Transcriptomic Insights into Metabolism-Dependent Biosynthesis of Bacterial Nanocellulose

Bacterial nanocellulose (BNC) is an attractive green-synthesized biomaterial for biomedical applications and various other applications. However, effective engineering of BNC production has been limited by our poor knowledge of the related metabolic processes. In contrast to the traditional perception that genome critically determines biosynthesis behaviors, here we discover that the glucose metabolism could also drastically affect the BNC synthesis in Gluconacetobacter hansenii. The transcriptomic profiles of two model BNC-producing strains, G. hansenii ATCC 53582 and ATCC 23769, which have highly similar genomes but drastically different BNC yields, were compared. The results show that their BNC synthesis capacities were highly related to metabolic activities such as ATP synthesis, ion transport protein assembly, and carbohydrate metabolic processes, confirming an important role of metabolism-related transcriptomes in governing the BNC yield. Our findings provide insights into the microbial biosynthesis behaviors from a transcriptome perspective, potentially guiding cellular engineering for biomaterial synthesis.

Nonsterilized Fermentation of Crude Glycerol for Polyhydroxybutyrate Production by Metabolically Engineered Vibrio natriegens

Polyhydroxybutyrate (PHB) is an attractive biodegradable polymer that can be produced through the microbial fermentation of organic wastes or wastewater. However, its mass production has been restricted by the poor utilization of organic wastes due to the presence of inhibitory substances, slow microbial growth, and high energy input required for feedstock sterilization. Here, Vibrio natriegens, a fast-growing bacterium with a broad substrate spectrum and high tolerance to salt and toxic substances, was genetically engineered to enable efficient PHB production from nonsterilized fermentation of organic wastes. The key genes encoding the PHB biosynthesis pathway of V. natriegens were identified through base editing and overexpressed. The metabolically engineered strain showed 166-fold higher PHB content (34.95 wt %) than the wide type when using glycerol as a substrate. Enhanced PHB production was also achieved when other sugars were used as feedstock. Importantly, it outperformed the engineered Escherichia coli MG1655 in PHB productivity (0.053 g/L/h) and tolerance to toxic substances in crude glycerol, without obvious activity decline under nonsterilized fermentation conditions. Our work demonstrates the great potential of engineered V. natriegens for low-cost PHB bioproduction and lays a foundation for exploiting this strain as a next-generation model chassis microorganism in synthetic biology.

Genome Sequence of a Heavy Metal-Detoxifying Actinomycete, Microbacterium proteolyticum ustc

A complete genome is presented for Microbacterium proteolyticum ustc, a member of the Gram-positive order Micrococcales of the phylum Actinomycetota that is resistant to high concentrations of heavy metals and participates in metal detoxification. The genome consists of one plasmid and one chromosome.

AQDS Activates Extracellular Synergistic Biodetoxification of Copper and Selenite via Altering the Coordination Environment of Outer-Membrane Proteins

The biotransformation of heavy metals in the environment is usually affected by co-existing pollutants like selenium (Se), which may lower the ecotoxicity of heavy metals, but the underlying mechanisms remain unclear. Here, we shed light on the pathways of copper (Cu²⁺) and selenite (SeO₃^2-) synergistic biodetoxification by Shewanella oneidensis MR-1 and illustrate how such processes are affected by anthraquinone-2,6-disulfonate (AQDS), an analogue of humic substances. We observed the formation of copper selenide nanoparticles (Cu_2-xSe) from synergistic detoxification of Cu²⁺ and SeO₃^2- in the periplasm. Interestingly, adding AQDS triggered a fundamental transition from periplasmic to extracellular reaction, enabling 14.7-fold faster Cu²⁺ biodetoxification (via mediated electron transfer) and 11.4-fold faster SeO₃^2- detoxification (via direct electron transfer). This is mainly attributed to the slightly raised redox potential of the heme center of AQDS-coordinated outer-membrane proteins that accelerates electron efflux from the cells. Our work offers a fundamental understanding of the synergistic detoxification of heavy metals and Se in a complicated environmental matrix and unveils an unexpected role of AQDS beyond electron mediation, which may guide the development of more efficient environmental remediation and resource recovery biotechnologies.

