GDF6 in gastric cancer upregulated by helicobacter pylori induces epithelial-mesenchymal translation via the TGF-ß/SMAD3 signaling pathway.

OBJECTIVE: To investigate the association between Helicobacter pylori infection and GDF6 expression in gastric cancer patients, and to determine its influence on prognosis and resistance to capecitabine. METHODS: Tumor and adjacent non-tumor tissues were collected from 148 gastric cancer patients who underwent surgery in our department from October 2019 to June 2022. Of these patients, 78 tested positive for Helicobacter pylori and 70 tested negative. Hematoxylin-eosin (HE) and immunofluorescence staining were utilized to quantify GDF6 expression in cancerous and adjacent tissues. Patient prognosis was monitored via follow-up. Western blotting analyzed GDF6 expression in common gastric cancer cell lines. HGC27 cells exhibiting high GDF6 expression and BGC823 cells with low expression were used to create GDF6-silenced and overexpressed cell lines. The impact of GDF6 on the proliferation, migration, invasion, and cloning abilities of gastric cancer cells was evaluated using the CCK-8 assay, scratch test, Transwell assay, and plate colony formation assay. Fluorescent quantitative PCR and Western blotting assessed the effects of GDF6 levels on epithelial-mesenchymal transition (EMT) and tumor cell stemness. RESULTS: GDF6 expression in gastric cancer tissues was significantly correlated with cancer grading and staging (P<0.05). Helicobacter pylori-positive tissues exhibited significantly higher GDF6 expression levels than negative samples (P<0.05). Kaplan-Meier survival analysis indicated that high GDF6 expression was associated with poor survival prognosis. Overexpressed GDF6 enhanced the proliferation, migration, and invasion abilities of gastric cancer cells, while silencing GDF6 yielded opposite results. Increased GDF6 expression upregulated TGF-ß expression and the phosphorylation levels of SMAD3, leading to an elevation in mesenchymal cell markers N-cadherin, vimentin, and a reduction in epithelial cell markers cytokeratins, E-cadherin. Moreover, high GDF6 levels contributed to increased resistance to capecitabine and enhanced the expression of tumor stem cell markers Nanog, Sox-2, Oct-4, CD44, amplifying tumor cell stemness. CONCLUSION: Helicobacter pylori infection is associated with increased GDF6 expression in gastric cancer tissue, correlating with poor survival prognosis. Elevated GDF6 expression promotes the proliferation, migration, and invasion abilities of gastric cancer cells, facilitates EMT via the TGF-ß/SMAD3 pathway, and intensifies cell stemness and capecitabine resistance. Consequently, GDF6 presents itself as a potential new target for gastric cancer treatment. DATA AVAILABILITY STATEMENT: The data that support the findings of this study are available from the corresponding author upon reasonable request.

Carbonyl- and Nitrogen-Embedded Multi-Resonance Emitter with Ultra-Pure Green Emission and High Electroluminescence Efficiencies.

Multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters with narrow emission spectra have garnered significant attention in future organic light-emitting diode (OLED) displays. However, current C=O/N-embedded MR-TADF systems still lack satisfactory performance in terms of electroluminescence bandwidths and external quantum efficiencies (EQEs). In this study, a C=O/N-embedded green MR-TADF emitter, featuring two acridone units incorporated in a sterically protected 11-ring fused core skeleton, is successfully synthesized through finely controlling the reaction selectivity. The superior combination of multiple intramolecular fusion and steric wrapping strategies in the design of the emitter not only imparts an extremely narrow emission spectrum and a high fluorescence quantum yield to the emitter but also mitigates aggregation-induced spectral broadening and fluorescence quenching. Therefore, the emitter exhibits leading green OLED performance among C=O/N-based MR-TADF systems, achieving an EQE of up to 37.2 %, a full width at half maximum of merely 0.11 eV (24 nm), and a Commission Internationale de l'Éclairage coordinate of (0.20, 0.73). This study marks a significant advance in the realization of ideal C=O/N-based MR-TADF emitters and holds profound implications for the design and synthesis of other MR-TADF systems.

