Investigation of Metabolites Isolated from Sphingomonas egypticus DM, A Rhizosphere of Datura metel

Abstract

Using naturally occurring bioactive compounds has been crucial in progressing contemporary medical practices. The rhizosphere, which refers to the narrow region of soil surrounding plant roots, serves as a highly dynamic environment for soil bacteria owing to the substantial quantity of organic compounds released into the soil by plant roots. This paper outlines the fermentation and subsequent processing of rhizosphere Sphingomonas egypticus DM. The culture media of Sphingomonas was cultivated and subsequently subjected to propagation. The ethyl acetate extract was then obtained and subjected to fractionation and purification utilizing various chromatographic techniques. This process led to the isolation of a compound under investigation that exhibited a distinct spot on thin-layer chromatography (TLC) plates, with a calculated retention factor (Rf = 0.56) using a mobile phase composed of methylene chloride and methanol (9:1). Upon spraying with anisaldehyde/sulphuric reagent and subsequent heating for a brief period, the compound displayed a violet colour. This compound was investigated in vitro to assess its antimicrobial and minimum inhibitory concentration (MIC) capabilities. The results demonstrated a significant inhibitory effect against phytopathogenic fungi, specifically Rhizoctonia solani (21.3 mm) and Alternaria alternate (18.3 mm). Additionally, a moderate inhibitory effect was observed against Pseudomonas aeruginosa (12.7 mm), whereas a somewhat less inhibitory effect was shown against Streptococcus mutans (9.3 mm). The study also demonstrated that (MIC) against Fusarium oxysporum was seen at a concentration of 125 µg/mL compared to various conventional antibiotics. Finally, the strain underwent PCR screening to detect PKS and lipopeptide 4'-phosphopantetheinyl transferase sfp genes. The PCR amplification assay demonstrated the presence of genes encoding the KS domain and Surfactin. Furthermore, the sequences of Sphingomonas egypticus DM have been officially recorded in the NCBI GenBank database and can be accessed using the accession codes OR469907 and OR499756.