The CURE for Cultivating Fastidious Microbes

Analysis of ten-year teaching evaluation of oral microbiology lab curriculum

BACKGROUND

Based on the updated teaching philosophy of oral microbiology, Wuhan University School of Stomatology initiated a reform in the teaching of oral microbiology in 2009. As part of this reform, an oral microbiology laboratory course was introduced to cultivate students' fundamental skills, professional competence, comprehensive abilities, and innovation capabilities through experimental design. This paper provides thorough examination of the teaching experiment findings from 2013 to 2022, a ten-year timeframe, building on earlier data.

METHODS

The curriculum targets fourth-year undergraduate students in a five-year program and adopts a cooperative learning approach. The experimental teaching mainly involves four parts: plaque collection and processing, isolation and cultivation of dental plaque bacteria, staining and biochemical identification of dental plaque bacteria. This article presents a comprehensive analysis of the student experiment results from 2013 to 2022. Statistical analysis was conducted using the chi-square test to assess whether there were any differences in students' experimental grades between different years. A significance level of P < 0.05 was considered statistically significant. Additionally, we evaluated the impact of teaching methods and educational systems on improving students' practical skills and overall innovative abilities.

RESULTS

The performance of 664 undergraduate students showed improvement in the oral microbiology laboratory course, with a noticeable decrease in the proportion of "C" grades in Experiments 2, 3, and 4 compared to Experiment 1. These results indicate that the laboratory course enhanced students' academic achievements, aiding their understanding and mastery of course content, and received positive feedback from the students.

CONCLUSION

This lab curriculum, through systematic laboratory teaching and practical experience, contributes to the enhancement of students' professional skills and research abilities. It fosters students' interest in scientific research and improves the quality of dental education.

A CURE for Physiological Characterization of Bacterioplankton in Liquid Culture

Bacterial characterization is an important aspect of microbiology that includes experimentally determining growth rates, environmental conditions conducive to growth, and the types of energy sources microorganisms can use. Researchers use this information to help understand and predict an organism's ecological distribution and environmental functions. Microbiology students generally conduct bacterial characterization experiments in their coursework; however, they are frequently restricted to model organisms without ecological relevance and already well-studied physiologies. We present a course-based undergraduate research experience (CURE) curriculum to involve students in characterization of previously untested, ecologically relevant aquatic free-living bacteria (bacterioplankton) cultures to identify the usable nutrient substrates, as well as the temperature and salinity ranges conducive to growth. Students use these results to connect their organism's physiology to the isolation environment. This curriculum also exposes students to advanced microbiology methods such as flow cytometry for measuring cell concentrations, teaches them to use the programming language R for data plotting, and emphasizes scientific communication through writing, speaking, poster creation/presentation, and social media. This CURE is an attractive introduction to scientific research and was successfully tested with 187 students in three semesters at two different universities. Students generated reproducible growth data for multiple strains across these different deployments, demonstrating the utility of the curriculum for research support.

Integrating CUREs in Ongoing Research: Undergraduates as Active Participants in the Discovery of Biodegrading Thermophiles

Research-based courses are a powerful way to engage undergraduates in the scientific process while simultaneously teaching participants relevant laboratory, analysis, and scientific communication skills. In most programs, students conduct a simulated project which effectively improves student conceptions of scientific thinking but does not produce research-quality data. The course described here delivered an authentic research experience by assigning undergraduates an objective from an active grant-funded project. Participants contributed to research aimed at culturing biodegrading thermophiles from hot springs in Yellowstone National Park. Students participated in a backcountry field experience, collecting environmental samples of their choosing and determining appropriate culturing conditions. Following high-temperature incubations, 16S rRNA gene sequencing identified enriched microbial populations, with analytical and microscopy methods tracking degradation and growth. Importantly, several teams successfully cultivated thermophilic plastic-degrading consortia. Student learning was assessed using several methods, including grade distributions on assignments and statistical comparisons of pre- and posttests. A consistent and, in most cases, statistically significant increase was observed in the students' posttest scores. The grade distribution on summative assessments also suggests that students achieved the desired learning outcomes. Student perceptions of their learning and experience gains were high, with participants reporting improvements in components emphasized in the research activities. Overall, the findings highlight how involving undergraduates in real-world research projects can enhance student interest and ownership of scientific research, along with contributing quality data that inform active studies.

