Rheological, mass transfer, and mixing characterization of cellulase-producing Trichoderma reesei suspensions

Journal Article · Sun Sep 01 04:00:00 EDT 1996 · Biotechnology Progress

DOI:https://doi.org/10.1021/bp950066b· OSTI ID:420928

Marten, M R; Velkovska, S; Khan, S A; Ollis, D F ^[1]

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1. North Carolina State Univ., Raleigh, NC (United States)

Steady and dynamic shear measurements are utilized to characterize the rheological behavior of Trichoderma reesei RUT-C30 fungal suspensions during batch growth on xylose (soluble substrate) or cellulose (particulate solid substrate) at three different fermentor impeller speeds (250, 400, and 550 rpm). Biomass concentrations versus time were unimodal on xylose and bimodal on cellulose. This behavior is consistent with relatively rapid, early growth on easily metabolized growth medium components (yeast extract), followed by a second, slower growth phase due to hydrolysis of recalcitrant cellulose by increasing cellulose concentrations. Critical dissolved oxygen (DO) concentration for T. reesei growth on cellulose was found to be 0.073 mmol/L. The DO was kept above this level by supplementing the air feed with pure oxygen, implying that mass transfer limitations were not the cause of bimodal cell growth. Steady shear rheological data showed shear thinning behavior and a yield stress for all broth samples regardless of substrate. Dynamic shear measurements on broth suspensions indicated `gel-like` behavior at low strains, with microstructural breakdown at larger displacements. Time variations of the Casson model parameters (yield stress and Casson viscosity) and dynamic moduli (elastic and viscous modulus) followed both cell mass and morphology. 45 refs., 14 figs.

• OSTI ID: 420928
• Journal Information: Biotechnology Progress, Journal Name: Biotechnology Progress Journal Issue: 5 Vol. 12; ISSN 8756-7938; ISSN BIPRET
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
42 ENGINEERING
55 BIOLOGY AND MEDICINE
BASIC STUDIES
BIOTECHNOLOGY
CELLULASE
CELLULOSE
FUNGI
GROWTH
MASS TRANSFER
MIXING
RHEOLOGY
SHEAR PROPERTIES
SUSPENSIONS
TRICHODERMA
XYLOSE