Identification and combinatorial engineering of indole-3-acetic acid synthetic pathways in Paenibacillus polymyxa

Abstract

Background Paenibacillus polymyxa is a typical plant growth-promoting rhizobacterium (PGPR), and synthesis of indole-3-acetic acid (IAA) is one of the reasons for its growth-promoting capacity. The synthetic pathways of IAA in P. polymyxa must be identified and modified. Results P. polymyxa SC2 and its spontaneous mutant SC2-M1 could promote plant growth by directly secreting IAA. Through metabonomic and genomic analysis, the genes patA, ilvB3, and fusE in the native IPyA pathway of IAA synthesis in strain SC2-M1 were predicted. A novel strong promoter P04420 was rationally selected, synthetically analyzed, and then evaluated on its ability to express IAA synthetic genes. Co-expression of three genes, patA, ilvB3, and fusE, increased IAA yield by 60% in strain SC2-M1. Furthermore, the heterogeneous gene iaam of the IAM pathway and two heterogeneous IPyA pathways of IAA synthesis were selected to improve the IAA yield of strain SC2-M1. The genes ELJP6_14505, ipdC, and ELJP6_00725 of the entire IPyA pathway from Enterobacter ludwigii JP6 were expressed well by promoter P04420 in strain SC2-M1 and increased IAA yield in the engineered strain SC2-M1 from 13 to 31 μg/mL, which was an increase of 138%. Conclusions The results of our study help reveal and enhance the IAA synthesis pathways of P. polymyxa and its future application.

The ability of bacteria from legume plant roots grown on former coal mining soil to produce Indole-3-Acetic Acid (IAA)

“…These results confirm that the genetic factors of bacterial isolates have a very strong influence in expressing their ability to produce IAA, considering that the environmental conditions in the implementation of this study were the same. Other researchers said that coexpression patA, ilvB3, and fusE, increased IAA yield by 60% in strain bacteria that isolated [38]. When viewed from the value of the ability to produce IAA, then when compared with research by Dewi et al [39] is relatively small because with the same concentration of tryptophan the highest IAA produced reached 158, 651 ppm.…”

Abh, AbrB3, and Spo0A play distinct regulatory roles during polymyxin synthesis in Paenibacillus polymyxa SC2

“…First, the primer pairs abh-cF1/R1, abrB3-cF1/R1, and spo0A-cF1/R1 were used to amplify the promoter P 04420 from the gDNA of SC2 via PCR ( 42 ). The primer pairs abh-cF2/R2, abrB3-cF2/R2, and spo0A-cF2/R2 were used to PCR amplify the genes abh , abrB3 , and spo0A from the gDNA of SC2, respectively.…”

Massilia luteola sp. nov., a novel indole-producing and cellulose-degrading bacterium isolated from soil

“…Therefore, the IAA synthesis pathway and related genes of the strain were predicted using the kegg Automatic Annotation Server. Two IAA synthesis genes (K00128 and K00274 orthologues) belonging to the tryptamine (TPM) pathway [46] were identified from the tryptophan metabolism pathway (map 00380). One IAA synthesis gene (K00274 orthologue) is coding for a monoamine oxidase (EC:1.4.3.4), which catalyses a reaction from TPM to indole-3-acetaldehyde.…”