[4] Members of the Mollicutes class, such as Spiroplasma, are characterized by their reduced genomes and lack of a conventional cell wall, which is a result of their adaptation to parasitic or symbiotic lifestyles.
[9] This taxonomic affiliation places S. citri within the Citri-Chrysopicola-Mirum clade; relevant neighboring species within this genus include S. kunkelii, S. phoeniceum, S. eriocheiris, S. melliferum, and S. penaei, which infect a variety of hosts including specific species of corn, periwinkles, shrimps, crabs, and honeybees.
[12] S. citri belongs to the Spiroplasma genus within the mollicutes class, which is composed of Gram-positive bacteria that lack a cell wall.
[14] In its helical form, S. citri moves in a corkscrew motion, which plays a significant role in cell division and elongation.
[13] However, its alternate forms—spherical or ovoid shapes and branches, non-helical filaments—use intracellular fibril filaments for motility, compensating for the absence of flagella.
The tricarboxylic acid cycle is missing from S. citri which means that this bacterium predominantly relies on glycolysis for ATP production.
[15] S. citrihas a reduced genome and lacks various metabolic pathways which explains its heavy dependence on its hosts for nutrients, including amino acids, sugars, nucleotides, and vitamins.
[19] S. citri's genomics, pieced together through shotgun and chromosome-specific libraries sequencing, reveal key features of its 1820 kbp chromosome.
[7] Functional complementation and gene inactivation studies demonstrated that S. citri fructose consumption induces plant disease symptoms, and the ABC-type transporter solute binding protein is implicated in insect transmission.
[20] S. citri thrives and spreads in hot, dry weather, making it commonly found in the United States, the Middle East, North Africa, Central America, New Zealand, and part of Western Europe, particularly France, Italy, and Spain.
It is important we further study this bacteria in order to learn how to effectively combat it, so that we can develop better management strategies to help minimize financial losses in the produce industry, and to reduce its impact on citrus production as well as on native plant species.