Solka Floe

The effects of feedstock cellulose content on cellulase enzyme activities in the digester system were examined in multiple laboratory-scale CSTR digesters operated under similar conditions with identical levels of feedstock organic loading (g VS/reactor d) but different levels of cellulose (Solka Floe). In general, all celli se enzyme... 

Four categories of effectors (additives to the Solka Floe fermentations) can be classified by comparing relative maximum emgmie concentration and relative time required to reach the maximum FPA, to the chemical structures of these supplementing compounds. 

The first group is comprised that of compounds which potentially could be degraded to form G-l-P by phosphorolysis by beta-linkage specific enzymes. They include IPTGlu, cellobiose, sophorose, salicin, and sucrose. Addition of these compounds, or exogenous G-l-P, to Solka Floe fermentations improved maximum cellulase yields from 171 to 309%, and the time period for enzyme synthesis was reduced from 95 to 59% compared with using Solka Floe only. 

Figure 2. Time course of cellulase activity accumulation in A. cellulofyticus cultures containing 15 g/L Solka Floe and various concentrations of glucose-l-phosphate.

Table HI. Comparison of Cellulase Production Parameters Obtained Using Various Substance Addition with Parameters Obtained Using Solka Floe Only...

Concentrations of effectors added to 15 g/L Solka Floe fermentations... 

The third group is that of compounds which may potentially be transported by the PTS and inhibit cAMP production. Cellulase synthesis is initiated after these compounds are consumed for cell growth. This group includes D-glucose, D-fructose, maltose, mannitol, glycerol, sorbitol, and -methyl glucoside. The presence of these compounds in Solka Floe fermentations, enhanced enzyme yields (132 to 254%) but the time required to complete cellulase synthesis took longer (106 to 148%) than the control. 

Source of Enzymes. Culture filtrates of T. reesei strains VTT-D-79125 and Rut C-30 were used as starting material for purification of the individual enzymes and also as crude enzyme preparations in the hydrolysis experiments. Cultivations were carried out in a laboratory fermentor at 30°C for 4d on media containing Solka floe cellulose (James River Corp., New Hampshire, USA), or glucose and distiller s spent grain (Alko, Ltd., Koskenkorva, Finland). 

Figure 1. Induction of xylanases in Trichoderma harzianum. The ratios of xylanase to endocellulase activities were determined in the culture filtrates of T. harzianum grown on steam treated aspenwood. Aspen chips were steam treated from 20 to 240 s at 240° C to produce a series of samples with a variable content of xylan and cellulose. The specific content of these carbohydrates were expressed as the ratio of xylan to glucan. Enzyme activities were determined on culture filtrates of 300 mL batch cultures of T. harzianum grown on these wood samples at a loading of 1% (w/v) as described by Saddler and Mes-Hartree (66). Enzyme activities were also determined in culture filtrates of T. harzianum grown on Avicel, Solka Floe and oat spelts xylan.

The raw material that reaches the factory is a far cry from Avicel or Solka Floe that are used by many experimenters to simulate cellulosic products (Table I). In addition to the fact that the cellulose is tied up in a lignin-hemicellulose-cellulose (LHC) complex, it should be recognized that the terms lignin and hemicellulose are catchall terms covering a range of compositions and molecular weights. 

Grethlein (13) and Saeman (33) have estimated values of the various constants for acid hydrolysis of Solka Floe and Douglas Fir. These are given in Table III. 

Howell, J. A. and J. D. Stuck, "Kinetics of Solka Floe Cellulose Hydrolysis by Trichoderma viride Cellulase," Biotechnol. Bioeng. 17 (1975) 873-893. 

Fig. 2. Reducing sugars ( ) determined by DNS method and OD (A) vs time for aerobic batch cultivation of T. reesei Rut-C30. The initial growth medium was a Mandels medium with 10 g/L of glucose as the carbon source. At t = 67 h, Solka Floe was added to a concentration of 10 g/L. (There were no measurements of OD after the addition of cellulose.)...

Grafted cellulose powders such as Solka Floe have been grafted with polyacrylic acid and also rendered cationic by direct chemical reaction (54). Both of these modified cellulose products have been prepared on a large scale. They appear to show considerable promise for the removal of dyestuffs and other charged impurities from waste water such as textile effluents. They are also able to break emulsions of water and organics by removal of the surfactants (55). 

More recently, Gangneux et al (11) developed a method for grafting acrylic acid onto cellulose powder, "Solka Floe," for use in textile waste treatment. The cellulose was treated with ceric ion in aqueous solution prior to its reaction with acrylic acid. A benzene-acrylic acid solution was used for grafting to reduce homopolymerization. Presumably, the hydrated ceric ion would not diffuse into the monomer solution to initiate homopolymerization although the reverse could still take place. They obtained grafting yields up to approximately 70% accompanied by 45% homopolymer. In the present investigation, their method is extended to fibers and additional emphasis is placed on the reduction of homopolymerization. 

The product from Step 4 was cooled to 14 °C and treated with lithium t-amylate (504mmol) followed by the addition of 16.7ml (S)-l,2-chloropropanediol over 45 minutes. The temperature was maintained between 28 and 32 °C 2 hours, quenched using 37.5 ml HOAc and 225 ml water, and the pH adjusted to 6 to 9 using NH4OH. Solka floe (53.74 g) was added and the mixture heated to 75 °C. Thereafter, the solids were removed, washed with 805 ml THF, and the filtrate concentrated. The mixture was cooled to -10 °C and the precipitated product isolated by filtration, mp = 194-197 °C. H-NMR and MS data supplied. 

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