Abstract: Pyropia haitanensis collected from the culture area of the Xiangshan, Zhejiang Province, was pure cultured and co-cultured with Bacillus sp. WPySW2 from Porphyra-epiphytic bacteria under different time (0, 6, 12, 24, 48 and 72 h). They grew at the normal culture temperature (20℃), and the physiology were measured, including the activities of (POD), superoxide dismutase (SOD), and also photosynthetic pigments, total protein, free proline and malondialdehyde (MDA) levels. The results showed that the content of photosynthetic pigments and protein in co-culture group was better than that in the control. Both were no significant difference in antioxidant enzyme activity because of cell membranes been not oxidized (P>0.05). The two groups produced excessive membrane lipid peroxidation and osmotic pressure regulating substance, but the control group produced more (P<0.05). It was speculated that the phycosphere epiphytic bacteria would provide nutrients for the algae in phycosphere to affect their growth status and the accumulation of nutrients.

Key words: Pyropia haitanensis, Bacillus sp. WPySW2, phycosphere