Control of citrus blue and green molds by Actinomycin X2 and its possible antifungal mechanism.

Citrus blue and green molds caused by Penicillium digitatum, P. italicum, and P. polonicum, are the major postharvest diseases of citrus fruit. In the present study, Actinomycin X2 (Act-X2), a naturally occurring antibiotic produced by Streptomyces species, was found to show excellent antifungal effect against these three pathogens with a minimum inhibitory concentration (MIC) value of 62.5 µg/mL for them all, which was better than the positive control thiophanate-methyl. Act-X2 significantly reduced the percentage of spore germination, and highly inhibited the mycelial growth of P. italicum, P. digitatum, and P. polonicum with EC50 values being 34.34, 13.76, and 37.48 µg/mL, respectively. In addition, Act-X2 greatly decreased the intracellular protein content while increasing the reactive oxygen species (ROS) level and superoxide anion (O2-) content in the mycelia of pathogens. In vivo test indicated that Act-X2 strongly inhibited the infection of navel oranges by these three Penicillium species, with an inhibition percentage of >50% for them all at the concentration of 10 MIC. Transcriptome analysis suggested that Act-X2 might highly influence the ribosomal functions of P. polonicum, which was supported as well by the molecular docking analysis of Act-X2 with some key functional proteins and RNAs of the ribosome. Furthermore, Act-X2 significantly reduced the decay percentage and improved the firmness, color, and sugar-acid ratio of navel oranges spray-inoculated with P. polonicum during the postharvest storage at 4 °C for 60 d.

Outbreak of Septoria leaf spot caused by Sphaerulina musiva on Populus × euramericana in China.

In June 2023, severe leaf spots were noted in Populus × euramericana cv 'Nanlin95' plantations located in the Nanjing Baguazhou Wetland Park (32°09'16.97″N, 118°48'16.74″E) of Jiangsu Province and Populus × canadensis cv 'Sacrau 79' and Populus × canadensis cv 'Guariento' in the Liyuan Village in Nanyang City (32°53'43.70″N, 112°17'29.12″E) of Henan Province, respectively. The disease incidence in both locations could reach 97.9% (556 out of 568 trees) and 98.9% (2409 out of 2436 trees), respectively. The initial symptoms appear as numerous small and circular spots (1.59 to 3.18 mm in diameter) with gray or tan centers and dark-brown margins on the leaves. As the spots age, they sometimes enlarge, often coalesce, and may extend down the petioles. Diseased leaves and petioles were both surface sterilized with 75% ethanol for 30 seconds. With the aid of a hand lens, pycnidia (brown to black, spherical in profile, 90 to 250 µm diam) were easily picked out in the center of the spots and subsequently transferred into 1 mL sterilized water for preparing the spore suspension plated on KV8 medium amended with 100 mg/liter streptomycin sulfate and 50 mg/liter chloramphenicol. After 12 days of incubation, 86 single-spore isolates were obtained and identified as typical Septoria-like fungi according to morphological features, including slow-growing, gray or black colonies with pink mucilaginous matrix and hyaline, straight or curved conidia (size = 25 to 59 × 3.5 to 4 µm; septa = 1 to 6). Species identification was further validated by PCR amplification and sequencing of the internal transcribed spacer (ITS) region with ITS1/ITS4 primer pairs. Multiple sequence alignments with ClustalW revealed that the obtained ITS sequences of 86 isolates were 100% identical to each other. A BLAST search in GenBank indicated that the selfsame sequences of two representative isolates (isolate BGZ11 of Jiangsu Province, accession no. OR660379; isolate KZB22 of Henan Province, accession no. OR711499) shared 99.8% identity (494 of 495 bp) and 100% identity (504 of 504 bp) with related sequences of Sphaerulina musiva (Peck) Quaedvlieg, Verkley, and Crous (syn. = Septoria musiva Peck) in GenBank (MN275187; KF251619), respectively. Furthermore, we used a S. musiva-specific PCR assay (Abraham et al. 2018) on symptomatic leaf samples collected from the plantation. Each sample consisted of 20 cut-out leaf spots per leaf. Eight of the 10 samples were positive for S. musiva DNA. To confirm pathogenicity, six sterile tissue culture of poplar plants (Populus trichocarpa and Populus × euramericana cv 'Nanlin895') were respectively transplanted into pots and grown in a greenhouse for a week and for a month with an 18-h photoperiod augmented with sodium lamps and a 20°C (day)/16°C (night) temperature regime. Inoculations were conducted by spraying the plants with conidia suspension (106 conidia/mL) (LeBoldus et al. 2010). Control plants were sprayed with distilled water. Leaf spots were developed on the inoculated P. trichocarpa leaves at one week and P. × euramericana cv 'Nanlin895' leaves at 10 days after inoculation while no symptoms were observed on the control plants. The fungus S. musiva was successfully reisolated from all symptomatic leaves fulfilling Koch's postulates. Sphaerulina musiva only causes an endemic leaf spot disease on its natural North American host Populus. deltoides (Feau et al. 2010; Ostry 1987). However, on susceptible Populus species (e.g., P. balsamifera, P. trichocarpa, P. maximowiczii) and hybrids, S. musiva causes not only leaf spots but also severely damaging stem and branch cankers (Jeger et al. 2018; LeBoldus et al. 2009; Sondreli et al. 2020). To our knowledge, this is the first report of S. musiva causing leaf spots on poplar in China. Large-scale timber imports (e.g., cut branches, isolated bark, wood with and without bark) potentially lead to anthropogenic-facilitated transport of this pathogen. This outbreak of Septoria leaf spot underscores the potential threat of this pathogen to P. × euramericana in China, where it is widely planted as a keystone forestry species.

