Isolation of Glyphosate-Resistant Bacterial Strains to Improve the Growth of Maize and Degrade Glyphosate under Axenic Condition

Abstract

Glyphosate is a non-selective herbicide that is used to control perennial weeds in agriculture. However, its vast application may result in glyphosate residues in the food chain. Due to its toxicity to non-target organisms, glyphosate-contaminated soils needed to be remediated, and bioremediation is a conventional remedial method. The success of this depends on the isolation of bacteria with the ability to degrade glyphosate. The goal of this study was to isolate glyphosate-degrading bacteria from the rhizosphere of maize and wheat with a repeated application history of glyphosate for 5–10 years and test their roles in promoting the growth of maize (Zea mays) and glyphosate degradation in vitro. Eleven isolated bacteria were inoculated, and their role in plant growth was compared at different levels (100 and 200 mg/kg) of glyphosate. The results revealed that E. ludwigii improved the highest shoot length by 26% and the root length by 34% compared to the control at 100 mg/kg. The relative water contents in leaves significantly improved by 58% using P. aeruginosa at 100 mg/kg. The maximum electrolyte leakage from leaves significantly reduced by 73% using E. ludwigii at 100 mg/kg compared to the control (uninoculated). A high-pressure liquid chromatography instrument was used to assess the glyphosate concentrations. The highest degradation of glyphosate was observed in treatments inoculated with E. ludwigii (99 and 40%), P. aeruginosa (95 and 39%), K. variicola, (91 and 38%) E. cloacae (92 and 38%), and S. liquefaciens (87 and 36%), respectively, at 100 and 200 mg/kg within 28 days. These five strains demonstrated a great potential for degrading glyphosate and promoting the growth of maize in vitro, and they will be further exploited for the biodegradation of glyphosate and the growth promotion of broader crop species in situ in the near future.

Unlocking the potential of glyphosate-resistant bacterial strains in biodegradation and maize growth

“…It is noteworthy that, in most instances, only a limited number of colonies exhibited growth on individual culture plates ( Table 1 ). To explore their potential to enhance plant development, we subjected these strains to comprehensive characterization, evaluating their capabilities in exopolysaccharide production, 1-aminocyclopropane-1-carboxylic acid (ACC) utilization, catalase and oxidase activities, indole acetic acid production, siderophore secretion, phosphorus solubilization, root colonization, and chitinase production (Mohy-Ud-Din et al, 2023 ). Initially, t hese 11 rhizobacterial strains were designated as WAG1-WAG11.…”

“…The average temperature was 41 • C and 10 h of daylight. Soil samples were taken at different intervals of days to check the GP biodegradation according to standard procedure (Mohy- Ud-Din et al, 2023).…”

“…The results signify the mean value of triplicates, and ± represents standard deviations. Same letters shared by means do not differ significantly at a p-value of < 0.05.production, 1-aminocyclopropane-1-carboxylic acid (ACC) utilization, catalase and oxidase activities, indole acetic acid production, siderophore secretion, phosphorus solubilization, root colonization, and chitinase production (Mohy-Ud-Din et al, 2023). Initially, these 11 rhizobacterial strains were designated as WAG1-WAG11.…”

Potential Use of Plant Growth-Promoting Bacteria to Enhance Growth and Soil Fertility in Marginal Areas: Focus on the Apulia Region, Italy

“…Very few studies have been conducted to assess the simultaneous growth-promoting and glyphosate-detoxifying effects of PGPB. A recent study compared eleven PGPB strains and selected five microorganisms capable of simultaneously enhancing maize (Z. mays) growth and degrading glyphosate at various concentrations [132]. Enterobacter ludwigii, Pseudomonas aeruginosa, Klebsiella variicola, Enterobacter cloacae and Serratia liquefaciens led to a reduction in glyphosate levels after 28 days under axenic conditions, using two concentrations of glyphosate, i.e., 100 and 200 mg/kg.…”

Recent Advances in Microbial-Assisted Remediation of Cadmium-Contaminated Soil

“…In a natural ecosystem, microbes are widely distributed and thrive in HM-polluted environments [12]. However, the ability of microbes to remediate contaminants can halt when they run out of food [23]. An enrichment method for the isolation of microbes that combines the properties of (1) the degradation of a chosen pollutant and (2) excellent root colonization has been developed [24,25] to ensure that these microbes can access the best available food source in soil, namely root exudates [26].…”