Global diversity and biogeography of DNA viral communities in activated sludge systems.

BACKGROUND: Activated sludge (AS) systems in wastewater treatment plants (WWTPs) harbor enormous viruses that regulate microbial metabolism and nutrient cycling, significantly influencing the stability of AS systems. However, our knowledge about the diversity of viral taxonomic groups and functional traits in global AS systems is still limited. To address this gap, we investigated the global diversity and biogeography of DNA viral communities in AS systems using 85,114 viral operational taxonomic units (vOTUs) recovered from 144 AS samples collected across 54 WWTPs from 13 different countries. RESULTS: AS viral communities and their functional traits exhibited distance-decay relationship (DDR) at the global scale and latitudinal diversity gradient (LDG) from equator to mid-latitude. Furthermore, it was observed that AS viral community and functional gene structures were largely driven by the geographic factors and wastewater types, of which the geographic factors were more important. Carrying and disseminating auxiliary metabolic genes (AMGs) associated with the degradation of polysaccharides, sulfate reduction, denitrification, and organic phosphoester hydrolysis, as well as the lysis of crucial functional microbes that govern biogeochemical cycles were two major ways by which viruses could regulate AS functions. It was worth noting that our study revealed a high abundance of antibiotic resistance genes (ARGs) in viral genomes, suggesting that viruses were key reservoirs of ARGs in AS systems. CONCLUSIONS: Our results demonstrated the highly diverse taxonomic groups and functional traits of viruses in AS systems. Viral lysis of host microbes and virus-mediated HGT can regulate the biogeochemical and nutrient cycles, thus affecting the performance of AS systems. These findings provide important insights into the viral diversity, function, and ecology in AS systems on a global scale. Video Abstract.

Control of motor landing and processivity by the CAP-Gly domain in the KIF13B tail.

Microtubules are major components of the eukaryotic cytoskeleton. Posttranslational modifications (PTMs) of tubulin regulates interactions with microtubule-associated proteins (MAPs). One unique PTM is the cyclical removal and re-addition of the C-terminal tyrosine of α-tubulin and MAPs containing CAP-Gly domains specifically recognize tyrosinated microtubules. KIF13B, a long-distance transport kinesin, contains a conserved CAP-Gly domain, but the role of the CAP-Gly domain in KIF13B's motility along microtubules remains unknown. To address this, we investigate the interaction between KIF13B's CAP-Gly domain, and tyrosinated microtubules. We find that KIF13B's CAP-Gly domain influences the initial motor-microtubule interaction, as well as processive motility along microtubules. The effect of the CAP-Gly domain is enhanced when the motor domain is in the ADP state, suggesting an interplay between the N-terminal motor domain and C-terminal CAP-Gly domain. These results reveal that specialized kinesin tail domains play active roles in the initiation and continuation of motor movement.

Response surface optimization of poly-ß-hydroxybutyrate synthesized by Bacillus cereus L17 using acetic acid as carbon source.

A strain of Bacillus that can tolerate 10 g/L acetic acid and use the volatile fatty acids produced by the hydrolysis and acidification of activated sludge to produce polyhydroxyalkanoate was screened from the activated sludge of propylene oxide saponification wastewater. The strain was identified by 16S rRNA sequencing and phylogenetic tree analysis and was named Bacillus cereus L17. Various characterization methods showed that the polymer synthesized by strain L17 is poly-ß-hydroxybutyrate, which has low crystallinity, good ductility and toughness, high thermal stability and a low polydispersity coefficient. It has wide thermoplastic material operating space as well as industrial and medicinal applications. The optimal fermentation conditions were determined by single factor optimization. Then, Plackett-Burman and Box-Behnken design experiments were carried out according to the single factor optimization results, and the response surface optimization was completed. The final results were: initial pH 6.7, temperature 25 °C, and loading volume 124 mL. The verification experiment showed that the yield of poly-ß-hydroxybutyrate after optimization increased by 35.2 % compared to that before optimization.

The synergized diagnostic value of VTQ with chemokine CXCL13 in lung tumors.

