| With the rapid development of science and technology,economic development has been promoted and people’s living standards have been improved.At the same time,heavy metal pollution has been aggravated,especially cadmium pollution.Cadmium and its compounds are highly toxic,easy to migrate,difficult to degrade,will cause serious damage to the balance of the ecosystem,and can cause great harm to human health through bioenrichment.In order to find a more efficient and environmentally friendly measure to control cadmium pollution,we screened out a Cd-resistant fungus Vanrija humicola sp.GN1.In this study,characterization analysis,genomics analysis and transcriptomic analysis methods were used to study this strain.To explore the cadmium resistance ability and mechanism of cadmium resistance under different pH conditions,and further analyze the important metabolic pathways of the differences in the expression of functional genes under cadmium stress in different pH environments.The main research results are as follows:(1)GN1 can grow well under pH3 conditions and has good acid resistance,but the acidic environment also aggravates the toxic effect of cadmium pollution on GN1.Under acidic conditions,GN1 still has a high removal rate of low concentration of cadmium ions,and the optimal adsorption temperature of GN1 under acidic conditions is 30℃.The characterization results show that the adsorption process of GN1 on Cd2+under acidic conditions involves multiple functional groups on cell wall and cell membrane,mainly including amide group,phosphoacyl group,amino group,carboxyl group,etc.Cd2+was adsorbed to form CdO,Cd3(PO4)2,Cd(CO3)2,CdSO4 and other compounds.(2)After genome sequencing and assembly,the results showed that the total genome length of GN1 was 22.01Mb and the GC content was 63%.The GN1 genome data obtained were classified and annotated with NR,KOG,GO,KEGG and other databases.The results showed that GN1 contained a large number of genes related to biological regulation and metabolism,with rich biological processes,strong catalytic activity,and powerful functions of information exchange,material transport and energy metabolism.(3)Transcriptome sequencing results showed that the expressions of genes related to antioxidant function,such as SOD1,PRDX5 and CAT,were significantly up-regulated under cadmium stress,and the degree of induction was higher under acidic conditions.In addition,the expressions of GSR,GST and Gsh-Px related to GSH synthesis were also significantly upregulated under acidic conditions.According to the results of differential gene annotation,the expressions of Cdc28,Cdc20,APC/C and Mad2 genes related to cell cycle regulation were significantly up-regulated,as well as the expressions of Smc2 and Smc4 genes related to chromosome structure maintenance and al,Pri1 and Pri2 genes related to DNA replication under acidic conditions.Under cadmium stress at different pH conditions,the expressions of SP,MCT and SVOP related genes in the MFS transporter family of GN1 were significantly upregulated,as well as the expressions of ion-transporter ATPase related genes,including Na+-K+-ATPase and Ca2+-ATPase.These results indicate that the cadmium resistance of Vanrija humicola sp.GN1 is a synergistic process involving multiple genes and metabolic pathways under different pH conditions. |
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