Swarming motility and biofilm formation of Paenibacillus larvae, the etiological agent of American Foulbrood of honey bees (Apis mellifera)

Abstract

American Foulbrood is a worldwide distributed, fatal disease of the brood of the Western honey bee (Apis mellifera). The causative agent of this fatal brood disease is the Gram-positive, spore-forming bacterium Paenibacillus larvae, which can be classified into four different genotypes (ERIC I-IV), with ERIC I and II being the ones isolated from contemporary AFB outbreaks. P. larvae is a peritrichously flagellated bacterium and, hence, we hypothesized that P. larvae is capable of coordinated and cooperative multicellular behaviors like swarming motility and biofilm formation. In order to analyze these behaviors of P. larvae, we firstly established appropriate functional assays. Using these assays we demonstrated that P. larvae ERIC II, but not P. larvae ERIC I, was capable of swarming. Swarming motility was hampered in a P. larvae ERIC II-mutant lacking production of paenilarvin, an iturin-like lipopeptide exclusively expressed by this genotype. Both genotypes were able to form free floating biofilm aggregates loosely attached to the walls of the culture wells. Visualizing the biofilms by Congo red and thioflavin S staining suggested structural differences between the biofilms formed. Biofilm formation was shown to be independent from paenilarvin production because the paenilarvin deficient mutant was comparably able to form a biofilm.

Biological role of EPS from Pseudomonas syringae pv. syringae UMAF0158 extracellular matrix, focusing on a Psl-like polysaccharide

“…Swarming motility is related to biofilm formation, as the two processes are frequently co-regulated [52][53][54][55][56] . Biosurfactants have been frequently associated with bacterial motility, since for many strains swarming motility on semi-solid agar plates is dependent upon such compounds [57][58][59] .…”

Antimicrobial Activity against Paenibacillus larvae and Functional Properties of Lactiplantibacillus plantarum Strains: Potential Benefits for Honeybee Health

“…The EPS production and the biofilm formation by LAB could be an effective strategy against biofilms and colonization of pathogenic bacteria, since they compete with them for nutrients and space with different mechanisms of action [85][86][87][88][89][90][91][92]. Fünfhaus et al [93] showed that P. larvae were able to form biofilms at the beginning of the saprophytic phase, and this could promote optimal colonization of the honeybee larvae cadaver and the access to all nutrients. Several studies reported that some L. plantarum strains produce exopolysaccharides that, as well as contributing to biofilm formation, can exert an antimicrobial action [89,[94][95][96].…”

Piperine as a new natural supplement with beneficial effects on the life-span and defence system of honeybees

“…Honeybees ( Apis mellifera L.) are a key element in maintaining biodiversity and, moreover, provide ecosystem services (Fünfhaus et al ., 2018). Through pollination, insects are responsible for a global service worth $215 billion to food production (Goulson et al ., 2015).…”