Secondary metabolites and genetic system of the rare actinobacteria Lechevalieria rhizosphaerae NEAU-A2

Abstract:

[Background] Lechevalieria rhizosphaerae NEAU-A2 was identified as a novel rare actinobacteria, and genomic analysis shows that it contains a variety of biosynthetic gene clusters with the potential to generate multiple natural products. [Objective] Study on the secondary metabolites in L. rhizosphaerae NEAU-A2 to discover compounds with novel structures or unique biological activities, and further establish the genetic system of the strain. [Methods] The secondary metabolites were isolated and purified by using silica gel column chromatography, high performance liquid chromatography and other methods. The structures of compounds were elucidated by analysis of NMR and MS data. The mutant cosmid with the disruption of the gene 1609 (a PKS-NRPS hybrid gene) was constructed using PCR-targeting method. Intergeneric conjugation was conducted for plasmid the transformation into wild type strain. [Results] Two new dimeric indole alkaloids (1-2), along with five known compounds, N-acetyltryptamine (3), 4-((2-(1H-indol-3-yl)ethyl)amino)-4-oxobutanoic acid (4), brevianamide F (5), 4S,7R-germacra-1(10)E,5E-diene-11-ol (6), 1H-pyrrole-2-carboxylic acid (7), were isolated and identified from the fermentation broth of L. rhizosphaerae NEAU-A2. The double crossover recombinant strains were obtained after culturing two generations, and further verified by polymerase chain reaction (PCR). [Conclusion] Seven compounds were isolated and identified from strain NEAU-A2, and the genetic system of this novel rare actinobacteria L. rhizosphaerae NEAU-A2 was successfully established.