1979 Volume 25 Issue 2 Pages 71-93
The attaching ability of a number of bacteria, isolated from bovine rumen and animal intestine, to starch granules was examined in vitro. Among bacteria examined in the present investigation, strains possessing the attaching ability to starch were those belonging to an untypable Bacteroides sp., Bacteroides amylophilus, Bacteroides oralis, Bacteroides ruminicola ss. ruminicola, an untypable Bifidobacterium sp., Bifidobacterium thermophilum, Bifidobacterium pseudolongum, and Bifidobacterium longum.
The reaction temperature had a profound effect on the attachment of bacteria to starch. All of bacteria listed above attached well to starch at 38°. Strains of the untypable Bacteroides sp., B. oralis, B. thermophilum, B. pseudolongum, and B. longum attached to starch even at the reaction temperature of 4°. On the other hand, those of B. amylophilus did not attach to starch at 4°.
The activity of several hydrolases of various kinds of bacteria was examined. The amylase activity of cells of bacteria capable of attaching to starch was remarkably high, compared with that of bacteria incapable of attaching. Bacteria such as B. fibrisolvens and Streptococcus bovis, which were incapable of attaching to starch but possessed intense amylolytic activity, secreted extracellularly large parts of amylase produced by them. Only Peptostreptococcus productus among examined bacteria exhibited remarkably intense urease activity. There was no significant difference in the specific activity of the remaining three hydrolases between bacteria capable and incapable of attaching to starch. The attachment of bacteria to starch was inhibited by various carbohydrates. Carbohydrates like dextrin, amylose, amylopectin, soluble starch, and derivatives of starch except carboxymethyl-starch inhibited the attachment of bacteria to starch. The degree of this inhibition by these carbohydrates depended on their concentrations. Other carbohydrates examined, including derivatives of cellulose and dextran, did not inhibit significantly the attachment of bacteria to starch.
An attempt was made to detach or elute bacteria from starch by some means. Cells of B. amylophilus, once attached to starch at 38°, were detached by the cooling treatment at 4°. Although both cells of B. thermophilum and B. pseudolongum were not detached from starch by the cooling treatment at 4°, they were eluted from starch with a solution of dextrin or partially-hydrolysed hydroxypropyl-starch. Cells of Bacteroides sp. 7-4, once attached to starch, were not detached either by the cooling treatment at 4° or by the elution treatment with a solution of above two carbohydrates.
