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Biochemical characterization of different genotypes of Paenibacillus larvae subsp. larvae, a honey bee bacterial
Sandra Neuendorf1, Kati Hedtke1, Gerhard Tangen2
1Länderinstitut für Bienenkunde, Friedrich-Engels-Str. 32, 16540 Hohen Neuendorf, Germany.
Abstract:
Paenibacillus larvae subsp. larvae (P. l. larvae) is the aetiological agent of American foulbrood (AFB), the most virulent bacterial disease of honey bee brood worldwide. In many countries AFB is a notifiable disease since it is highly contagious, in most cases incurable and able to kill affected colonies. Genotyping of field isolates of P. l. larvae revealed at least four genotypes (AB, Ab, ab and alpha B) present in Germany which are genotypically different from the reference strain DSM 7030. Therefore, based on these data, five different genotypes of P. l. larvae are now identified with genotype AB standing out with a characteristic brown-orange and circled two-coloured colony morphology. Analysing the metabolic profiles of three German genotypes (AB, Ab and ab) as well as of the reference strain using the Biolog system, a characteristic biochemical fingerprint could be obtained for each strain. Cluster analysis showed that while genotypes Ab, ab and the reference strain DSM 7030 are rather similar, genotype AB is clearly different from the others. Analysis of all isolates for plasmid DNA revealed two different plasmids present only in isolates belonging to genotype AB. Therefore, genotype AB is remarkable in all aspects analysed so far. Future analysis will show whether or not these differences will expand to differences in virulence.
Insights
Paenibacillus larvae subsp. larvae (P. l. larvae), the cause of American foulbrood (AFB) in honey bees, exhibits distinct genotypes. Genotype AB shows unique colony morphology, metabolic profiles, and plasmid DNA, differentiating it from other P. l. larvae strains.
Area of Science:
- Microbiology
- Apiculture
- Bacterial genetics
Background:
- Paenibacillus larvae subsp. larvae (P. l. larvae) causes American foulbrood (AFB), a severe, contagious, and often incurable bacterial disease affecting honey bee colonies globally.
- AFB is a notifiable disease in many regions due to its high contagion and potential to decimate bee populations.
Purpose of the Study:
- To characterize and differentiate field isolates of P. l. larvae from Germany.
- To investigate genotypic variations, specifically focusing on colony morphology, metabolic profiles, and plasmid DNA presence.
Main Methods:
- Genotyping of P. l. larvae field isolates.
- Analysis of colony morphology (color, shape).
- Metabolic profiling using the Biolog system.
- Plasmid DNA analysis.
Main Results:
- Four P. l. larvae genotypes (AB, Ab, ab, alpha B) were identified in Germany, distinct from the reference strain.
- Genotype AB exhibited unique brown-orange, circled, two-colored colony morphology.
- Metabolic profiling and cluster analysis revealed genotype AB as biochemically distinct from genotypes Ab, ab, and the reference strain.
- Two distinct plasmids were exclusively found in P. l. larvae genotype AB isolates.
Conclusions:
- Genotype AB of P. l. larvae is phenotypically and genotypically unique among the analyzed strains.
- The distinct characteristics of genotype AB warrant further investigation into potential differences in virulence.
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