Endophytes play an important role in protection of host plants from infection by phytopathogens. Endophytic bacteria were isolated from five different parts (root, stem, petiole, leaf and seed) of Panax notoginseng and evaluated for antagonistic activity against Fusarium oxysporum, Ralstonia sp. and Meloidogyne hapla, three major pathogens associated with root-rot disease complex of P. notoginseng. From 1000 endophytic bacterial strains evaluated in vitro, 104 strains exhibited antagonistic properties against at least one of these three pathogens. Phylogenetic analyses of their 16S rRNA gene sequences showed that these 104 antagonistic bacteria belong to four clusters: Firmicutes, Proteobacteria, Actinobacteria and Bacteroidetes/Chlorobi. Members of the Firmicutes, in particular the Bacillus spp., were predominant in all analyzed tissues. The root was the main reservoir for antagonistic bacteria. Of the 104 antagonists, 51 strains showed antagonistic activities to one pathogen only, while 43 and 10 displayed the activities towards two and all three pathogens, respectively. The most dominant species in all tissues were Bacillus amyloliquefaciens subsp. plantarum and Bacillus methylotrophicus, which were represented by eight strains with broad antagonistic spectrum to the all three test pathogens of root-rot disease complex of P. notoginseng.

Objective To investigate the prognostic value of serum amyloid A (SAA) in the patients with Corona Virus Disease 2019 (COVID-19). Methods The medical data of 89 COVID-19 patients admitted to Renmin Hospital of Wuhan University from January 3, 2020 to February 26, 2020 were collected. Eighty-nine cases were divided into survival group (53 cases) and non-survival group (36 cases) according to the results of 28-day follow-up. The SAA levels of all patients were recorded and compared on 1 day after admission (before treatment) and 3 days, 5 days, and 7 days after treatment. The ROC curve was drawn to analyze the prognosis of patients with COVID-19 by SAA. Results The difference of comparison of SAA between survival group and non-survival group before treatment was not statistically significant, Z 1 = − 1.426, P = 0.154. The Z 1 values (Z 1 is the Z value of the rank sum test) of the two groups of patients at 3 days, 5 days, and 7 days after treatment were − 5.569, − 6.967, and − 7.542, respectively. The P values were all less than 0.001, and the difference was statistically significant. The ROC curve results showed that SAA has higher sensitivity to the prognostic value of 1 day (before treatment), 3 days, 5 days, and 7 days after treatment, with values of 0.806, 0.972, 0.861, and 0.961, respectively. Compared with SAA on the 7th day and C-reactive protein, leukocyte count, neutrophil count, lymphocyte count, and hemoglobin on the 7th day, the sensitivities were: 96.1%, 83.3%, 88.3%, 83.3%, 67.9%, and 83.0%, respectively, of which SAA has the highest sensitivity. Conclusion SAA can be used as a predictor of the prognosis in patients with COVID-19.

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