Swainsonine Accumulation by Endophytic Undifilum Fungi in Liquid Media and Determined by Means of a Modified Enzymatic Assay

摘要

Endophytic Undifilum oxytropis found within locoweeds produces the poisonous alkaloid swainsonine which is responsible for locoism in grazing animals. A modified enzymatic assay for swainsonine in the mycelia of Undifilum fungi was developed. The standard equation was Y = 0.5169X- 0.1129 (regression coefficient r = 0.9985). The calibration graph of swainsonine was linear in the range 0.05-0.5 μg mL-1. The method was validated for linearity, precision and accuracy. The modified method has been applied to explore the swainsonine accumulation properties in the endophytic Undifilum fungi in liquid media. Under the described culture condition, the mycelia weight reached a maximum value on the 20th day whereas the peak of swainsonine biosynthesis took place on the 28th day. The result indicated that the increment of mycelium weight and the swainsonine accumulation in the endophytic Undifilum fungi is not completely synchronous.