Isolation, identification and prokaryotic expression of a bacteriocin-like substance from Bacillus licheniformis / 生物工程学报

The ban on addition of antibiotics in animal feed in China has made the search for new antibiotics substitutes, e.g. bacteriocin, a hot topic in research. The present study successfully isolated an antibacterial substance producing strain of Bacillus sp. from alpaca feces by agar diffusion method, using Escherichia coli, Salmonella enterica, Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus luteus and Listeria monocytogenes as indicator bacteria. The isolated strain was named as B. licheniformis SXAU06 based on colony morphology, Gram staining and 16S rRNA gene sequence. The antibacterial substance was isolated and purified through a series of procedures including (NH4)2SO4 precipitation, chloroform extraction, molecular interception and SDS-PAGE analysis. Bioinformatics analysis of the LC-MS/MS data indicated that the antibacterial substance was a bacteriocin-like substance (BLIS) with an approximate molecular weight of 14 kDa, and it was designated as BLIS_SXAU06. BLIS_SXAU06 exhibited high resistance to treatment of proteinase K, high temperature, high acidity and alkalinity. BLIS_SXAU06 was heterologously expressed in E. coli and the recombinant BLIS_SXAU06 exhibited effective antibacterial activity against S. aureus, S. epidermidis, M. luteus, and L. monocytogenes, showing potential to be investigated further.

Clinical features of 9 cases of Brucella endocarditis / 中华心血管病杂志

Objective@#To explore the clinical characteristics of patients with Brucella endocarditis.@*Methods@#The clinical data of 9 patients with Brucella endocarditis admitted to Beijing Ditan Hospital from October 2008 to August 2018 were retrospectively analyzed. Through the electronic medical record system of the hospital. Through assessing the electronic medical record system of the hospital, demographic data, main symptoms, vital signs, blood culture, Rose Bengal Plate Agglutination Test, echocardiography, electrocardiogram, chest imaging and other clinical data of included patients were inquired and recorded. Patients were followed up by telephone for medication, operation and outcome.@*Results@#The 9 patients were all Han nationality, aged from 25 to 66 years, 7 out of 9 patients were male, and they came from Hebei, Shandong, Shanxi, Inner Mongolia and Beijing. Of the 9 patients, 5 were farmers, 2 were self-employed, 1 was a technician, and 1 was unemployed. Of the 9 cases, 8 had a history of close contact with cattle and sheep, and 5 had a history of eating beef and mutton. Rose-Bengal Plate Agglutination Test and blood culture were positive in all 9 patients. Aortic valve was involved in 7 out of 9 patients, mitral and tricuspid valve was involved in 1 patient, respectively, and aortic dissection occurred in 1 patient. Condition of 1 patient rapidly deteriorated after admission and finally died during hospitalization despite antibiotic therapy, the remaining patients received long-term antibiotic treatment. A total of 7 patients who underwent valve replacement were followed up. One patient died of cerebral hemorrhage 6 months after operation, and the remaining 6 patients recovered well after valve replacement. Heart failure occurred in all 9 patients, and pericardial effusion occurred in 8 patients. Electrocardiogram showed low voltage of the QRS complex in the limb in 3 cases and poor R-wave progression in V1-V3 lead in 2 cases, and sinus tachycardia in 2 cases. One patient developed non-specific ST-T abnormalities. All patients had fever, 7 patients complained of weakness, and 6 patients complained of palpitations. Among the 9 patients, 7 cases had anemia, 7 patients had pneumonia, 6 had bilateral pleural effusion, 4 had thrombocytopenia. Creatinine was above normal in 4 patients, urine protein was positive in 3 patients, Delta Bilirubin was higher in 3 cases.@*Conclusions@#Patients with Brucella endocarditis often suffer from heart failure and have severe complications. Adequate antibiotic therapy in combination with valve replacement is effective for the treatment of patients with Brucella endocarditis.