Secreted Effector Proteins of Poplar Leaf Spot and Stem Canker Pathogen Sphaerulina musiva Manipulate Plant Immunity and Contribute to Virulence in Diverse Ways.

Fungal effectors play critical roles in manipulating plant immune responses and promoting colonization. Sphaerulina musiva is a heterothallic ascomycete fungus that causes Septoria leaf spot and stem canker disease in poplar (Populus spp.) plantations. This disease can result in premature defoliation, branch and stem breakage, increased mortality, and plantation failure. However, little is known about the interaction between S. musiva and poplar. Previous work predicted 142 candidate secreted effector proteins in S. musiva (SmCSEPs), 19 of which were selected for further functional characterization in this study. SmCSEP3 induced plant cell death in Nicotiana benthamiana, while 8 out of 19 tested SmCSEPs suppressed cell death. The signal peptides of these eight SmCSEPs exhibited secretory activity in a yeast signal sequence trap assay. Confocal microscopy revealed that four of these eight SmCSEPs target both the cytoplasm and the nucleus, whereas four predominantly localize to discrete punctate structures. Pathogen challenge assays in N. benthamiana demonstrated that the transient expression of six SmCSEPs promoted Fusarium proliferatum infection. The expression of these six SmCSEP genes were induced during infection. SmCSEP2, SmCSEP13, and SmCSEP25 suppressed chitin-triggered reactive oxygen species burst and callose deposition in N. benthamiana. The candidate secreted effector proteins of S. musiva target multiple compartments in the plant cell and modulate different pattern-triggered immunity pathways. [Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 "No Rights Reserved" license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2023.

Nonlinear relationship between glycated hemoglobin and cognitive impairment after acute mild ischemic stroke.

BACKGROUND: Stroke is the second most common cause of morbidity and mortality. Even mild stroke survivors have an increased risk of cognitive impairment. Studies have been conducted on the relationship between glycated hemoglobin (HbA1c) and cognitive decline, but the findings have been inconsistent. Therefore, this study examined the link between HbA1c levels and cognitive impairment following acute mild ischemic stroke. METHODS: Data from 311 patients with acute mild ischemic stroke admitted to Suining Central Hospital, Sichuan Province, China, from January 1, 2015, to December 31, 2018, were evaluated. Fasting venous blood was taken to assess HbA1c levels on the day after admission. Cognitive function was assessed using the Chinese version of the Montreal Cognitive Assessment Scale (MoCA) 3-6 months after stroke onset. We used a generalized additive model and smooth curve fitting (penalty spline method) to assess the nonlinear relationship between HbA1c and poststroke cognitive impairment (PSCI). RESULTS: This study included 311 patients aged 23 to 96 years old (mean age: 67.37 ± 11.92 years), of whom 198 (63.67%) were men. Among the 311 stroke patients, 120 (38.59%) had PSCI. After adjusting for potential confounders, there was a nonlinear relationship between HbA1c and PSCI, with an inflection point of 8.2. To the left of the inflection point, the effect size, 95% confidence interval, and P value were 0.87, 0.58 to 1.31, and 0.5095, respectively; however, to the right of the inflection point, these numbers were 1.96, 1.08 to 3.58, and 0.0280. CONCLUSION: We found a nonlinear relationship between HbA1c and PSCI. When HbA1c was greater than 8.2%, HbA1c was positively correlated with PSCI.

