Isolation, identification and characterization of Streptomyces metabolites as a potential bioherbicide

Abstract

Bioactive herbicidal compounds produced by soil microorganisms might be used to creating a bioherbicide for biological weed control. A total of 1,300 bacterial strains were isolated and screened for herbicidal activity against grass and broadleaf weeds. Among primarily selected 102 strains, the herbicidal activity of bacterial fermentation broths from the following three isolates strain-101, strain-128, and strain-329 reduced the growth of D. sanguinalis by 66.7%, 78.3%, and 100%, respectively as compared with control. Phylogenetic analysis of 16S rRNA gene sequencing determined that the strain-329 has 99% similarity to Streptomyces anulatus (HBUM 174206). The potential bioherbicidal efficacy of Streptomyces strain-329 was tested on grass and broadleaf weeds for phytotoxic activity through pre- and post-emergence applications. At pre-emergence application, the phytotoxic efficacy to D. sanguinalis and S. bicolor on seed germination were 90.4% and 81.3%, respectively at the 2x concentration, whereas in the case of Solanum nigrum, 85.2% phytotoxic efficacy was observed at the 4x concentration. The efficacy of Streptomyces strain-329 was substantially higher at post-emergence application, presenting 100% control of grass and broadleaf weeds at the 1x concentration. Two herbicidal compounds coded as 329-C1 and 329-C3 were extracted and purified by column chromatography and high-performance liquid chromatography methods. The active compound 329-C3 slightly increased leaf electrolytic leakage and MDA production as concentration-dependent manner. These results suggest that new Streptomyces sp. strain-329 produced bioherbicidal metabolites and may provide a new lead molecule for production an efficient bioherbicide to regulate grass and broadleaf weeds.

Deciphering the Relationship Between Cycloheximides Structures and Their Different Biological Activities

“…The antifungal activities of CHs and its derivatives ACH and HCH, which were isolated from the culture filtrate of Streptomyces anulatus strain-329 ( Bo et al, 2019 ), were determined using the broth dilution method ( Nguyen et al, 2020 ). The three chemicals were dissolved in acetone at a concentration of 10 mg mL –1 as a stock solution and were treated in a range of 0.012–100 μg mL –1 .…”

“…The phytotoxicity of three chemicals was evaluated by observation of the physiological symptoms of nine crops and 10 weeds, according to previous procedures ( Bo et al, 2019 ). CH and its derivatives were diluted at 100 and 50 μg mL –1 containing 0.1% Tween 20 and sprayed on the leaves of 14-days-old weeds and plants.…”

“…Acetoxycycloheximide (ACH), which showed the strongest phytotoxicity in the whole-plant experiments, was tested for its effect on the chlorophyll content of cucumber plants compared with glufosinate and paraquat ( Bo et al, 2019 ). In brief, leaf disks (1 g fresh weight) of cucumber plants were transferred to Falcon tubes containing 7 mL of distilled water.…”

“…The effect of ACH, glufosinate, and paraquat on cellular leakage was determined using leaf tissues of 7 days-old Crocus sativus seedlings ( Bo et al, 2019 ). The leaf disks were placed in Petri dishes containing ACH, glufosinate, and paraquat at different concentrations and incubated in a growth chamber for 12 h. Electrolyte leakage was measured using an electronic conductivity meter (Denki Kagaku Co., Ltd., Mushashino, Japan).…”

“…Two derivatives, acetoxycycloheximide (ACH) and streptovitacin-A [also named as hydroxycycloheximide (HCH)], showed less toxic to Saccharomyces pastorianus cells but higher toxic to cell-free protein-synthesizing system ( Siegel et al, 1966 ). Furthermore, CH and HCH produced by Streptomyces anulatus also reported as herbicidal chemicals which displayed strong phytotoxicity against broadleaf weeds ( Bo et al, 2019 ). HCH (a derivative of CH with a hydroxy group attached to C13 of cyclohexanone) which has previously been isolated from the culture broth of S. griseus , exhibited antifungal and antitumor activities ( Kondo et al, 1990 ).…”