Terpenes are structurally diverse compounds that are of interest because of their biological activities and industrial value. These compounds consist of chirally rich hydrocarbon backbones derived from terpene synthases, which are subsequently decorated with hydroxyl substituents catalyzed by terpene hydroxylases. Availability of these compounds is, however, limited by intractable synthetic means and because they are produced in low amounts and as complex mixtures by natural sources. We engineered yeast for sesquiterpene accumulation by introducing genetic modifications that enable the yeast to accumulate high levels of the key intermediate farnesyl diphosphate (FPP). Co-expression of terpene synthase genes diverted the enlarged FPP pool to greater than 80 mg/L of sesquiterpene. Efficient coupling of terpene production with hydroxylation was also demonstrated by coordinate expression of terpene hydroxylase activity, yielding 50 mg/L each of hydrocarbon and hydroxylated products. These yeast now provide a convenient format for investigating catalytic coupling between terpene synthases and hydroxylases, as well as a platform for the industrial production of high value, single-entity and stereochemically unique terpenes.
Measurements of oxidation rates, respiratory quotients (RQ), and release of
14
CO
2
from uniformly labeled substrates showed that glutamate, α-ketoglutarate, and synthetic and natural amino acid mixtures are oxidized by suspensions of
Bdellovibrio bacteriovorus
strain 109J. The oxidation of these substrates largely suppress the endogenous respiration of the
Bdellovibrio
cells and may or may not cause a small increase, 20 to 50%, in their rate of oxygen consumption. The failure of respired substrates to increase markedly the respiration rate of the
Bdellovibrio
cells over the endogenous value is discussed. Carbon from these substrates is incorporated into the
Bdellovibrio
cells during oxidation. Acetate is also oxidized, but its oxidation inhibits endogenous respiration by only about 40% and no acetate is assimilated. The RQ of the
Bdellovibrio
cells changes from a value characteristic of endogenous respiration to that characteristic of the oxidation of glutamate or of a balanced amino mixture very shortly after the attack of the
Bdellovibrio
cells on their prey, and the latter RQ is maintained during intraperiplasmic growth. Glutamate, or a mixture of amino acids in the external environment, contributes to the carbon dioxide produced by the
Bdellovibrio
cells growing intraperiplasmically. It is concluded from these data that amino acids, derived from the breakdown of the protein of the prey, serve as a major energy source during intraperiplasmic growth of
B. bacteriovorus
108J. Insofar as they were tested,
B. bacteriovorus
strains 109D and A. 3. 12 were similar in respiration to strain 109J.
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