Significant Differences in Gut Microbiota Between Irritable Bowel Syndrome with Diarrhea and Healthy Controls in Southwest China.

BACKGROUND: Irritable bowel syndrome (IBS) is a heterogeneous disease, which is closely related to environmental factors and gut microbiota. OBJECTIVE: To study gut microbiota in IBS-D of Han nationality in Southwest China and explore its relationship with environmental factors. METHODS: One hundred and twenty cases of IBS-D and 63 cases of HCs were recruited; baseline data such as age, height, and weight were collected. HAMA, HAMD, IBS-SSS, IBS-QOL, and laboratory tests were performed. Feces were collected for 16S rDNA sequencing. Then, the differences of gut microbiota were analyzed and looked for biomarkers of each. FAPROTAX was used to predict the functional differences of gut microbiota. Spearman analysis was conducted between the phylum level and environmental factor. RESULTS: There were significant differences in daily life between IBS-D and HCs, especially in the spicy taste. The scores of HAMA and HAMD, urea, and transaminase in IBS-D were significantly higher than those of HCs. The richness of gut microbiota in IBS-D was significantly lower than that of HCs, as well as the beta diversity, but not diversity. The biomarkers of IBS-D were Prevotella, Clostridiales, and Roseburia, and the biomarkers of HCs were Veillonellaceae, Bacteroides coprocola, and Bifidobacteriales. The functions of gut microbiota in IBS-D were significantly different from HCs. Correlation analysis showed that multiple gut microbiota were closely related to HAMA, IBS-SSS, IBS-QOL, inflammatory indexes, and liver enzymes. CONCLUSION: There are significant differences in richness of gut microbiota, flora structure, and flora function between IBS-D and HCs in Southwest China. These differences may be closely related to environmental factors such as eating habits, living habits, and mental and psychological factors. CLINICAL TRIAL REGISTRATION: The trial was registered and approved in China Clinical Trial Registry (Registration No. ChiCTR2100045751).

Long-term exposures to ambient particulate matter and ozone pollution with lower extremity deep vein thrombosis after surgical operations: a retrospective case-control study in Beijing, China.

BACKGROUND: Lower extremity deep vein thrombosis (LEDVT) after surgical operations is a common and fatal disease leading to unfavorable outcomes including death. Nevertheless, there has been insufficient evidence on the associations between ambient air pollution and LEDVT, particularly studies from developing regions. METHODS: Based on 302 LEDVT cases and 302 controls in a general hospital in Beijing, China, this unmatched retrospective case-control study investigated the associations of fine particulate matter (PM2.5), inhalable particulate matter (PM10), and ozone (O3) with odds of LEDVT. RESULTS: Per 10 µg/m3 increase in PM2.5, PM10, and O3 at 3-month, 6-month, and 2-year average was associated with increased LEDVT odds [odds ratios (ORs) for PM2.5: 1.10 (95%CI: 1.05, 1.14), 1.14 (95%CI: 1.09, 1.18), and 1.30 (95%CI: 1.06, 1.61); ORs for PM10: 1.06 (95%CI: 1.02, 1.10), 1.12 (95%CI: 1.08, 1.16), and 1.29 (95%CI: 1.03, 1.61); ORs for O3: 1.00 (95%CI: 0.96, 1.04), 1.16 (95%CI: 1.02, 1.31), and 2.08 (95%CI: 1.03, 4.18), respectively]. The stratified analyses, exposure-responses curves, and sensitivity analyses further highlighted the robustness of our findings. CONCLUSIONS: Long-term exposures to ambient PM2.5, PM10, and O3 may increase the risk of LEDVT in patients after surgical operations. The results may be implicated in the prevention and control of adverse clinical outcomes of surgical patients associated with ambient air pollution.

