Though minerals can be produced by fungi, they can also be degraded; mainly by oxalic-acid producing strains of fungi. Oxalic acid production is increased in the presence of glucose for three organic acid producing fungi – "Aspergillus niger", "Serpula himantioides", and "Trametes versicolor". These fungi have been found to corrode apatite and galena minerals. Degradation of minerals by fungi is carried out through a process known as neogenesis. The order of most to least oxalic acid secreted by the fungi studied are "Aspergillus niger", followed by "Serpula himantioides", and finally "Trametes versicolor". These capabilities of certain groups of fungi have a major impact on corrosion, a costly problem for many industries and the economy.