C 4 -dicarboxylate uptake C family, are likely involved in the transport of malate, which can be used as the sole carbon source for L. hongkongensis in minimal medium [unpublished data]. The remaining class 2 transporters were ion-gradient-driven energizers belonging to the TonB family (6 CDSs). The third most abundant class of transporters was the channels and pores (class 1), with 39 CDSs including 12 a-type channels, 26 b-barrel porins. Among the 12 a-type channels, four were mechanosensitive channels and G+C content (10-kb window with 100-b step); circles 3 to 7, red, light purple, orange, aqua and teal bars show BLAST hits to Neisseria gonorrhoeae FA 1090, Neisseria gonorrhoeae MC58, Neisseria gonorrhoeae FAM18, Neisseria gonorrhoeae Z2491 and Chromobacterium violaceum ATCC 12472, respectively; circle 8, green arcs show location of eight putative prophages; circles 9 and 12, colors reflect Cluster of Orthologous Groups of coding sequences (CDSs). Maroon, translation, ribosomal structure and biogenesis; navy, transcription; purple, DNA replication, recombination and repair; light brown, cell division and chromosome partitioning; aqua, posttranslational modification, protein turnover, chaperones; teal, cell envelope biogenesis, outer membrane; blue, cell motility and secretion; orange, inorganic ion transport and metabolism; light purple, signal transduction mechanisms; olive, energy production and conversion; lime, carbohydrate transport and metabolism; green, amino acid transport and metabolism; fuchsia, nucleotide transport and metabolism; light pink, coenzyme metabolism; red, lipid metabolism; yellow, secondary metabolites biosynthesis, transport and catabolism; gray, general function prediction only; silver, function unknown; circles 10 and 11, dark blue, dark red and dark purple indicate CDSs, tRNA and rRNA on the 2 and + strands, respectively. doi:10.1371/journal.pgen.1000416.g001 which are important for mediating resistance to mechanophysical changes. The remaining transporters belong to four other classes, namely group translocators (class 4, 9 CDSs), transport electron carriers (class 5, 16 CDSs), accessory factors involved in transport (class 8, 9 CDSs) and incompletely characterized transport system (class 9, 54 CDSs). In line with their asaccharolytic nature, the genomes of L. hongkongensis and C. jejuni do not contain genes that encode a complete phosphotransferase system. The five families of multidrug efflux transporters, including MFS (6 CDSs), RND (8 CDSs), small multidrug resistance family (2 CDSs), multidrug and toxic compound extrusion family (2 CDSs) and ABC transporter superfamily (5 CDSs), were all present in L. hongkongensis, which may reflect its ability to withstand toxic substances in different habitats [20] . 20 CDSs were related to iron metabolism, including hemin transporters, ABC transporters of the metal type and ferrous iron, iron-storage proteins and the Fur protein responsible for iron uptake regulation. In contrast to C. violaceum which produces siderophores for iron acquisition, but similar to the pathogenic Neisseria species, proteins related to siderophore formation are not found in L. hongkongensis genome. In addition to a TonB-dependent siderophore receptor (LHK_00497), a set of genes (LHK_01190, LHK_01193, LHK_01427-1428) related to the transport of hemin were present, suggesting that L. hongkongensis is able to utilize exogenous siderophores or host proteins for iron acquisition, which may be important for survival in different environments and hosts.