Linoleic acid from the endophytic fungus Diaporthe sp. HT-79 inhibits the growth of Xanthomonas citri subsp. citri by destructing the cell membrane and producing reactive oxygen species (ROS).

Citrus canker disease caused by Xanthomonas citri subsp. citri (Xac) severely influences the quality and quantity of citrus fruits. The current management of this disease mainly relies on the application of copper-associated chemicals, which poses a threat to human health and the environment. The present study isolated an endophytic fungus HT-79 from the healthy navel orange tree, whose crude fermentation product significantly inhibited the growth of Xac. The strain HT-79 was identified as a species of the Diaporthe genus. The petroleum ether extract (PEE) of the crude fermentation product of HT-79 exhibited remarkable activity against Xac with a MIC (minimum inhibitory concentration) value of 0.0625 mg/mL, significantly better than the positive control CuSO4 (MIC = 0.125 mg/mL). Bioassay-guided isolation of PEE resulted in the discovery of one highly potent anti-Xac subfraction, namely fraction 5 (MIC = 0.0156 mg/mL). Gas chromatography-mass spectrometry (GC-MS) analysis revealed that fraction 5 mainly consisted of palmitic acid (18.17%), ethyl palmitate (15.66%), linoleic acid (6.80%), oleic acid (18.32%), ethyl linoleate (21.58%), ethyl oleate (15.87%), and ethyl stearate (3.60%). Among these seven compounds, linoleic acid (MIC = 0.0078 mg/mL) was found to be the most potent against Xac, followed by oleic acid (MIC = 0.0156 mg/mL), while all others were less pronounced than CuSO4. Linoleic acid highly inhibited the growth of Xac via the destruction of the cell membrane and overproduction of reactive oxygen species (ROS). A preliminary in vivo experiment revealed that linoleic acid was effective in the control of citrus canker disease.

Microbiome-Mediated Protection against Pathogens in Woody Plants.

Pathogens, especially invasive species, have caused significant global ecological, economic, and social losses in forests. Plant disease research has traditionally focused on direct interactions between plants and pathogens in an appropriate environment. However, recent research indicates that the microbiome can interact with the plant host and pathogens to modulate plant resistance or pathogen pathogenicity, thereby altering the outcome of plant-pathogen interactions. Thus, this presents new opportunities for studying the microbial management of forest diseases. Compared to parallel studies on human and crop microbiomes, research into the forest tree microbiome and its critical role in forest disease progression has lagged. The rapid development of microbiome sequencing and analysis technologies has resulted in the rapid accumulation of a large body of evidence regarding the association between forest microbiomes and diseases. These data will aid the development of innovative, effective, and environmentally sustainable methods for the microbial management of forest diseases. Herein, we summarize the most recent findings on the dynamic structure and composition of forest tree microbiomes in belowground and aboveground plant tissues (i.e., rhizosphere, endosphere, and phyllosphere), as well as their pleiotropic impact on plant immunity and pathogen pathogenicity, highlighting representative examples of biological control agents used to modulate relevant tree microbiomes. Lastly, we discuss the potential application of forest tree microbiomes in disease control as well as their future prospects and challenges.

Network meta-analysis on efficacy and safety of different Janus kinase inhibitors for ulcerative colitis.

