All bacteria in ODB-G1 and ODB-G2 were cloned again
from colonies formed on NSW agar plates. White opaque
colonies and transparent colonies were formed. The
transparent colonies were difficult to find on the plates.
We temporarily designated the bacterium-forming opaque
colonies in ODB-G1 as G1 and those in ODB-G2 as G2,
and the bacteria-forming transparent colonies in ODB-G1
as G1ST (ST: stealth) and those in ODB-G2 as G2ST. All
of these bacteria were Gram-negative. G1 corresponds to
the one that was morphologically identified as a Caulobacter
sp. (see above). G2 was a motile rod bacterium in
ODB-G2 and was identified as Halomonas sp. based on its
carbon substrate utilization in the BiOLOG profile. Both
G1ST and G2ST were non-motile rod bacteria, and they
were identified as Alcanivorax sp. from their sequence of
16S rDNA (98–99% similarity). Kasai et al. (2001) also
show that Alcanivorax sp. is found in high abundance in
seawater and coastlines contaminated by the Nakhodka
tanker oil-spill accident. Similarly, Maruyama et al. (2003)
have reported the domination by Cycloclasticus sp. and
Alcanivorax sp. of the microbial communities in the heavily
oil-contaminated coastal sites immediately after the Nakhodka
oil spill.