Virtual Touch Tissue Quantification (VTQ) offers several advantages in the diagnosis of various lung diseases. Chemokine expression levels, such as CXCL13, play a vital role in the occurrence and development of tumors and aid in the diagnosis process. The purpose of this study was to evaluate the combined value of VTQ and changes in CXCL13 expression levels for the diagnosis of lung tumors. A total of 60 patients with thoracic nodules and pleural effusion were included, with 30 of them having malignant pleural effusion (based on pathology) and the remaining 30 having benign thoracic nodules and pleural effusion. The relative expression level of CXCL13 was measured in the collected pleural effusions using Enzyme-Linked Immunosorbent Assay (ELISA). The relationship between CXCL13 expression levels and various clinical features was analyzed. A Receiver Operating Characteristic (ROC) curve analysis was conducted on the VTQ results and relative expression levels of CXCL13, and the areas under the curve, critical values, sensitivity, and specificity were calculated. Multivariate analysis incorporating multiple indicators was performed to determine the accuracy of lung tumor diagnosis. The results showed that the expression levels of CXCL13 and VTQ were significantly higher in the lung cancer group compared to the control group (P < 0.05). In the Non-Small Cell Lung Cancer (NSCLC) group, CXCL13 expression levels increased with later TNM staging and poorer tumor differentiation. The expression level of CXCL13 in adenocarcinoma was higher than that in squamous cell carcinoma. The ROC curve analysis revealed that CXCL13 had an area under the curve (AUC) of 0.74 (0.61, 0.86) with an optimal cut-off value of 777.82 pg/ml for diagnosing lung tumors. The ROC curve analysis of VTQ showed an AUC of 0.67 (0.53, 0.82) with a sensitivity of 60.0% and a specificity of 83.3%, and an optimal diagnostic cut-off of 3.33 m/s. The combination of CXCL13 and VTQ for diagnosing thoracic tumors had an AUC of 0.842 (0.74, 0.94), which was significantly higher than either factor alone. The results of the study demonstrate the strong potential of combining VTQ results with chemokine CXCL13 expression levels for lung tumor diagnosis. Additionally, the findings suggest that elevated relative expression of CXCL13 in cases of malignant pleural effusion caused by non-small cell lung cancer may indicate a poor prognosis. This provides promising potential for using CXCL13 as a screening tool and prognostic indicator for patients with advanced lung cancer complicated by malignant pleural effusion.

Review on two-dimensional material-based field-effect transistor biosensors: accomplishments, mechanisms, and perspectives.

Field-effect transistor (FET) is regarded as the most promising candidate for the next-generation biosensor, benefiting from the advantages of label-free, easy operation, low cost, easy integration, and direct detection of biomarkers in liquid environments. With the burgeoning advances in nanotechnology and biotechnology, researchers are trying to improve the sensitivity of FET biosensors and broaden their application scenarios from multiple strategies. In order to enable researchers to understand and apply FET biosensors deeply, focusing on the multidisciplinary technical details, the iteration and evolution of FET biosensors are reviewed from exploring the sensing mechanism in detecting biomolecules (research direction 1), the response signal type (research direction 2), the sensing performance optimization (research direction 3), and the integration strategy (research direction 4). Aiming at each research direction, forward perspectives and dialectical evaluations are summarized to enlighten rewarding investigations.

Tundra Soil Viruses Mediate Responses of Microbial Communities to Climate Warming.

