Tackling Real-World Environmental Paper Pollution: A Problem-Based Microbiology Lesson About Carbon Assimilation

Abstract

Governmental and educational organizations advocate for the adoption of inquiry-based, student-centered educational strategies in undergraduate STEM curricula. These strategies are known to benefit students by increasing performance, enhancing mastery of class content, and augmenting affect, particularly in underrepresented racial/ethnic minority students. Among these strategies, case study and project-based learning allow students to master course content while collectively tackling relevant, real-world societal problems. In particular, environmental pollution with paper-based products provide a current problem by which microbiology students learn about the role of microorganisms in paper waste management as well as the microbiological and biochemical processes involved in protein secretion, nutrient uptake, and energy metabolism. Delivered in a flipped, hybrid class in a Technology-Enabled Active Learning (TEAL) laboratory, this lesson taught students about exoenzyme secretion, biopolymer hydrolysis, intracellular transport of sugars, and sugar catabolic reactions. Students demonstrated increased comprehension of exoenzyme function and secretion, as well as how cells uptake the products of exoenzyme hydrolysis. However, students had challenges in placing the transported exoenzyme products within metabolic processes. Our results show increased perceived learning from the students as well as an understanding of the societal implications of these microbiological concepts. Our lesson deviated from knowledge silos in which students learn information in discrete topics. While departing from employing traditional, compartmentalized learning approaches, this student-centered guided lesson frames the systemic nature of the microbiological and biochemical processes underlying the decomposition of organic matter in a real-world context.

Keywords: 5E model; microbiology; paper pollution; pedagogy; problem-based learning.

FIGURE 1

Comparison of student’s responses to metacognitive questions before and after the activity. (A) Students were asked the question “To what extent did you understand the role played by microbes in the biodegradation of paper waste products?” before and after the class activity. The graph displays the responses before the activity (blue bars) and after the activity (orange bars) for the Spring 2020 semester (n = 88). This 5-point Likert survey question was deployed via clickers before the activity or via the Learning Management System after the class. Numbers above the columns represent the percent of students selecting a response. (B) Alluvial plot mapping the change in prediction before and after the activity from students in Spring 2020. The left column indicates the predictions before the activity, while the right column indicates the predictions after the activity. Only statements included in the data are shown. (C) Pie chart showing student’s predictions of the fate of paper before and after the activity. After a brief introduction, students were asked to predict the fate of paper in a landfill via a multiple-choice clicker question. The answer choices included “It remains in the landfill, as paper is not degradable.” (blue), “It will decompose by microbial activity involving respiration.” (orange), “It will decompose by microbial activity involving fermentation.” (gray), and “Something else will happen.” (yellow). The graphs display the before (left pie) and after (right pie) responses for the Spring 2020 semesters (n = 88).

FIGURE 2

Illustration of enzyme secretion, macromolecule degradation and nutrient transport. Individual groups of students were provided a template to illustrate the processes of enzyme secretion, cellulose hydrolysis and glucose transport. (A) Provided template containing the cell envelope of a Gram-negative bacteria, illustrating the correct placement of cell membrane secretion systems and porins, as well as the common misconceptions illustrated by students. (B) Correct illustration and (C) illustration with misconceptions. The numbers in these images, and the legend, show the most common misconceptions. PTS, phosphotransferase system; Tat, twin-arginine translocation.

FIGURE 3

Word clouds illustrating terms in the responses to metacognitive questions. (A) Microbes and environmental goals. Following the activity, students were asked the question: Based on today’s work, tell us what you think about the following statement: the power of microbes can be harnessed to reach environmentally sustainable goals. (B) The relationship between microbiology and society. Following the activity, students answer the question: Does today’s work illustrates the relationship of microbiology to society? Explain. Both of these free-response survey questions were deployed via the Learning Management System after the class. Text from the student’s responses was organized using a word cloud software that highlights, by word size, how often a term was used. The images display the responses from the Spring 2020 semester (n = 88). To simplify the image, only terms used at least 4 times are shown.

FIGURE 4

(A) The activity strongly influences student’s opinions about recycling. Following the activity, students were asked: “Tell us how much you agree with this statement: Today’s activity did NOT influence my opinion about recycling paper waste.” (B) The activity strongly enhances student’s understanding of enzyme secretion and nutrient transport. Following the activity, students were asked: “Tell us how much you agree with this statement: After today’s activity, I will be able to explain how enzyme secretion and sugar transport are related to cell wall and membrane function.” These 5-point Likert survey questions were deployed via the Learning Management System after the class. The graphs display the responses from the Spring 2020 semester (n = 88). Numbers above the columns represent the percent of students selecting a response.

FIGURE 5

Comparison of exam performance in summative assessment questions for the Fall 2019 and the Spring 2020 cohorts. All graphs compare the mean percentage score and error bars are the standard error of the mean. (A) Question 5a: Protein Secretion, t(177) = –1.20, p = 0.232. (B) Question 5b: Exoenzyme Function, t(177) = –3.24, p = 0.001. (C) Question 5c: Nutrient Transport, t(177) = 2.63, p = 0.009. (D) Question 5d, Metabolism, t(177) = –4.68, p < 0.00001. Bar graphs display the responses for Fall 2019 (n = 89) and Spring 2020 semester (n = 90). All statistics are unpaired, two-tailed, Student’s t-Tests. For details on the questions and their answers, please see the Supplementary Material.