(I) Bacillus vulgaris - Saprophyte - Mineralization
(II) Erwinia amylovora - Saprophyte - Biopesticide
(III) Agrobacterium tumefaciens - Saprophyte - Genetic Engineering
(IV) Bdellovibrio bacteriovorus - Parasite - Water Purification
$\begin {array} {1 1} (1)\;(I),(II) & \quad (2)\;(II),(III) \\ (3)\;(I),(IV) & \quad (4)\;(II),(IV) \end {array}$
