Biochemical analysis of starch degradation by Ruminobacter amylophilus 70.

摘要: Ruminobacter amylophilus is an obligate anaerobe that uses only alpha-linked glucose molecules (i.e., maltose, maltodextrins, and starch) as a source of energy, making it excellent model for the study bacterial starch degradation. Constitutive amylase, amylopectinase, pullulanase activities were found in intracellular extracellular fractions R. amylophilus. However, apparently resulted from cell lysis. Both soluble membrane-bound polysaccharidase detected. Most activity partitioned with periplasmic fraction. No alpha-glucosidase or maltase was detected either cellular In addition, intact cells bound U-14C-starch. This binding could be saturated constitutive sensitive to proteinase K, indicating protein complex mediation. Competition experiments showed these starch-binding sites had equally high affinities maltodextrins larger than maltotriose. The reduced affinity maltose virtually no nonstarch polysaccharides. These findings suggest binds surface initial step transporting molecule through outer membrane into space. Extracellular polysaccharides do not appear involved