Effects of nitrogen on mineral nutrients and cadmium accumulation in a strain of DSE mycelium under cadmium stress

Abstract

The dark septate endophytic fungus (DSE) Exophiala pinsciphila was used to study the effect on growth and mineral nutrients (Ca, Mg, N, P, S) and cadmium (Cd) accumulation of DSE under the different nitrogen concentration and cadmium stress (100 mg·L−1). Under cadmium stress, treatment with low nitrogen significantly increased the pH of the mycelium and culture medium, while high nitrogen significantly reduced the mycelium dry weight, the number of spores, and the pH of the culture medium. The minerals in the mycelium were significantly affected by nitrogen concentration; the Ca and P contents were significantly increased under high nitrogen conditions, while Mg and N content decreased significantly. Under normal nitrogen conditions while under cadmium stress, the nitrogen content of the mycelium was significantly decreased, while higher nitrogen significantly increased the cadmium content of the mycelium. The dry weight of DSE mycelium, the mycelium Cd content, and the mycelium Mg content were significantly negatively correlated, along with the dry weight of P and hyphae. Studies have shown that under cadmium stress, exogenously added high concentrations of nitrogen reduce DSE cadmium tolerance, inhibit growth, and cause the absorption and utilization of minerals; in contrast, low concentrations of nitrogen enhance the growth of the strain.