Endophytic Bacillus velezensis strain B-36 is a potential biocontrol agent against lotus rot caused by Fusarium oxysporum.

AIM: The aim of this study was to screen potential lotus plant endophytic bacterial isolate for effective inhibition against lotus rot causing fungal pathogen Fusarium oxysporum. METHODS AND RESULTS: In this study, endophytic bacteria were isolated from lotus tissues and tested for antagonistic activities against the pathogenic fungus F. oxysporum. Among the putative endophytic Bacillus strains identified, suspensions of the strain B-36 showed the highest inhibition rate against F. oxysporum growth. Pot assays indicated that B-36 was effective in controlling F. oxysporum-inducing lotus rot. However, the control efficiency varied with the inoculation method and concentration, where injection of 800 µl B-36 suspension per plant (2 × 108  CFU per ml) into stems showed the highest control efficiencies of 77·1 and 60·0% for pre-inoculation and post-inoculation. In addition, the colonizing population levels (CPLs) of B-36 on lotus also varied with the inoculation method and concentration, with the highest CPLs, that is, 3·05 and 2·83 log(CFU per gram), being observed on lotus leaves and stems respectively for stem injection of 200 µl per plant. Moreover B-36 showed no noticeable effects on lotus seed germination rate or seedling growth. Finally, B-36 was characterized as Bacillus velezensis based on its morphology, Gram-positive characteristics, as well as its 16S rDNA and gyrB sequences. CONCLUSION: The isolate B-36 can be applied as a biocontrol agent against F. oxysporum-inducing lotus rot. SIGNIFICANCE OF IMPACT OF THE STUDY: The soil-borne fungus F. oxysporum causes lotus rot and severe yield loss, and currently available control methods are very limited. Here we identify a new promising biocontrol agent against lotus rot caused by F. oxysporum.

[Microbiome analysis of diabetic foot osteomyelitis by metagenome sequencing technology].

Objective: To analyze the microbiome of diabetic foot osteomyelitis (DFO) by means of metagenome sequencing and provide evidence for identification of pathogenic bacteria in DFO. Methods: A total of 5 patients (3 males and 2 females) with DFO hospitalized at the Department of Endocrinology and Metabolism, Nanfang Hospital, Southern Medical University were enrolled and infected bone specimens were obtained between September 2016 and April 2017. The mean age was (55.8±9.5) years. Metagenome sequencing was performed to explore the characteristics of microbiome, and compared with the results of 16S rRNA sequencing. Results: The results of metagenome sequencing showed that DFO contained diverse microorganism. Totally, 22 dominant species were obtained, Klebsiella pneumoniae (69.66%) was the most abundant, followed by Veillonella parvula (36.93%) and Prevotella intermedia (34.19%). Compared with the 16S rRNA sequencing, metagenome sequencing could obtain more species information on the basis of fewer samples. At the genus level, both sequencing techniques suggested the most dominant pathogen in DFO was anaerobe. All bone specimens had polymicrobial communities. Conclusions: More microecological diversity and abundance of DFO can be found by using metagenome sequencing. At the species level, more bacteria, even bacterial strains can be identified by metagenome sequencing. At the genus level, the most abundant bacteria is anaerobe, however, at the species level, it is facultative anaerobe.

Polymorphism R62W results in resistance of CD23 to enzymatic cleavage in cultured cells.

A nonsynonymous single nucleotide polymorphism (SNP) of the low-affinity IgE receptor (FcvarepsilonRII/CD23) gene resulting in an arginine to tryptophan exchange at amino-acid position 62 (R62W) has been associated with enhanced T-cell responses to antigen in allergic subjects. To explore the mechanism, a CD23(a) cDNA was cloned into the plasmid pCMVScript-CD23a-C with a C allele (R62). The pCMVScript-CD23a-T with T (W62) was produced using a site-directed mutagenesis approach. The pCMVScript-CD23a-C only (CC), mixture of pCMVScript-CD23a-T and pCMVSCript-CD23a-C (CT) and pCMVScript-CD23a-T only (TT) plasmids were transfected in Cos-7 cells at equivalence in transfection efficiency. No soluble CD23 was released from TT transfectants whereas a higher level of soluble CD23 was detected in CC than in CT transfectants. Human leukocyte elastase (HLE), cathepsin G, the dust mite allergen Der p I and ADAM 33 (A disintegrin and metalloproteinase) were found to cleave membrane CD23 in CC but not in TT transfectants, implying the resistance of CD23 to enzymatic cleavage associated with T mutant. Addition of tunicamycin resulted in the resistance of CD23 to Der p I mediated cleavage in CC but no change in TT transfectants. These results indicate that R62W influences the stability of membrane CD23 molecules due to possibly diminished N-glycosylation.