The rise of global temperature causes the degradation of the substantial reserves of carbon (C) stored in tundra soils, in which microbial processes play critical roles. Viruses are known to influence the soil C cycle by encoding auxiliary metabolic genes and infecting key microorganisms, but their regulation of microbial communities under climate warming remains unexplored. In this study, we evaluated the responses of viral communities for about 5 years of experimental warming at two depths (15 to 25 cm and 45 to 55 cm) in the Alaskan permafrost region. Our results showed that the viral community and functional gene composition and abundances (including viral functional genes related to replication, structure, infection, and lysis) were significantly influenced by environmental conditions such as total nitrogen (N), total C, and soil thawing duration. Although long-term warming did not impact the viral community composition at the two depths, some glycoside hydrolases encoded by viruses were more abundant at both depths of the warmed plots. With the continuous reduction of total C, viruses may alleviate methane release by altering infection strategies on methanogens. Importantly, viruses can adopt lysogenic and lytic lifestyles to manipulate microbial communities at different soil depths, respectively, which could be one of the major factors causing the differences in microbial responses to warming. This study provides a new ecological perspective on how viruses regulate the responses of microbes to warming at community and functional scales. IMPORTANCE Permafrost thawing causes microbial release of greenhouse gases, exacerbating climate warming. Some previous studies examined the responses of the microbial communities and functions to warming in permafrost region, but the roles of viruses in mediating the responses of microbial communities to warming are poorly understood. This study revealed that warming induced changes in some viral functional classes and in the virus/microbe ratios for specific lineages, which might influence the entire microbial community. Furthermore, differences in viral communities and functions, along with soil depths, are important factors influencing microbial responses to warming. Collectively, our study revealed the regulation of microbial communities by viruses and demonstrated the importance of viruses in the microbial ecology research.

Production of polyhydroxyalkanoate by mixed cultivation of Brevundimonas diminuta R79 and Pseudomonas balearica R90.

The microflora in the activated sludge of propylene oxide saponification wastewater is characterized by a clear succession after enrichment and domestication, and the specifically enriched strains can significantly increase the yield of polyhydroxyalkanoate. In this study, Pseudomonas balearica R90 and Brevundimonas diminuta R79, which are dominant strain after domestication, were selected as models to examine the interactive mechanisms associated with the synthesis of polyhydroxyalkanoate by co-cultured strains. RNA-Seq analysis revealed the up-regulated expression of the acs and phaA genes of strains R79 and R90 in the co-culture group, which enhanced their utilization of acetic acid and synthesis of poly-ß-hydroxybutyrate. Cell dry weight and the yield of poly-ß-hydroxybutyrate in the co-culture group were accordingly considerably higher than those in the respective pure culture groups. In addition, two-component system, quorum-sensing, flagellar synthesis-related, and chemotaxis-related genes were enriched in strain R90, thereby indicating that compared with the R79 strain, R90 can adapt more rapidly to a domesticated environment. Expression of the acs gene was higher in R79 than in R90, and consequently, strain R79 could more efficiently assimilate acetate in the domesticated environment, and thus predominated in the culture population at the end of the fermentation period.

Microbial and phage communities as well as their interaction in PO saponification wastewater treatment systems.

Viruses or phages were considered affecting microbial community composition, metabolic process, and biogeochemical cycles. However, phage communities and their potential associations with microbial community are not well understood in the activated sludge (AS) of wastewater treatment plants (WWTPs). In this study, we explored the interactions between phages and microbial community by using propylene oxide (PO) saponification WWTPs as an example. Bacterial, eukaryal and archaeal communities were investigated and 34 phage contigs (>10 kb) were recovered from PO saponification WWTPs. At least 3 complete phage genomes were assembled. In all 34 phages, 21 of them have been predicted to their host. The association network analysis showed that abundant phages were associated with abundant microorganisms. This result conformed to Kill-the-Winner model. Notably, 45 auxiliary metabolic genes (AMGs) were identified from phage genomes (including small contig fragments). They influenced bacterial metabolism through facilitating phages replication and avoiding host death. Collectively, our results suggested that phage community affect microbial community and metabolic pathways by killing their hosts and AMGs transfer in AS of PO saponification WWTPs.

Hijacking the self-replicating machine of bacteriophage for PCR-based cascade signal amplification in detecting SARS-CoV-2 viral marker protein in serum.

In this work, the nucleic acid detection of SARS-Cov-2 is extended to protein markers of the virus, utilizing bacteriophage. Specifically, the phage display technique enables the main protease of SARS-Cov-2 to control the self-replication of m13 phage, so that the presence of the viral protease can be amplified by phage replication as the first round of signal amplification. Then, the genome of replicated phage can be detected using polymer chain reaction (PCR), as the second round of signal amplification. Based on these two types of well-established biotechnology, the proposed method shows satisfactory sensitivity and robustness in the direct serum detection of the viral protease. These results may point to clinical application in the near future.

