| Because unique environment of the sea, there were different metabolisms and defense systems between marine microorganisms and the terrestrial ones. Bio-active substances extracted from marine microorganisms had unique chemical structure and physiological function, which were widely used in biological control in recent years. Therefore, it had become a new way in the exploitation of agricultural antibiotics. At present, devolopment of marine microbial resources were mainly concentrated on coastal waters in the world. In this paper, the samples of the sediment and seawater were collected from coastal areas of mangrove forest of the Beibu Bay in China, and strains with antifungal activity against plant pathogen from the samples were screened out. Then the physiological and biochemical characteristics and ITS sequence of these strains were investigated. It was hoped that we could provide active strains and basic parameters in biological control on plant disease for further.Samples of sediment and seawater were collected three times from Shajing port in Qinzhou and waters from offshore sea of Dazaojiang in the Beibu Bay, and marine fungi were also isolated from these samples. Peronophythora litchii,Colletotrichum gloeosporioides,Phyricularia grisea,Thanatephorus cucumeris,were used as indicator fungi. First, strains with antifungal activity were screened by the dural culture method. Second, the fermentation liquor of these strains was produced and used for a further screen by inhibitory hyphae method, through which the antifungal activity could be determined. Then several strains which had high antifungal activity in the fermentation liquor were chosen to experiment on litchi after picking to validate their practical application. Through salt tolerance test, the strict marine microorganisms were determined. Finally, the morphology and ITS sequence were studied for the representative strains. According to the the molecular identification and phylogenetic analysis, the species were determined.In our experiment, a total of 64 strains of marine mold fungi were isolated from samples. Through primary screening,13 strains with antifungal activity to plant pathogenic fungi were obtained from 14 ones, in which the 020103,020204,020102 had the significant effect. Then,10 strains were chosen from 13 strains primary screened out for further research and they all inhibited the mycelial growth of Thanatephorus cucumeris.The 010104 had the best effect and the inhibition rate was 71%. When Phyricularia grisea were used as indicator fungi, two kinds of results were showed. 4 srtains of marine fungi inhibited the growth of indicator strain, while 6 strains promoted the growth on the contrary. Especially, the 010104 strain had the best inhibitory effectiveness, and inhibition rate was 61%. Most of strains inhibited the growth of Peronophythora litchi, of which the inhibitory effectiveness of 020202 was best. The inhibition rate of 020202 was 93%, and 020103,010104 had inhibition rates of 86%, 71%, respectively. Inhibitory effectiveness of 020103 was the best to Colletotrichum gloeosporioides, and the inhibition rate was 55%.Five strains with high antifungal activity and typical colony characteristics of marine-derived fungi were chosen and numbered with 010104,020205,020202,020102 and 020103, respcetively. The results of antifungal test on postharvest litchi showed that the fruit browning index treated with several fermented marine fungi was less than fungicide at room temperature, and 020102 had the best effectiveness. The fermentation broth of 010104 had certain inhibitory effect on Colletotrichum gloeosporioides desease. Through morphology, molecular identification and phylogenetic analysis, the identification of five marine fungi were determined.020103,010104,020205,020102 and 020202 were Eupenicillium brefeldianum, Penicillium janthinellum, Penicillium adametzii, Penicillium oxalicum and Aspergillus clavatonanicus, respectively.
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