Extracellular proteases produced by the Quorn® myco-protein fungus Fusarium graminearum in batch and chemostat culture

Abstract

Fusarium gramhearum was grown in batch and continuous (chemostat) culture on a glucose-mineral salts medium in the presence and absence of casein. In the absence of casein no protease activity was detected in the culture filtrate from either batch or chemostat culture. For batch cultures grown on medium containing casein, most of the proteolytic activity detected in the supernatant during exponential growth had an optimum at ca pH 50. However, as the cultures passed from late exponential into stationary phase, the pH profile of the protease activity broadened until most of it was in the alkaline pH region. For glucose-limited chemostat cultures grown on media containing casein, protease activity had a narrow pH optimum with maximum activity at pH 59. For all concentrations of casein examined, protease activity was greater in chemostat culture than in batch culture. Extracellular proteases from batch and chemostat cultures were purified by bacitracin-Sepharose affinity chromatography. A t least seven proteins were purified from batch cultures but chemostat cultures contained only a single aspartic protease with a molecular mass of 40 kDa.

Recombinant Glucoamylase Production byAspergillus nigerB1 in Chemostat and pH Auxostat Cultures

“…Significantly, regulation of genes in Aspergillus nidulans by ambient pH (e.g., elevated penicillin biosynthesis at high pH) has been observed previously (Espeso et al, 1993). Alternatively, the increase in GAM concentration at pH 4.0 may be due to a decrease in protease activity at this pH (Archer et al, 1992;Griffen et al, 1997). However, protease expression and secretion is highly nitrogen regulated and extracellular GAM concentrations are unlikely to be reduced by protease activity in the presence of excess ammonium (Davies, 1990).…”

Role of the Botrytis cinerea FKBP12 ortholog in pathogenic development and in sulfur regulation

“…The serine protease activity from culture filtrates was determined according the procedure established by Griffen et al (1997) and adapted by Billon-Grand et al (2002). The assays were performed with 300 ll of the culture filtrates mixed with 800 ll of citrate phosphate buffer 150 mM pH 7.0 and 100 ll of azocasein solution at 15 mg/ml (Sigma-Aldrich, dissolved in 150 mM Tris/HCl buffer, pH 8.0) used as a substrate.…”

Production of tissue plasminogen activator (t‐PA) in Aspergillus niger

“…Protease activity was assayed using azocasein as a substrate, as described by Griffen et al (1997), at pH 4 (Naacetate buffer), 5 (Na-acetate buffer), 6 (Na-acetate buffer), and 7 (piperizine-N,NЈ-bis-2-ethane-sulfonic acid buffer). Protease assays were carried out in triplicate.…”