Straw Degradation In The Red Soil Microbial Succession And Application Research

Many studies have shown that lignin was the limited factor of straw degradation. In this study we screened a strain named B3 from the stem's inner bark of Bischofia polycarpam Airy Shaw which yielded high level of ligninase. The strain B3's ability in straw degradation and its effect on the next season crop's growth were then studied by making it into microbial agent in the potted experiment. Brief results are followed:1. The changes of microorganisms' number in different kind of Red Soil from CAS Ecological Experiment Station were surveyed. The results showed in the paddy field the bacteria were predominated, in the dry land the proportion of fungi and actinomyces was distinctly higher than the other two kinds of soil, in the woodland abundant species of basidiomycetes were found; the natural degradation speed was low, with the degradation the number and composition of microorganisms changed regularly; when the C / N ratio was adjusted to25 '?1, the degradation remnant ratio reduced 10.67% than the control.2. By morphological and molecular methods the strain B3 was identified as Diaporthe and could exist under acidic condition, whose laccase had good thermostability. CMC-Na could induce laccase maximally. The composition of fermentation medium was potato 200g / L, CMC-Na 20g / L, NH4Cllg / L, KH2PO4 3g / L, MgSO4 7H2O 1.5g / L, VB10.01g / L, mixed solution of trace metals 7ml / L, and the optimal conditions were pH of medium was 4.0, and incubation with 150r / min at 25 C for 4d. According to that it was made into microbial agent in 7 liter bioreactor.3. The microbial agent's ability in straw degradation was detected by potted experiment and scanning electron microscope. The result indicated that after 15d the structure of straw was destroyed and did not float longer, which did not affect crop's rootage; furthermore the effect on the next crop's growth was studied, and the results shown that the microbial agent could accelerate the next crop's growth. The strain B3 secreted incretion IAA and ABA by TLC and immunological analysis.