Anaerobic self-assembly of a regenerable bacteria-quantum dot hybrid for solar hydrogen production

Inorganic-biological hybrid systems (bio-hybrids), comprising fermentative bacteria and inorganic semiconductor photosensitizers for synergistic utilization of solar energy and organic wastes, offer opportunities for sustainable fuel biosynthesis, but the low quantum efficiency, photosensitizer biotoxicity and inability for self-regeneration are remaining hurdles to practical application. Here, we unveil a previously neglected role of oxygen in suppressing the biosynthesis of cadmium selenide quantum dots (CdSe QDs) and the metabolic activities of Escherichia coli, and accordingly propose a simple oxygen-regulation strategy to enable the self-assembly of bacterial-QD hybrids for efficient solar hydrogen production. Shifting from aerobic to anaerobic biosynthesis significantly lowered the intracellular reactive oxygen species level and increased NADPH and thiol-protein production, enabling a two-order-of-magnitude higher bio-QD synthesis rate and resulting in CdSe-rich products. Bacteria with abundant biocompatible intracellular bio-QDs naturally formed a highly active and self-regenerable bio-hybrid and achieved a quantum efficiency of 28.7% for hydrogen production under visible light, outperforming all the existing bio-hybrids. It also exhibited high stability during cyclic operation and robust performance for treating real wastewater under simulated sunlight. Our work provides valuable new insights into the metallic nanomaterial biosynthesis process to guide the design of self-assembled bio-hybrids towards sustainable energy and environmental applications.

Mechanical Insights into Thiol-Mediated Synergetic Biotransformation of Cadmium and Selenium in Nematodes

Cadmium ion (Cd²⁺) is a common environmental pollutant with high biotoxicity. Interestingly, the Cd²⁺ biotoxicity can be alleviated by the coexisting selenite (SeO₃^2-), which induces the formation of cadmium selenide-rich nanoparticles (CdSe NPs) under the function of thiol-capping peptides. However, the detailed biochemical mechanisms by which Cd and Se are synergistically transformed into CdSe NPs in living organisms remain unclear so far. Here, we shed light on the molecular basis of such biotransformation processes in Caenorhabditis elegans by focusing on the roles of several key thiol-capping peptides. By monitoring the compositional and structural changes of the Cd and Se species and the genetic-level responses of nematodes, we revealed the specific roles of glutathione (GSH) and phytochelatins (PCs) in mediating the CdSe NP formation. With the aid of in vitro bioassembly assay and density functional theory calculations, the detailed Cd-Se interaction pathways were further deciphered: the ingested Cd binds predominantly to GSH and PCs in sequence, then further interacts with selenocysteine to form tetrahedral-structured PC2-Cd₂-Sec₂ complex, and ultimately grows into CdSe NPs. This work provides molecular-level insights into the Cd-Se interaction in C. elegans and lays a basis for controlling the ecological and health risks of heavy metals in polluted environment.

[Effects of glycyrrhizic acid on ERK1/2 and p38 MAPK signaling pathway in a murine model of asthma]

