构巢曲霉冻干菌粉的制备及优化

Preparation and optimization of lyophilized powder of Aspergillus nidulans

摘要:

【背景】目前，用以降解园林绿化废弃物中木质素的菌剂多为液体菌剂或固体菌剂，鲜有对粉状菌剂的研究。【目的】研制高活性冻干菌粉，提高其冻干存活率并优化其工艺，以解决液体菌剂或固体菌剂在运输、储藏及使用上存在的问题。【方法】以一株木质素降解菌构巢曲霉(Aspergillus nidulans)为研究对象，利用真空冷冻干燥法制备冻干菌粉。以菌株的冻干存活率为评价指标，通过单因素试验筛选适于菌株冻干过程的保护剂种类及浓度梯度，再通过正交试验优化冻干菌粉复合保护剂配方。获得配方后，进一步探究冻干菌粉的复水条件和储藏条件。【结果】保护效果较优的4种保护剂成分经复配后对冻干存活率的影响顺序为蔗糖>葡萄糖>脱脂乳粉> α-乳糖。经优化后的保护剂配方以蔗糖15%、葡萄糖1%、α-乳糖10%、脱脂乳粉1%为最佳；复水条件以生理盐水为溶剂，复水30 min为最优。在此条件下制备和使用冻干菌粉，菌株的冻干存活率可达83.33%，有效活菌数可达1.2×10¹⁰ CFU/g。最佳储藏温度为-20 ℃，在此温度下保存28 d后，菌粉活性无明显下降。【结论】该研究获得的制备和储藏构巢曲霉冻干菌粉条件，具有菌株损失率低、可长时间保存的特点，对推进木质素降解菌在实际生产中应用具有积极作用。

Abstract:

[Background] At present, the bacterial agents used to degrade lignin in landscaping waste are mostly liquid or solid bacterial agents, and there is few research on powdered bacterial agents. [Objective] To develop the lyophilized powder with high activity and high lyophilized survival rate and optimize the process, thus solving the existing problems in transportation, storage, and application of the liquid or solid bacterial agents. [Methods] Aspergillus nidulans, a lignin-degrading strain, was taken as the research object, and the lyophilized powder was prepared by vacuum lyophilization. The lyophilized survival rate of the strain was used as the evaluation index. The types and concentration gradients of protective agents suitable for the lyophilizing process of the strain were screened out through the single factor test, and the compound formula of protective agents of lyophilized bacterial powder was optimized through the orthogonal test. The rehydration and storage conditions of lyophilized powder were further explored after obtaining the formula. [Results] The influencing order of the four protective agents with a superior protective effect on the lyophilized survival rate after compounding was sucrose>glucose>skimmed milk powder>α-lactose. The optimum formula for protective agents was 15% sucrose, 1% glucose, 10% α-lactose, and 1% skimmed milk powder. The optimum rehydration condition was 30 min rehydration with normal saline as the solvent. The lyophilized survival rate of the strain of lyophilized powder prepared and applied under the above conditions reached 83.33% with 1.2×10¹⁰ CFU/g effective live bacteria. There was no significant decrease of the activity of lyophilized powder storing at the optimum temperature (-20 ℃) for 28 days. [Conclusion] The preparation and storage conditions of the lyophilized powder of A. nidulans obtained in this study have low strain loss rate and can be stored for a long term time, which plays a positive role in promoting the application of lignin-degrading bacteria in practical production.