ABSTRACT
In order to reveal the accumulation trend of polysaccharides in Dendrobium catenatum and determine the effect of sampling time on polysaccharides, D. Catenatum D21 clone was harvested from January to December after culturing for 2 to 5 months in the growth chamber with constant temperature. Polysaccharides were determined by phenol-sulfuric acid method and the monosaccharide compositions were analyzed by pre-column derivative-UPLC. The results showed that the content of polysaccharide and its key component mannose was positively correlated with the culture time, but the contents of polysaccharides in all kinds of culture peaked from 5 to 6 months, which were consistent with the trend of field planting. The results suggested that the trend of polysaccharide accumulation in the plant could be related to the life rhythm of the sensory seasons of D. catenatum, which was significantly affected by the harvesting season, even under the constant condition of the culture chamber.
Subject(s)
Dendrobium/chemistry , Polysaccharides/chemistry , Seasons , Phytochemicals/chemistry , TemperatureABSTRACT
BACKGROUND: Carbapenem-resistant Acinetobacter baumannii poses a significant threat to hospitalized patients, as few therapeutic options remain. Thus, we investigated the molecular epidemiology and mechanism of resistance of carbapenem-resistant A.baumannii isolates in Beijing, China. METHODS: Carbapenem-resistant A.baumannii isolates (n = 101) obtained between June 2009 and November 2014 were used. Multilocus sequence typing (MLST) and PCR assays for class C and D ß-lactamase were performed on all isolates. S1 nuclease pulsed-field gel electrophoresis (PFGE) and Southern blot hybridization were performed to identify the resistance gene location. RESULTS: All 101 A.baumannii isolates were highly resistant to frequently used antimicrobials, and were considered multidrug resistant. A total of 12 sequence types (STs) were identified, including 10 reported STs and 2 novel STs. Eighty-seven isolates were classified to clonal complex 92 (CC92), among which ST191 and ST195 were the most common STs. The bla OXA-23 gene was positive in most (n = 95) of the A.baumannii isolates. Using S1-nuclease digestion PFGE and Southern blot hybridization, 3 patterns of plasmids carrying bla OXA-23 were confirmed. ST191 and ST195 (both harboring bla OXA-23 ) caused outbreaks during the study period, and this is the first report of outbreaks caused by ST191 and ST195 in north China. CONCLUSION: bla OXA-23 -producing A.baumannii ST191 and ST 195 isolates can disseminate in a hospital and are potential nosocomial outbreak strains. Surveillance of imipenem-resistant A.baumannii and antimicrobial stewardship should be strengthened.