Objective: To explore the effects of glycyrrhizic acid (GA) on Extracellular regulated protein kinases (ERK1/2) and p38 mitogen-activated protein kinases (p38 MAPK) signaling pathways in a murine model of asthma. Methods: Sixty female BALB/c mice were randomly divided into 6 groups (n=10 each): a control group, an asthmatic group, two treatment groups with low and high doses of GA, U0126 group and SB203580 group. Within 24 hours after the last OVA challenge, histological studies of lung were conducted with the hematoxylin and eosin staining (HE) and alcian blue-periodic acid-Schiff (AB-PAS), the relative protein expression of ERK1/2 and p38 MAPK were detected by immunohistochemistry and Western blotting in vivo. CD4(+) T cells were purified from spleens of OVA-sensitized and challenged mice by using the Mouse CD4 Cell Positive Isolation Kit and incubated with anti-CD3 mAb (1 μg/ml) in the presence of various concentrations of GA (10 and 100 μg/ml), U0126 (10 μmol/L) or SB203580(10 μmol/L). After 72 h of incubation, the relative protein expression of ERK1/2 and p38 MAPK of CD4(+) T cells were detected by Western blotting in vitro. Results: The asthmatic mice induced infiltration of inflammatory cells around airways and blood vessels, airway goblet cell hyperplasia and mucus production. Administration of GA at a dose of 100 mg/kg, U0126 or SB203580 significantly reduced the infiltration of inflammatory cells in the peribronchial areas and goblet cell hyperplasia compared with the asthmatic mice. The protein expressions of p-ERK1/2 were lower in GA at a dose of 100 mg/kg (0.090±0.022) and U0126 group (0.072±0.017) than those in asthmatic group (0.143±0.022) (all P<0.05). The protein expressions of p-p38 MAPK were lower in GA at a dose of 100 mg/kg (0.072±0.019) and SB203580 group (0.061±0.015) than those in asthmatic group (0.121±0.022) (all P<0.05) by immunohistochemistry. Compared with asthmatic group (0.783±0.133, 0.649±0.095), the protein expressions of p-ERK1/2 and p-p38 MAPK in GA at a high dose group (0.385±0.186, 0.275±0.089) and in U0126 group (0.117±0.051) or in SB203580 group (0.108±0.043) were decreased by Western blotting (all P<0.05). The expressions of p-ERK1/2 in CD4(+) T cells after 72 h incubation were lower in 100 μg/ml concentrations of GA (0.579±0.184) and group U0126 (0.249±0.082) and the expressions of p-p38 MAPK were much lower in 100 μg/ml concentrations of GA (0.445±0.081) and group SB203580 (0.249±0.082) compared with those in group CD3 (1.028±0.147, 0.902±0.107) (all P<0.05). Conclusion: ERK1/2 and p38 MAPK signaling pathways are activated in asthmatic mice and GA may negative regulate this activation.

Significant association between lower pulse pressure and increasing levels of a novel type of phospholipid

The aim of this study was to analyze the association between pulse pressure and a novel type of phospholipid with solubility similar to that of lysophosphatidic acid (LPA), designated as AP, which was reported to be elevated during ischemia. In this cross-sectional study, 416 hypertensive patients and 252 controls aged between 35 and 70 years were enrolled consecutively. Fasting blood samples were extracted for assays of phospholipids and other biomarkers. Compared to controls, the hypertensive patients had higher levels of both LPA [odds ratio (OR) = 3.83] and AP (OR = 4.30). Changes in blood pressure did not affect the levels of LPA or AP. However AP, but not LPA, levels were significantly higher in patients with lower or higher pulse pressure (Pearson χ(2) = 11.239, P = 0.001). For patients whose pulse pressure was ≤60 mmHg, plasma levels of AP were significantly negatively correlated with pulse pressure. However, this was not observed for LPA and nine other biomarkers, including lipoproteins. Plasma levels of AP increased in hypertensive patients with higher or lower pulse pressure. Thus, attention should be paid to the possibility of cerebral ischemia in hypertensive patients when they have abnormal pulse pressure, especially for those with relatively low pulse pressure.

