title: Halogenated monoterpene production by microplantlets of the marine red alga Ochtodes secundiramea within an airlift photobioreactor under nutrient medium perfusion.
abstract: Macrophytic marine red algae are a unique source of novel and bioactive terpenoids, including halogenated monoterpenes. Biomass and halogenated monoterpene production by regenerated microplantlet suspension cultures derived from the red alga Ochtodes secundiramea were studied within a perfusion airlift photobioreactor. Photobioreactor cultivations were carried out at 26 degrees C, 140 microE m(-2)s(-1) light intensity, 0.3 air L(-1) culture min(-1) aeration (3500 ppm CO(2)), and ESS/seawater medium perfusion rate of 0.2 L medium L(-1) culture d(-1). Macronutrient concentrations in the perfusion medium were adjusted to provide nitrate delivery rates of 0.0063, 0.077, and 0.74 mmol L(-1) d(-1) at a fixed N:P ratio of 19:1. Growth was maximized at the highest nutrient delivery rate, where 10 g dry biomass L(-1) culture was achieved after 30 days of cultivation. GC-MS analysis of dichloromethane extracts from cell biomass revealed that O. secundiramea microplantlets produced myrcene, three acyclic halogenated monoterpenes (10-bromomyrcene, 10-bromo-7-chloromyrcene, 3,10-dibromomyrcene), and one cyclic halogenated monoterpene (6-bromo-1,2,8-trichloro-3,4-ochtodene). 10E-bromomyrcene levels were much higher than those of its isomer 10Z-bromomyrcene, demonstrating stereoselective halogenation. Maximum yields of 10E-bromomyrcene and 6-bromo-1,2,8-trichloro-3,4-ochtodene were 15 and 13 micromol/g dry cell mass, respectively. Increasing the rate of nutrient delivery increased the accumulation of myrcene and 10-bromomyrcene during the first 14 days in culture. Furthermore, the yield selectivity toward higher halogenated monoterpenes increased as the rate of nutrient delivery decreased. From this data, a biogenic scheme was proposed where cyclic and acyclic halogenated monoterpenes are derived from sequential halogenation of myrcene, their common precursor.
authors.affiliation: Department of Chemical Engineering, Oregon State University, Corvallis, Oregon 97331, USA.
authors.forename: Jason P
authors.initials: JP
authors.lastname: Polzin
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Rorrer
mesh_terms: D019149:Bioreactors; D018929:Cell Culture Techniques / Q000295:instrumentation / Q000379:methods; D002455:Cell Division; D002478:Cells, Cultured; D006846:Hydrocarbons, Halogenated / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D039821:Monoterpenes / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D018462:Photobiology / Q000295:instrumentation / Q000379:methods; D010788:Photosynthesis / Q000502:physiology*; D000461:Rhodophyta / Q000166:cytology / Q000378:metabolism* / Q000502:physiology
chemical_list: D006846:Hydrocarbons, Halogenated; D039821:Monoterpenes