Distribution Of Integrons In Guangxi Farmlands And The Effects Of Biochar On Integrons Abundance And Diversity In Paddy

Bacterial genomes contain versatile gene accretion systems called integrons,which are commonly found in most Gram-negative bacteria.Integrons are documented to be involved in the propagation and expression of genes in the bacterial community and play a major role in bacterial evolution,including antimicrobial resistance development.Manure was introduced to the fields as a fertilizer since decades;however its applications boost the antimicrobial resistance.The entire study was divided into three major groups.(1)The role of agriculture in the dissemination of class 1 Integrons,antimicrobial resistance and diversity of their gene cassettes in southern China(2)Biochar sole application and in combination with manure,mitigate the class 1 integrons,antibiotic resistance genes(ARGs)and gene cassettes diversity at the paddy field soil(3)The combined application of manure and biochar elevate the microbial diversity at the paddy fields soil.The first study examines the abundance of integrons,their gene cassette diversity in various crop soils,and their role in the dissemination of integrons and antimicrobial resistance in the southern region of China.Samples from different agric-crop soil,such as rice(R.S),sugarcane(S.S),citrus(C.S),banana(B.S),agricultural runoff(the point where the runoff of all sites meet(R.O),and wild(non-agricultural)soil(WS)were collected.Quantitative PCR was used to determine the abundance of integrons,and clone libraries were constructed to examine the gene cassette arrays.All the tested samples were found positive for class 1(class 1)integrons and revealed a higher concentration and higher relative abundance of R.S than the others,with the least found at the WS site.The W.S class 1 cassette arrays were found empty,and no putative conserved domains were found.The R.O was found to contain a high number of gene cassettes with various functions,while the smallest number of gene cassettes was found in the S.S among the crop soils.Most of the gene cassettes presented by the R.O were primarily shared with other sites,and the ARGs were consistently observed to be dominant.The constructed clone libraries represented a diverse gene cassette array with 16 percent novel gene cassettes that play a vital role in pathogenesis,transportation,biosynthesis,and antimicrobial resistance(AMR).Most resistance-related gene cassettes were associated with the genes encoding resistance to quaternary ammonium compound(QAC)aminoglycosides.The paddy soil contains the high number of integrons and ARGs.Manure and biochar were amended to the field and the results revealed that class 1 integrons is prevalent in all samples,with higher concentration and relative abundance in the manure amended field and lowest in the biochar amended field.The gene cassettes array represents a diverse pool of gene cassettes,majority of resistance genes cassettes were encoding resistance to aminoglycosides,heat shock protein,heavy metal resistance,type ⅰ,ⅱ,ⅲ,ⅳ,pillus secretary protein and twin arginine translocases,TatA,TatB,TatC were the most prevalent.The introduction of manure significantly increase the integrons and antibiotic resistance and gene cassettes diversity,while the biochar amendments significantly decrease the integrons,antibiotic resistance,and gene cassettes array.These environments are the rich sources of horizontal gene transfer and subsequently the diversity of integrons and its gene cassettes are diverse.Here we discovered novel gene cassettes expressed by the integrons,the functions of novel gene cassettes are diverse including antimicrobial resistance,involved in pathogenicity,virulence,horizontal gene transformation,biosynthesis,replication and hypothetical protein whose functions are to be unknown.The microbiome analyses were performed to find the effects of biochar and manure and their combine effects on the microbial community of paddy rhizosphere microorganisms.The soil physiochemical and physical properties were analyzed before and after the experiment.Illumina sequencing technology was used to sequence the 16 S rRNA and ITS of rhizosphere microorganisms.Moreover,the soil physicochemical properties,cane yield,and the changes in rhizosphere microbial community were analyzed.The results showed that both the manure and biochar have distinct effects on the microbial diversity.From the abundance level we noticed that biochar has significantly reduced the Xanthomonas and fermicutes.Xanthomonas is the ancestral specie of carrying integrons.The whole analysis shows that the combined application of biochar and manure increase the microbial diversity from the other three treatments.The beta and alpha diversity was significant(P < 0.05)among the treatments,while the applications of biochar and manure did not show significant effects on the fungal diversity.This study highlights the significant differences in the abundance of integrons among various agricultural soils and offers deep insight into the pools of gene cassettes and the distinctive effects of biochar to mitigate integrons,antimicrobial resistance and gene cassettes diversity at the paddy level.