Isolation and identification of infectious bronchitis virus from chickens in Sichuan, China

A nonhemagglutinating virus was isolated from kidneys and lungs of chickens suspected of having infectious bronchitis infection. Specific-pathogen-free embryonated chicken eggs were used as the cultural system. With the use of the ciliary activity of chicken embryo tracheal organ cultures as indicator system, the physicochemical properties of one of the isolated strains (SAIB3) were shown to be similar to infectious bronchitis virus (IBV) strain M41 (standard strain); whereas electron microscopy of the isolate showed coronavirus particles. Virus-neutralization tests were performed in tracheal organ cultures to compare the serotypes of five IBV isolates and six known IBV strains on the basis of reciprocal neutralization titers and euclidean distance. The cross-neutralization pattern indicated that one isolate was of the T-strain IBV serotype, another of the M41 IBV serotype, while others had partial serotype relationship to M41 and T-strains of IBV.

[Long-term effect of Schonlein-Henoch nephritis with nephritic-nephrotic syndrome in children by traditional Chinese medicine and Western medicine]

21 cases are fully agreed with the diagnosis standard of Schonlein-Henoch nephritis. Biopsy on the kidney of 5 cases with resistant duration was made and all were diagnosed as mesenteric hyperplastic glomerular nephritis, among them, one with segmental sclerosis, one with segmental sclerosis and crescents in some glomerulus. 13 cases were treated with prednisone, cyclophosphamide and Traditional Chinese herbs. 8 cases with wilfordine adding and/or traditional Chinese herbs. The results showed that 15 of 21 cases were cured, one case perfect remission, 4 cases part remission. All of the cases were followed-up from 2 years and 10 months to 12 years and 4 months, average 7.34 years. The late results: Group A, 16 cases with symptom, physical exam, urine routine normal. Group B, 4 cases with microscopic hematuria and/or "a little-(+)" urinary protein. Group C, one case with "+2" urinary protein and/or hypertension, urinary creatinine clearance rate normal. Of 5 cases, whose biopsies of kidney were made, one with glomerular segmental sclerosis belonged to Group B. 13 of 21 cases had recurrence for 1-6 times, which was closed related with up respiratory tract infection.

[Idiopathic thrombocytopenic purpura in children treated with replenishing qi and tonifying kidney and the changes in thrombocyte aggregative function]

Forty-one children with idiopathic thrombocytopenic purpura (ITP) were reported in this paper. Of all, 36 with petechia and ecchymosis, 28 with nasal hemorrhage, 5 with hematochezia and 1 with subcutaneous hematoma. According to the TCM differentiation, 24 and 17 of all belonged to the type of impairment of Yin due to blood-heat and both deficiencies of Qi and tonifying Kidney and its basic prescriptions were: dried Radix Rehmanniae, Radix Angelicae Sinensis, Radix Paeoniae Rubra, Radix Rubiae, Fructus Psoraleae, stir-frying Radix Astragali, Semen Cuscutae, Caulis Spatholob; Chinese Jujubae, Radix et Rhizoma Rhei. The average treating duration was 5.02 months.

RESULTS

24 cases cured, 6 recovered, 10 improved, 1 failed, with a total effective rate of 97.6%. 22 of the cured were followed-up without recurrence in average 10.4 months after withdrawal. In 32 cases, the thrombocyte aggregative function was tested with ADP induction, meanwhile in 20 of 32 cases aggregation with adrenaline induction was tested. The results before and after treatment showed an evident difference, with low function before treatment and normal after treatment. It is concluded that the replenishing Qi and tonifying Kidney may have a better effect on both acute and chronic children ITP without recurrence after withdrawal.

[Teratogenic studies on stannous chloride in rats]

This paper describes teratogenic studies of stannous chloride in rats. The compound was administered to pregnant rats on gestational days 7 through 12 orally by a stomach tube at dose levels of 0 mg, 20 mg, 100 mg, 500 mg/kg of stannous chloride and fish liver oil for the positive control group. The experimental results showed that the placenta not only retains some stannous chloride but also diverts parts of the stannous chloride is the fetus. Stannous chloride showed teratogenic effects on the early growing embryos and protruding tongue of fetus.