摘要:
由于发光细菌的在线毒性监测技术受到了细菌生物活性稳定性保持问题的制约,探索一种脱脂牛奶菌悬液冷藏复苏方法,以提高发光细菌活性的保持时间。比较了明亮发光杆菌新鲜菌液冷藏、冻干粉菌悬液冷藏和脱脂牛奶菌悬液冷藏对发光细菌生物活性的影响,同时,比较了不同渗透压调节液对菌悬液急性毒性测试的灵敏度和稳定性的影响。结果表明,质量分数为25%的脱脂牛奶可提高发光细菌生物活性的稳定性,菌悬液冷藏7 d后复苏,相对发光率仍可达92%。2% NaCl和10%蔗糖为渗透压调节液时,冷藏至第7天的发光细菌脱脂牛奶菌悬液对重金属毒性测试的灵敏度,与新鲜菌液基本相同,但添加蔗糖降低了其对有机物的测试灵敏度。利用发光细菌脱脂牛奶冷藏菌悬液对Zn2+进行连续7 d的毒性测试,EC50的变异系数小于15%,结果稳定性良好。
Abstract:
Long-term maintenance of biological activity of luminescent bacteria is required for the development of its application in on-line toxicity monitoring. To enhance the stability of luminescent bacteria activity, a cold storage method of skimmed-milk bacteria suspension was explored. The survival and activity of luminescent bacteria was evaluated and compared among three methods including fresh bacteria suspension cold storage, freeze-dried bacteria suspension cold storage and skimmed milk-bacteria suspension cold storage. Moreover, the effects of different osmoregulatory factors on the sensitivity and stability of toxicity tests were investigated and compared. Results showed that 25% (w/w) skimmed milk enhanced the stability of luminescent bacteria activity. The relative luminosity of luminescent bacteria reached 92% when they were reactivated after 7 days cold storage. When applying 2% (w/w) NaCl and 10% (w/w) sucrose as the osmoregulatory factors, the toxicity test sensitivity to heavy metals using skimmed milk-bacteria suspension after 7 d-cold storage was approximately the same with that of using fresh bacteria suspension. However, the addition of sucrose decreased the sensitivity of luminescent bacteria to organic compounds. The toxicity of Zn2+ solutions with the same concentration was measured by using skimmed milkbacteria suspension kept in cold storage for 7 consecutive days and the variation coefficient of EC50 values was less than 15%, indicating good stability of test results.
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