The Screening Of Cellulase Producer Strains And Their Application In The Development Of WMFC

As the carbohydrate most broadly existing in the world, cellulose is a kind of abundant and sustainable resource. However, only a small part of the cellulose in the nature is used, with a large amount wasted, and even brings pollution to the world because of improper usage.The waste material from fungal culture (WMFC) is waste material after fruiting body harvest with remnant of edible fungi and carbohydrate such as cellulose, hemicellulose and lignin degraded by the edible fungi. Before desposal, WMFC has low level of raw protein, but high level of carbohydrate such as celloluse and lignin.In order to find a method to produce cellulase by microorganism, get energy resource, food and chemical material from cellulose, and solve problems such as the pollution to the environment, the lack of food and energy resource crisis, microorganisms from the soil are screened. After getting the strain that can make use of WMFC in high effect, the study of optimal fermentation condition and mixed culture fermentation are launched to get the technic producing single cell protein form WMFC.First, 40 strains are gained by the screening of medium with cellulose as only carbon resource, then, 8 strains a gotten from cellulose-Gango red medium. Finally, strains A, B, E, F, G are gotten from WMFC medium. By glass slide culture and observation, F is judged as Mucor, while G Rhizopus. Continuous fermentation with double purposes both screening and ascertaining the fermentation condition is launched later. Strain F is ascertained as the best strain for using wood bits WMFC, while strain G the best for cottonseed hull. The best fermention time is 24 hours.Both strains F and G have the highest enzyme activity and population at 30℃. Strain F has the best enzyme activity at pH=7, but highest population at pH=6; strain G has highest enzyme activity and population at pH=6. Every kind of metal ions used in the study brings bad effect to the strains'growth, accordingly, Co²⁺,Mn²⁺,Fe³⁺,Zn²⁺ have the enzyme activity declined. However, Fe²⁺ is harmful to strains'growth, but it has strong activation to the enzyme activity, and makes it higher. Both strains F and G grow best in 2×nutrition concentration, and show highest enzyme activity. Over high concentration is not good for the growth of strain and fermention because of high filter pressure. Neither of the strains is sensitive to carbamide and ammonium chloride. The extract of enzyme proves that the enzyme activity of strains F and G are not lower than the strain bought.After the ascertaining of optimal sugar producing condition of strains F and G, how we can heighten the protein produce capability is to be studied. By mixed culture fermentation of strains F and G with yeast, we got the way to produce protein in higher level. The mixed culture fermentation with yeast hightened the production of protein of strain F by one time, while more than twice of strain G. The peak of protein production by solid mixed culture fermentation of strain F and yeast is 5.46 g/L, 6.42 times of liquid, while strain G and yeast 5.75 g/L, and 6.05 times.