Indirect validation of benzene exposure assessment by association with benzene poisoning.

We present a validation study of a quantitative retrospective exposure assessment method used in a follow-up study of workers exposed to benzene. Assessment of exposure to benzene was carried out in 672 factories in 12 cities in China. Historical exposure data were collected for 3179 unique job titles. The basic unit for exposure assessment was a factory/work unit/job title combination over seven periods between 1949 and 1987. A total of 18,435 exposure estimates was developed, using all available historical information, including 8477 monitoring data. Overall, 38% of the estimates were based on benzene monitoring data. The highest time-weighted average exposures were observed for the rubber industry (30.7 ppm) and for rubber glue applicators (52.6 ppm). Because of its recognized link with benzene exposure, the association between a clinical diagnosis of benzene poisoning and benzene exposure was evaluated to validate the assessment method that we used in the cohort study. Our confidence in the assessment method is supported by the observation of a strong positive trend between benzene poisoning and various measures, especially recent intensity of exposure to benzene.

Mortality among benzene-exposed workers in China.

A large cohort of 74,828 benzene-exposed and 35,805 nonexposed workers employed between 1972 and 1987 in 12 cities in China was followed to determine mortality from all causes. Benzene-exposed study subjects were employed in a variety of occupations including coating applications, and rubber, chemical, and shoe production. Mortality was slightly increased among workers with greater cumulative exposure to benzene (ptrend < 0.05), but this excess was largely due to cancer deaths (ptrend < 0.01). Deaths due to lymphatic and hematopoietic malignancies (ptrend = 0.01) and lung cancer (ptrend = 0.01) increased with increasing cumulative exposure to benzene. Investigations continue to relate benzene exposure to specific lymphatic and hematopoietic malignancies and other causes of death.

A cohort study of cancer among benzene-exposed workers in China: overall results.

A large cohort study of 74,828 benzene-exposed and 35,805 unexposed workers employed between 1972 and 1987 in 12 cities in China were followed to determine mortality from all causes and the incidence of lymphohematopoietic malignancies and other hematologic disorders. Benzene-exposed study subjects were employed in a variety of occupations, including painting, printing, and the manufacture of footwear, paint, and other chemicals. All-cause mortality was similar in the benzene-exposed and unexposed comparison group. Statistically significant excess deaths were noted among benzene-exposed subjects for leukemia (RR = 2.3, 95% CP 1.1-5.0), malignant lymphoma (RR = 4.5, 95% CI: 1.3-28.4), and nonneoplastic diseases of the blood (RR = 95% CP 2.5-infinity), and a marginally significant excess was noted for lung cancer (RR = 1.4, 95% CI: 1.0-2.0). Risk was significantly elevated for the incidence of all lymphohematopoietic malignancies (RR = 2.6, 95% CI: 1.5-5.0), malignant lymphoma (RR = 3.5, 95% CI: 1.2-14.9), and leukemia (RR = 2.6, 95% CI.. 1.3-5.7). Among the leukemia subtypes, only acute myelogenous leukemia (AML) incidence was significantly elevated (RR = 3.1, 95% CI: 1.2-10.7), although nonsignificant excesses were also noted for chronic myelogenous leukemia (CML) (RR = 2.6, 95% CI: 0.7-16.9) and lymphocytic leukemias (RR = 2.8, 95% CI.. 0.5-54.5). Significant excesses were found for aplastic anemia (RR = infinity, 95% CI: 2.2-co) and myelodysplastic syndrome (RR = infinity, 95% CI: 1.7-infinity). Employment in benzene-associated occupations in China is associated with a wide spectrum of myelogenous and lymphocytic malignant diseases and related disorders. Investigations continue to assess the nature of these associations.