Effect of cell morphology on dead-end filtration of the dimorphic yeast Kluyveromyces marxianus var. marxianus NRRLy2415

The dead-end filtration characteristics of the dimorphic yeast Kluyveromyces marxianus var. marxianus (formerly fragilis) NRRLy2415 were investigated for a range of mean cell morphologies, ranging from predominantly yeast-like to predominantly filamentous. Semiautomated image analysis was used to measure the mean cell specific surface area, S-v, and the mean ratio of cell length to equivalent cylindrical diameter, L-dm, in each broth. The method of Ju and Ho (Biotechnol. Bioeng. 1988, 32, 95-99) was used to show that for broths with L-dm values between 1.72 and 10.03, the voidage of cell pellets formed by centrifugation increased with increasing L-dm In the pressure range 30-180 kPa, the specific filter cake resistance, alpha, was found to be related to pressure, Delta P, through the equation alpha = alpha(0)(1 + k(c) Delta P). The dependence of alpha(0)/S-v(2) on L-dm was found to be qualitatively consistent with the pellet voidage data and the Carman-Kozeny equation. Considerably better agreement with the experimental data was obtained when the Kozeny constant, K, was treated as variable and related to L-dm through the equation K = 4.83 + 7.08 log(10) L-dm. The cake compressibility constant, k(c), was found to increase with increasing L-dm, a phenomenon consistent with the wide range of voidages that can be displayed by beds of long cylinders.