Decomposing Strains Capable Of The Residual Organic Mulch Materials Of Phyllostachys Proecox Forest And Optimization Of Enzyme Production Condtions

Phyllostachys proecox is a early shooting, high yield and delicious scattered bamboo species, planted in large area of south of the Yangtse River. Since 1990s, with the popularization and application of organic materials mulch technology, advance in shooting and supply of shoot in off-season significantly improved the economic benefits of P. proecox. But long-term mulch management of bamboo forest caused adverse impact, the most outstanding disadvantage was productivity decline. One of the main reasons was residual organic material in the forest, and was difficult to be decomposed in short term. Tt is a great significance of investigation on the microbial response to organic materials mulching and degradation of organic materials by microbe to recover and promote sustainable management of P. proecox forest.In this study, soil from different mulch year forest was selected as experiment materials, spatial variation regularity of soil nutrient and microbial biomass was studied. In addition, strains with high efficiency degradation ability of organic mulch was isolated and identified, and enzyme production condtions was optimized. The conclusions are as following:1. The influence of mulch management on soil nutrientContent of soil organic matter increased with the increase of mulch years. Content of soil organic matter of 1a,3a,6a was 7.64%,14.07% and 36.16% more than that of CK in 0-10cm soil layer. Soil total nitrogen and available nitrogen content of mulch years has no obvious difference, and the C/N of soil increased, the C/N of 6a mulched P. proecox forest was 1.42 times of CK in 0-10cm soil layer. Total phosphorus decreased while the available phosphorus increased with the increase of mulch years, the content of total phosporus in 6a mulched P. proecox forest was only 55.17% of CK. Available phosphorus content increased with the increase of mulch years, and there was 108.19% more than that of CK in 6a mulched P. proecox forest. The content of total potassium and available potassium increased firstly and then decreased, that of 3a mulched P. proecox forest was highest of all treatments which was 1.42 and 4.55 times that of CK. The pH value decreased with the increase of mulch year, soil pH was 18.18%,24.04% and 31.72% less than that of CK in 0-10cm soil layer.2. The influence of mulch management on soil microorganismThe quantity of total microbes decreased with the increase of mulch years. The quantity of total microbes of 6a mulched P. proecox forest soil was just 28.42% that of CK. During mulching, bacteria was the dominant population of soil, and accounted for more than 90% that of total microbe, and the proportion of fungi increased at the end of mulching, but actinomycetes rarely was detected. In 0-10cm layer, soil microbial biomass carbon and phosphorus declined with the increase of mulch year, the soil microbial biomass carbon and phosphorus of 6a mulched P. proecox forest was 64.13% and 90.64% less than that of CK. No obvious difference on microbial biomass nitrogen was found among mulch year forest. During mulching, the peak value of soil microbial biomass carbon and nitrogen appeared in February, and that of soil microbial biomass phosphorus appeared in January.3. Isolation and identification of high efficiency organic mulch decomposing strains38 cellulase producing strains was isolated from the rotted straw, rice hull and long-term mulched P. proecox forest soil, and determination the strain number 2.1 was the purpose strain by fermentation broth filter paper activity. According to its culture characteristics and analysis of the 26SrDNA, strain 2.1 was identified as Penicillium oxalicum, and it was clustered to Penicillium oxalicum in the Phylogenetic tree.4. Optinization of enzyme-producing of strain 2.1The optimal carbon sources for strain 2.1 was straw, the best nitrogen source was beef extract. FeCl3(0.01 g·L-1)and KH2PO4(1.5 g·L-1)had greater influence on enzyme activity than other inorganic salt in medium. The optimal fernentation condition:pH was 3.0-5.0, temperature was 30-40℃, and the optimal fermentation culture time was 5 days.