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Odor of earth: Several homomonoterpenes were identified in actinomycetes that produce 2-methylisoborneol (2-MIB, see scheme, which is responsible for an earthy odor in drinking water). Their occurrence clarifies the 2-MIB pathway, because they are derived from cationic intermediates that are otherwise difficult to detect. A highly sensitive method using feeding experiments with 13C-labeled precursors gives detailed insights into 2-MIB biosynthesis.
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Brock et al. (2013) studied this question.
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