Safety Evaluation Of Thermoactinomyces Daqus CICC 10681

Thermoactinomyces is one of the dominant bacteria in high temperature Daqu liquor.The new species,Thermoactinomyces daqus,is thermophilic and has developed mycelium and high temperature protease activity,which will help to loosen the structure of Daqu,increase the oxygen flux,decompose the protein under high temperature environment and produce flavor substances.Its excellent functional characteristics make it have a good prospect in the production of sesame flavor and Maotai flavor liquor.At present,there are no reports about the safety of T.daqus strains,therefore,this subject conducted a safety study on the type strain T.daqus CICC 10681.Phenotypic study was carried out,including antimicrobial susceptibility test,rats virulence test,hemolysis test and antimicrobial production test.In terms of genotype analysis,relevant databases used to carry out genetic analysis for potential resistance-related genes,virulence-related genes,pathogenic proteins and resistance metabolite-related gene clusters in the strain genome.Both phenotypic and genotype analysis results were used for the safety studies on antibiotic resistance,virulence and metabolite resistance of T.daqus CICC 10681.The main results are as follows:1.The whole genome of T.daqus CICC 10681 was sequenced and the data were processed.The genome size of T.daqus CICC 10681 was 3.46 M.3705 protein coding genes were predicted and the total length of genes was 3.32 M.2.Antimicrobial susceptibility test on T.daqus CICC 10681 was conducted.The MIC value of ampicillin,vancomycin,gentamicin,clindamycin,tetracycline,erythromycin,imipenem,meropenem are 0.094,0.38,0.016,0.016,0.016,0.5,0.032,0.094?g/m L,respectively.Preliminary analysis showed that T.daqus CICC 10681 is sensitive to these 8 antibiotics that were commonly used for Gram-positive bacteria.3.In the genomic sequence of T.daqus CICC 10681,no antimicrobial resistance-related genes were detected for aminoglycosides,?-lactams,glycopeptides,macrolides,tetracyclines,lincomamides and carbapenems.And other antimicrobial resistance-related genes in the database were also not detected in this strain.4.The results of virulence test showed that T.daqus CICC 10681 had no virulence and pathogenicity to rats.Hemolysis test showed that the strain had no hemolysis.Antimicrobial production test showed that no antimicrobials are produced during the metabolic process of the strain.5.Virulence-related genes commonly carried by pathogenic microorganisms were not detected in the genome sequence of T.daqus CICC 10681,and there are no protein sequences similar to those of common pathogenic family proteins in the protein sequence.Prediction results of resistance metabolite related gene clusters showed that there were similar gene sequences in the genome of the strain with known synthetic gene clusters of aurantinin B / aurantinin C / aurantinin D.