红壤中秸秆降解的微生物演替及应用研究

【作者】 史央；

【导师】 戴传超； 陆玲；

【作者基本信息】 南京师范大学 ， 微生物学， 2003， 硕士

【摘要】 微生物在秸秆降解中发挥了巨大作用，而多项研究表明，秸秆中的木质素成分是秸秆降解速度的限制因素。鉴于此，本论文即从筛选高产木质素酶的菌株入手，结果从重阳木茎内皮中筛选到一株有较高漆酶（木质素酶之一）活性的菌株B3，并将其制成秸秆降解剂，模拟大田试验研究了它对秸秆的降解效果及对后季作物生长的影响。 本论文包括三个部分：1．调查了中科院红壤生态站内不同土壤中的微生物数量及区系组成，跟踪检测秸秆自然降解状况。结果表明，水田以细菌为主，旱地中真菌和放线菌数量最多，林地中有大量的高等担子菌；秸秆自然降解较慢，土壤微生物也随着降解的进行而呈现一定的变化规律；当调节C/N比为25：1时，秸秆的腐解残留率比对照组下降10.67％。2．通过形态学观察及测定其rDNA ITS序列对菌株B3进行鉴定，该菌株属于子囊菌亚门的腐皮壳属（Diaporthe）。纤维素类物质CMC-Na是其最佳碳源诱导物，正交优化后的发酵条件是马铃薯200g/L,CMC-Na 20g/L，NH₄Cl 1g/L,KH₂PO₄3g/L,MgSO₄·7H₂O 1.5g/L,VB₁0.01g/L,pH4.0，培养温度25℃；同时发现菌株B3分泌的漆酶有较好的耐热性，在酸性条件下能很好的生长，可以适应红壤酸性条件，因此根据其最佳发酵条件在7L发酵罐内发酵制成秸秆降解剂。3．通过盆栽试验和扫描电镜观察检测了秸秆降解剂对秸秆的降解效果，结果发现，该降解剂在15d内就能破坏秸秆的结构，使秸秆不再漂浮，不影响作物的生根；进一步检测其对后季作物生长的影响发现，该降解剂还能促进后季作物的生长，薄板层析和免疫学检测均显示菌株B3分泌了IAA和ABA。更多还原

【Abstract】 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.更多还原