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

Go Furusawa,Appalasamy Suganthi,Abdullah Al-Ashraf Amirul,Nyok-Sean Lau

doi:10.1002/mbo3.405

Go Furusawa, Appalasamy Suganthi + Show 2 more

Open Access

https://doi.org/10.1002/mbo3.405

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Abstract

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.

Highlights

Agar is a polysaccharide found in the cell walls of marine red algae, such as Gelidium, Gracilaria, Gracilariopsis, Porphyra, and Pterocladia (Renn, 1997)
Sugano and colleagues reported that agarase 0107 isolated from Vibrio sp. strain JT0107 digested agarose gel used for DNA electrophoresis, allowing 60% of the applied DNA to be recovered after incubating at 65°C for 5 min (Sugano, Terada, Arita, Noma, & Matsumoto, 1993)
Our results suggest that this bacterium metabolizes galactose with the Leloir pathway in the second growth phase of diauxic growth

Summary

Introduction

Agar is a polysaccharide found in the cell walls of marine red algae, such as Gelidium, Gracilaria, Gracilariopsis, Porphyra, and Pterocladia (Renn, 1997). The agarase activity of cells grown without agar remained in lower level (0.014 unit ml−1) throughout incubation (Fig. 2A and B).

Results

Conclusion