An Alternative Approach to "Identification of Unknowns": Designing a Protocol to Verify the Identities of Nitrogen Fixing Bacteria
An Alternative Approach to "Identification of Unknowns": Designing a Protocol to Verify the Identities of Nitrogen Fixing Bacteria
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DOI：
10.1128/jmbe.v16i2.973
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发表时间：
2015-12-01
影响因子：
1.9
通讯作者：
Sadowsky, Michael J.
中科院分区：
文献类型：
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作者：
Martinez-Vaz, Betsy M.;Denny, Roxanne;Sadowsky, Michael J.
微生物学课程通常包括鉴定未知微生物的实验室活动。这项活动包括为学生提供微生物培养和运行生化分析，以确定有机体。这种方法缺乏分子技术，如编码16S rRNA的基因测序，这是目前鉴定未知细菌的首选方法。开发了一个实验室活动，教学生如何使用16S rRNA聚合酶链反应（PCR）识别微生物，并使用生物化学技术验证微生物身份。我们假设，设计一个实验方案，以确认细菌的身份将提高学生的微生物鉴定技术和细菌物种的生理特性的知识。从截形苜蓿（Medicago truncatula）根瘤中分离出固氮细菌并进行16S rRNA PCR分析。一旦DNA测序揭示了生物体的身份，学生们设计了实验方案来验证根瘤菌的身份。通过分析前测和后测的分数以及对学生的验证协议和演示文稿进行评分来进行评估。后测分数高于或低于p = 0.001的前测分数。归一化学习增益（G）显示学生对微生物鉴定方法（LO4，G = 0.46）、固氮细菌的生化特性（LO3，G = 0.45）和导致固氮共生体建立的事件（LO1和2，G = 0.51，G = 0.37）的知识有所提高。验证方案的评价也显示出显著改善，p值小于0.001。
Microbiology courses often include a laboratory activity on the identification of unknown microbes. This activity consists of providing students with microbial cultures and running biochemical assays to identify the organisms. This approach lacks molecular techniques such as sequencing of genes encoding 16S rRNA, which is currently the method of choice for identification of unknown bacteria. A laboratory activity was developed to teach students how to identify microorganisms using 16S rRNA polymerase chain reaction (PCR) and validate microbial identities using biochemical techniques. We hypothesized that designing an experimental protocol to confirm the identity of a bacterium would improve students' knowledge of microbial identification techniques and the physiological characteristics of bacterial species. Nitrogen-ixing bacteria were isolated from the root nodules of Medicago truncatula and prepared for 16S rRNA PCR analysis. Once DNA sequencing revealed the identity of the organisms, the students designed experimental protocols to verify the identity of rhizobia. An assessment was conducted by analyzing pre- and posttest scores and by grading students' verification protocols and presentations. Posttest scores were higher than pretest scores at or below p = 0.001. Normalized learning gains (G) showed an improvement of students' knowledge of microbial identification methods (LO4, G = 0.46), biochemical properties of nitrogen-fixing bacteria (LO3, G = 0.45), and the events leading to the establishment of nitrogen-fixing symbioses (LO1&2, G = 0.51, G = 0.37). An evaluation of verification protocols also showed significant improvement with a p value of less than 0.001.