Microbial production of valuable chemicals by modular co-culture strategy.

Nowadays, microbial synthesis has become a common way for producing valuable chemicals. Traditionally, microbial production of valuable chemicals is accomplished by a single strain. For the purpose of increasing the production titer and yield of a recombinant strain, complicated pathways and regulation layers should be fine-tuned, which also brings a heavy metabolic burden to the host. In addition, utilization of various complex and mixed substrates further interferes with the normal growth of the host strain and increases the complexity of strain engineering. As a result, modular co-culture technology, which aims to divide a target complex pathway into separate modules located at different single strains, poses an alternative solution for microbial production. Recently, modular co-culture strategy has been employed for the synthesis of different natural products. Therefore, in this review, various chemicals produced with application of co-cultivation technology are summarized, including co-culture with same species or different species, and regulation of population composition between the co-culture members. In addition, development prospects and challenges of this promising field are also addressed, and possible solution for these issues were also provided.

Has China's Low-Carbon City Construction Enhanced the Green Utilization Efficiency of Urban Land?

China has implemented the low-carbon city pilot (LCCP) policy in the hopes of efficiently limiting carbon emission intensity to combat global warming and promote green economic growth. Urban land utilization, the second-largest source of carbon emissions, is key to the LCCP policy being able to have the desired effect, which has attracted widespread attention. Based on the panel data from prefecture-level cities in China from 2006 to 2019, this study used the propensity score matching difference-in-differences method (PSM-DID) to examine the impacts of LCCP policy on green utilization efficiency of urban land (GUEUL). The results reveal that LCCP policy has a beneficial impact on GUEUL and can effectively boost the future possibilities of green and low-carbon city development. Due to variances in regional economic and resource endowment level, the impacts of LCCP are different. The pilot has pushed GUEUL in the eastern region, western region, and growing resource-based cities, but has failed to improve GUEUL in other regions. Policymakers should adhere to the long-term sustainability of the LCCP policy and adopt differentiated action strategies to promote GUEUL when implementing it in different regions.

Construction of a miRNA Signature Using Support Vector Machine to Identify Microsatellite Instability Status and Prognosis in Gastric Cancer.

Background: The specific role and prognostic value of DNA repair and replication-associated miRNAs in gastric cancer (GC) have not been clearly elucidated. Therefore, comprehensive analysis of miRNAs in GC is crucial for proposing therapeutic strategies and survival prediction. Methods: Firstly, clinical information and transcriptome data of TCGA-GC were downloaded from the database. In the entire cohort, we performed differential analysis in all miRNAs and support vector machine (SVM) was used to eliminate redundant miRNAs. Subsequently, we combined survival data and cox regression analysis to construct a miRNA signature in the training cohort. In addition, we used PCA, Kaplan-Meier, and ROC analysis to explore the prognosis value of risk score in the training and testing cohort. It is worth noting that multiple algorithms were used to evaluate difference of immune microenvironment (TME), microsatellite instability (MSI), tumor mutational burden (TMB), and immunotherapy in different risk groups. Finally, we investigated the potential mechanism about miRNA signature. Results: We constructed miRNA signature based on the following 4 miRNAs: hsa-miR-139-5p, hsa-miR-139-3p, hsa-miR-146b-5p, and hsa-miR-181a-3p. Univariate and multivariate Cox regression analyses suggested that risk score is a risk factor and an independent prognostic factor in GC patients. The AUC value of ROC analysis showed a robust prediction accuracy in each cohort. Moreover, significant differences in immune functions, immune cell content, immune checkpoint, MSI status, and TMB score were excavated in different groups distinguished by risk score. Finally, based on the above four miRNA target genes, we revealed that the signature was enriched in DNA repair and replication. Conclusion: We have developed a robust risk-formula based on 4 miRNAs that provides accurate risk stratification and prognostic prediction for GC patients. In addition, different risk subgroups may potentially guide the choice of targeted therapy.

Metabolic engineering for biosynthesis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) from glucose and propionic acid in recombinant Escherichia coli.

