Extension and application of a database for the rapid identification of Vibrio using MALDI-TOF MS

Rapid and accurate identification of Vibrio species has been problematic because phenotypic characteristics are variable within species and biochemical identification requires two or more days to complete.Matrix-assisted laser desorption ionization–time of flight mass spectrometry(MALDI-TOF MS)has become a powerful tool for rapidly distinguishing between related bacterial species.However,its accuracy depends on the number of strains in a database.In the current study,we extend and apply the Vibrio database based on MALDI-TOF MS.A total of 74 strains of Vibrio representing 28 species were identified and included in new database.A phylogenetic tree based on rpoB sequence and dendrograms were constructed.We analyzed 30 clinical Vibrio of three species to evaluate the new database and carried out PCA dendrogram analyses for differences of strains.We created a new database that offered fast and accurate Vibrio identification.MSP and PCA dendrogram analyses provided technical support to track sources and incidences of Vibrio infection.In addition,the discovery of characteristic and differential peaks is useful for the future identification of Vibrio.This represents a powerful tool for the rapid and accurate classification and identification of Vibrio and closely related species.

Distribution of Initial Vegetation Recruitment on Bare Bar in Sand Bed River

Riparian vegetation is known to affect the flood flow and the riparian environment, and it is important for river engineers to know the vegetation dynamics in river. Despite a number of researches have been performed for vegetation dynamics, the mechanism of initial vegetation recruitment is still not clear. In this study, two field surveys by using Unmanned Aerial Vehicle (UAV) remote sensing, UAV aerial photographs analysis and a numerical simulation were conducted to detect the location of initial vegetation recruitment and explore its relationship with hydrology and river morphology. The initial vegetation recruitment was identified by comparing vegetation distributions before and after vegetation germination. Most of the initial vegetation recruitment locations were found either along dunes on sandbar or along the wet/dry rotational area of shore bank. Results of the aerial photographs analysis showed that the initial vegetation recruitment occurred at the downstream side of crest of dunes. As for the vegetation recruitment zone located along shore bank, the relative elevation of different recruitment zones is almost same, and the mean value of the relative elevation is around 0.33 m. With the comparison of the contour map of river morphology and the initial vegetation recruitment zone, the shape of initial vegetation recruitment zone is positively consistent with the shape of river morphology distribution. The results of numerical analysis show that the initial vegetation recruitment zone located along shore bank experienced intermediate flood pulse. The inundation frequencies during seed dispersal and germination period for the internal and external boundaries of vegetation recruitment zone are 23.87% and 6.2%, respectively.