If a bacteria cannot ferment glucose, then we do not test its ability to ferment other carbohydrates because the glucose is monosaccharides, the bacteria required enzymes that used to ferment glucose.
Bacteria cannot ferment carbohydrates because carbohydrates may include non-reducing sugar like sucrose and lactose, which is disaccharide, that must be cleaved into monosaccharides. Not all, bacteria can do this to may or may not ferment sucrose.
Many microorganism can grow in the base broth without the carbohydrates, but if they can ferment a sugar that is available. It is possible that one bacteria metabolize some sugar but can't work on other.
To learn more about non-reducing sugar here
brainly.com/question/13154500
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