Abstract
In the experiments reported here we have studied the utilization by bacteria of a number of derivatives of the commoner sugars. The sugars used comprised several methyl glycosides, an amino sugar, a sugar acid, a sulphur-containing sugar, and 2 heptoses. The availability of these unusual sugars was compared with that of the common sugars from which they were derived.
All sugars were sterilized by filtration and added to suitable culture media to give a concentration of 0.5 to 1.0%. Each lot of medium containing a test sugar was then inoculated with about 25 representative species of the commoner bacteria. Fermentation of the sugar was determined by the usual methods of detecting acid and gas production.
It was found that when the hydrogen of the hydroxyl group attached to the number one carbon of the sugar molecule was replaced by a methyl group, the resultant modified sugar was distinctly more resistant to bacterial attack. Thus, of many bacteria which fermented glucose, only a few were able to make use of alpha methyl glucoside. Those able to ferment the methyl glucoside included: Proteus, Bact. friedländeri, Bact. aerogenes, pneumococci, several hemolytic streptococci, and a yeast.
Similar comparative tests with mannose and alpha methyl mannoside showed that the latter was not fermented by any of the organisms capable of using mannose. Two methyl pentoses, beta-methyl-1-arabinoside and beta-methyl-d-xyloside, were not used by those organisms capable of fermenting 1-arabinose and d-xylose.
Two sugars containing 7 carbon atoms, alpha glucoheptose and alpha glucoheptulose, were not fermented by any of the organisms. Glucosamine was used by most of the cultures which fermented glucose, with the exception of Proteus and 2 yeasts which gave negative results. Gluconic acid was also fermented by most of the glucose-splitting types, with the exception of the streptococci, pneumococci and the yeasts.
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