Insights into the microbial degradation pathways of the ioxynil octanoate herbicide

Metabolic Profiling and Comparative Proteomic Insight in Respect of Amidases during Iprodione Biodegradation

The fungicide iprodione (IPR) (3-(3,5-dichlorophenyl) N-isopropyl-2,4-dioxoimidazolidine-1-carboxamide) is a highly toxic compound. Although IPR has been restricted, it is still being applied in many places around the world, constituting an environmental risk. The biodegradation of IPR is an attractive option for reducing its residues. In this study, we isolated thirteen IPR-tolerant bacteria from a biopurification system designed to treat pesticides. A study of biodegradation using different strains was comparatively evaluated, and the best degradation rate of IPR was presented by Achromobacter sp. C1 with a half-life (T1/2) of 9 days. Based on a nano-LC-MS/MS analysis for the strains, proteins solely expressed in the IPR treatment were identified by highlighting the strain Achromobacter sp. C1, with 445 proteins primarily involved in the biosynthesis of secondary metabolites and microbial metabolism in diverse environments. Differentially expressed protein amidases were involved in six metabolic pathways. Interestingly, formamidase was inhibited while other cyclases, i.e., amidase and mandelamide hydrolase, were overexpressed, thereby minimizing the effect of IPR on the metabolism of strain C1. The dynamic changes in the protein profiles of bacteria that degrade IPR have been poorly studied; therefore, our results offer new insight into the metabolism of IPR-degrading microorganisms, with special attention paid to amidases.

Contributions of Beneficial Microorganisms in Soil Remediation and Quality Improvement of Medicinal Plants

Medicinal plants (MPs) are important resources widely used in the treatment and prevention of diseases and have attracted much attention owing to their significant antiviral, anti-inflammatory, antioxidant and other activities. However, soil degradation, caused by continuous cropping, excessive chemical fertilizers and pesticide residues and heavy metal contamination, seriously restricts the growth and quality formation of MPs. Microorganisms, as the major biota in soil, play a critical role in the restoration of the land ecosystem. Rhizosphere microecology directly or indirectly affects the growth and development, metabolic regulation and active ingredient accumulation of MPs. Microbial resources, with the advantages of economic efficiency, harmless to environment and non-toxic to organisms, have been recommended as a promising alternative to conventional fertilizers and pesticides. The introduction of beneficial microbes promotes the adaptability of MPs to adversity stress by enhancing soil fertility, inhibiting pathogens and inducing systemic resistance. On the other hand, it can improve the medicinal quality by removing soil pollutants, reducing the absorption and accumulation of harmful substances and regulating the synthesis of secondary metabolites. The ecological and economic benefits of the soil microbiome in agricultural practices are increasingly recognized, but the current understanding of the interaction between soil conditions, root exudates and microbial communities and the mechanism of rhizosphere microecology affecting the secondary metabolism of MPs is still quite limited. More research is needed to investigate the effects of the microbiome on the growth and quality of different medicinal species. Therefore, the present review summarizes the main soil issues in medicinal plant cultivation, the functions of microbes in soil remediation and plant growth promotion and the potential mechanism to further guide the use of microbial resources to promote the ecological cultivation and sustainable development of MPs.

High-throughput screening for distinguishing nitrilases from nitrile hydratases in Aspergillus and application of a Box-Behnken design for the optimization of nitrilase

Nitrilases and nitrile hydratases/amidases hydrolyze nitriles into carboxylic acids and/or amides, which are used in industrial chemical processes. In the present study, 26 microorganisms, including yeasts and filamentous fungi, in a minimum solid mineral medium supplemented with glucose and phenylacetonitrile were screened to evaluate their biocatalytic potential. Of these microorganisms, five fungi of the genus Aspergillus were selected and subjected to colorimetry studies to evaluate the production and distinction of nitrilase and nitrile hydratase/amidase enzymes. Aspergillus parasiticus Speare 7967 and A. niger Tiegh. 8285 produced nitrilases and nitrile hydratase, respectively. Nitrilase optimization was performed using a Box-Behnken design (BBD) and fungus A. parasiticus Speare 7967 with phenylacetonitrile volume (μl), pH, and carbohydrate source (starch:glucose; g/g) as independent variables and nitrilase activity (U ml^-1 ) as dependent variable. Maximum activity (2.97 × 10^-3  U ml^-1 ) was obtained at pH 5.5, 80 μl of phenylacetonitrile, and 15 g of glucose. A. parasiticus Speare 7967 showed promise in the biotransformation of nitriles to carboxylic acids.

Study on the simultaneous degradation of five pesticides by Paenibacillus polymyxa from Panax ginseng and the characteristics of their products

The quality and safety of ginseng products were seriously affected due to the slow metabolism and long-term residual pesticides in ginseng. Microbial degradation is an effective method to degrade pesticide residues. In this study, ginseng endophytic Paenibacillus polymyxa was used to degrade pesticide residues. A method of simultaneous determination of fluazinam, BHC, PCNB, chlorpyrifos and DDT in ginseng roots and ginseng stems and leaves by GC was established. The sample was extracted with n-hexane and purified by Florisil solid phase extraction column. The limit of quantitation was 0.01 μg mL^-1, the linear relationship was good (r ≥ 0.9901). 7 days after inoculated with P. polymyxa, the degradation rates of fluazinam, BHC, PCNB, chlorpyrifos, and DDT in the medium were 94.77%, 70.34%, 77.92%, 78.30%, 66.70%, respectively (P < 0.05). The safety of 5 pesticide degradation products was investigated by GC-MS. The results showed that after 7 days degradation, the main degradation products were alkanes, which are non-toxic and can't cause secondary pollution to the environment. The actual degradation results were verified by field experiments. The results indicated that after sprayed 5 times with P. polymyxa, the degradation rates of fluazinam, BHC, PCNB, chlorpyrifos and DDT in the ginseng roots were 66.07%, 46.24%, 21.05%, 72.40%, 54.21%, respectively (P < 0.05). The degradation rates in ginseng stems and leaves were 74.18%, 55.61%, 73.65%, 58.13%, 46.91%, respectively (P < 0.05). The results indicated that Paenibacillus polymyxa was an effective degradation strain of 5 pesticides.