Week 9: Bacterial Bonanza

Riya d -

Hello everyone, I can’t believe it’s already Week 9!

As I write my paper and discuss in depth the bacteria I studied, this week, I’d also like to share that information here. Again, my study aimed to identify the effects of essential oils on pathogenic bacteria, as well as symbiotic bacteria found in the hive and gut.

First are the pathogenic bacteria:

      1. Melissococcus plutonius: The causative agent of European Foulbrood (EFB). More controllable and less infectious than American Foulbrood (AFB).2
      2. Paenibacillus alvei: Can cause symptoms similar to AFB.6 Accompanying pathogen to M. plutonius.7

 

Next, are the symbiotic gut and hive bacteria. These bacteria are part of a larger community of “social resource microbiota” (SRM) that are essentially the bacteria found in the “social resource niche” (SRN) identified by the lead researchers at the lab I interned at (Anderson, K.E and Copeland D.C, 2024).1 The SRN and SRM is complex, but to simplify it a bit for the purpose of this blog and my study, the SRM includes the bacteria found in: various anatomical parts of queen and worker bees (such as the digestive tracts, mouthparts, glands), developing larvae, hive building material (propolis) and their food (including royal jelly, honey, bee bread). In their study, they then classify the most commonly found bacteria in the SRM as “core” bacteria. Other bacteria that are not found in the same high levels of abundance as the core bacteria and are found in lower abundance are not considered core bacteria, and can potentially be part of the “rare biosphere” of honey bees.

      1. Lactobacillus panisapium: Core bacteria. Commonly in bee bread, queens, less so in workers.
      2. Gilliamella: Core bacteria. More prevalent in workers.
      3. Lactobacillus kunkeei: Core bacteria. Found in many locations throughout the hive, particularly in bee bread, honey, bee mouthparts, and the gut.
      4. Commensalibacter: Core bacteria. More prevalent in queens.

 

The next category is unique. These are the pathobiont bacteria. Pathobionts are bacteria that are normally present, but under certain conditions can cause ill effects.

      1. Frischella perrara: Core bacteria, more prevalent in workers. However, there is reason to believe it can trigger bees’ immune response and causes melanization and scabbing in the gut.3
      2. Serratia nematodiphila: Found in lower abundance, there may be part of “rare biosphere” of honey bee gut. Potential concern as its development can be enhanced by presence of the parasite Nosema ceranae.4
      3. Enterococcus faecalis: Found in lower abundance, there may be part of “rare biosphere” of honey bee gut. Potential concern as they are brought in by varroa mites, bee parasites. 5

 

Finally are the control bacteria, non bee related bacteria that serve as validation for out methods and materials:

      1. Escherichia coli (E. coli)
      2. Bacillus thuringiensis (Bt)

The above summary is a very brief look into the microbial world associated with honey bees. For more detailed and complete information, I would strongly suggest the Anderson and Copeland 2024 paper — it’s a fascinating read. Thank you for reading, see you next week!

References

1. Anderson, K. E., & Copeland, D. C. 2024. The honey bee “hive” microbiota: Meta-analysis reveals a native and aerobic microbiota prevalent throughout the social resource niche. Frontiers in Bee Science, 2, Article 1410331. https://doi.org/10.3389/frbee.2024.1410331

2. Johnson BR. 2023. Honey bee biology. Princeton (NJ): Princeton University Press.

3. Engel P, Bartlett KD, Moran NA. 2015. The bacterium Frischella perrara causes scab formation in the gut of its honeybee host. mBio. 6(3):e00193-15. doi:10.1128/mBio.00193-15.

4. Braglia C, Alberoni D, Garrido PM, et al. 2024. Vairimorpha (Nosema) ceranae can promote Serratia development in honeybee gut: an underrated threat for bees? Front Cell Infect Microbiol. 14:1323157. doi:10.3389/fcimb.2024.1323157.

5. Zhang W, Sun C, Lang H, Wang J, Li X, Guo J, Zhang Z, Zheng H. 2023. Toll receptor ligand Spätzle 4 responses to the highly pathogenic Enterococcus faecalis from Varroa mites in honeybees. PLoS Pathog. 19(12):e1011897. doi:10.1371/journal.ppat.1011897.

6. Jurat-Fuentes JL, Jackson TA. 2012. Bacterial entomopathogens. In: Vega FE, Kaya HK, editors. Insect pathology. 2nd ed. San Diego (CA): Academic Press. p. 265–349.

7. Djordjevic SP, Forbes WA, Smith LA, Hornitzky MA. 2000. Genetic and biochemical diversity among isolates of Paenibacillus alvei cultured from Australian honeybee (Apis mellifera) colonies. Appl Environ Microbiol. 66(3):1098–1106. doi:10.1128/aem.66.3.1098-1106.2000.

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Comments:

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    madeleine_k
    Hi Riya! The many different types of bacteria prevalent in bees is fascinating. Can't wait to see your final results with your presentation!
    April 21, 2025 at 12:37 pm - Reply
    riya_d
    Thanks Maddie!
    April 23, 2025 at 5:55 pm - Reply
    shaivi_s
    Hi, Riya! It's so interesting to read about these different types of bacteria and what type of bees they are found in. This might be a silly question, but I'm curious if there was a type of bacteria that intrigued you the most- maybe one of the pathobiont bacteria? I'm excited to see the results in your presentation!
    April 23, 2025 at 11:32 pm - Reply
    riya_d
    Hey Shaivi! It was definitely interesting to learn about how pathobionts can go from being symbiotic bacteria to pathogens. But I would say that Lactobacillus kunkeei and the roles it plays as a mutualistic bacteria in the gut and hive intrigued me the most though. It can not only protect bees against excessive growth of pathobionts like Serratia marcescens in the gut, but it can also prevent the growth of bee pathogens in larvae food. Food contamination is actually how common bacterial diseases in bees such as EFB or AFB spread, so it's interesting to think about how symbiotic bacteria can actually prevent the spread of such diseases. You can read more about this from: Zirihi NA, Mokgokong MY, Yusuf AA, Apostolides Z. 2023. Lactobacillus kunkeei impacts the health of honey bees, Apis mellifera scutellata, and protects the bees against the opportunistic pathogen Serratia marcescens. Int J Trop Insect Sci. 43:1947–1955.
    April 24, 2025 at 2:55 pm - Reply

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