Safety Evaluation Of Yeast Adsorbed Heavy Metal Lead

With the wide application of biosorption in the treatment of heavy metal pollution,microorganisms with heavy metal adsorption characteristics have become the current research hotspot;however,if such microorganisms are to be applied to food,medicine and other fields,their safety needs to be evaluated.In this paper,the yeast isolated and screened in the early stage of the laboratory with the characteristics of adsorbing heavy metal Pb²⁺was evaluated by the harmful metabolite test,drug resistance test,hemolysis test and toxicology test.The harmful metabolites of Wickerhamomyces anomalus QF-1-1,QI-1-6,QI-1-7 and Metschnikowia chrysoperlae QK-1-5 were evaluated,including indole test,nitrate reductase test and amino acid decarboxylase test.The results showed that all tested strains were negative and did not produce such metabolites.The results of the drug resistance test showed that the test strains QF-1-1,QI-1-6,QI-1-7,and QK-1-5 were all resistant to itraconazole and amphotericin B;QF-1-1 And QI-1-6 are mediated by fluconazole,QI-1-7 and QK-1-5 are sensitive to fluconazole;all 4strains are sensitive to voriconazole.The results of the hemolysis test showed that the test strains QF-1-1,QI-1-6,QI-1-7,and QK-1-5 were all negative,and there was no hemolysis.The results of Wickerhamomyces anomalus QF-1-1 toxicology test showed:The 7-day acute toxicity test did not yield a half-lethal dose,and the behavior and performance of the mice were not abnormal.The maximum tolerated dose(MTD)was greater than 10¹⁰CFU/(MLBW)20 ml/(kg·d),which was a non-toxic level.And there was no significant difference between the experimental group and the control group in terms of body weight,food intake,and organ-to-body ratio.Genetic toxicity includes mouse sperm abnormality test and mouse bone marrow polychromatic erythrocyte micronucleus test;the results of each dose group in the mouse sperm abnormality test are negative,which is significantly different from the positive control group,indicating that QF-1-1 can affect the reproduction of mice Cells have no damaging effect;in the mouse bone marrow polychromatic erythrocyte micronucleus test,there is no significant difference between each dose group.The positive group has obvious mutation effect,and the test result is negative,indicating that QF-1-1 has no mutagenic effect.In the 28-day oral toxicity test,no mice died in the high,medium,and low dose groups.The weight gain trend,food utilization rate of the strains in each dose group and the indicators of the heart,liver,spleen,lung and kidney of the mice were compared with the control There was no significant difference between the groups and no bacterial translocation was found.The serum biochemical indicators of 7d and 28d mice were tested for aspartate aminotransferase(AST),alanine aminotransferase(ALT),and?-glutamyltransferase(?-GT).The results showed that the test group had no significant difference compared with the control group.It shows that QF-1-1 does not affect liver function health.