Developing a glyphosate-bioremediation strategy using plants and actinobacteria: Potential improvement of a riparian environment

Utilizing actinobacteria for glyphosate biodegradation: innovative solutions for sustainable agricultural soil remediation

Glyphosate is one of the most widely used herbicides globally, yet its extensive application has raised significant ecological concerns. The objective of this study is to evaluate the ability of actinobacteria to degrade glyphosate under various environmental conditions. Four strains of actinobacteria were selected for their ability to thrive in a minimal medium containing 50 mg/L of glyphosate. The optimization of glyphosate biodegradation was assessed through a colorimetric method, which showed that the highest biodegradation rate occurred at a pH of 7.2, a temperature of 30 °C and an inoculum volume of 4%. The isolates were identified as follows: Streptomyces sp. strain SPA2 (accession number pp413753), Streptomyces rochei. strain IT (accession number pp413751), Streptomyces variabilis. strain Herb (accession number pp413750), and Streptomyces griseoincarnatus. strain SC (accession number PP413754). Analysis of total organic carbon reduction demonstrated that the strains SPA2, IT, Herb, and SC achieved reductions of 56.11%, 47.96%, 82.06%, and 67.12%, respectively. Furthermore, ATR-FTIR spectroscopy indicated alterations in the chemical structure of glyphosate post-biodegradation. These findings underscore the significant potential of the identified actinobacterial strains as viable agents for the bioremediation of glyphosate-contaminated agricultural soils.

Strategies for phosphorus management and greenhouse gas reduction via plant harvesting in the water-level fluctuation zone of the Three Gorges Reservoir

The water-level fluctuation zones (WLFZ) in Three Gorges Reservoir encounter several ecological challenges, particularly potential greenhouse gas (GHG) emissions and water eutrophication due to water level variations. Therefore, to address those challenges, our study explores the relationships between soil properties (Phosphorus cycle), plant conditions, microbial community, and GHG emissions. Our findings reveal that aboveground plants are the key link in the WLFZ ecosystem, which has previously been overlooked. Hydrological variations are continuously resetting the soil microbial system, keeping their ecological function in a primary state. Variations in elevation and soil nutrients have a minimal impact on GHG emissions in harvested plant areas. In contrast, in native plant areas, these variations significantly influence both GHG emissions and the phosphorus cycle. A strategic harvesting approach targeting high and low-elevation areas is also proposed, focusing on plants with high phosphorus enrichment coefficients (ECp > 1) to effectively counter eutrophication and GHG emissions. This selective harvesting in specific elevations could reduce CO2, CH4, and N2O emissions by 27378, 21, and 5 tonnes, respectively, and remove over 228934 tonnes of phosphorus. Our study emphasizes the significance of targeted vegetation management in WLFZ, providing a sustainable pathway to counter water eutrophication and achieve carbon neutrality.

Enhancing environmental decontamination and sustainable production through synergistic and complementary interactions of actinobacteria and fungi

Actinobacteria and fungi are renowned for their metabolic diversity and adaptability to various environments, thus exhibiting significant potential for environmental decontamination and sustainable production. Both actinobacteria and fungi excel in producing diverse secondary metabolites and enzymes, offering valuable tools for industrial and environmental applications. Their ability to detoxify metals and degrade a wide range of organic pollutants, such as pesticides, hydrocarbons, and dyes, positions them as promising candidates for bioremediation. Recent shifts in microbiological sciences emphasize research on mixed microbial populations. Microbial interactions in mixed communities emulate natural processes and yield emergent properties such as stability, robustness, and enhanced metabolism. Co-cultures of actinobacteria and fungi harness a broader range of genes and metabolic capabilities through their distinctive interactions, opening new avenues for developing novel products and/or technologies. This review provides a critical analysis of the present status of knowledge regarding the potential of actinobacteria-fungi co-cultures with a particular focus on novel functionalities and heightened production efficiency. These consortia are promising in several fields, from environmental applications to the biosynthesis of industrially relevant metabolites and enzymes, and enhancements in agricultural production. Although challenges still exist, their potential to address complex problems has been demonstrated and deserves further investigation.

How do glyphosate and AMPA alter the microbial community structure and phosphorus cycle in rice-crayfish systems?

Glyphosate, a commonly used organophosphorus herbicide in rice-crayfish cropping regions, may alter regional phosphorus cycle processes while affecting the structure of microbial communities. However, the effects of glyphosate residues on rice-crayfish systems remain unclear. In this study, we assessed the spatial and temporal distribution characteristics of glyphosate and its primary degradation products, as well as the impact mechanisms of glyphosate on microbial communities and the phosphorus cycle in rice-crayfish systems such as paddy fields, breeding ditches and recharge rivers. The detection rates of glyphosate and aminomethylphosphonic acid (AMPA) were 100% in rice-crayfish systems. Concentrations of glyphosate in the water phase and soil/sediment were as high as 0.012 μg/L and 7.480 μg/kg, respectively, and concentrations of AMPA were as high as 17.435 μg/L and 13.200 μg/kg, respectively. Glyphosate concentrations were not affected by rainfall or sampling site, but concentrations of AMPA in the water phase of recharge rivers were affected by rainfall. The glyphosate concentration was significantly and positively correlated with RBG-16-58-14 abundance, and the AMPA concentration was significantly and positively correlated with Actinobacteria and Lysobacter abundance, and negatively correlated with Cyanobacteria abundance (P < 0.05). The highest abundances of phoD, phnK, and ppx genes were found in all soils/sediments. Glyphosate concentration in soil/sediment was significantly and positively correlated with the abundance of phoD gene encoding an organophosphorus-degrading enzyme and ppx gene encoding poly inorganic phosphate (Pi) hydrolase (P < 0.05). In addition, the glyphosate concentration was significantly and positively correlated with the Ca-bonded Pi content (P < 0.05). This implies that glyphosate may promote the production of stable Pi in rice-crayfish systems by increasing the abundance of phoD and ppx genes. The results of this study reveal the impact mechanism of glyphosate on the phosphorus cycle in rice-crayfish systems and provide a basis for the risk assessment of glyphosate.

Influence of land use on spatial distribution of mobile phosphorus forms in the sediment of a tropical semi-arid reservoir

Changes in land use and land cover influence the transport of nutrients, mainly phosphorus (P), to aquatic ecosystems. P can be available in the water column to primary producers' assimilation or be stored in different forms in limnic sediment. Therefore, this study aims to analyze the impact of land use and land cover on the spatial distribution of phosphorus forms in the sediment of a tropical semi-arid reservoir. We hypothesize that agriculture, exposed soil and the presence of floodable vegetation increase the amount of mobile phosphorus in the sediment and the sediment closer to the dam show a greater amount of mobile phosphorus due to the confluence of the flows. The classification of land use and land cover was carried out through supervised analysis at the level of the reservoir's drainage basin and area of influence. Sediment samples from the reservoir were collected at four different sampling points within the influence of two sub-basins. P forms were obtained through chemical fractionation of these sediment samples along the reservoir. Sparse Caatinga was the predominant land cover in the drainage basin and in the influence area, accounting for >50 % of these areas. This land cover represents a risk for nutrient transport to aquatic environments. The sediment samples from Boqueirão reservoir exhibited a high amount of phosphorus, mainly in the mobile forms. These forms were heterogeneously distributed throughout the reservoir. Agriculture activities, exposed soil, and floodable vegetation, influence the distribution and increase of mobile forms of phosphorus in the reservoir sediment. This suggests the need for specific strategies for manage these activities properly. Additionally, the sediment closest to the dam showed a lower amount of mobile phosphorus compared to samples further upstream.