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| 冷冻干燥法制备孔雀石绿降解菌剂及其应用效果研究 |
| Freeze-drying technology and its application to prepare bacteria that degrades malachite green |
| 投稿时间：2020-05-14 |
| DOI：10.13254/j.jare.2020.0248 |
| 中文关键词: 孔雀石绿，冷冻干燥，菌剂，渔业环境，降解 |
| 英文关键词: malachite green, freeze-drying technology, bacterial degradation agent, piscatorial environment, degradation |
| 基金项目:上海市农委青年成长计划项目（沪农青字（2018）第3-6号） |
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| 中文摘要: |
| 利用两株对孔雀石绿具有高效降解能力的菌株，采用冷冻干燥法制备孔雀石绿复合型降解菌剂，通过冻干保护剂的种类、预冷冻时间、菌体含量和冻干厚度等因素对降解菌剂进行性能优化，并对降解菌剂在渔业养殖水体及底泥中的应用进行初步研究。结果表明：多种类的冻干保护剂比单一的保护剂菌体成活率更高，采用冻干保护剂为15 mL·g-1的15%脱脂乳、5 mL·g-1的10%蔗糖和0.25 mL·g-1的甘油，冻干厚度为0.4 cm，预冷冻时间为48 h，真空冷冻干燥16 h，该条件下获得的孔雀石绿降解菌剂外观良好，菌剂细腻，菌体成活率约82.3%。光照条件下，菌剂对渔业养殖水体中浓度为5 mg·L-1孔雀石绿12 h降解率超过90%，对渔业底泥中浓度为2 mg·kg-1孔雀石绿及代谢产物隐性孔雀石绿25 d降解率分别为73.36%和76.80%。避光条件下，环境中孔雀石绿更容易转化为隐性孔雀石绿，添加菌剂可有效降低底泥中隐性孔雀石绿转化为孔雀石绿，增加光照可促进菌剂对两种药物的降解速率，在菌剂和光照的共同作用下，可有效减弱两类药物互相转化，同时提高降解效率。菌剂对养殖环境中的鱼体生长无显著影响（P>0.05）。本研究获得的孔雀石绿复合型降解菌剂具有良好的应用前景。 |
| 英文摘要: |
| Two strains of malachite green with a high degradation ability were used to prepare a compound degradation bacterial powder. The powder was prepared using a freeze-drying method, and its performance was optimized by the type of lyophilized protective agent used, pre-freezing time, bacterial content, and the thickness of the lyophilized product. A preliminary study on the application of the powder was conducted in water and sediment from fisheries. The results showed that the use of multiple types of lyophilized protective agents resulted in higher survival rates than when only single protective agents were used. The lyophilized protective agent consisted of 15 mL·g-1 of 15% skim milk powder, 5 mL·g-1 of 10% sucrose, and 0.25 mL·g-1 of glycerol. The thickness of the lyophilized product was 0.4 cm, pre-freezing time was 48 h, and the vacuum freeze-drying process took 16 h. The malachite green powder obtained had a good appearance, was fine, and the survival rate of the bacteria was approximately 82.3%. Under light conditions, the degradation rate of the powder of 5 mg·L-1 malachite green in water from fisheries was above 90% for 12 h, and the degradation rates of concentrations of 2 mg·kg-1 malachite green and the metabolite of latent malachite green were 73.36% and 76.80%, respectively, for 25 d in sediment from fisheries. Under dark conditions, malachite green was more easily converted into recessive malachite green in the environment. However, the addition of bacteria could effectively reduce the conversion of invisible malachite green to malachite green in the sediment. Increasing light exposure could promote the effect of bacteria on the degradation rate and, under the combined effect of bactericide and light, the mutual conversion of two types of drugs could be reduced effectively, thereby improving the degradation efficiency. The bacterial agent had no significant effect on the growth of fish in the culture environment(P>0.05). There are good prospects for the application of the malachite green composite degrading bacterial agent obtained in this study. |
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