Research On Gene Features Of Port Pathogenic Microorganisms Based On Metagenomics Technology

Pathogenic microorganisms at ports mostly refer to pathogenic microorganisms in bulk cargoes,ballast water,animal-derived samples,soil,personnel and so on.In recent years,the outbreak of infectious diseases has become more and more frequent,and the increasing trade between countries has provided a way for the spread of infectious diseases,which poses a great threat to life,health and property safety.Port quarantine as the first checkpoint is particularly important to prevent and control of pathogenic microorganisms.However,at present,there are the following problems in port quarantine.On the one hand,there is a lack of database related to pathogenic microorganisms at the port,and the integration rate of a large number of important monitoring data is low,which leads to a waste of data resources.On the other hand,there are relatively few comprehensive studies on pathogenic microorganisms in soil and marine samples all over the world.As a result,it is difficult to carry out targeted quarantine on goods from different sources.Therefore,we adopted metagenomic technology to study the genetic characteristics of pathogenic microorganisms at ports,in order to establish a database of port microbial genetic characteristics,and summarize the characteristics of pathogenic microorganisms in environmental samples from different regions of the world.It will strengthen the pertinence of port quarantine and improve the efficiency of port work.In this study,729 pathogenic species were sorted out by referring to multiple quarantine directories and relevant quarantine standards.The relevant genomes and annotation files was retrieved and downloaded from the public database.Finally,the port quarantine microbiome database including the genomes of 95 pathogenic bacteria,21 pathogenic fungi and 65 pathogenic viruses was constructed for providing data support of port health and quarantine work.The database has a complete process of metagenomic analysis and 16 S r DNA amplicon analysis of uploaded data,which will help to test and analyse the pathogenic microorganisms in port samples.In order to summarize the characteristics of pathogenic microorganisms in different regions,this study analyzed the metagenomic data of 28 soil samples and 15 marine samples in the world under the principle of ensuring the quality of sequencing data.The alpha diversity analysis showed that the microbial diversity of marine samples was higher than of soil samples.The structure of pathogenic microorganisms from discrete sampling points was studied respectively.Among all the bacterial pathogens,Bacillus cereus is the dominant pathogens of seven continents.However,the relative abundance of Bacillus cereus in Antarctica is much higher than the other continents,showing the adaptability of Bacillus cereus to extreme environments.Fungi are mostly concentrated in Fusarium.Preliminary analysis show that the strong variability of the virus makes the types of pathogenic viruses unique to each continent significantly more than pathogenic bacteria and fungi.The uniqueness of the composition of pathogenic microorganisms in Antarctica show that the pathogenic bacteria in Antarctica need to be further studied.When studying the samples in different temperature zones of soil,we found that the number of differential pathogenic bacteria in the cold zone are significantly more than those in the temperate zone and tropical zone.It indicated that there are more species adapted to the extreme environment in the pathogenic bacteria.Compared with soil samples,the abundance of pathogenic bacteria in marine samples is more uniform,and the flora structure of marine pathogenic bacteria is more similar.The pathogenic fungi in seawater samples are mainly concentrated in Candida,and the pathogenic virus African swine fever virus has an absolute advantage.The similarity of microbial community structure of marine samples also increases the difficulty of targeted detection of pathogenic microorganisms of goods from different sources at the port.The functional metabolic genes related to the basic biological characteristics in the COG functional gene annotation are the most abundant.The KEGG functional gene annotation shows that the abundance of functional genes related to the biofilm synthesis of pathogenic bacteria is the highest.The annotation results of antibiotic resistance genes show that the abundance of mac B is the highest in all samples.In addition,the abundance of msb A is second higher only to mac B.msb A is closely related to the synthetic function of pathogenic bacteria biofilm.Antibiotic efflux pump is the main drug resistance mechanism of pathogenic bacteria,which interact with the synthesis of biofilm.Therefore,interfering with the formation function of pathogenic biofilm may be an important pathway to inhibit pathogenic bacteria.High abundance and common virulence factors detected in soil and marine samples are acp XL and htp B respectively.Among them,htp B is widely infectious for aquatic products.The quarantine of marine products and ship ballast water at ports should pay special attention to htp B.All in all,the microbial flora structure of samples from different sources shows obvious differences,which will contribute to the targeted detection of pathogenic microorganisms at the port and improve the work efficiency of the port.However,the functional genes,antibiotic resistance genes,resistance mechanisms and virulence factors show similarities,which provides a direction for the prevention and control of pathogenic microorganisms at the port.For example,inhibiting the function of biofilm synthesis can eliminate pathogenic bacteria from all sources of cargo and ship ballast water through the same measures.At present,there is little research on port pathogenic microorganisms.The microbiome database of port quarantine constructed in this study will provide application support for port quarantine work,and the analysis of metagenomic data of global samples will provide preliminary theoretical support for port quarantine work.By this way,they can jointly promote the development of port pathogenic microorganism research.