Harnessing the Biocontrol Potential of Bradyrhizobium japonicum FCBP-SB-406 to Manage Charcoal Rot of Soybean with Increased Yield Response for the Development of Sustainable Agriculture.

Plant growth-promoting bacteria (PGPRs) have the potential to act as biofertilizers and biopesticides. This study was planned to explore indigenously isolated PGPRs as a potential candidate to control charcoal rot that affects various crops including soybean. Among the four different tested species of PGPRs, Bradyrhizobium japonicum (FCBP-SB-406) showed significant potential to enhance growth and control soil borne pathogens such as Macrophomina phaseolina. Bacillus subtilis (FCBP-SB-324) followed next. Bradyrhizobium japonicum (FCBP-SB-406) reduced disease severity up to 81.25% in comparison to the control. The strain showed a strong fertilizing effect as a highly significant increase in biomass and other agronomic parameters was recorded in plants grown in its presence. The same was supported by the Pearson's correlation and principal component analysis. A decrease in disease incidence and severity may be due to the induced resistance imparted by the bacterium. This resulted in significant increments in quantities of defense enzymes, including catalase, peroxidase (PO), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL) and superoxide dismutase (SOD). A significant production of proteases, catalases and hydrogen cyanide by B. japonicum (FCBP-SB-406) can also be associated to mycoparasitism. The establishment of PGPRs in treated soils also showed positive effects on soil health. Total metabolite profiling of treated plants in comparison to the control showed the upregulation of many flavonoids, isoflavonoids and amino acids. Many of these compounds have been well reported with antimicrobial activities. Bradyrhizobium japonicum (FCBP-SB-406) can be employed for the production of a potential formulation to support sustainable agriculture by reducing the input of synthetic pesticides and fertilizers.

Antioxidant, antibacterial, and antimutagenic activity of Piper nigrum seeds extracts.

Piper nigrum is a widely used plant in traditional remedies and known for its numerous biological properties. However, fraction-based antioxidant activity and their antimutagenic potential are not yet fully investigated. Different extracts of the seeds P. nigrum were obtained by sequential extraction in different solvents. All extracts were evaluated for antibacterial and antioxidant activities using different methods. The most active fraction was analyzed for antimutagenic activity using the Ames Salmonella test. The antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) was found to be more prominent compared to ESßL producing Klebsiella pneumoniae isolates. The MIC values were found to be lower against MRSA than K. pneumoniae. The extract showing highest antioxidant activity (methanol extract) was further tested for antimutagenic activity both against direct and indirect-acting mutagens. A varying level of antimutagenic activity was shown by methanol extract at highest tested concentration (200 µg/plate). Alkaloids, phenols, and flavonoids were detected as major class of compounds in methanol extract. Gas chromatography-mass spectrometry (GC-MS) analysis showed the presence of various phytocompounds. Based on molecular docking of two major active phytocompounds (piperine and copaene), they were found to interact at the minor groove of DNA. Molecular dynamics (MD) simulation revealed that both the ligands were quite stable with DNA under physiological conditions. The ability of phytocompounds to interact with DNA might be reducing the interaction of mutagens and could be one of the possible mechanism of anti-mutagenic activity of P. nigrum extract. This study highlights the antioxidant and antimutagenic potential of Piper nigrum. The role of phytocompounds present in the bioactive extract is needed to be explored further for herbal drug research.

Biosynthesis of silver nanoparticles using Malva parviflora and their antifungal activity.

Cheeseweed mallow (Malva parviflora L.) was used to biosynthesize silver nanoparticles. The biosynthesized silver nanoparticles were classified by UV-vis Spectroscopy and Fourier-Transform Infrared Spectroscopy (FT-IR). The shape and size distribution were visualized by Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FE-SEM), and Zeta potential analysis. The chemical composition of M. parviflora leaf extract was identified by Gas Chromatography and Mass Spectroscopy (GC/MS). Finally, in vitro antifungal assay was done to assess the potential of biosynthesized silver nanoparticles and crude leaf extract of M. parviflora for inhibiting the mycelial growth of phytopathogenic fungi. The UV-vis analysis manifests the formation of silver nanoparticles. FTIR analysis established that chemicals of the leaf extract stabilized the biosynthesized silver nanoparticles by binding with the free silver ions. The TEM, FE-SEM and zeta potential analyzer confirmed that the biosynthesized silver nanoparticles were mostly spherical with an average diameter of 50.6 nm. The biosynthesized silver nanoparticles and leaf extract of M. parviflora effectively mitigate the mycelial growth of Helminthosporium rostratum, Fusarium solani, Fusarium oxysporum, and Alternaria alternata. The maximum reduction in mycelial growth by biosynthesized nanoparticles was observed against H. rostratum (88.6%). Whereas, the leaf extract of M. parviflora was most effective against F. solani (65.3%). Thus, the biosynthesis of nanoparticle assisted by M. parviflora is a feasible and eco-friendly method for the synthesis of silver nanoparticles. Further the silver nanoparticles and leaf extract of M. parviflora could be explored for the development of the fungicide.