Suspensions of the polymorphic yeast Kluyveromyces marxianus var. marxianus NRRLy2415 were grown in batch and continuous culture, producing broths with a range of mean cell morphologies. The mean cell aspect ratio, L-dm, defined as the mean ratio of total cell length to equivalent cylindrical diameter, was measured for each broth by image analysis and ranged from 1.7 to 51. The porosity of the cell pellet formed in a bench-top centrifuge was measured for each broth and in all cases, the pellet porosity decreased linearly with increasing centrifuge speed. This decrease became more pronounced as L-dm increased. The extrapolated zero-speed pellet porosity, epsilon(0), was correlated with L-dm by the expression epsilon(0) = 1-1/(1.24+0.062L(dm)). The dead-end specific cake resistance, alpha, was measured for each broth in the pressure range 30-180 kPa. The cake compressibility constant, k(c) defined by the expression alpha = alpha(0)(1+k(c) Delta P) was found to increase with increasing values of L-dm. The increase was most rapid in the region, L-dm < 10. Microscopic observations indicate that cell deformation at branching points may contribute to cake compressibility. (C) 2002 Elsevier Science B.V. All rights reserved.