The main organism studied is Penicillium ochrochloron (= P. simplicissimum in older publications). Major research topics are growth phases, sudden onset of – and relief from – nutrient exhaustions (at the levels metabolism, electron transport chain and plasma membrane), overflow metabolism (organic acid excretion), bioenergetics (adenine and pyridine nucleotides), and plasma membrane transport. Further foci include the rapid stop of metabolism, the extraction and quantification of metabolites (HPLC, CE, MS), and the purification of plasma membranes. Sophisticated bioreactor cultivation (continuous and batch) is used to guarantee highly standardized growth conditions.