Table 2.

Distribution of structural arrangements in known gene cassette pools

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  • a Open arrowed boxes denote ORFs and their orientation. No obvious ORFs are present in type G cassettes.

  • b An additional seven cassettes in V. cholerae are atypical and may represent illegitimate recombination or transposition events (10).

  • c Forty-five cassettes were contained within arrays, and the presence of internal 59-be sites within such arrays confirms their identity as gene cassettes. The remaining 78 cassettes were not part of arrays and therefore did not possess an internal 59-be (this includes OrnC5, which comprises two type A cassettes within a single plasmid). The numbers of these single cassettes for each type are indicated in parentheses in this and the remaining columns.

  • d Libraries were constructed from 15 samples. These columns display data from the three most extensively sequenced libraries, Balmain (Bal), Homebush (HB), and Cape Denison ornithogenic soil (Orn).