Investigation of the role of the alternative NADH dehydrogenase in submerged cultures of Aspergillus niger B1-D
The electron transfer chain (ETC) of many filamentous fungi is highly branched, containing numerous â€˜coreâ€™ and alternative respiratory enzymes, such as the alternative oxidase (AOX) and alternative NADH dehydrogenases. Although the precise physiological role of the alternative respiratory enzymes in fungi is somewhat obscure at present, they have been implicated in various cellular mechanisms, for example, reduced reactive oxygen species (ROS) generation in Aspergillus niger by enhanced activity of the alternative NADH dehydrogenases. In order to better understand the physiological relevance of the alternative NADH dehydrogenases in fungi, the effects of inhibition of these enzymes in submerged cultures of A. niger was investigated. Cultures were grown in the presence of a known inhibitor of the alternative NADH dehydrogenases of plants, 7-iodoacridone 4-carboxylic acid (IACA), and culture metabolism and performance was assessed. In IACA-pretreated cultures, both growth and glucose consumption rates decreased, the yield of biomass on glucose and intracellular protein concentrations increased, although intracellular ATP concentrations were lower. These distinct differences are consistent with an increased electron flux via Complex I of the â€˜coreâ€™ ETC paired with AOX, and accordingly further work will focus on investigation of this relationship.
Full conference title:
158th Meeting of the Society of General Microbiology