Abstract

ORTEGA-SANCHEZ, E.; LOERA, O.  and  VINIEGRA-GONZALEZ, G.. The effect of the ratio between substrate concentration and specific area of the support on the biomass yield of fungal surface cultures. Rev. Mex. Ing. Quím [online]. 2012, vol.11, n.3, pp.485-494. ISSN 1665-2738.

A parameter, σ₀ = S₀α^-1 (gcm²), is defined. Where, S₀, (gcm^-3) is the initial substrate concentration and α is the specific area of the solid support. This parameter helps comparing the biomass yields, Y_X/S, of fungical superficial cultures either with a fixed S₀ value and variable α or with fixed α and variable S₀. A. niger cultures followed the logistic equation with maximal surface density _ρAM (gcm^-2). Final average thickness, h, was measured by image analysis. The values of h, followed a saturation function of σ₀(R² = 0.965) with extrapolated value h_MAX ≈ 0.4 cm. But the volumetric density _ρV =_ρAMh^-1 was nearly constant_ρV≈ 0.046 ± 0.005 (gcm^-3). The regression = Y₀^-1 + σ₀ε^-1 (R² = 0.95) in the range, 5.9 mgcm^-2 < (σ₀ < 62.8 mgcm^-2 indicated, Y₀ = 0.5, as the maximal biomass yield, and ε = _ρVh_MAX ≈ 0.02 gcm^-2, as a measurement of the biosynthetic efficiency. This approach could be useful for the normalization end comparison of screening tests of fungal surface cultures with a variety of solid supports and culture conditions. For example, cultures with different S₀ values but, similar yield coefficient Y_X/S.

Keywords : fungal surface cultures; mass balance; specific area; biomass yield; Aspergillus niger.