Abstract:The bacteriostatic effect of 24 kinds of Chinese herbs and 9 kinds of herb compounds were determined in vitro by improved microdilution procedure and the bacteriostatic circle. This work conducted as the herbs were against four kind of causative pathogens (Vibrio splendidus, Pseudoalteromonas nigrifaciens, Vibrio harveyi, Pseudomonas putida) of skin ulcer syndrome in sea cucumber Apostichopus japonicus. The results illustrated that different herbs showed different susceptivities to given pathogens. The lowest minimal inhibitory concentration（MIC）was 1.56 mg/ml. Decoctum of H-5 and H-9 had maximal bacteriostatic circles against P. nigrifaciens with 22 mm. Four kinds of Chinese herbs (H-5, H-6, H-9 and H-14 ) had better bacteriostatic effect on the four pathogens, in which the average MIC of the decoctum were 6.25 mg/ml, 7.81 mg/ml, 5.86 mg/ml and 3.52 mg/ml respectively, and the average bacteriostatic circles were 17.5 mm, 11.3 mm, 14.0 mm and 11.5 mm. Nine herbal compounds were composed by 4 herbs, the bacteriostatic effect of 9 compounds enhanced remarkably than single herbs, and the lowest MIC reduced to 0.20 mg/ml. The best compounds were HC-G and HC-D, and the average MIC and bacteriostatic circle were 0.54 mg/ml, 0.64 mg/ml, 15.3 mm and 16.3 mm respectively. According to their bacteriostatic effects, the best ratio of the compounds was determined as H-5∶H-6∶H-9∶H-14=2∶1∶3∶2.
