View Source

WHAT IT PRODUCES

the bacterium produces acetate, pyruvate, and lactate when grown on monosaccharides and soluble cellulosic carbon sources.

GROWTH & DEGRADATION MECHANISM

C. japonicus is able to utilize corn stover and switchgrass as sole sources of carbon and energy for growth.
- corn stover and switchgrass subjected to the AFEX process
- When added to M9 minimal medium, the washed, autoclaved, AFEX-treated corn stover (or AFEX-treated switchgrass) failed to support the growth of E. coli but allowed the growth of C. japonicus (Fig. 2 A). Growth of C. japonicus in the presence of AFEX-treated corn stover was associated with release of glucose and xylose monosaccharides (Gardner and Keating, unpublished), suggesting that cellulose and hemicellulose were used as carbon sources.
efficient cellulase secretion and growth on biomass are prevented by disruption of the type II secretion system
suggests that C. japonicus utilizes a combination of hydrolytic and oxidative cleavage mechanisms to degrade cellulose

FIG. 2.

GENETIC MANIPULATION

C. japonicus can be metabolically engineered using broad-host-range plasmids.
We developed tools for directed gene disruptions in C. japonicus and used this system to construct a mutant in the gspD gene, which is predicted to encode a component of the type II secretion system. The gspD::pJGG1 mutant displayed a greater-than-2-fold decrease in endoglucanase secretion compared to wild- type C. japonicus. In addition, the mutant strain showed a pronounced growth defect in medium with biomass as a carbon source, yielding 100-fold fewer viable cells than the wild type.

HOW TO MEASURE

SOURCES