Study on metsulfuron-methyl degradation in simulated wheat (Triticum asetivum L.) rhizospheric soil with Penicillium sp inoculation

The rapid biodegradation of metsulfuron-methyl in contaminated soil was studied in this paper. The wheat (Triticum aestivum L.) rhizosphere was well simulated by setting up a hydroponic system that allowed the aseptic wheat root exudates flow onto columns containing soil previously contaminated with metsulfuron-methyl. The root-colonizing strain Penicillium sp. containing highly effective degrading plasmid on metsulfuron-methyl was inoculated in the soil, with the bulk and sterile ones as control. In soil from columns that received root exudates from a planted (versus an unplanted) apparatus, there was a significant increase in the growth of the tolerant fungi and the degradation of metsulfuron-methyl. On the other hand, the inoculation of Penicillium sp. also notably enhanced the degradation of the target herbicide. The extent of stimulation was more than twice of that measured in bulk soil. The fastest rate of disappearance of the xenobiotic occurred in the amended inoculated microcosms with 8.6 days of the half-life. The main types of low molecular weight organic acids and amino acids in the root exudates was determined to be oxalic acid, succinic acid and threonine, alanine, proline, methionine, lysine, isoleucine and leucine. What's more, by means of applying metsulfuron-methyl once again, the acclimated soil microorganisms with Penicillium sp. inoculation could sustainable rapid degrade metsulfuron-methyl. The results show that inoculation of the root-colonizing Penicillium sp. in wheat rhizosphere may be an effective approach for the rapid detoxification of soil metsulfuron-methyl contamination.