Physiological characteristics of a low-pH tolerant strain Torulopsis glabrata RT-6

Abstract:

Abstract: [Objective] With the aim of elucidating the physiological characteristics of a low-pH tolerant strain Torulopsis glabrata RT-6. [Methods] The intracellular pH, ATP level, the membrane bound H+-ATPase activity, the membrane fatty acid composition and the intracellular polyphosphate content of the parent strain CCTCC M202019 and the mutant strain RT-6 were determined and compared under different pH conditions. [Results] Compared to that of the parent strain, the cell growth and pyruvate concentration of the mutant strain RT-6 were increased by 60.6 % and 85.4 % (56 h), respectively. Similarly, the strain RT-6 had higher intracellular pH compared to the control strain at external pH5.0, 4.5, and 4.0. The ATP content, the membrane bound H+-ATPase activity and the intracellular polyphosphate content of the mutant strain RT-6 were increased by 11.7 %, 13.6 %, and 3.5 % at external pH 5.5, while at external pH 4.0, increased by 61 %, 38.6 %, and 30.8 % , respectively. Furthermore, the mutant strain RT-6 exhibited higher content of the unsaturated fatty acids and higher membrane fluidity. [Conclusion] Discharging more intracellular H+ and inhibiting the intracellular H+ production contributed to the strain RT-6’s higher intracellular pH, and therefore the acid tolerance.