RESEARCH SPOTLIGHT: Late-blowing defect in cheese caused by Clostridium tyrobutyricum
This week, we will be highlighting a project that PhD Student Margarita Valdiviezo is working on with assistance from one of our lab techs, Dana. They are working with an interesting organism that has long acted as a pest to cheese producers- Clostridium tyrobutyricum. C. tyrobutyricum is a spore forming bacteria; this means that it is able to survive pasteurization temperatures that kill off most other unwanted microbes. Once conditions are favorable, and vegetative cells begin to grow in the cheese from the spores. Butyric acid and gas are produced as a byproduct of their metabolism. This causes a defect knowing as “late-blowing”. As you can see in the photo, this causes cracks and bubbles to form in the cheese that are not desirable.
Samples were received from a cheese producer to isolate and confirm the identity of C. tyrobutyricum, as well as to develop a sporulation protocol that Margarita will be able to apply to her research. Margarita plans to develop biotechnological strategies that will reduce spore forming bacteria in organic dairy products.
Margarita and Dana are still in the process of attempting sporulation. The process has been as follows: a sample of the cheese was digested in a stomacher and plated. Then, an overnight tube was made with an isolated colony from the plate. The following day, 1mL of that tube was transferred to a biphasic media bottle and allowed to incubate. All of this took place in an anaerobic chamber, as C. tyrobutyricum is a very oxygen sensitive organism and can only grow in anaerobic environments. The next step in this process is to confirm the presence of spores using a phase-contrast microscope.