Objective In this study,we investigated the pathogenicity and genome-wide characteristics of a strain of Macrococcus caseo-lyticus(M.caseolyticus),and explored the virulence and drug resistance-related genes of this strain.Methods A strain of bovine-de-rived M.caseolyticus was isolated and identified from the dead bovine lungs collected at a cattle farm in Shihezi City,Xinjiang.Subse-quently,drug sensitivity tests,animal tests,and pathological and histological observations were conducted.The draft genome sequen-cing of this strain was then performed using second-generation sequencing technology of illumina.Further,species affinities were fur-ther evaluated based on the sequencing results.The composition of the target genome,including coding genes,repetitive sequences,and non-coding RNAs,was determined,and basic functional features of the genome were annotated in databases such as GO,KEGG,COG,NR,and CAZy.Furthermore,a combination of annotations from the NR database and the PHI and CARD databases was utilized to identify genome virulence factors,drug resistance,and other related genes.Results Pathological section results revealed various ab-normalities in the rabbit,including a decrease in the alveoli count,exudation of inflammatory cells,enlargement and filling of alveolar sacs with exudate,thinning of vascular walls,decreased permeability,exudation of red blood cells,and collapse of the fine bronchial tube walls.The pathogen was identified as M.caseolyticus through mean nucleotide similarity classification and phylogenetic tree analy-sis.Its draft genome size is 2 209 314 base pairs,with a CG％content of 37.22％and an average gene length of 855 base pairs.The genome encodes 2 304 genes,including 58 tRNAs,8 rRNAs,and 1 sRNA,as well as 3 sequences of CRISPRs.Additionally,1 028 genes were annotated in the GO database,covering three major categories:molecular functions,cellular components,and biological processes.Furthermore,1 420 coding genes were annotated in the KEGG database,and 1 961 genes were annotated with 23 functions in the COG database,including 96 genes with unknown functions.The whole genome sequencing results identified 51 virulence factors and multiple resistance genes to antibiotics,such as aminoglycosides,β-lactams,and peptides.However,in the drug susceptibility test,the strains were found to be resistant only to sulfonamides(cotrimoxazole),lincomycins(lincomycin),and penicillins(ampicil-lin)out of the 12 classes of antibiotics tested.Conclusion In this study,a strain of M.caseolyticus was isolated from the lungs of dead bovine and named SHZXbov7,which has strong pathogenicity and contains a variety of virulence factors and drug resistance genes;and the genome sequencing and annotation of strain SHZXbov7 will enrich the gene database of M.caseolyticus and provide a reference for the prevention and control of M.caseolyticus-related diseases.
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