WHAT IS KNOWN AND OBJECTIVE: In the absence of head-to-head comparisons, the objective of this study was to conduct a network meta-analysis (NMA) to indirectly compare the relative efficacy and safety of Janus kinase (JAK) inhibitors for ulcerative colitis (UC). METHODS: We searched PubMed, EMBASE, Web of Science and Cochrane Library from the database inception until 13 August 2021. No randomized controlled trials (RCTs) that directly compared these interventions were identified. Therefore, a fixed-effects Bayesian NMA was conducted by identifying a connected (via comparison to placebo) network of RCTs. Ranking was assessed using surface under the cumulative ranking (SUCRA) probabilities. RESULTS AND DISCUSSION: Seven RCTs including 3190 patients met the inclusion criteria. Filgotinib 100 mg was ranked highest for induction of endoscopic remission (SUCRA, 0.67) whereas peficitinib 75 mg BID was ranked highest for induction of clinical response (SUCRA, 0.72). Peficitinib 75 mg was ranked highest for induction of mucosal healing (SUCRA, 0.71), whereas peficitinib 150 mg was ranked highest for clinical remission (SUCRA, 0.74). Tofacitinib 3 mg had the highest probability of being the best treatment in terms of change from baseline in Mayo score (SUCRA, 0.78). Adverse events (AEs) and treatment discontinuations or withdrawals from the study due to AEs did not differ between JAK inhibitors and placebo groups. WHAT IS NEW AND CONCLUSION: Based on indirect comparisons, peficitinib 75 mg/75 mg BID/150 mg, tofacitinib 3 mg and filgotinib 100mg were the most efficacious JAK inhibitor interventions in patients with UC. However, head-to-head trials are warranted to inform clinical decision-making with greater confidence.

A novel photoreactive DNA-binding dye for detecting viable Klebsiella pneumoniae in powdered infant formula.

In addition to Cronobacter spp., Klebsiella pneumoniae is another opportunistic bacterial pathogen present in powdered infant formula (PIF) that can cause pneumonia, septicemia, and other diseases. In this study, a rapid and specific method based on a fluorescence probe was developed for detecting viable K. pneumoniae in PIF samples via the combination of recombinase-aided amplification (RAA) with thiazole orange monoazide (TOMA) dye (the TOMA-RAA assay hereafter). As a novel photosensitive DNA-intercalating dye, TOMA was used to penetrate bacterial cells, including both dead and viable cells, as verified by confocal laser scanning microscopy and fluorescent emission spectrometry. Importantly, the RAA assay exhibited good performance in detecting K. pneumoniae within 40 min at 39°C. Under optimal conditions, the TOMA-RAA assay can detect as low as 2.6 × 103 cfu/mL of K. pneumoniae in pure culture and 2.3 × 104 cfu/g of K. pneumoniae in spiked PIF sample. After 3 h of pre-enrichment, 3 × 100 cfu/g of K. pneumoniae can be detected. Furthermore, the TOMA-RAA assay displayed an excellent anti-interference ability to nontarget bacteria. In short, the proposed method has great potential application for the rapid and accurate detection of viable K. pneumoniae in PIF.

Real-time recombinase-aided amplification with improved propidium monoazide for the rapid detection of viable Escherichia coli O157:H7 in milk.

Escherichia coli O157:H7, the causative agent of thrombotic thrombocytopenic purpura and hemolytic uremic syndrome in humans, generates a effective harm to community health because of its high pathogenicity. A real-time recombinase-aided amplification (rRAA) is an emerging method for nucleic acid detection. However, genomic DNA of bacteria could exist in food and the environment for a long time after death and could be amplified by rRAA assay, resulting in false-positive signal; thus, developing a fast and sensitive method is necessary to detect viable foodborne pathogens in food products. In our research, rRAA assay coupled with an enhanced nucleic acid binding dye named improved propidium monoazide (PMAxx) was established and applied in viable E. coli O157:H7 identification in skim milk. The PMAxx could eliminate interference from dead bacteria by permeating impaired membranes and covalently linking to DNA to prevent DNA amplification. The PMAxx-rRAA assay was performed with high sensitivity and good specificity. The PMAxx-rRAA assay could detect as low as 5.4 × 100 cfu/mL of viable E. coli O157:H7 in pure culture, and 7.9 × 100 cfu/mL of viable E. coli O157:H7 in skim milk. In addition, the PMAxx-rRAA assay was performed in the presence of a high concentration of dead bacteria or nontarget bacteria in skim milk to verify the capacity to resist interference from dead bacteria and nontarget bacteria. Therefore, the established PMAxx-rRAA assay is a valuable tool for the identification of viable E. coli O157:H7 in complex food matrix.

Complete chloroplast genome features of the model heavy metal hyperaccumulator Arabis paniculata Franch and its phylogenetic relationships with other Brassicaceae species.

