<prompt> . Swarming growth on culture is characteristic of which Gram-negative organism?Clostridium welchiiClostridium tetaniBacillus cereusProteus mirabilis  <response>: Ans. is d i.e., Proteus mirabilis Swarmin growth . Swarming growth is due to motility of bacteria. . In young culture discrete colonies are seen but thereafter actively motile cells spread on the surface of the plate in successive waves to form a thin filmy layer in concentric circles. 