Measurement of fungi through its perpendicular diameters is one method while it is growing on insoluble carbon (cellulose) and nitrogen sources. We can also observe the hydrolytic activity of fungi if it is forming a halo clear zone on petriplates.

You can add the sterile carbon or nitrogen sources in to the media. Then known fungi is inoculate into plates contain media, after few days (appropriate temperature and time) you can measure colony diameter. Using the time period and colony diameter you can measure growth rate. 

You can measure the growth diametre of the fungus for estimating the effects of different parameters on its growth rate. You can use also the mycelial dry weight of the fungus after growth on broth medium for different incubation intervals or at different incubation  temperatures.

if fungal culture is in a liquid medium, you can measure the growth in these ways:

-pick up a representative part of the crop and dry it in the oven at 80 ° C until the weight is constant; do the same procedure on the same amount of the growth substrate. The difference in weight between the two samples corresponds (approximately) to the fungal growth.

-take a representative portion of the fungal culture, filter it through a 0.45 mm filter and analyze the ergosterol present in the solid part.

-take a representative part of the fungal culture and plate it, either directly or after dilution series, on Petri dishes filled with a suitable medium. In this case the result will be a measure of the colony forming units and not a direct measure of growth.

Best regards

Thank you Dr. Ricelli. I think method 2 is more relevant.

You could measure the diameter of the colony every day after you inoculated the pathogen and then calculate the growth rate from one day to another. Or you could also calculate the surface of the colony by the mathematical formula for Sphere Surface Area = 4 • π • r² = π • d² and then observe the differences that appear from one day to another.

http://www.usamvcluj.ro/files/teze/en/2012/miclea.pdf

pg 41 

I've often found this to be an issue. Ergosterol analysis is good, otherwise, depending on what equipment you have you could consider monitoring the Oxygen usage and CO2 production and with a bit of maths this could give you the growth rate.

You may take dry weight as a measurement. Control flasks without fungal inoculation (that may contain media and your insoluble substance) may serve as control from which you can derive the actual growth of fungus. 

dry weight measurement is misleading during cellulase production from insoluble carbon/nitrogen sources, since the insoluble material will also be de-polymerised/Utilized during fungal growth progression.

Anybody using ATP measurement for growth estimation in fungi??

ATP measurement is not feasible in routine as kit available is costly and results we get can not give direct correlation between biomass and cellulase production phase

Thank you all for your views and suggestions

I am lichenologist!

Your question is valid. I am also facing the same problem in the similar type of experiments. We also find it difficult get the growth rate as the  non utilized nitrocellulosic biomass is interfering.

We are trying to solve the problem we shall reply to you if we reach to some solution.

We expect that you will also intimate if you find some solution to it.

Thanks Dr. Tandon,

I will be in touch.

I am presently facing the same problem. kindly intimate me on how you go about it. interference of undissolved particles has been my challenge