Cellulolytic activity

The strains were cultured on Mandels medium + 1% citrus pectin for 5 days and the enzymatic activities of culture filtrates were determined on three substrates citrus pectin, polygalacturonic acid and filter paper, (a) extracellular proteins are in p.g/ml. (b) p>ectinolytic activities on pectin (PC) and on polygalacturonic acid (TO) and Pectin esterase (PE) are in units/ml. (c) total cellulolytic activity (filter paper, fp) are in mg of liberated reducing sugars/ml. 

Farris, J.L., S.E. Belanger, D.S. Cherry, and J. Cairns, Jr. 1989. Cellulolytic activity as a novel approach to assess long-term zinc stress to Corbicula. Water Res. 23 1275-1283. 

In searching for means to enhance this in vitro activity, a range of fungal isolates were screened for cellulolytic activity on straw. The tests used to assay activity included clearing of cellulose agar (zone size measured), loss of weight from straw, colony radial extension rate on a water-soluble extract... 

The proteolysis of cellulases has been previously investigated. Nakayama et al. (14) found that mild proteolysis of endoglucanase from T. reesei by a protease prepared from the same fungus resulted in cellulase enzymes which still possessed cellulolytic activity. Earlier, Eriksson and Petterson (24) investigated the effect of various proteolytic enzymes on the cellulase activities on Penicillium notatum. They found that different proteases affected enzyme activities to different degrees. 

Location and Development of Cellulolytic Activities in a Culture of Thermoactinomyces sp. 

Extracellular Cellulolytic Activities. The appearance of the CM-cellulase activity in a culture of Thermoactinomyces grown on 1% microcrystalline cellulose is shown in Figure 2. The extracellular CM-cellulase activity approached a maximum of 14-16 mg reducing sugar (RS) mL-1 min"1 within 18-24 hr. The Avicelase activity of the culture filtrate developed simultaneously with the CM-cellulase activity and amounted to 3 mg RS mL"1 hr"1. The extracellular protein concentration reached 1.7 mg/mL in the stationary phase (6). 

The CM-cellulase activity of the solids fraction shows a skewed curve over the period of 4-24 hr with a maximum of 3 mg RS mL"1 min"1 around 8 hr, at which point it makes up about 50% of the activity in the whole culture broth (Figure 2). No activity could be detected in the solids fraction in the late stationary growth phase. Within experimental error, the CMC activity of the culture filtrate plus that of the culture solids equals the activity of the whole broth. Similarly, it was found for Thermoactinomyces, strain MJ0r, grown on 0.5% microcrystalline cellulose, that there was a lag before an appearance of extracellular cellulolytic activity, as compared with the activity in the whole culture broth (4). In a culture of Thermoactinomyces, strain YX, the CM-cellulase activity can be desorbed readily by washing the solids fraction with water. These wash fractions also show Avicelase activity (6). This result, and the fact... 

Cell-Associated Cellulolytic Activities. The / -glucosidase activity is associated with the culture solids throughout the entire growth period, and no activity is found in the culture filtrate (Figure 3). A maximum... 

Stability of Cellulolytic Activities of Thermoactinomyces with Respect to pH and Temperature... 

Figure 7. Temperature-activity profile for cellulolytic activities from Thermoactinomyces sp. under assay conditions. Same symbols and conditions as Figure 6.

Optimum cellulolytic activity is produced within 24 hr of growth, at which time the culture can be harvested to obtain enzyme for saccharification. 

The extracellular cellulolytic activities, CM-cellulase and Avicelase, are stable over 24 hr at 55°C in the pH range of 6.0-7.3, which suggests that no enzymatic activity would be lost in a saccharification under these conditions and that the enzymes would be recoverable. 

Filter paper activity, which describes the overall cellulolytic activity of an enzyme preparation, was determined by the method of Mandels et al. (16). A 1 x 6 cm strip of Whatman no.l filter paper (Hillsboro, OR), which equals 50 mg of cellulose, served as the substrate and was added to the sample solution containing 0.5 mL of appropriate diluted enzyme (supernatant of culture broth) and 1.0 mL of 0.05 M citrate buffer (pH 4.8). After 60 min of incubation at 50°C, the hydrolysis was terminated by the addition of 3 mL of DNS solution, and the mixture was further assayed for reducing sugar content by the DNS method. One international filter paper unit (FPU) was defined as the amount of enzyme that releases 1 pmol of glucose/min under the assay conditions. Activities were reported as FPU/milliliter. 

Total cellulolytic activity was measured using the filter paper assay (FP A) according to Ghose (11) based on an estimation of the released reducing sugars by dinitrosalicylic (DNS) acid (12). 

Fig. 1. Cellulolytic and xylanolytic activities and extracellular protein during time course of the cultivation of P. brasilianum IBT 20888. (A) Cellulolytic activities on cellulose (B) cellulolytic activities on xylan (C) xylanase activities on cellulose and (D) xylanolytic activities on xylan. ( ) BG ( ) CBH ( T ) EG ( O ) BX ( O ) AF ( V ) EX (+) extracellular protein ( —) cultivation on cellulose and (----) cultivation on xylan.

Cellulolytic Activities for T. reesei Rut C30 and for Four Penicillium Species with Highest FPA After Cultivation in Shake Flasks"... 

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