Fermentation in 24-well plates is an efficient screening platform for filamentous fungi.

UNLABELLED: Fermentation by filamentous fungi in Erlenmeyer flasks is a favoured method for comparing different fermentation conditions. However, significant inter-flask variation often occurs when using Erlenmeyer flasks, which makes the comparison of fermentation product levels less reliable. We have investigated the use of a 24-well plate method for citric acid, ethanol and glycerol batch fermentation using the filamentous fungi Aspergillus carbonarius and compared the relative standard deviation (RSD) from sextuplicates obtained using Erlenmeyer flasks and 24-well plates. The production levels using the Erlenmeyer flasks showed a combined average RSD of 29%, which is two and a half-fold higher than what was measured using the 24-well plates showing an average RSD of 12%. We conclude that fermentation in 24-well plates is a more reliable screening method for metabolite production by filamentous fungi and possibly for screening metabolites in general. SIGNIFICANCE AND IMPACT OF THE STUDY: Fermentation studies with filamentous fungi and especially screening experiments often struggle with high inter-vessel variations in metabolite production. This study compares two different types of frequently used screening methods namely batch fermentation in Erlenmeyer flasks with batch fermentation in 24-well plates. The results demonstrate that the variance potentially can be reduced two and a half-fold using 24-well plates leading to improved resolution when testing the impact of varying fermentation parameters on product formation.