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The secretome of honey bee-specific lactic acid bacteria inhibits Paenibacillus larvae growth

Lamei, Sepideh LU ; Stephan, Jörg G. ; Riesbeck, Kristian LU ; Vasquez, Alejandra LU ; Olofsson, Tobias LU ; Nilson, Bo ; de Miranda, Joachim R. and Forsgren, Eva (2019) In Journal of Apicultural Research 58(3). p.405-412
Abstract

American Foulbrood (AFB) is a particularly pernicious bacterial disease of honey bees due to the extreme persistence of endospores of the causative agent Paenibacillus larvae. These spores are resistant to harsh environmental conditions, unaffected by antimicrobial agents and can remain viable for decades. The germination of the endospore in the larval midgut is the crucial first step leading to infection, followed by vegetative growth, tissue invasion and disease, culminating in spore formation when the host´s nutrients have been exhausted. Therefore, inhibiting spore germination or impeding early vegetative growth would be a highly effective strategy for limiting the impact of AFB. We previously showed that honey bee-specific lactic... (More)

American Foulbrood (AFB) is a particularly pernicious bacterial disease of honey bees due to the extreme persistence of endospores of the causative agent Paenibacillus larvae. These spores are resistant to harsh environmental conditions, unaffected by antimicrobial agents and can remain viable for decades. The germination of the endospore in the larval midgut is the crucial first step leading to infection, followed by vegetative growth, tissue invasion and disease, culminating in spore formation when the host´s nutrients have been exhausted. Therefore, inhibiting spore germination or impeding early vegetative growth would be a highly effective strategy for limiting the impact of AFB. We previously showed that honey bee-specific lactic acid bacteria (hbs–LAB) had a major inhibitory effect on P. larvae both in culture and in larval bioassays. The present study documents the progress towards characterization of compounds, processes and interactions between P. larvae and the hbs–LAB responsible for this inhibitory effect. Firstly, we used an agar diffusion assay and larval infection bioassay to show that most, if not all, of the inhibitory effect was associated with the extracellular fraction (secretome). Secondly, we employed a turbidimetric growth assay to demonstrate that the hbs–LAB secretome strongly inhibited P. larvae vegetative growth, however, probably not by reducing spore germination. The inhibition was similarly effective against both major P. larvae genotypes (ERIC-I and II) in all experiments. The implications of our results for characterization of the secretome and for the management and treatment of AFB and P. larvae are further discussed.

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author
organization
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Contribution to journal
publication status
published
subject
keywords
American foulbrood, antimicrobial factors, honey bee-specific lactic acid bacteria, honey bees, Paenibacillus larvae, secretome, spore germination, vegetative cells
in
Journal of Apicultural Research
volume
58
issue
3
pages
8 pages
publisher
Taylor & Francis
external identifiers
  • scopus:85064941181
ISSN
0021-8839
DOI
10.1080/00218839.2019.1572096
language
English
LU publication?
yes
id
7802cd55-9cca-4c2f-a6ee-39563ceb9384
date added to LUP
2019-05-13 13:03:51
date last changed
2020-01-22 07:35:30
@article{7802cd55-9cca-4c2f-a6ee-39563ceb9384,
  abstract     = {<p>American Foulbrood (AFB) is a particularly pernicious bacterial disease of honey bees due to the extreme persistence of endospores of the causative agent Paenibacillus larvae. These spores are resistant to harsh environmental conditions, unaffected by antimicrobial agents and can remain viable for decades. The germination of the endospore in the larval midgut is the crucial first step leading to infection, followed by vegetative growth, tissue invasion and disease, culminating in spore formation when the host´s nutrients have been exhausted. Therefore, inhibiting spore germination or impeding early vegetative growth would be a highly effective strategy for limiting the impact of AFB. We previously showed that honey bee-specific lactic acid bacteria (hbs–LAB) had a major inhibitory effect on P. larvae both in culture and in larval bioassays. The present study documents the progress towards characterization of compounds, processes and interactions between P. larvae and the hbs–LAB responsible for this inhibitory effect. Firstly, we used an agar diffusion assay and larval infection bioassay to show that most, if not all, of the inhibitory effect was associated with the extracellular fraction (secretome). Secondly, we employed a turbidimetric growth assay to demonstrate that the hbs–LAB secretome strongly inhibited P. larvae vegetative growth, however, probably not by reducing spore germination. The inhibition was similarly effective against both major P. larvae genotypes (ERIC-I and II) in all experiments. The implications of our results for characterization of the secretome and for the management and treatment of AFB and P. larvae are further discussed.</p>},
  author       = {Lamei, Sepideh and Stephan, Jörg G. and Riesbeck, Kristian and Vasquez, Alejandra and Olofsson, Tobias and Nilson, Bo and de Miranda, Joachim R. and Forsgren, Eva},
  issn         = {0021-8839},
  language     = {eng},
  number       = {3},
  pages        = {405--412},
  publisher    = {Taylor & Francis},
  series       = {Journal of Apicultural Research},
  title        = {The secretome of honey bee-specific lactic acid bacteria inhibits Paenibacillus larvae growth},
  url          = {http://dx.doi.org/10.1080/00218839.2019.1572096},
  doi          = {10.1080/00218839.2019.1572096},
  volume       = {58},
  year         = {2019},
}