Production of volatile organic compounds by cyanobacteria Synechococcus sp.

Abstract:

Phytoplankton are known to produce volatile organic compounds (VOCs), which contribute to environmental problems such as global warming and decomposition of stratospheric ozone. For example, picophytoplankton, such as Prochlorococcus and Synechococcus, are distributed in freshwater and oceans worldwide, accounting for a large proportion of biomass and primary production in the open ocean. However, to date, little is known about the production of VOCs by picophytoplankton. In this study, VOCs production by cyanobacteria Synechococcus sp. (NIES-981) was investigated. Synechococcus sp. was obtained from the National Institute for Environmental Studies (NIES), Japan, and cultured at 24°C in autoclaved f/2-Si medium under 54 ± 3 µE m⁻² s⁻¹ (1 E = 1 mol of photons) with a 12-h light and 12-h dark cycle.

VOCs concentrations were determined using a purge-and-trap gas chromatograph–mass spectrometer (Agilent 5973). The concentrations of chlorophyll a (Chl a) were also determined using a fluorometer (Turner TD-700). Bromomethane (CH₃Br) and isoprene were produced by Synechococcus sp. Isoprene production was similar to those of other phytoplankton species reported earlier. Isoprene was produced when Chl a was increasing in the early stage of the incubation period (5–15 days of incubation time, exponential phase), but CH₃Br was produced when Chl a was reduced in the late stage of the incubation period (30–40 days of incubation time, death phase).