Influence of temperature on growth and production of pectenotoxin-2 by a monoclonal culture of Dinophysis caudata

Abstract

The effects of temperature on growth and production of Lipophilic Toxins (LT) by a monoclonal culture of Dinophysis caudata was studied. The cell density of D. caudata increased significantly with increasing temperature, and was the highest under 27, 30, and 32.5 °C. Temperature affected the average specific growth rate (μ) during the exponential growth phase (EG), which increased from 15 °C to 30 °C, and then decreased at 32.5 °C. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) revealed that this strain of D. caudata produced only pectenotoxin-2 (PTX-2) whose concentration increased significantly with incubation period, except at 32.5 °C. It was significantly different between temperatures ≤18 °C, ≥21 °C, and 32.5 °C. The cellular toxin production (CTP, pg· cell-1· day-1) showed variation with growth phase and temperature, except at 32.5 °C. The average net toxin production (Rtox) was not affected by temperature. During EG, the average specific toxin production rate (μtox) increased significantly with increase in temperature, reaching a peak of 0.66 ± 0.01 day-1 at 30 °C, and then decreased. Over the entire growth span, μtox was significantly correlated to μ, and this correlation was most significant at 27 and 30 °C. During EG, μtox was affected by both temperature and growth. This study shows that temperature affects growth and toxin production of this strain of D. caudata during EG. In addition, a positive correlation was found between toxin production and growth.