[Superoxide dismutase, malondialdehyde and proline as new quality criteria for Schizochytrium sp. fermentation].

The aim of our study was to find a novel method to evaluate the strain quality of Schizochytrium sp. HX-308. An acclimatized strain and an original strain were cultivated under normal condition. Meanwhile, the same acclimatized strain was cultured under two different conditions, the optimum condition and the harsh condition. We detected the activity of superoxide dismutase and the contents of malondialdehyde and proline by WST-1 method, thiobarbituric acid test and colorimetry, respectively. The relationship between the three criteria and the fermentation performance of Schizochytrium sp. HX-308 was studied. The acclimatized strain cultured under the optimal fermentation condition had the lowest superoxide dismutase activity (0.025 U/g protein), malondialdehyde (26.20 mmol/g x Fw) and proline contents (0.098 mg/g x Fw). In contrast, the superoxide dismutase activity of the original strain cultured in the harsh conditions was 5 times higher than that of the acclimatized strain, the malondialdehyde and proline contents were both 2 times as high as the acclimatized strain. The three criteria were correlated negatively with the fermentation performance. Thus, they could be used to evaluate quality and fermentation performance of Schizochytrium sp.