Gram-positive bacterium Paenibacillus larvae strains isolated from Lithuanian honeybees

Abstract

Paenibacillus larvae is a Gram-positive bacterium which is known as the causative agent of the American foulbrood (AFB), a highly contagious and fatal, widespread disease of honeybees (Apis mellifera). There are four strains of Paenibacillus larvae, named after their enterobacterial repetitive consensus (ERIC), and recently newly found fifth ERIC genotype. ERIC I and ERIC II genotypes are spread worldwide and are considered as the most important because of high virulent. In this study a total 108 independent P. larvae isolates from different geographical regions of Lithuania collected from 2011 till 2021 were investigated first time for genetic diversity using multiple locus variable number of tandem repeat analysis (MLVA). For MLVA, five primers pairs representing different gene loci were used in multiplex PCR and analysed by capillary electrophoresis (QIAxcel system). The aim of the study was by using MLVA method detect which enterobacterial repetitive intergenic consensus (ERIC) genotypes are most common in Lithuania apiaries, identify and differentiate subtypes of defined genotype, and analyse how bacterial molecular diversity change and spread over the years in different regions of Lithuania. Molecular analysis data showed that 100 % of P. larvae bacterial isolates from Lithuania represent the ERIC I genotype, and capillary electrophoresis results let us to differ 9 P. larvae strains subtypes according to different length of VNTR by using MLVA method.