RESPIRATION OF [C-14] ALANINE BY THE ECTOMYCORRHIZAL FUNGUS PAXILLUS-INVOLUTUS

The ectomycorrhizal fungus Paxillus involutus efficiently took up exogenously supplied [C-14]alanine and rapidly converted it to pyruvate, citrate, succinate, fumarate and to CO2, thus providing direct evidence for the utilisation of alanine as a respiratory substrate. [C-14]alanine was further actively metabolised to glutamate, glutamine and aspartate. Exposure to aminooxyacetate completely suppressed (CO2)-C-14 evolution and greatly reduced the flow of carbon from [C-14]alanine to tricarboxylic acid cycle intermediates and amino acids, suggesting that alanine aminotransferase plays a pivotal role in alanine metabolism in Paxillus involutus.