Iron is an essential element for living organisms that plays critical roles in the process of bacterial growth and metabolism. However, it remains to be elucidated whether piuB encoding iron-uptake factor is involved in iron uptake and pathogenicity of Xanthomonas axonopodis pv. glycines (Xag). To investigate the function of piuB, we firstly generated a piuB deletion mutant (ΔpiuB) by homologous recombination. Compared with the wild-type, the piuB mutant exhibited significantly reduced growth and virulence in host soybean. The mutant displayed markedly increased siderophore secretory volume, and its sensitivity to Fe³⁺, Cu²⁺, Zn²⁺ and Mn²⁺ was significantly enhanced. Additionally, the H₂O₂ resistance, exopolysaccharide yield, biofilm formation, and cell mobility of ΔpiuB were significantly diminished compared to that of the wild-type. The addition of exogenous Fe³⁺ cannot effectively restore the above characteristics of ΔpiuB. However, expressing piuB in trans rescued the properties lost by ΔpiuB to the levels in the wild-type. Taken together, our results demonstrated that PiuB is a potential factor for Xag to assimilate Fe³⁺, and is necessary for Xag to be pathogenic in host soybean.
Iron ; Glycine max ; Virulence ; Xanthomonas axonopodis/genetics* ; Hydrogen Peroxide

Lysobacter harbors a plethora of cryptic biosynthetic gene clusters (BGCs), albeit only a limited number have been analyzed to date. In this study, we described the activation of a cryptic polyketide synthase (PKS)/nonribosomal peptide synthetase (NRPS) gene cluster (lsh) in Lysobacter sp. DSM 3655 through promoter engineering and heterologous expression in Streptomyces sp. S001. As a result of this methodology, we were able to isolate two novel linear lipopeptides, lysohexaenetides A (1) and B (2), from the recombinant strain S001-lsh. Furthermore, we proposed the biosynthetic pathway for lysohexaenetides and identified LshA as another example of entirely iterative bacterial PKSs. This study highlights the potential of heterologous expression systems in uncovering cryptic biosynthetic pathways in Lysobacter genomes, particularly in the absence of genetic manipulation tools.
Lysobacter/metabolism* ; Streptomyces/metabolism* ; Lipopeptides/metabolism* ; Polyketide Synthases/genetics* ; Multigene Family

Stenotrophomonas species are non-fermentative Gram-negative bacteria that are widely distributed in environment and are highly resistant to numerous antibiotics. Thus, Stenotrophomonas serves as a reservoir of genes encoding antimicrobial resistance (AMR). The detection rate of Stenotrophomonas is rapidly increasing alongside their strengthening intrinsic ability to tolerate a variety of clinical antibiotics. This review illustrated the current genomics advances of antibiotic resistant Stenotrophomonas, highlighting the importance of precise identification and sequence editing. In addition, AMR diversity and transferability have been assessed by the developed bioinformatics tools. However, the working models of AMR in Stenotrophomonas are cryptic and urgently required to be determined. Comparative genomics is envisioned to facilitate the prevention and control of AMR, as well as to gain insights into bacterial adaptability and drug development.
Stenotrophomonas/genetics* ; Drug Resistance, Bacterial/genetics* ; Anti-Bacterial Agents/pharmacology* ; Gram-Negative Bacteria ; Genomics ; Microbial Sensitivity Tests

In this study, a new Bacillus velezensis strain Bv-303 was identified and its biocontrol effect against rice bacterial-blight (BB) disease caused by Xanthomonas oryzae pv. oryzae (Xoo) was investigated. Cell-free supernatant (CFS) of strain Bv-303 under different growth conditions were prepared to test the antagonistic activity and stability against Xoo by the Oxford-cup method in vitro. The antibacterial effect of strain Bv-303 to BB disease in rice were further analyzed in vivo by spraying the cell-culture broth (CCB), CFS and cell-suspension water (CSW), respectively, on the rice leaves inoculated with Xoo. Additionally, rice seeds germination rate and seedling growth under the strain Bv-303 CCB treatment were tested. The results showed that the strain Bv-303 CFS significantly inhibited Xoo growth by 85.7%‒88.0% in vitro, which was also stable under extreme environment conditions such as heat, acid, alkali and ultraviolet light. As tested in vivo, spraying the CCB, CFS or CSW of strain Bv-303 on the Xoo-infected leaves enhanced rice plant resistance to BB disease, with CCB showing the highest increase (62.7%) in disease-resistance. Notably, CCB does not have negative effects on rice seed germination and seedling growth. Therefore, strain Bv-303 has great potential for biocontrol of the rice BB disease.
Oryza ; Fatigue Syndrome, Chronic ; Bacillus ; Xanthomonas ; Plant Diseases/microbiology*

