A novel bacteriocin BM1029: physicochemical characterization, antibacterial modes and application.

AIM: Bacteriocins with antimicrobial activity are considered as potential natural bio-preservatives to control the growth of food spoilage bacteria. The aim of this work was to characterize a novel bacteriocin BM1029 discovered from Lactobacillus crustorum MN047 and evaluate its antibacterial mechanism. METHODS AND RESULTS: Bacteriocin BM1029 was purified by cation-exchange chromatography and reversed-phase chromatography. Antibacterial activity assay showed that BM1029 is antagonistic against both Gram-positive and Gram-negative bacteria. Furthermore, it was found that BM1029 showed low haemolysis with high stability to the pretreatment with different temperatures, pH and surfactants. Moreover electron microscopy and flow cytometry suggested that BM1029 inhibit indicator strains by damaging the cell envelope integrity. Cell cycle assay suggested that BM1029 arrested cell cycle in R-phase. CONCLUSION: The novel bacteriocin BM1029 showed high bactericidal activity against Escherichia coli and Staphylococcus aureus through a cell envelope-associated mechanism. SIGNIFICANCE AND IMPACT OF THE STUDY: Application of BM1029 inhibited the growth of indicator strains on beef meat storage at 4°C suggesting that this bacteriocin is promising to be used as a novel preservative in food processing and preservation.

[Meta-analysis of efficacy and safety of vitamin D supplementation in the treatment of pulmonary tuberculosis].

Objective: To systematically evaluate the efficacy and safety of vitamin D supplementation in the treatment of pulmonary tuberculosis. Methods: Biomedical Database was searched to collect randomized controlled trials (RCT) related to vitamin D supplementation in tuberculosis patients, and the retrieval time was from establishment to November 2019. Two evaluators independently screened the literature and extracted the data. The negative conversion rate of acid-fast-bacilli of sputum smear, the negative conversion rate of mycobacterium tuberculosis culture and the change of serum vitamin D level were the main outcome indicators, and the body mass index was the secondary outcome indicator. The incidence of hypercalcemia and abnormal urinary calcium were used as adverse event indicators and the RevMan 5.2 software was used for meta-analysis. Results: A total of 8 RCT(S) met the inclusion criteria, including 850 patients with tuberculosis. Meta-analysis showed that compared with the control group, negative conversion rate of acid-fast-bacilli of sputum smear and serum vitamin D level increased after 8 weeks of vitamin D supplementation [RR (95%CI) and mean deviation (MD) (95%CI) were 1.06 (1.00, 1.13) and 8.81 (1.81, 15.81), respectively; negative conversion rate of acid-fast-bacilli of sputum smear was not increased at week 4 and 12 [RR (95%CI) were 1.08 (0.97, 1.20) and 1.01 (0.91, 1.12), respectively]; negative conversion rate of mycobacterium tuberculosis culture in sputum was not increased after 4 and 8 weeks [RR (95%CI) were 1.06 (0.91, 1.22) and 1.02 (0.96, 1.08), respectively]; there was no change in body mass index [MD (95%CI):-0.02 (-0.53, 0.50)]; there was increased risk of abnormal urinary calcium [RR (95%CI): 2.45 (1.75, 3.41)], while no increase in risk of hypercalcemia [RR (95%CI): 1.99 (0.96, 4.13)]. Conclusion: Vitamin D supplementation is safe but not effective in the treatment of pulmonary tuberculosis.

Study on cytomegaloviral infection in acute leukemia patients by polymerase chain reaction.

Polymerase chain reaction (PCR) and blot hybridization by probe labelled with digoxin were used to detect human cytomegalovirus (HCMV) DNA in 31 patients with acute leukemia and 20 controls. The positive rate detected by PCR in acute leukemia was 74.2% and 15.0% in the controls. The difference was statistically significant. The results suggest that acute leukemia patients are the high risk population with high infection rate of HCMV. The positive rate detected by digoxin method in acute leukemia was 58.1%. Six patients showed negative results by digoxin method, but positive by PCR. It was demonstrated that PCR was superior to digoxin method in sensitivity. Anti-HCMV IgM in serum of patients was detected at the same time, the positive rate was 16.1%. Only 6 of the 23 PCR positive patients showed positive anti-HCMV IgM. It suggests that the immune response is weak in acute leukemia patients and HCMV recently infected could not be excluded in the anti-HCMV IgM negative cases.

Detection of HCV infection by cPCR in patients with acute leukemia.

HCV RNA and anti-HCV were detected respectively by complemented DNA polymerases chain reaction (cPCR) and ELISA in the sera of 28 acute leukemia patients with repeated blood transfusion and changes in liver function. HCV RNA positive rate was 78.6%. Anti-HCV positive rate was 60.7%. 25 subjects showed positive results in HCV RNA or anti-HCV, or in both of them. By combined assessment, the HCV infection rate was 89.3%. Acute leukemia patients were the high risk group of HCV infection because of the lowered immune function and repeated blood transfusion. By cPCR, HCV RNA can be detected earlier and the sensitivity is higher than by anti-HCV. So cPCR is a sensitive and specific method for early diagnosis of HCV infection. The combination of HCV RNA and anti-HCV detection methods may improve the diagnostic rate of HCV infection.