Agarolytic bacterium Persicobacter sp. CCB-QB2 exhibited a diauxic growth involving galactose utilization pathway

The agarolytic bacterium Persicobacter sp. CCB-QB2
was isolated from seaweed
(genus Ulva) collected from a coastal area of Malaysia. Here, we report a high-quality
draft genome sequence for QB2. The Rapid Annotation using Subsystem Technology
(RAST) annotation server identified four β-agarases
(PdAgaA, PdAgaB, PdAgaC, and
PdAgaD) as well as galK, galE, and phosphoglucomutase, which are related to the
Leloir pathway. Interestingly, QB2 exhibited a diauxic growth in the presence of two
kinds of nutrients, such as tryptone and agar. In cells grown with agar, the profiles of
agarase activity and growth rate were very similar. galK, galE, and phosphoglucomutase
genes were highly expressed in the second growth phase of diauxic growth,
indicating that QB2 cells use galactose hydrolyzed from agar by its agarases and exhibit
nutrient prioritization. This is the first report describing diauxic growth for agarolytic
bacteria. QB2 is a potential novel model organism for studying diauxic growth in
environmental bacteria.