Aims: This study was aimed to evaluate the potential of several carriers to formulate the phages and retain their activity under various pH and temperature conditions. Methodology and results: The skim milk, rice flour, corn flour and CalnuXan (calcium and magnesium) as carriers to formulate the isolated phage to maintain its activity under extreme pH and temperature conditions. Two phages formulated with carriers retained their viability at pH 5, pH 7 and pH 9 compared to that of the unformulated phages. Besides, the formulated phages also retained a high titre compared to the unformulated phages when they were exposed to 37 °C and 45 °C. Based on the in vitro study of the formulation, it was applied in the glass house. The plant height, leaf chlorophyll and disease scoring were recorded and analyzed. In the glass house, the rice plant treated with formulated phages showed higher plant height and chlorophyll content than those treated with unformulated or untreated phages. Nonetheless, both formulated and unformulated protected the rice plant, which showed lower disease severity than the untreated group. Conclusion, significance and impact of study Phage therapy has been used for treating plant diseases caused by pathogenic bacteria. Despite their effectiveness in killing the pathogen in vitro, the results were not reproducible in the field. Bacteriophages (phages) are sensitive to environmental factors and infection efficiency was dropped when exposed to harmful environments. However, this study successfully formulated two novels Xanthomonas phages, as biocontrol agents against bacterial leaf blight (BLB) disease in rice.
Xanthomonas ; Bacteriophages

Xanthomonas albilineans (Ashby) Downson is a quarantine pest for importing plants to China that causes leaf scald bacterial disease on sugarcane. X. albilineans produces a potent phytotoxin/antibiotic called albicidin. As a pathogenic factor, albicidin causes typical white leaf stripes by inhibiting plastid DNA gyrase and disturbing chloroplast differentiation. Meanwhile, the antibacterial activity of albicidin gives X. albilineans a competitive advantage against rival bacteria during their colonization. Furthermore, albicidin has a rapid bactericidal activity against a variety of Gram-positive and Gram-negative pathogenic bacteria of human species at nanomolar concentrations, making it a potential antimicrobial drug for clinical application. This article reviews the advances of albicidin from the aspects of its molecular structure, traditional extraction methods, mechanism of action, biosynthetic genes and processes, chemical synthesis method and improvement, in order to provide insights into the prevention and treatment of the sugarcane leaf scald disease, and the development of new antibiotics.
Anti-Bacterial Agents/pharmacology* ; China ; Humans ; Organic Chemicals ; Xanthomonas/genetics*

MarR family transcription regulators are ubiquitous among bacteria and archaea. They extensively control multiple cellular processes and elaborately regulate the expression of genes involved in virulence, stress response and antibiotics at translational level. In Xanthomonas campestris pv. campestris, insertional inactivation of MarR family transcription regulator HpaR (XC2827) resulted in significantly decrease in virulence and increase in the production of the extracellular proteases. Here, we reported that the genome of Xcc 8004 encodes nine MarR family transcription regulators. The MarR family transcription regulators, HpaR (XC2827) and XC0449, were heterologous expressed and purified. In vitro MST and Pull-down assay confirmed the physical interaction between HpaR and XC0449. Phenotypical assay determined that deletion of XC0449 resulted in substantial virulence attenuation. In vitro EMSA, in vivo qRT-PCR and GUS activity assay identified that HpaR and XC0449 coordinately act as the transcriptional activator to regulate the expression of the virulence-associated gene XC0705, and eventually control the bacterial virulence and the production of extracellular proteases.
Bacterial Proteins ; Gene Expression Regulation, Bacterial ; Transcription Factors ; Virulence ; Xanthomonas campestris

