Screening Of Cellulose-decomposing Strain From Bamboo Forest And Optimization Of Its Fermentation Condition

In recent years, with the widespread application of technology organic mulch materials of bamboo forest, immeasurable economic benefits was gained from the production of bamboo shoots. However, because covered organic materials on bamboo forest soil is difficult to decay in the short term, normal growth and development of bamboo whip are seriously influence. And bamboo forest soil physical and chemical properties will change. It has become one of the main squeeze of degradation of bamboo forest. But, degradation bacteria of efficient cellulose can increase the decomposition rate of organic mulch material of bamboo forest, further relieve or eliminate degradation of bamboo forest. In addition, cellulose, a potential energy resources, is the most extensive and the abundant renewable resources in the nature. The vast majority of cellulose resources has been used unreasonably, and even abandoned directly, not only waste resources, and pollute the environment. Screening high efficient degradation of cellulose strain is the key link of cellulose convers to energy.To provide candidate strains for developing microbial inoculum of degradation of cellulose and industrialized production of cellulase, this research isolated and screened efficient cellulolytic microorganism from bamboo forest soil in Linan. The main research work containing some aspects as following:(1) 87 cellulose-decomposing microorganisms was isolated from gathering samples of litters,mulch,humus from bamboo forest in Linan.10 strains was primarily screened by Congo red stain.strain J6-1 was finally screened and its Hc,filter paper degradation rate,enzyme activity respectivelyis 2.62, 42.3%,6.87 IU/mL.(2) Based on morphological observation on carboxymethyl cellulose sodium medium, preliminarily identified Strain J6-1 as Penicillium. Through analysis of 18 s ribosomal RNA, Strain J6-1 and Penicillium oxalicum were very similar genetic relationship, J6-1 was ultimately identified as penicillium oxalate.(3) On the basis of single-factor experiments, the orthogonal experiment of 4 factors at 3 levels was then taken to optimize the liquid fermentation conditions conditions of cellulase production. The experimental results showed that the optimum conditions for cellulase production were as follow: 15 g/L straw powder as carbon, 3 g/L yeast extract as nitrogen source, 10% inoculation quantity, fermentation at 40℃ and initial pH 5.0 for 5 d. After optimizing the highest activities of CMCase and FPase enzyme of strain J6-1 reached as 41.82 IU/mL and 17.26 IU/mL respectively(4) The hereditary stability of cellulase produced Strain J6-1 was evaluated by the cellulase activity analysis of 5 consecutive generations. its characteristics of high cellulose activities can be subcultured serially.(5) Through 40 days test on degradation of bamboo forest covering, the results show that lignin maximum degradation rate and cellulose maximum degradation rate of Strain J6-1 was 26.73% and 38.73%, and weight total decreased by 153.73 g about 40 days. Compared with the untreated group of microbial inoculant, treatment group of inoculant obviously increase the degradation speed of bamboo organic mulch. Therefore, Strain J6-1 has good degradation effect on bamboo organic mulch.