In this study, novel polyhydroxyalkanoate (PHA)-associated genes (phaCp and phaABp) cloned from Propylenella binzhouense L72T were expressed in Escherichiacoli cells for PHA production, and the recombinant strains were used to analyze PHA yields with various substrates. The highest poly (3-hydroxybutyrate-co-3-hydroxy-valerate) (PHBV) yield (1.06 g/L) and cell dry weight (3.31 g/L) in E. coli DH5α/ΔptsG-CpABp were achieved by using glucose and propionicacid as substrates. Structural verification of PHBV produced by E. coli DH5α/ΔptsG-CpABp was performed to evaluate the characteristics of the polymers using Fourier transform infrared spectroscopy and nuclear magnetic resonance analysis. In addition, the X-ray diffraction results showed improved crystallinity of PHBV, and thermogravimetric analysis showed good thermal stability of 298 °C. The above findings indicated that the expression of phaCp and phaABp genes resulted in improved PHBV synthesis activity, and the polymer had better performance at higher processing temperatures.

Piperlongumine alleviates corneal allograft rejection via suppressing angiogenesis and inflammation.

Background: Neovascularization and inflammatory response are two essential features of corneal allograft rejection. Here, we investigated the impact of Piperlongumine (PL) on alleviating corneal allograft rejection, primarily focusing on pathological angiogenesis and inflammation. Methods: A murine corneal allograft transplantation model was utilized to investigate the role of PL in preventing corneal allograft rejection. PL (10 mg/kg) or vehicle was intraperitoneally injected daily into BALB/c recipients from day -3 to day 14. The clinical signs of the corneal grafts were monitored for 30 days. Corneal neovascularization and inflammatory cell infiltration were detected by immunofluorescence staining and immunohistochemistry. The proportion of CD4+ T cells and macrophages in the draining lymph nodes (DLNs) was examined by flow cytometry. In vitro, HUVECs were cultured under hypoxia or incubated with TNF-α to mimic the hypoxic and inflammatory microenvironment favoring neovascularization in corneal allograft rejection. Multiple angiogenic processes including proliferation, migration, invasion and tube formation of HUVECs in hypoxia with or without PL treatment were routinely evaluated. The influence of PL treatment on TNF-α-induced pro-inflammation in HUVECs was investigated by real-time PCR and ELISA. Results: In vivo, PL treatment effectively attenuated corneal allograft rejection, paralleled by coincident suppression of neovascularization and alleviation of inflammatory response. In vitro, PL distinctively inhibited hypoxia-induced angiogenic processes in HUVECs. Two key players in hypoxia-induced angiogenesis, HIF-1α and VEGF-A were significantly suppressed by PL treatment. Also, TNF-α-induced pro-inflammation in HUVECs was hampered by PL treatment, along with a pronounced reduction in ICAM-1, VCAM-1, CCL2, and CXCL5 expression. Conclusions: The current study demonstrated that PL could exhibit both anti-angiogenic and anti-inflammatory effects in preventing corneal allograft rejection, highlighting the potential therapeutic applications of PL in clinical strategy.

Paracoccus shandongensis sp. nov., Isolated from Activated Sludge.

A novel strain, wg2T, was isolated from activated sludge obtained from wastewater treatment plant in Shandong province, China. The bacterium was Gram-strain-negative, aerobic, rod-shaped, non-flagellated and non-gliding. This bacterium was characterized to determine its taxonomic position using the polyphasic approach. Strain wg2T grew at 25-45 °C (optimum, 30 °C), at salinities of 0-7.0% (w/v) NaCl (optimum, 0-2.0%) and at pH 7-9 (optimum, pH 7.0). Phylogenetic analysis based on 16S rRNA gene sequence showed that strain wg2T clustered with species of genus Paracoccus and shares high similarities with Paracoccus sediminis DSM 26170 T (98.1%) and Paracoccus fontiphilus MVW-1 T (97.7%), respectively. The genome size of strain wg2T was 3.93 Mbp and the DNA G + C content was 66.05%. The dDDH values and ANI between strain wg2T and each of reference strains P. sediminis DSM 26170 T, P. fontiphilus MVW-1 T and P. denitrificans DSM 413 T were 18.3, 12.5, 24.5% and 85.3, 87.0, 78.4%, respectively. The major respiratory quinone was found to be Q-10 and the major fatty acid was C18:1 ω7c. The polar lipids consisted of aminoglycolipid (AGL), phosphatidylcholine (PC), glycolipid (GL), phosphatidylserine (PS), phosphatidylglycerol phosphate (PGP), aminophospholipids (APL). Combining above descriptions, strain wg2T should represent a novel species of genus Paracoccus, for which the name Paracoccus shandongensis sp. nov., is proposed. The type strain is wg2T (= KCTC 72862 T = CCTCC AB 2019401 T).

