Influence of spore morphology on spectrophotometric quantification of Trichoderma inocula - headings

Supplementary Figure 1. Influence of spore morphology on spectrophotometric quantification of Trichoderma inocula

Schematic diagram of the workflow. Starting at the left upper panel, fungal cultures with mature conidia are required, and are harvested by lifting the cells into 0.05% Tween® 20 solution. For each dilution, absorbance and cell count should be determined and the absorbance plotted against the number of cells per unit. The calibration curves can then be used to determine the cell count of other inocula of the same species by simply measuring the absorbance.

Supplementary Figure 2. Influence of spore morphology on spectrophotometric quantification of Trichoderma inocula

Without the effect of multiple scattering, the optical cross section for scattering per cell, σS, is the ratio of absorbance (Abs) and cell count (Spores) as follows: σ_S=Abs/Spores. To eliminate the effect of multiple scattering and to obtain σS [17], the empirical equation:

Spores/Abs=α+β*Spores,

with α and β as coefficients for a linear regression, respectively, is extrapolated to zero cells. When Spores tends to zero, we receive the simpler form Abs=Spores/α, and after rewriting σ_S=1/α . The intercept on the y-axis α gives the value of σS. In our study, all four Trichoderma strains have similar values of σ_S=6.9*10^(-8) 〖cm〗^2,6.7*10^(-8) 〖cm〗^2,6.6*10^(-8) 〖cm〗^2 "and" 6.9*10^(-8) 〖cm〗^2 for Tr QM9414, Tr Δxyr1, Tr Δpks4 and Ta P1, respectively (ANOVA, p > 0.05). Tr and Ta annotate the species names T. reesei and T. atroviride, respectively.


Article Abstract:

Species of the genus Trichoderma are filamentous fungi commonly used in research, industry and agriculture. T. reesei strains are prominent producers of cellulolytic and hemicellulolytic enzymes as well as expression hosts, and several other species such as T. atroviride might be exploited as biocontrol agents. A careful preparation of Trichoderma inocula, which consist mainly of conidia (asexual spores), is of immense importance. Conidia concentration is still mostly determined with the help of a hemocytometer, however, as a more accurate and timesaving alternative, absorbance can be used to estimate fungal spore counts. We established a spectrophotometric method for fast and reliable preparation of Trichoderma inocula by evaluating the effect of size, shape and pigmentation of the conidia at different wavelengths.