3-methylbutanal is known to contribute to a nutty aroma in cheese. A paper on a Lactococcus cremoris strain producing 3-methylbutanal has recently been published. Previous studies have reported that 3-methylbutanal is produced most efficiently at temperatures of 37°C or higher. However, in this strain, the highest production level was observed at the relatively low temperature of 20°C. In addition, two metabolic pathways for 3-methylbutanal production have been proposed: a direct pathway and an indirect pathway. The direct pathway has generally been considered the major pathway. In contrast, our findings suggest that the indirect pathway may be the predominant pathway in this strain. Such a difference in the dominant pathway might …