Amaral J A, Ekins A, Richards S R, Knowles R
Department of Natural Resource Sciences, McGill University, Ste. Anne-de-Bellevue, Québec, Canada.
Appl Environ Microbiol. 1998 Feb;64(2):520-5. doi: 10.1128/AEM.64.2.520-525.1998.
Selected monoterpenes inhibited methane oxidation by methanotrophs (Methylosinus trichosporium OB3b, Methylobacter luteus), denitrification by environmental isolates, and aerobic metabolism by several heterotrophic pure cultures. Inhibition occurred to various extents and was transient. Complete inhibition of methane oxidation by Methylosinus trichosporium OB3b with 1.1 mM (-)-alpha-pinene lasted for more than 2 days with a culture of optical density of 0.05 before activity resumed. Inhibition was greater under conditions under which particulate methane monooxygenase was expressed. No apparent consumption or conversion of monoterpenes by methanotrophs was detected by gas chromatography, and the reason that transient inhibition occurs is not clear. Aerobic metabolism by several heterotrophs was much less sensitive than methanotrophy was; Escherichia coli (optical density, 0.01), for example, was not affected by up to 7.3 mM (-)-alpha-pinene. The degree of inhibition was monoterpene and species dependent. Denitrification by isolates from a polluted sediment was not inhibited by 3.7 mM (-)-alpha-pinene, gamma-terpinene, or beta-myrcene, whereas 50 to 100% inhibition was observed for isolates from a temperate swamp soil. The inhibitory effect of monoterpenes on methane oxidation was greatest with unsaturated, cyclic hydrocarbon forms [e.g., (-)-alpha-pinene, (S)-(-)-limonene, (R)-(+)-limonene, and gamma-terpinene]. Lower levels of inhibition occurred with oxide and alcohol derivatives [(R)-(+)-limonene oxide, alpha-pinene oxide, linalool, alpha-terpineol] and a noncyclic hydrocarbon (beta-myrcene). Isomers of pinene inhibited activity to different extents. Given their natural sources, monoterpenes may be significant factors affecting bacterial activities in nature.
所选单萜类化合物抑制了甲烷营养菌（ trichosporium甲基孢囊菌OB3b、 luteus甲基杆菌）的甲烷氧化、环境分离株的反硝化作用以及几种异养纯培养物的有氧代谢。抑制作用在不同程度上发生且是短暂的。1.1 mM（-）-α-蒎烯对trichosporium甲基孢囊菌OB3b的甲烷氧化的完全抑制持续了超过2天，在活性恢复之前，培养物的光密度为0.05。在表达颗粒性甲烷单加氧酶的条件下，抑制作用更强。气相色谱未检测到甲烷营养菌对单萜类化合物有明显的消耗或转化，且短暂抑制发生的原因尚不清楚。几种异养菌的有氧代谢比甲烷营养作用的敏感性要低得多；例如，大肠杆菌（光密度为0.01）在高达7.3 mM（-）-α-蒎烯的情况下不受影响。抑制程度取决于单萜类化合物和物种。来自污染沉积物的分离株的反硝化作用未被3.7 mM（-）-α-蒎烯、γ-萜品烯或β-月桂烯抑制，而来自温带沼泽土壤的分离株则观察到50%至100%的抑制。单萜类化合物对甲烷氧化的抑制作用在不饱和环状烃形式（如（-）-α-蒎烯、（S）-（-）-柠檬烯、（R）-（+）-柠檬烯和γ-萜品烯）中最为显著。氧化物和醇衍生物（（R）-（+）-氧化柠檬烯、α-蒎烯氧化物、芳樟醇、α-松油醇）和一种非环状烃（β-月桂烯）的抑制水平较低。蒎烯异构体对活性的抑制程度不同。鉴于其天然来源，单萜类化合物可能是影响自然界中细菌活性的重要因素。
