Submitted to: International Journal of Systematic and Evolutionary Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 14, 1996
Publication Date: N/A
Interpretive Summary: Spiroplasmas (helical wall-less procaryotes) are ubiquitously associated with insects. Some are frank insect pathogens, some transmit plant pathogens, some cause vertically transmitted sex ratio traits. Other species are apparently commensals. The latter group includes some host specialists and species that can invade hemolymph. This genus, because of its immense diversity, has great promise as a source for biocontrol agents. Before any agent can be adapted for biocontrol, its place in the systematics of the genus must be ascertained. In this paper, we describe a new species associated with horse flies and deer flies at northern latitudes in North America. This species has been a principal laboratory research tool in investigating the dynamics of insect/spiroplasma interactions. Because this research could lead to control of haemotophagous insects, the results will be of interest to research workers involved in biological control of insects, and to microbial ecologists and systematists.
Spiroplasma strain HYOS-1-T from the horse fly Hybomitra opaca [Diptera: Tabanidae] was serologically distinct from other spiroplasma species, groups, and subgroups. Cells of strain HYOS-1 as envisioned by light microscopy were long motile helices with six or more turns. Electron microscopic examination showed wall-less cells delimited by a single membrane. The cells passed through 450-nm filter pores with a tenfold loss of titer, and through 300- and 220-nm filter pores with a tenfold reduction in titer. The organisms failed to pass filters with 100-nm pores. The organisms grew well in M1D and SP-4 liquid media, in conventional horse serum medium, and in 1% bovine serum fraction medium. Strain HYOS-1-T grew over a temperature range from 5 to 41C with an optimum at 32C. The doubling time at the optimal temperature was 0.7 h, reflecting one of the fastest growth rates in the genus. The strain catabolized glucose and hydrolyzed arginine but did not hydrolyze urea. The guanine + cytosine content of the deoxyribonucleic acid was about 27 + 1 mol%. The genome size was about 1,225 kbp. Strain HYOS-1-T, the representative of group XXXI, is herein designated the type strain (ATCC 51745) of a new species, Spiroplasma montanum.