Elevation of ceramide in Acetobacter malorum S24 by low pH stress and high temperature stress

Acetic acid bacteria have unique and highly pure membrane lipid components, such as 2-hydroxypalmitoyl-sphinganine (dihydroceramide) and can grow and produce acetic acid at around pH 3.0, suggesting that ceramide in cell membranes may be involved in the tolerance to acidic pH. Acetobacter malorum S24 was selected for the production of ceramide and grown in YPG medium containing 0.8% ethanol. Ceramide biosynthesis was induced at pH 4 and below, suggesting that ceramide biosynthesis is induced by low pH stress. Elevation of ceramide was also induced by high temperature stress (40–70 °C). After the strain was cultured in an optimal growth medium, the cells were collected and treated at pH 3 and 40 °C for 4 days, resulting in a 30-fold elevation of both the yield and content of ceramide.