Screening Of The Thermophilic Actinomycetes And Molds With The Capability Of Lignocellulose-degrading And The Optimization Of Medium

Agricultural production brings large amount of waste such as straw, so establishing an effective way of straw processing is very necessary. In the process of straw degradation, the difficult point is the decomposition of lignocellulose, it seriously affecting the degradation rate of straw. The aim of this work is to separate thermophilic actinomycetes and molds from the compost samples, and screen out the strains those have the ability of degrading lignocellulose, next explore the suitable medium, pH and other conditions for the cultivation of these strains. Finally, the combined-culture of strains those had the higher lignocellulose degradation ability and the optimizing of media formula were carried out.By using dilution spread plate,27 strains of thermopylae molds and 42 strains of thermophilic actinomycetes were isolated from mushroom compost.8 strains of thermophilic actinomycetes and 8 strains of thermophilic molds, which could degrade cellulose and lignin, were selected out by using Congo red staining method, filter paper culture, aniline blue flat fading law and guaiacol flat fading method. After the preliminary appraisal, M2, M8, M24, M31 strains were identified as Penicillium, M14 strain belonged to Monilochaetes, M22 strain belonged to Mucor, M26 strain belonged to Paecilomyces, M28 strain belonged to Aspergillus.8 strains of thermophilic actinomycetes belonged to Streptomyces, and based on 16s rDNA sequence alignment results, AG3, AG4, BG23, FG25, FG35 and FG39 strains could be confirmed their classification status, but EG 16 and EG 17 strains could not be identified because there were no matched gene sequence to be found in the GenBank. The optimal culture temperature of these strains was 45℃.The effects of selected substrates on the thermophilic molds and actinomycetes were examined. By comparing the CMC activity and MnP activity in 4 different solid media (i.e. Agaricus blazei fungal chaff medium, cottonseed shell medium, sawdust medium and Pleurotus ostreatus fungal chaff medium), the result showed that Agaricus blazei fungal chaff medium was the best substrate for the culture of thermophilic mold and actinomycete strains. Meanwhile, M2, M22 and M28 strains were proved to be the better thermophilic mold strains and AG4, BG23 and FG25 were proved to be the better thermophilic actinomycete strains for efficiently degrading lignocellulose. The results also demonstrated that the moisture content and pH of culture medium had a significant impact on CMC enzyme activity and MnP enzyme activity of these strains. M2 strain had the highest enzyme activity in the medium of pH 7 and moisture content of 54%, M22 strain had the highest enzyme activity in the medium of pH9 and moisture content of 54%-62%, M28 strain had the highest enzyme activity in the medium of pH9 and moisture content of 62%, AG4 strain had the highest enzyme activity in the medium of pH7 and moisture content of 62%, BG23 strain had the highest enzyme activity in the medium of pH9 and moisture content of 54%, FG25 strain had the highest enzyme activity in the medium of pH9 and moisture content of 54%.The combined-culture of thermophilic mold strains M2, M22 and M28 and thermophilic actinomycete strains AG4, BG23 and FG25 as well as formulation optimization of Agaricus blazei fungal chaff medium were studied. The results showed that in the medium favored the improvement of CMC activity and MnP activity. Adding 5% wheat bran in medium resulted in the higher enzyme activity of M2 strain. Adding 10% corn flour or 15% wheat bran in medium resulted in the higher enzyme activity of M22 strain. Adding 10% corn flour or wheat bran in medium resulted in the higher enzyme activity of M28 strain. Adding 10% wheat bran in medium resulted in the higher enzyme activity of AG4 strain. Adding 10% wheat bran in medium resulted in the higher CMC enzyme activity of BG23 strain. Adding 10% or 15% wheat bran in medium resulted in the higher MnP enzyme activity of BG23 strain. Adding 15% corn flour or wheat bran in medium resulted in the higher enzyme activity of FG25 strain. Comparing the effects of the three kinds of supplementary material to the enzyme activity, wheat bran was proved to be the optimal auxiliary material and favored the decrease of culture time and the increase of effective cell number of molds or actinomycetes. By orthogonal test, the optimum culture conditions for the combined-culture of M2, M22 and M28 strains were moisture content of 62%, wheat bran of 15%, pH 9 and culture time of 5 days. The optimum culture conditions for the combined-culture of AG4, BG23 and FG25 strains were moisture content of 62%, wheat bran of 15%, pH 7 and culture time of 7 days.