Arabis paniculata Franch (Brassicaceae) has been widely used for the phytoremediation of heavy mental, owing to its hyper tolerance of extreme Pb, Zn, and Cd concentrations. However, studies on its genome or plastid genome are scarce. In the present study, we obtained the complete chloroplast (cp) genome of A. paniculata via de novo assembly through the integration of Illumina reads and PacBio subreads. The cp genome presents a typical quadripartite cycle with a length of 153,541 bp, and contains 111 unigenes, with 79 protein-coding genes, 28 tRNAs and 4 rRNAs. Codon usage analysis showed that the codons for leucine were the most frequent codons and preferentially ended with A/U. Synonymous (Ks) and non-synonymous (Ka) substitution rate analysis indicated that the unigenes, ndhF and rpoC2, related to "NADH-dehydrogenase" and "RNA polymerase" respectively, underwent the lowest purifying selection pressure. Phylogenetic analysis demonstrated that Arabis flagellosa and A. hirsuta are more similar to each other than to A. paniculata, and Arabis is the closest relative of Draba among all Brassicaceae genera. These findings provide valuable information for the optimal exploitation of this model species as a heavy-metal hyperaccumulator. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-022-01151-1.

Dibenzo[b,f][1,4,5]chalcogenadiazepine Photoswitches: Conversion of Excitation Energy into Ring Strain.

Tetra-ortho-substituted, heteroaryl and cyclic azobenzenes have emerged as three key strategies on morphology design of photoswitch to diversify controllability. Cyclic azobenzene is of particular utilization in photo-energy conversion due to rigid and ring-strain structure. Despite the well-recognized diazocine, the photo-switching properties of seven-membered cyclic azobenzenes (diazepines) have yet been exploited. Herein, we report a family of dibenzo[b,f][1,4,5]chalcogenadiazepines (DBChDs) and their T-type photo-switching nature with tunable relaxation rate. Based on experiments together with DFT calculations, we found that an unsymmetric 2-bithiophenyl-dibenzo[b,f][1,4,5]thiadiazepine exhibited an efficient response to 445 nm laser stimulation (quantum efficiency, ΦZ→E =0.71) with millisecond relaxation half-life (t1/2 =40 ms). Photo-energy transduction efficiency was also exceptionally high with 29.1 % converted into ring-strain energy mainly loaded on azo π-bond.

The Plant-Beneficial Rhizobacterium Bacillus velezensis FZB42 Controls the Soybean Pathogen Phytophthora sojae Due to Bacilysin Production.

Soybean root rot caused by the oomycete Phytophthora sojae is a serious soilborne disease threatening soybean production in China. Bacillus velezensis FZB42 is a model strain for Gram-positive plant growth-promoting rhizobacteria and is able to produce multiple antibiotics. In this study, we demonstrated that B. velezensis FZB42 can efficiently antagonize P. sojae. The underlying mechanism for the inhibition was then investigated. The FZB42 mutants deficient in the synthesis of lipopeptides (bacillomycin D and fengycin), known to have antifungal activities, and polyketides (bacillaene, difficidin, and macrolactin), known to have antibacterial activities, were not impaired in their antagonism toward P. sojae; in contrast, mutants deficient in bacilysin biosynthesis completely lost their antagonistic activities toward P. sojae, indicating that bacilysin was responsible for the activity. Isolated pure bacilysin confirmed this inference. Bacilysin was previously shown to be antagonistic mainly toward prokaryotic bacteria rather than eukaryotes. Here, we found that bacilysin could severely damage the hyphal structures of P. sojae and lead to the loss of its intracellular contents. A device was invented allowing interactions between P. sojae and B. velezensis FZB42 on nutrient agar. In this manner, the effect of FZB42 on P. sojae was studied by transcriptomics. FZB42 significantly inhibited the expression of P. sojae genes related to growth, macromolecule biosynthesis, pathogenicity, and ribosomes. Among them, the genes for pectate lyase were the most significantly downregulated. Additionally, we showed that bacilysin effectively prevents soybean sprouts from being infected by P. sojae and could antagonize diverse Phytophthora species, such as Phytophthora palmivora, P. melonis, P. capsici, P. litchi, and, most importantly, P. infestans. IMPORTANCEPhytophthora spp. are widespread eukaryotic phytopathogens and often extremely harmful. Phytophthora can infect many types of plants important to agriculture and forestry and thus cause large economic losses. Perhaps due to inappropriate recognition of Phytophthora as a common pathogen in history, research on the biological control of Phytophthora is limited. This study shows that B. velezensis FZB42 can antagonize various Phytophthora species and prevent the infection of soybean seedlings by P. sojae. The antibiotic produced by FZB42, bacilysin, which was already known to have antibacterial effectiveness, is responsible for the inhibitory action against Phytophthora. We further showed that some Phytophthora genes and pathways may be targeted in future biocontrol studies. Therefore, our data provide a basis for the development of new tools for the prevention and control of root and stem rot in soybean and other plant diseases caused by Phytophthora.

