Comparison of hyphal length, ergosterol, mycelium dry weight, and colony diameter for quantifying growth of fungi from foods

Fungi are significant environmental microorganisms, as they are responsible for spoilage of foods, production of mycotoxins and in some cases desirable bioconversions. It is important therefore to have reliable, convenient methods for measuring fungal growth. However, the growth of fungi is not easy to quantify because, unlike bacteria and yeasts, fungi do not grow as single cells, but as hyphal filaments that cannot be quantified by the usual enumeration techniques. Fungal hyphae can penetrate solid substrates, such as foods, making their extraction difficult. In addition, fungi differentiate to produce spores, resulting in large increases in viable counts often with little relationship to biomass.