A CURE for Meat: Comparing Bacterial Contaminants on Different Ground Beef Sources Emphasizes Process of Science and Quantitative Reasoning

To broaden and emphasize the educational benefits of research to more biology majors in a course setting, we developed and assessed a microbiology-focused course-based undergraduate research experience that utilizes culture-based bacterial enumeration to compare contamination present on different ground beef sources (conventional vs. organic). During the final 3 weeks of the quarter, students learned and practiced common microbiology techniques like dilution math, selective and differential media-based identification, and statistical analysis to evaluate data and test hypotheses. Students were assessed primarily via a formal lab report and a lab practical focused on evaluating process of science and quantitative reasoning skills. The majority of students could write hypotheses and describe variables but were challenged when asked to describe the limitations of the experiments that were conducted as part of this research project. Most students could perform Excel-based graphing and a t test, but many could not solve the complex dilution math required for this project. The greatest barriers to skills mastery represented microbiology-focused concepts, like understanding selective media biases and the nuances of multistep viable counting procedures and outcomes.

A Large-Class Undergraduate Microbiology Laboratory Activity on Microbial Diversity and Antimicrobial Resistance

The investigation of microbial diversity and adaptation is essential to comprehend biological processes. Yet, teaching basic microbiology techniques to large groups of students in limited time is challenging, as most approaches are time-consuming or require special equipment. In this activity, students performed three laboratory exercises in three hours involving the analysis of inoculated agar plates they prepared by swabbing samples from an environment of their choice, the examination of antimicrobial effects on growth, and the assessment of microbial enzymatic activity in soil. The activity was field tested in two classes (70 and 76 students, respectively) of first-year undergraduate biology and zoology students at the Bangor University (UK) using pre- and post-tests (n = 84). Based on the answers, learning gain scores (G) were calculated for each learning objective (LO). For all LOs, the mean post-test scores were higher than the mean pre-test scores. The activity significantly improved students' understanding of microbial diversity (G = 0.36, p = 0.010) and microbial detection and quantification (G = 0.18 to 0.773, p ≤ 0.004). The lack of significant differences in scores for questions targeting microbial growth (G = 0.31, p = 0.292) and antimicrobial resistance (G = 0.38, p = 0.052) suggested some existing knowledge amongst undergraduates. However, the extent of knowledge showed great variation. The results may suggest that the activity is suitable to introduce microbiology-related laboratory work to students with limited laboratory skills and knowledge. Furthermore, the pre- and post-test approach used here is suitable for both course evaluation and monitoring attainment and can be used for program validation and quality control.

Fiber Force: A Fiber Diet Intervention in an Advanced Course-Based Undergraduate Research Experience (CURE) Course

Course-based undergraduate research experiences (CUREs) are an effective way to introduce students to contemporary scientific research. Research experiences have been shown to promote critical thinking, improve understanding and proper use of the scientific method, and help students learn practical skills including writing and oral communication. We aimed to improve scientific training by engaging students enrolled in an upper division elective course in a human microbiome CURE. The "Fiber Force" course is aimed at studying the effect of a wholesome high-fiber diet (40 to 50 g/day for two weeks) on the students' gut microbiomes. Enrolled students participated in a noninvasive diet intervention, designed health surveys, tested hypotheses on the effect of a diet intervention on the gut microbiome, and analyzed their own samples (as anonymized aggregates). The course involved learning laboratory techniques (e.g., DNA extraction, PCR, and 16S sequencing) and the incorporation of computational techniques to analyze microbiome data with QIIME2 and within the R software environment. In addition, the learning objectives focused on effective student performance in writing, data analysis, and oral communication. Enrolled students showed high performance grades on writing, data analysis and oral communication assignments. Pre- and post-course surveys indicate that the students found the experience favorable, increased their interest in science, and heightened awareness of their diet habits. Fiber Force constitutes a validated case of a research experience on microbiology with the capacity to improve research training and promote healthy dietary habits.

Culturing the Uncultured: Risk versus Reward

Isolation of new microorganisms is challenging, but cultures are invaluable resources for experimental validation of phenotype, ecology, and evolutionary processes. Although the number of new isolates continues to grow, the majority of cultivars still come from a limited number of phylogenetic groups and environments, necessitating investment in new cultivation efforts.

Isolation of new microorganisms is challenging, but cultures are invaluable resources for experimental validation of phenotype, ecology, and evolutionary processes. Although the number of new isolates continues to grow, the majority of cultivars still come from a limited number of phylogenetic groups and environments, necessitating investment in new cultivation efforts. While most microbiologists probably agree that axenic cultures have great value, we need to collectively put our money where our mouth is. I propose that we examine cultivation from the perspective of expected value to rationally incorporate risks and rewards of isolating new microbes. If we can even broadly constrain the cultivation probability and relative values of isolates, we can use this information to evaluate and improve experimental design. There are numerous scenarios for which isolation projects have positive expectations and therefore represent a sound investment.