Assessing biodeterioration in wood using ATP photometry: Part II. Calculating a conversion factor for Phanerochaete chrysosporium using ATP and adenylate Energy Charge

The ATP content and Energy Charge (EC) of Phanerochaete chrysosporium (a white rot), was measured at different phases of growth in batch culture. The nucleotide, protein and chitin contents, and the dry weight of the mycelium were measured during 4 weeks of incubation. The log growth phase was associated with the highest ATP concentrations and highest EC values. The variation in the ATP content of the mycelium was classified using the EC values. Two classes were identified: class 1 included samples with EC equal to or larger than 0.65; and class 2 included samples with EC below 0.65. The average ATP content for class 1 was 4.57 nM mg−1 of dry weight, and for class 2, 0.99 nM mg−1 of dry weight. These average values were adopted as conversion factors (ATP/biomass) to estimate fungal biomass in field samples. Protein and chitin measurements were not as consistent and varied more than the ATP values. Protein concentrations varied between 12.43 μg mg−1 of dry weight, on the third day of growth, and 87.03 μg mg−1 of dry weight on the seventh day of growth. Similarly, the chitin content of P. chrysosporium varied between 4.59 μg mg−1 of dry weight on the first day of growth and 82.25 μg mg−1 of dry weight on the tenth day. The variability found in the protein and chitin content was not as classifiable as the ATP data. An average of all the protein and chitin measurements (protein = 48.34 μg mg−1 of dry weight; CHITIN = 49.96 μg mg−1 of dry weight), regardless of the phase of growth, was adopted as the conversion factor to estimate fungal biomass.