MHC-I(neg), compared to MHC-I(mix) and MHC-I(pos) cocultures. In vivo, MHC-I(neg) as well as MHC-I(mix) were found under both syngeneic and allogeneic transplantation in infarcted male hearts, to significantly improve cardiac function and reduce the scar size, via promoting angiogenesis in the infarcted area. All of these findings thus support the view that males could also benefit from the cardio-protective effects observed among females, via cell therapy approaches involving the transplantation of immuno-privileged uterine reparative cells in infarcted hearts.

Flexible Transparent Electrode Based on Ag Nanowires: Ag Nanoparticles Co-Doped System for Organic Light-Emitting Diodes.

Flexible organic light-emitting diodes (FOLEDs) have promising potential for future wearable applications because of their exceptional mechanical flexibility. Silver nanowire (Ag NW) networks are the most promising candidates to replace indium tin oxide (ITO), which is limited by its poor bendability. In this study, three different methods including methanol impregnation, argon plasma treatment, and ultraviolet radiation were used to reduce the junction resistance of Ag NWs to optimize the flexible transparent electrodes (FTEs); which were prepared using Ag NWs and poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS). Then, the optoelectronic properties of the FTEs were further improved by using a co-doped system of silver nanowires and silver nanoparticles (Ag NPs), the structure of which consisted of PET/Ag NWs: Ag NPs/PEDOT: PSS/DMSO. The largest FOM value of 1.42 × 10-2 ohm-1 and a low sheet resistance value of 13.86 ohm/sq were obtained using the optimized FTEs. The prepared FOLED based on the optimized FTEs had a luminous efficiency of 6.04 cd/A and a maximum EQE of 1.92%, and exhibited no observed decline in efficiency when reaching maximum luminance. After 500 bending tests, the luminance still reached 82% of the original value. It is demonstrated that the FTEs prepared via the co-doped system have excellent optoelectronic properties as well as high mechanical stability.

The Optimization of Hole Injection Layer in Organic Light-Emitting Diodes.

Organic light-emitting diodes (OLEDs) are widely recognized as the forefront technology for displays and lighting technology. Now, the global OLED market is nearly mature, driven by the rising demand for superior displays in smartphones. In recent years, numerous strategies have been introduced and demonstrated to optimize the hole injection layer to further enhance the efficiency of OLEDs. In this paper, different methods of optimizing the hole injection layer were elucidated, including using a suitable hole injection material to minimize the hole injection barrier and match the energy level with the emission layer, exploring new preparation methods to optimize the structure of hole injection layer, and so on. Meanwhile, this article can help people to understand the current research progress and the challenges still faced in relation to the hole injection layer in OLEDs, providing future research directions to enhance the properties of OLEDs.

Risk of reinfection and severity with the predominant BA.5 Omicron subvariant China, from December 2022 to January 2023.

Data on reinfection in large Asian populations are limited. In this study, we aimed to evaluate the reinfection rate, disease severity, and time interval between the infections in the symptomatic and asymptomatic populations which are firstl infected with BA.2 Omicron Variant. We retrospectively included adult patients with COVID-19 discharged from four designated hospitals between 27 April 2021 and 30 November 2022, who were interviewed via telephone from 29 January to 1 March 2023. Univariable and multivariable analyses were used to explore risk factors associated with reinfection. A total of 16,558 patients were followed up, during the telephone survey of an average of 310.0 days, 1610 (9.72%) participants self-reported reinfection. The mean time range of reinfection was 257.9 days. The risks for reinfection were analysed using multivariable logistic regression. Patients with severe first infection were at higher risk for reinfection (aORs, 2.50; P < 0.001). The male (aORs,0.82; P < 0.001), the elderly (aORs, 0.44; P < 0.001), and patients with full vaccination (aORs, 0.67; P < 0.001) or booster (aORs, 0.63; P < 0.001) had the lower risk of reinfection. Patients over 60 years of age (aORs,9.02; P = 0.006) and those with ≥2 comorbidities (aORs,11.51; P = 0.016). were at higher risk for severe reinfection. The number of clinical manifestations of reinfection increases in people with severe first infection (aORs, 2.82; P = 0.023). The overall reinfection rate was 9.72%, and the reinfection rate of Omicron-to-Omicron subvariants was 9.50% at one year. The severity of Omicron-Omicron reinfection decreased. Data from our clinical study may provide clinical evidence and bolster response preparedness for future COVID-19 reinfection waves.

Insight into a natural novel histidine decarboxylase gene deletion in Enterobacter hormaechei RH3 from traditional Sichuan-style sausage.

Histamine (HIS) is primarily formed from decarboxylated histidine by certain bacteria with histidine decarboxylase (hdc) activity and is the most toxic biogenic amine. Hdc, which is encoded by the hdc gene, serves as a key enzyme that controls HIS production in bacteria. In this paper, we characterized the changes in microbial and biogenic amines content of traditional Sichuan-style sausage before and after storage and demonstrated that Enterobacteriaceae play an important role in the formation of HIS. To screen for Enterobacteriaceae with high levels of HIS production, we isolated strain RH3 which has a HIS production of 2.27 mg/mL from sausages stored at 37°C for 180 days, using selective media and high-performance liquid chromatography. The strain RH3 can produce a high level of HIS after 28 h of fermentation with a significant hysteresis. Analysis of the physicochemical factors revealed that RH3 still retained its ability to partially produce HIS in extreme environments with pH 3.5 and 10.0. In addition, RH3 exhibited excellent salt tolerance (6.0% NaCl and 1.0% NaNO2 ). Subsequently, RH3 was confirmed as Enterobacter hormaechei with hdc gene deletion by PCR, western blot, and whole-genome sequencing analysis. Furthermore, RH3 exhibited pathogenicity rate of 75.60% toward the organism, indicating that it was not a food-grade safe strain, and demonstrated a high level of conservation in intraspecific evolution. The results of this experiment provide a new reference for studying the mechanism of HIS formation in microorganisms. PRACTICAL APPLICATION: This study provides a new direction for investigating the mechanism of histamine (HIS) formation by microorganisms and provides new insights for further controlling HIS levels in meat products. Further research can control the key enzymes that form HIS to control HIS levels in food.