Synthesis and Chemical Characterization of Secondary Metabolites of Weeds using FTIR and NMR Techniques

Abstract

Soil microorganisms have the ability to produce bioactive chemicals that can be utilized in the development of a bioherbicide for the purpose of biological weed control. A total of 34 bacterial strains were isolated and tested for their herbicidal activity against both grass and broadleaf weeds. From this group, six effective isolates were chosen for the purpose of characterization and identification. The actinomycete isolates were identified as Microbacterium sp and Streptomyces sp. based on an analysis of their morphological, biochemical and physiological characteristics. Out of the initially chosen 6 strains, the bacterial fermentation broths from one particular isolate strain exhibited herbicidal activity that resulted in a 95% reduction in the growth of weed when compared to the control. The Streptomycetes isolates underwent a germination inhibition assay to determine the presence of herbicidal properties. A total of 8 crop seeds were examined for herbicidal efficacy using Streptomycetes isolates and no growth inhibition was observed in the crop seeds. The herbicidal activity of Streptomyces isolates was tested on four weed seeds. Streptomyces inhibits the growth of nut grass. The current investigation establishes that Streptomyces isolates has the potential to function as a bioherbicide against nut grass. The strain SKI-[Z] was shown to have a 99% resemblance to Actinobacterial spp. through phylogenetic study of 16S rRNA gene sequencing. The FT-IR spectrum shows alkynes (-C≡C), alkenes (=C-H), amines (N-H), aliphatic amine (C-N) and alkanes (-C-H) and the NMR peak having ketone groups (C=O), di-ketone group (>C=O), ether (R-O-R) and aldehyde group (-CHO). Furthermore, upon ¹H NMR analysis of the secondary metabolites, the prominent peaks intensities at δ 2.4, 3.68 and 4.1 ppm correspond to the ketone groups (C=O), di-ketone group (>C=O), ether (R-O-R) and aldehyde group (-CHO) were found.