低温耐酸木质素降解菌的筛选及降解特性

Screening and degradation characterization of psychrotrophic acid-tolerant lignin-degrading bacteria

摘要:

背景 在土壤偏酸性的南方的晚稻收获后，秸秆通常燃烧处理，造成资源浪费和环境污染。目的 克服秸秆还田的低温限制，促进低温环境和酸性土壤晚稻秸秆还田快速降解，实现秸秆资源化利用。方法 以连续多年堆放水稻秸秆垛底部腐烂土壤为材料，利用富集培养基对具有木质素降解能力的低温耐酸菌株进行分离，通过响应面法，以单因素实验为基础，研究菌株的产酶特性，明确时间、pH值、温度、接种量等培养条件对低温耐酸木质素降解菌的降解性能、生物量及酶活的影响。结果 当培养时间为6 d、pH 6.0、培养温度为15 ℃、接种量为2%时，低温耐酸木质素降解菌的降解性能、生物量和酶活达到最高，并采用响应面法对最佳培养条件进行了优化。结论 本研究结果为低温酸性条件下促进木质纤维素的降解、实现秸秆资源化利用提供了理论依据。

Abstract:

Background In southern China where the soil is acidic, after the late rice harvest, straw is often disposed by burning, which leads to resource waste and environmental pollution.Objective To achieve the utilization of straw resources, we need to overcome the low-temperature limitations of straw incorporation and promote the rapid degradation of late rice straw under low-temperature and acidic soil conditions.Methods The decayed soil from the bottom of rice straw stacks that had been piled up for several years was used as material. An enrichment medium was used to isolate psychrotrophic acid-tolerant strains with lignin-degrading capabilities. Single-factor experiments and response surface methodology were employed to study the enzyme production characteristics of the strains. The effects of cultivation conditions such as time, pH, temperature, and inoculum size on the degradation performance, biomass, and enzyme activity of psychrotrophic acid-tolerant lignin-degrading strains were clarified.Results The degradation performance, biomass, and enzyme activity of these strains reached the highest levels in the case of the cultivation time of six days, pH 6, cultivation temperature of 15 ℃, and inoculum size of 2%. The response surface methodology was employed to optimize the cultivation conditions.Conclusion The results of this study provide a theoretical basis for promoting the degradation of lignocellulose under low-temperature and acidic conditions and achieving the utilization of straw resources.