W. Hashimoto et al., Enzymatic and genetic bases on assimilation, depolymerization, and transport of heteropolysaccharides in bacteria, J BIOSCI BI, 87(2), 1999, pp. 123-136
When microorganisms utilize macromolecules for their growth, they commonly
produce extracellular depolymerization enzymes and then incorporate the dep
olymerized low-molecular-weight products. Assimilation of heteropolysacchar
ides (gellan and xanthan) by Bacillus sp. GL1 depends on this generally acc
epted mechanism. On the other hand, Sphingomonas sp. Al represents an unexp
lored specific and interesting system for macromolecule assimilation. In th
e presence of heteropolysaccharide (alginate), the bacterium forms a mouthl
ike pit on its cell surface and directly incorporates the macromolecule usi
ng a novel ATP-binding cassette transporter (ABC transporter). In this revi
ew, we discuss enzymatic and genetic bases on the depolymerization and assi
milation routes of heteropolysaccharides in bacteria, with particular empha
sis on the novel incorporation system for macromolecules, characteristic po
st-translational modification processes of polysaccharide lyases and on the
mouthlike pit structure on the bacterial cell surface.