Cellulase formation

Cellulase Activities and Cellulase Formation Rates (rc) in Shake-Flask Experiments by d 4 of Cultivation... 

The sohd-state fermentation for cellulase production is an aerobic process therefore, aeration is necessary for cell growth and cellulase formation. In addition, aeration is important in order to maintain humidity, to remove gaseous metabolites, such as COj, as well as to remove the heat of metabolism [42,43]. In a large-scale solid-state fermentor, aeration is so important that it must be controlled carefully. The aeration method and the flow rate as well as the temperature and humidity of the air supply must be regulated to avoid sudden changes in temperature and water activity of the solid medium [29,31]. 

Cellulase Formation during Bacterial Growth. The cellulolytic Pseudomonas is, like Clostridium and Cellulomonas (12), known to produce cellulases constitutively, though they are very small in amount (0.5-5 CMC-liquefying units/ml. culture) when it was grown on individual various lower alcohols, organic acids, or amino acids as C-source (41). 

Each figure is an average value of three points in the maximal region of the cellulase formation. Abbreviations G2 to G6 cellobiose to cellohexaose, G25 cellodextrin of DP = 25... 

M. Mandels We are very interested in your results. In our experiments with Trichoderma viride we have had low yields of cellulase in 0.5-1.0% cellobiose culture, similar to your results with P. fluorescens. However, we could get excellent production of cellulase in these cultures when cellobiose consumption was slowed by sub-optimal temperatures, reduced aeration, or certain imbalances in the nutrients. We believe that high cellobiose levels repress cellulase formation. When the metabolic rate was decreased, however, the repression was relieved and cellobiose acted as an inducer. We believe, in fact, that cellobiose, the product of cellulase action, is the true inducer in a cellulose culture. Here the cellobiose is consumed by the fungus as rapidly as it is produced and never builds up to repressing levels. 

The role of cellobiose is complex (Figure 3). It is an inducer of cellulase, and can act also as an inhibitor of cellulase action (27). In addition, high concentrations (0.5-1.0%) of cellobiose or other rapidly metabolized carbon sources such as glucose or glycerol strongly repress cellulase formation (23, 24), so that cellulase does not normally appear... 

---