PURPOSE: To describe the clinical manifestations, treatment results, and antibiotic susceptibility in 6 cases of Stenotrophomonas maltophilia endophthalmitis. METHODS: We retrospectively reviewed 6 eyes of 6 patients who were diagnosed with Stenotrophomonas maltophilia endophthalmitis. Specifically, we considered each patient's age, sex, past history, visual acuity, hypopyon, treatment, and prognosis. RESULTS: For our study, we considered patients treated during the period of January 2008 to December 2015. Stenotrophomonas maltophilia (6 eyes) was the second most common gram-negative bacteria cause of total bacterial endophthalmitis while Pseudomonas aeruginosa (14 eyes) was the most common gram-negative bacteria cause during the same period. Visual disturbance was the dominant symptom being found in all 6 patients. Other symptoms include ocular pain and hypopyon. The initial visual acuity was light perception (1 patient), hand motion (3 patients), finger count (1 patient), and 0.02 (1 patient). Excluding the 1 patient with light perception, the mean initial visual acuity was logMAR 1.72 (Snellen equivalent; 20/1,049). Overall, 5 patients underwent vitrectomy and intravitreal antibiotics injection, while, the remaining other patient was treated with intravitreal antibiotics injection, followed by vitrectomy. All 6 patients showed sensitivity to Ceftazidime and Levofloxacin and 2 patients showed sensitivity to Trimethoprim/Sulfamethoxazole. CONCLUSIONS: Stenotrophomonas maltophilia endophthalmitis was the second most common gram negative organism to cause endophthalmitis after cataract surgery. All 6 of the tested isolates were found to be sensitive to ceftazidime and levofloxacin. Urgent treatment outcomes were similar to previous reports.
Anti-Bacterial Agents ; Cataract* ; Ceftazidime ; Endophthalmitis* ; Fingers ; Gram-Negative Bacteria ; Hand ; Humans ; Levofloxacin ; Prognosis ; Pseudomonas aeruginosa ; Retrospective Studies ; Stenotrophomonas maltophilia* ; Stenotrophomonas* ; Visual Acuity ; Vitrectomy

BACKGROUND: Prolonged transport or poor accessibility of blood culture equipment during night time may cause delayed entry of blood culture bottles. The effect of prestorage conditions on time to detection (TTD) for the blood culture was evaluated for the important gram-negative lactose nonfermentative bacteria. METHODS: Three different clinical isolates of Pseudomonas aeruginosa, Acinetobacter baumannii, Stenotrophomonas maltophilia, and Burkholdera cepacia were diluted to 150 CFU/mL and 15 CFU/mL and inoculated into standard aerobic bottles. These were stored at 25℃ and at 37℃ for 0, 6, 12, 18, and 24 h. They were entered to BacT/Alert 3D Systems (bio-Mérieux Inc.) and TTD was monitored for each condition. RESULTS: At the 150 CFU/mL concentration, P. aeruginosa and A. baumannii showed false-negative for the bottles prestored at 37℃ for 18 h and 24 h, respectively. However, there was no false-negative for S. maltophilia or B. cepacia at any prestorage conditions. There was a significant decrease of TTD for all experimental microorganisms except P. aeruginosa prestored for 24 h either at 25℃ or at 37℃ (P< 0.05). CONCLUSION: Delayed entry may cause false-negative, especially for the high level of bacteremia of P. aeruginosa or A. baumannii when the bottles are stored at 37℃ for ≥18 h. TTD could be reduced by prestorage of the bottles at 37℃ until 12 h without false-negative for nonfermentative bacteria.
Acinetobacter baumannii ; Bacteremia ; Bacteria ; Lactose* ; Pseudomonas ; Pseudomonas aeruginosa ; Sepsis ; Stenotrophomonas maltophilia

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disease, and bacterial infection plays a role in its pathogenesis. Bacteria secrete nanometer-sized extracellular vesicles (EVs), which may induce more immune dysfunction and inflammation than the bacteria themselves. We hypothesized that the microbiome of lung EVs might have distinct characteristics depending on the presence of COPD and smoking status. We analyzed and compared the microbiomes of 13 nonsmokers with normal spirometry, 13 smokers with normal spirometry (healthy smokers) and 13 patients with COPD by using 16S ribosomal RNA gene sequencing of surgical lung tissue and lung EVs. Subjects were matched for age and sex in all groups and for smoking levels in the COPD and healthy smoker groups. Each group included 12 men and 1 woman with the same mean age of 65.5 years. In all groups, EVs consistently showed more operational taxonomic units (OTUs) than lung tissue. In the healthy smoker and COPD groups, EVs had a higher Shannon index and a lower Simpson index than lung tissue and this trend was more prominent in the COPD group. Principal component analysis (PCA) showed clusters based on sample type rather than participants' clinical characteristics. Stenotrophomonas, Propionibacterium and Alicyclobacillus were the most commonly found genera. Firmicutes were highly present in the EVs of the COPD group compared with other samples or groups. Our analysis of the lung microbiome revealed that the bacterial communities present in the EVs and in the COPD group possessed distinct characteristics with differences in the OTUs, diversity indexes and PCA clustering.
Alicyclobacillus ; Bacteria ; Bacterial Infections ; Extracellular Vesicles* ; Female ; Firmicutes ; Humans ; Inflammation ; Lung* ; Male ; Microbiota* ; Passive Cutaneous Anaphylaxis ; Principal Component Analysis ; Propionibacterium ; Pulmonary Disease, Chronic Obstructive* ; RNA, Ribosomal, 16S ; Smoke ; Smoking ; Spirometry ; Stenotrophomonas