Project properties
Title Effects of Bacillus cereus and B. thuringiensis on mass-reared black soldier flies, Hermetia illucens
Group Entomology, Laboratory of
Project type internship
Credits 24
Supervisor(s) Nathan Meijer, Wageningen Food Safety Research
Examiner(s) prof. dr. Bregje Wertheim
Contact info nathan.meijer@wur.nl;
martine.kos@wur.nl
Begin date 2023/03/01
End date 2023/12/31
Description Insects are increasingly being reared as mini-livestock, for food and feed purposes. It is crucial that the final product is safe to consume. A variety of chemical and microbiological hazards can affect this safety. In terms of microbiological safety, bacterial pathogens such as Listeria monocytogenes, Salmonella, and Bacillus cereus, and others, can play a role. Of major importance is the latter, Bacillus cereus. These bacteria can produce heat-resistant spores and toxins. Processing of insect products (e.g., by heating) may not neutralize those spores and toxins, resulting in a potentially unsafe final product. Not much is known on the behaviour of Bacillus cereus in insect production facilities, making it difficult to implement appropriate control measures. A different species of the genus Bacillus is thuringiensis. These can also produce certain endotoxins (‘Cry proteins’), which are specifically toxic to insects, and are therefore used for pest control purposes. Again, little is known on the effects of this bacterium in insect rearing facilities.
The objective of this internship assignment is to perform a literature study on the effects of critical conditions (storage time, temperature, substrate characteristics, etc.) in insect rearing facilities on the growth and spore/toxin forming capacity of pathogenic B. cereus and B. thuringiensis. The primary research question is: under which conditions is there an increased risk for consumer of insect products for exposure with B. cereus (spores)? Secondary questions are, for instance: how do spores and vegetative cells behave in the insect production? Are spores triggered to germinate? Do conditions trigger vegetative cells to produce bacterial spores? And how does that affect spore characteristics (e.g., heat resistance)? The deliverable will be a scientific report with testable hypotheses for subsequent experimentation. These experiments are outside of the scope of the internship.
Used skills Information retrieval from scientific literature databases and internet resources; categorisation and interpretation of information from scientific experiments; report writing.
Requirements ENT-30806.
Note: this requirement does not apply for MBI students; they should check the requirements for doing an ENT MSc-thesis, Research Practice or Internship in the study programme of their specialisation.