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The aim of this study was to characterize qualitatively and quantitatively the composition of the main rhizodeposits emitted from maize (Zea mays) under Cd stress, in order to discuss their role in Cd availability and tolerance. Maize was grown for 6weeks in sand at four Cd exposure levels (0, 10, 20, and 40M Cd in nutrient solution) and two types of rhizodeposits were collected at the end of cultivation period. Mucilage and other molecules adhering to rhizospheric sand were extracted with a buffer before root exudates were collected by diffusion into water. Total carbon, proteins, amino acids, and sugars were analyzed for both rhizodeposit types and about 40 molecules were identified using GC-MS and LC-MS. Cadmium effect on plant morphology and functioning was slight, but consistent with previous works on Cd toxicity. However, rhizodeposition did tend to be impacted, with a decrease in total carbon, sugars, and amino acids correlating with an increasing Cd content. Such a decrease was not noticeable for proteins in root exudates. These observations were confirmed by the same trends in individual compound contents, although the results were generally not statistically significant. Many of the molecules determined are well-known to modify, whether directly or indirectly, Cd speciation and dynamics in the soil and could play a role in Cd tolerance.

This study aimed to evaluate the potential of five medicinal herbs in the enhancement of xanthan gum production when used against indigenously isolated (from molasses, an agricultural waste) phytopathogen Xanthomonas campestris MW741556. Antibiotic susceptibility of five medicinal herbs (Moringa oleifera, Bacopa monnieri, Glycyrrhiza glabra, Withania somnifera, and Arthrospira platensis) against X. campestris culture was first checked. All five herbs exhibited a clear zone of inhibition against X. campestris during the investigation. Thereafter their effect on enhancing the xanthan gum production was studied using molasses enriched medium. The results of this experiment showed that all five herbs were capable of enhancing xanthan gum production significantly. Xanthan gum produced differed in viscosity and dried biomass. Among all, A. platensis and M. oleifera were found to be the most promising for xanthan gum production with higher viscosity. These results were further confirmed by the characterization of xanthan gum produced by five herbs using Fourier Transform Infrared Spectroscopy. Further, a multivariate approach using principal component analysis confirmed the variability among the herbs used. This versatility of these medicinal herbs opens the possibility of their utilization and application in various fields.