Studies On The Biocontrol Potential Of A Marine Bacillus Amyloliquefaciens Txc2-1

Salinization is one of the major problems affecting agriculture. In particular, the soil-borne disease in salinated soil severely restricts agriculture development. Due to the good salt tolerance, the marine microbes showed great advantages in controlling soil-borne diseases in salinated soil. Thus far, the biocontrol microbes of registered microbial pesticides are all from terrene, except for Bacillus marinus B-9987. The Bacillus Amyloliquefaciens Txc2-1 in this article was isolated from ocean. In this study, the antibacterial activities of Txc2-1 were reseached and the separations of antimicrobial substance were studied; in the same time, the biocontrol efficacies against soil-borne diseases in salinated soil were also researched.The culture filtrate of Txc2-1 exhibited broad-spectrum antifungal activity against all testing plant pathogenic fungus in vitro. The salt tolerance of Txc2-1 was better than that of the commercialized terrestrial microbe Paenibacillus polymyxa HY96-2 because Txc2-1 grew well in the medium with 2% NaCl. However, the growth of HY96-2 was inhibited strongly in the medium with 2% NaCl. On the basis of the characteristics of morphology and biochemistry and the analysis of 16S rDNA sequence, Txc2-1 was identified as B. amyloliquefaciense.The pot test showed the Txc2-1 WP not only have good biocontrol efficacies for Chinese cabbage clubroot (Plasmodiophora brassicae), but also significantly promote the growth of plants. The maximum biomass of cucumber seedlings treated with Txc2-1 WP was 33.7% at 7 days after treatment.In the salinated field, the biocontrol efficacy of Txc2-1 WP on tomato bacterial wilt (Ralstorinia solanacearum) was 86.9% at 45 days after the last application; this biocontrol efficacy was significantly better than that of P. polymyxa HY96-2 WP (76.37%). Moreover, the biocontrol efficacy of Txc2-1 WP on tomato early blight (Alternaria solani) was 62.3% at 7 days after the last application; this biocontrol efficacy was significantly better than that of difenoconazole WP (46.8%). Furthermore, Txc2-1 WP also showed strong biocontrol efficacy on the Chinese cabbage clubroot and tobacco black shank in field.A total of 9 antifungal compounds from the culture filtrate of Txc2-1 were isolated by column chromatography and high-performance liquid chromatography via acidification precipitation and methanol extraction. One of the compounds was determined as iturin A2 through nuclear magnetic resonance and high-resolution mass spectrometry analysis.