一株耐高温硫氧化菌爱媛类芽孢杆菌的分离鉴定及其发酵条件优化

Isolation, identification and fermentation optimization of a thermophilic sulfide-oxidizing strain Paenibacillus ehimensis

摘要:

[背景] 市政污泥堆肥过程中大量释放的含硫臭气不仅会污染周围环境，也会降低堆肥质量。生物脱硫除臭技术具有效率高、无二次污染等优点，但目前研究较多的中常温硫氧化菌在堆肥高温环境中易失活，而耐高温菌的研究较少，其在高温条件下的脱硫性能有待进一步探究。[目的] 筛选并鉴定耐高温硫氧化菌株，研究并优化硫氧化的环境条件，为该菌在堆肥脱硫除臭方面的应用提供理论基础。[方法] 利用含硫化物的选择性培养基从污泥堆肥物料中筛选纯化耐高温菌株，从表观形态观察、生理生化分析和16S rRNA基因序列分析的角度确定其种属地位，结合单因素分析和正交试验优化影响菌株硫氧化作用和生长能力的环境条件，并用Logistic模型拟合该菌的生长动力学曲线。[结果] 筛选出一株耐高温硫氧化菌LYH-1，初步鉴定为爱媛类芽孢杆菌（Paenibacillus ehimensis），该菌的16S rRNA基因序列GenBank登录号为MW659161。优化后的最佳硫氧化条件为温度50 ℃、pH 7.5、接种量5%，此时硫酸盐的生成量可达到86.89 mg/L、生成率为36.20%。优化后的最佳生长条件为温度 50 ℃、pH 8.0、接种量5%，此时的OD₄₂₀可达到0.520；同时在该生长条件下拟合菌株的生长动力学，得到最大比生长速率μ_m为0.304 2 h^-1。[结论] 爱媛类芽孢杆菌LYH-1具有较强的硫氧化能力和环境抗逆性，这为生物脱硫研究领域提供了新的菌种资源，也为污泥堆肥高温期的含硫臭气控制提供了一定的理论支持。

Abstract:

[Background] The sulfur-containing odor emitted from municipal sludge composting could not only pollute the surrounding environment but also reduce the compost qualities. Biological desulfurization technology is highly efficient and without secondary pollutions. However, recent studies have been focused on the mesophilic strains, which are usually inactivated in thermophilic composting environments. Studies on the thermotolerant sulfide-oxidizing bacteria are scarce, and the desulfurization performance of the thermotolerant bacteria awaits further study. [Objective] To provide a theoretical basis for the biological application of composting desulfurization, a thermotolerant sulfide-oxidizing strain was isolated and identified, and the environmental conditions of the sulfide oxidation process were optimized. [Methods] The selective medium containing sulfide was used to screen and purify the thermophilic strain from sludge compost materials. The strain was identified by its morphological characteristics, physiological and biochemical analysis, and 16S rRNA gene sequence analysis. Single-factor and orthogonal experiments were used to optimize the fermentation conditions, and we also used the Logistic model to fit the growth kinetics curve of the strain. [Results] A thermophilic sulfide oxidizing strain LYH-1 was isolated and identified as Paenibacillus ehimensis; the GenBank accession number was MW659161. The optimized sulfide oxidation conditions were 50℃ of the temperature, pH 7.5, and 5% of the inoculation amount, the sulfate production amount reached 86.89 mg/L, and the production rate was 36.20%. The optimized growth conditions were 50℃ of the temperature, pH 8.0, and 5% of the inoculation amount, and the OD₄₂₀ reached 0.520; under these conditions, the growth kinetics were fitted to obtain the maximum specific growth rate at 0.304 2 h^-1. [Conclusion] Paenibacillus ehimensis LYH-1 has strong sulfide oxidation and environmental resistance abilities. It provides new bacterial resources for biological desulfurization and theoretical support for sulfur-containing odor control during the high-temperature period of sludge composting.