Characteristics of three spiroplasma isolates from honeybee (Apis mellifera)

Abstract:

Abstract: [Objective ] To investigate the kinds and characteristics of spiroplasma in honeybees, as well as to study the taxonomy and transmission of honeybee spiroplasma under natural conditions. [Methods] We examined the morphology of spiroplasma isolates by dark field and transmission electron microscopy and studied the biological characteristics by using conventional culture-dependent methods and molecular biology and serological methods. [Results] Three spiroplasma isolates were obtained from healthy Apis mellifera. All isolates exhibited helicity during their growth phase, with one isolate (MF0905) being shorter and having less helicity. This isolate also differed from the other two (MF0903 and MF0904) in having larger colonies with an irregular margin instead of being round. In addition, isolate MF0905 could not hydrolyze arginine whereas MF0903 and MF0904 could. All three isolates could use glucose and D-fructose as a carbon source but did not hydrolyse urea. Phylogenetic analysis based on the 16S rDNA, ITS and the rpoB gene showed that MF0903 and MF0904 had a close relationship with Spiroplasma melliferum, and MF0905 was close to S. clarkii. Serological studies including the growth inhibition test, metabolic inhibition test and deformation test gave the same result as the phylogenetic analysis. [Conclusion] The spiroplasma isolate MF0905 might be S. clarkii and other two isolates were S. melliferum. This result indicated that Spiroplasma melliferum is not the only spiroplasma species in honeybees in China.