Bacillus velezensis tolerance to the induced oxidative stress in root colonization contributed by the two-component regulatory system sensor ResE.

Efficient root colonization of plant growth-promoting rhizobacteria is critical for their plant-beneficial functions. However, the strategy to overcome plant immunity during root colonization is not well understood. In particular, how Bacillus strains cope with plant-derived reactive oxygen species (ROS), which function as the first barrier of plant defence, is not clear. In the present study, we found that the homolog of flg22 in Bacillus velezensis SQR9 (flg22SQR9 ) has 78.95% identity to the typical flg22 (flg22P.s. ) and induces a significant oxidative burst in cucumber and Arabidopsis. In contrast to pathogenic or beneficial Pseudomonas, live B. velezensis SQR9 also induced an oxidative burst in cucumber. We further found that B. velezensis SQR9 tolerated higher H2 O2 levels than Pst DC3000, the pathogen that harbours the typical flg22, and that it possesses the ability to suppress the flg22-induced oxidative burst, indicating that B. velezensis SQR9 may exploit a more efficient ROS tolerance system than DC3000. Further experimentation with mutagenesis of bacteria and Arabidopsis showed that the two-component regulatory system, ResDE, in B. velezensis SQR9 is involved in tolerance to plant-derived oxidative stress, thus contributing to root colonization. This study supports a further investigation of the interaction between beneficial rhizobacteria and plant immunity.

Spatiotemporal Resolved Live Cell Membrane Tracking through Photo-click Reactions Enriched in Lipid Phase.

A set of photo-switchable monopeptides derived from cis-ß-dibenzodiazocine-l-alanine (cis-DBDAA) have been designed and synthesized, which are capable of photo-click reacting with diaryltetrazoles or diarylsydnones in a hydrophobic phospholipid bilayer environment. The DBDAA monopeptides include both a hydrophobic tail on C-terminal, providing high affinity toward lipid membrane, and a modularized functional moiety on N-terminal, enabling rapid optimization of the self-assembly strength to form multifunctional supramolecules. With the cis-DBDAA monopeptides photo-switched into trans-configuration, we were able to disrupt the supramolecular assembly through an efficient photo-click reaction across the lipid bilayer of liposomes. We reveal that the performance of the photo-click reactions between the monopeptides and photo-generated nitrile imine intermediates is significantly enhanced by enrichment of both reactants in the hydrophobic membrane lamel of liposomes. Enrichment of the DBDAA monopeptide in lipid phase serves as a convenient method to introduce bioorthogonal chemical handles on live cell membranes, which enables fluorescence labelling of single cell's membrane with high spatiotemporal resolution to facilitate the studies on cell membrane dynamics.

Pontibacter flavimaris sp. nov., of the family Hymenobacteraceae, isolated from marine sediment.

A Gram-stain-negative, ovoid or rod-shaped, non-flagellated, motile-by-gliding and aerobic bacteria, designated S10-8T, was isolated from marine sediment of the Yellow Sea. Colonies of strain S10-8T had a pink-red pigmentation and its cells were approximately 0.5-0.8 µm×1.0-2.5 µm in size. Growth occurred at 10-45 °C (optimally at 33-37 °C), in the presence of 0-12.0 % NaCl (optimally at 2.0-5.0 %, w/v) and at pH 5.0-8.5 (optimally at pH 7.0-7.5). Phylogenetic analysis of the 16S rRNA gene indicated that strain S10-8T is a member of the genus Pontibacter within the family Hymenobacteraceae, and the 16S rRNA gene sequence similarity of strain S10-8T to its closest relative Pontibacter actiniarum KCTC 12367T was 96.9 %. Strain S10-8T contained MK-7 as the predominant menaquinone and summed feature 4 (iso-C17:1 I and/or anteiso-C17:1 B) and iso-C15:0 as the major fatty acids. The major polar lipids were phosphatidylethanolamine, an unidentified aminophospholipid and an unidentified lipid. The size of the draft genome was 4 623 791 bp and the G+C content was 53.5 mol%. There were low DNA-DNA hybridization values (<48.3±5.2 %) and average nucleotide identity values (<86.5 %) between strain S10-8T and the most closely related recognized Pontibacter species. Therefore, we propose a novel species in the genus Pontibacter to accommodate the novel isolate: Pontibacter flavimaris sp. nov. (type strain S10-8T=KCTC 42769T=ACCC 19859T).

