Abstract: The anti-microbial activities of hot water extract from Poria brick tea, PDA liquid medium and their fermentation supernatants by Eurotium cristatum against bacteria, fungi, mold and actinomycetes were determined by filter paper disc method. Meanwhile, the effects of factors including pH, temperature, UV on the anti-microbial activities of PDA fermentation supernatant were explored. The results indicated that both fermentation supernatants had an obvious anti-bacterial activity but no obvious inhibition effect against yeast and mold. Preliminary studies on the anti-microbial stability of the PDA fermentation supernatant showed that it had better stability under each of the following conditions: 40－120 ℃, UV irradiation for 10 h and pH 2－10.

Key words: Eurotium cristatum, fermented liquid, anti-microbial activity, stability