Mesorhizobium xinjiangense sp. nov., isolated from rhizosphere soil of Alhagi sparsifolia.

A beige-pigmented, Gram-strain-negative, aerobic, rod-shaped, non-flagellated and non-gliding bacterium, designated strain lm94T, was isolated from rhizosphere soil of Alhagi sparsifolia obtained from Alar city, located in Xinjiang province, China. Growth occurred at 20-45 °C (optimum, 37 °C), in the presence of 0-6% (w/v) NaCl (optimum, 0-1%) and at pH 6.0-9.5 (optimum, pH 7.0-7.5). Phylogenetic analysis based on 16S rRNA gene sequence showed that strain lm94T belonged to the genus Mesorhizobium, with highest sequence similarity to Mesorhizobium wenxiniae WYCCWR 10195T (96.6%). Genome sequencing revealed a genome size of 5 256 375 bp and a G + C content of 63.6 mol%. The average nucleotide identity value and the digital DNA-DNA hybridization value between strain lm94T and M. wenxiniae LMG 30254T were 75.0% and 20.0%, respectively. The major respiratory quinone was Q-10. The major fatty acids were C19:0 cyclo ω8c and Summed Feature 8 (C18:1 ω6c and/or C18:1 ω7c) and its polar lipids consisted of phosphatidylethanolamine (PE), phosphatidylglycerol (PG), unidentified phospholipid (PL), phosphatidylcholine (PC), diphosphatidylglycerol (DPG), unidentified aminolipid (AL), unknown glycolipid (GL), unidentified aminophospholipid (APL2) and unidentified polar lipid (L1 and L2). On the basis of these data, strain lm94T is considered to represent a novel species of the genus Mesorhizobium, for which the name Mesorhizobium xinjiangense sp. nov. is proposed. The type strain is lm94T (=KCTC 72863T=CCTCC AB2019377T).

Biosynthesis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in metabolically recombinant Escherichia coli.

In this study, a phaCR gene encoding PHA synthase was identified in Rhodoligotrophos defluvii which was adjacent to ß-ketothiolase encoded by phaAR gene and acetoacetyl-CoA reductase encoded by phaBR gene. Amino acid comparison of PhaCR showed the highest homology of 65.98% with PhaC of R. appendicifer, while its homology with typical class I PHA synthase in Cupriavidus necator was only 42.54%. PHA synthesis genes were then transformed into E. coli harboring phaCABR and phaCRABC which were cultured with 15 g/L glucose respectively, and 20.46 wt% and 16.95 wt% of CDW for poly(3-hydroxybutyrate) (PHB) were accumulated respectively. To further explore the effect of substrate specificity for PHA production, the ptsG gene was then deleted and 15 g/L glucose and 1.5 g/L propionate were co-employed as carbon sources, which enabled the synthesis of poly(3HB-co-3HV) copolymer. As a result, poly(3HB-co-3HV) was accumulated up to 24.74 wt% of CDW, and the highest content of 3-hydroxyvalerate (3HV) was 10.86 mol%. The Td5 was 260 °C, which implied that it possessed good thermal stability, and the Mw of GPC in recombinant strains were between 22 and 26 × 104 g/mol, and the highest PDI was 3.771. The structure of poly (3HB-co-3HV) copolymer was determined through 1H NMR analysis.