The fluorescent probe-based recombinase-aided amplification for rapid detection of Escherichia coli O157:H7.

Escherichia coli O157:H7 (E. coli O157:H7) is a common foodborne morbigenous microorganism, which can spread through fecal-oral transmission. Humans can be infected by ingesting foods and water contaminated with E. coli O157:H7, which can cause various symptoms. In present study, we have successfully developed a quick and hypersensitive fluorescent probe-based Recombinase-aided amplification (RAA) method and applied in E. coli O157:H7 detection at 39 °C in 20 min. The sensitivity of the assay in pure E. coli O157:H7 suspension was 5.6 × 100 CFU/mL. The fluorescent probe-based RAA assay was further applied in three samples, and the limit of detection (LOD) in skimmed milk, lettuces and lake water was 5.4 × 101 CFU/mL, 7.9 × 101 CFU/mL and 5.2 × 101 CFU/mL, separately. This method showed a high sensitivity and short detection time, which has the feasible application in on-site test in real samples.

Isolation and complete genome sequencing of the virulent phage vB_EcoS_XY3 infecting multidrug-resistant Escherichia coli.

A virulent phage, named vB_EcoS_XY3, was isolated from hospital wastewater in Xiangyang, China. Its morphological characteristics, growth parameters, adsorption rate, and pH and temperature stability were determined. Phage vB_EcoS_XY3 was found to be able to infect Escherichia coli laboratory strains and also some multidrug-resistant E. coli strains. Its complete genome consists of 51,345 base pairs of double-stranded DNA with an average GC content of 55.24% and 85 putative protein-coding genes. Forty-four genes were annotated with known functions. These results will not only provide further insights into E. coli phages but also have implications for the development of potential biocontrol agents.

Salimicrobium humidisoli sp. nov., Isolated from Saline-Alkaline Soil.

A Gram-staining-positive, aerobic, non-endospore-forming, coccus-shaped, non-flagellated, and non-motile bacterium, designated WN024T, was isolated from the natural saline-alkali wetland soil of Binhai new district, Tianjin, China. Cells of strain WN024T were catalase- and oxidase-positive. The isolate was able to grow between 20 and 45 °C (optimal at 33-37 °C), pH 6.5-11.0 (optimal 7.5-8.0), and in the presence of 5.0-25.0% NaCl (optimal at 10.0-15.0%, w/v). The isolate could be affiliated to the genus Salimicrobium and the highest 16S rRNA gene sequence similarity of strain WN024T to its closest relative Salimicrobium salexigens DSM 22782T was 97.9%. The size of the genome was 2,622,223 bp in size with a G + C content of 47.1%. The sole respiratory quinone of strain WN024T was MK-7, the predominant fatty acids were iso-C15:0, anteiso-C15:0 and anteiso-C17:0. The major polar lipids were phosphatidylglycerol (PG), glycolipid (GL), phospholipid (PL) and diphosphatidylglycerol (DPG). The cell-wall diamino acid was meso-diaminopimelic acid. The DNA-DNA hybridization values between strain WN024T and the closest relative S. salexigens DSM 22782T was 47.3 ± 2.3%. The highest average nucleotide identity (ANI) value was 92.3% to S. salexigens DSM 22782T (GenBank Accession No. GCA_900156705.1). Therefore, we propose a novel species in the genus Salimicrobium to accommodate this novel isolate, named Salimicrobium humidisoli sp. nov. The type strain is WN024T (= ACCC 19979T = KCTC 33897T).