Reclassification of Paenibacillus larvae subsp. pulvifaciens and Paenibacillus larvae subsp. larvae as Paenibacillus larvae without subspecies differentiation

Abstract

A polyphasic taxonomic study of the two subspecies of Paenibacillus larvae, Paenibacillus larvae subsp. larvae and Paenibacillus larvae subsp. pulvifaciens, supported the reclassification of the subspecies into one species, Paenibacillus larvae, without subspecies separation. Our conclusions are based on the analysis of six reference strains of P. larvae subsp. pulvifaciens and three reference strains and 44 field isolates of P. larvae. subsp. larvae. The latter originated from brood or honey of clinically diseased honey bee colonies or from honey of both clinically diseased and asymptomatic colonies from Sweden, Finland and Germany. Colony and spore morphology, as well as the metabolism of mannitol and salicin, did not allow a clear identification of the two subspecies and SDS-PAGE of whole-cell proteins did not support the subspecies differentiation. For genomic fingerprinting, repetitive element-PCR fingerprinting using ERIC primers and PFGE of bacterial DNA were performed. The latter method is a high-resolution DNA fingerprinting method proven to be superior to most other methods for biochemical and molecular typing and has not previously been used to characterize P. larvae. ERIC-PCR identified four different genotypes, while PFGE revealed two main clusters. One cluster included most of the P. larvae subsp. larvae field isolates, as well as all P. larvae subsp. pulvifaciens reference strains. The other cluster comprised the pigmented variants of P. larvae subsp. larvae. 16S rRNA gene sequences were determined for some strains. Finally, exposure bioassays demonstrated that reference strains of P. larvae subsp. pulvifaciens were pathogenic for honey bee larvae, producing symptoms similar to reference strains of P. larvae subsp. larvae. In comparison with the type strain for P. larvae subsp. larvae, ATCC 9545 T , the P. larvae subsp. pulvifaciens strains tested were even more virulent, since they showed a shorter LT 100 . An emended description of the species is given.

Honey Bees (Apis mellifera L.) and Pollination Issues: Current status, impacts and potential drivers of decline

“…There are two main bacterial pathogens of honey bees and both are pathogenic to larvae but not to adult bees: Melissococcus plutonius, causing European Foulbrood (Bailey, 1956(Bailey, , 1957 and Paenibacillus larvae, causing American Foulbrood (Genersch et al, 2006;Genersch, 2010a). P. larvae is a spore forming bacteria which makes control more difficult than M. plutonius, which is not a spore forming bacterium.…”

The Honeybee Disease American Foulbrood — An African Perspective

“…Several taxonomical revisions followed with the final status resulting in 2006 in the species Paenibacillus larvae (Genersch et al 2006). Since then a wide range of strains of P. larvae that all cause the typical AFB symptoms have been described.…”

“…Since then a wide range of strains of P. larvae that all cause the typical AFB symptoms have been described. Recently Genersch et al (2006) identified four genotypes (ERIC I to ERIC IV) of these bacteria with different levels of virulence (Genersch et al 2005(Genersch et al , 2006.…”

Potential Use of Buddleja Thyrsoides for the Control and Prevention of American Foulbrood Disease in Honey Bees

“…American foulbrood can also lead to the death of the colony (Genersch et al, 2005;Santos et al, 2012). The causative agent is Paenibacillus larvae (White), a gram positive and sporeforming bacterium that is distributed worldwide (Spivak and Reuter, 2001;Genersch et al, 2006). American foulbrood is considered a global threat to apiculture because the etiologic agent produces environmentally stable spores which are very virulent, and resistant to Antimicrobial activity and toxicity of B. thyrsoides heat, to desiccation, and to disinfectants (Genersch, 2010;Boligon et al, 2013a).…”