Effect of Culture Temperature on 2-Methylisoborneol Production and Gene Expression in Two Strains of Pseudanabaena sp.

The presence of the odorant 2-methylisoborneol (2-MIB) in drinking water sources is undesirable. Although 2-MIB production is known to be influenced by temperature, its regulation at the gene level and its relationship with Chlorophyll-<i>a</i> (Chl-<i>a</i>) at different temperatures remain unclear. This study investigates the impact of temperature on 2-MIB production and related gene expression in <i>Pseudanabaena</i> strains PD34 and PD35 isolated from Lake Paldang, South Korea. The strains were cultured at three temperatures (15, 25, and 30 °C) to examine cell growth, 2-MIB production, and <i>mic</i> gene expression levels. 2-MIB production per cell increased with higher temperatures, whereas <i>mic</i> gene expression levels were higher at lower temperatures, indicating a complex regulatory mechanism involving post-transcriptional and enzyme kinetics factors. Additionally, the relationship between Chl-<i>a</i> and 2-MIB involved in metabolic competition was analyzed, suggesting that high temperatures appear to favor 2-MIB synthesis more than Chl-<i>a</i> synthesis. The distinct difference in the total amount of the two products and the proportion of 2-MIB between the two strains partially explains the variations in 2-MIB production. These findings highlight the significant effect of temperature on 2-MIB biosynthesis in <i>Pseudanabaena</i> and provide a valuable background for gene data-based approaches to manage issues regarding 2-MIB in aquatic environments.