TOPIC AREA 2 Microbial Metabolism CASE STUDY 2 Termites and Symbiotic gut microbes A wood eating termite top next to a gut removed from a separate individual middle Microscopic examination of diluted hindgut contents bottom reveals an abundance of spirochetes arrows and protozoa P Image 1 courtesy John Breznak Michigan State University LEARNING GOAL TOPICS complexity microbial symbioses novel metabolic pathways tools of microscopy CASE STUDY DIRECTIONS I II Watch this introductory video by Ed Yong Termites digest wood thanks to microbes 7 12min It will introduce you to the amazing process of cellulose metabolism in termites that is due to their symbiotic microbes URL https www biointeractive org classroom resources termites digest wood thanks microbes Next watch Dr Jared Leadbetter s ibioseminar Termites and their symbiotic gut microbes 37 07 mins You will learn about the rich biological diversity in termite guts and the unique metabolisms they have to enable efficient breakdown of wood You will never look at termites the same again URL https www ibiology org ecology termite gut Answer the guided problem set questions below that are based on these talks The answers may not all be in the videos you may have to use outside resources such as the scientific literature to support your answers There is a list of related scientific articles to this video listed at the end of this case study Make sure to properly cite any references you use for answering the questions in the case study Use in text citations See course moodle page under citing references for format style of citations At minimum you should cite this case study as follows Lee A M 2025 Termites and Symbiotic gut microbes Class Assignment MB251 General Microbiology Lecture North Carolina State University Raleigh NC Spring semester 2025 Citing the Videos Yong E 2017 Termites digest wood thanks to microbes I Contain Multitudes Video https www youtube com watch v dOf9eJGHHUU Ledbetter J Termites and their symbiotic gut microbes IBiology seminar series Video https www ibiology org ecology termite gut The case study is available in 2 file formats as a pdf or a word doc for you to download You can type your answers directly onto the case study document preferably in a different color or bolded so that it is easier to read Keep questions with the answers together Then upload the completed document for submission III GUIDED PROBLEM SET QUESTIONS 25pts Part I 1 Ed Yong mentioned that many animals rely on microorganisms to digest the plants that they eat Do some research online and briefly discuss one example of an animal not an insect that relies on the symbioses of microorganisms in their gut to help with plant digestion 2pts Ruminants such as cows sheep and goats are among the largest populations of animals that use microbes to digest the plants they eat Without microbes a cow s digestive system would shut down and she would starve to death Cows and microbes have a mutually beneficial relationship where microbes give the cow labor to digest food a source of protein a source of volatile fatty acids and the ability to digest forage In return the cow provides the microbes with water warmth grinding of feed and anaerobic conditions The three main groups of rumen microbes are bacteria protozoa and fungi Bacteria carry out most of the digestion of sugars starch fibers and protein Protozoa swallow and digest the bacteria starch and some fiber Fungi make up a small number of microbes but they are important in splitting open plant fibers to make them more easily digested by bacteria According to Paul Weiner a Rumen Microbiologist at the University of Wisconsin https www ars usda gov ARSUserFiles 50901500 px based v3 2 educ matrls pdfs fs rumen microbes pdf 2 Why is it important for microbes found in the guts of adult termites to be passed to juvenile termites How do they pass these microbes to other termites that is what is the term used in Ed Yong s video and how does it work 2pts It turns out that termites evolved from omnivorous cockroaches like the ones you might find in your house The social behavior of the cockroaches allowed them to take advantage of wood as a very abundant food source Termites can inoculate their young with gut microbes This is important because without the specific gut microbes the termite would not be able to eat the wood The term used for the process of passing along the gut microbes is proctodeal trophallaxis Trophallaxis means when animals feed with regurgitated fluids Gut fluid will come out of the posterior end of the termite and juvenile termites will eat that This will allow the termite to obtain those gut microbes needed to digest the wood 2 Part II 3 Using the phylogenetic tree Fig 1 and what Dr Leadbetter talks about in his seminar explain why it is important to study microbial diversity 2pts Figure 1 Phylogenetic tree Three domain tree of Life courtesy of Norm Pace http pacelab colorado edu It is important to study microbial diversity because there are great differences between organisms which means that the possible differences in the way that these organisms live are close to endless So we may be missing out on not just the diversity of how things are related but also what they are doing in the environment 3 4 What are the advantages to studying the environment of the termite hindgut compared to studying the Sargasso Sea 2pts One advantage to studying the termite hindgut compared to the Sargasso Sea is the difference in size The Sargasso Sea is thousands of kilometers across whereas the hindgut of a termite is only about one cubic millimeter in volume Another advantage is being able to bring the termite into the lab and study the entire environment Another advantage is that although the hindgut is still a complex environment it is well bounded and there are many of the same environments available to use We know that the gut lining and the outside of the termite are where the boundaries of the system would be defined Whereas the boundaries of the Sargasso Sea are a little bit user defined and there is only one of them The termites allow for comparative studies and perturbation studies that are not possible in a large environment like the Sargasso Sea 3 Figure 2 The major microbial processes in the hindgut of lower termites Brune 2014 5 There are many symbiotic interactions Fig 2 found in the termite hindgut with representatives from all 3 domains of life The hindgut protozoa have a number of unique