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Fungi, in particular Aspergilli, are well known for their potential to overproduce a variety of organic acids. These microorganisms have an intrinsic ability to accumulate these substances and it is generally believed that this provides the fungi with an ecological advantage, since they grow rather well at pH 3 to 5, while some species even tolerate pH values as low as 1. 5. Organic acid production can be stimulated and in a number of cases conditions have been found that result in almost quantitative conversion of carbon substrate into acid. This is exploited in large-scale production of a number of organic acids like citric-, gluconic- and itaconic acid. Both in production volume as well as in knowledge available, citrate is by far the major organic acid. Citric acid (2-hydroxy-propane-1, 2, 3-tricarboxylic acid) is a true bulk product with an estimated global production of over 900 thousand tons in the year …