Chemoattraction of anaerobic ruminal fungi zoospores to selected phenolic acids.

Three phenolic acids, p-coumaric acid, ferulic acid and syringic acid, were evaluated as chemoattractants for zoospores of two monocentric and two polycentric isolates of anaerobic, zoosporic ruminal fungi. Attraction of fungal zoospores to the acids was determined by a modification of the Palleroni method and fungal thallus forming units were counted after incubating capillary tubes in a chemotaxis chamber. Chemotactic response was expressed as relative taxis response (RTR), which is the ratio of accumulation of zoospores in test capillaries to that in control capillaries. Monocentric isolates had greater RTR values then did the polycentric isolates. The order of chemoattraction for the uniflagellate isolates was p-coumaric acid > ferulic acid > syringic acid. The order of attraction was different between the two isolates with multiflagellate zoospores. Ferulic acid and p-coumaric acid were better chemoattractants than syringic acid. Peak response for the monocentric isolates was 1.0 mumol l-1 while that for the polycentric isolates was 0.1 mmol l-1.