Study On Bioactivity Of Volatiles By Streptomyces Sp. TD-1

Plant diseases and pests lead to a serious decline in crop yields and cause huge economic loss to world agriculture. Utilization of volatile organic compounds released by microorganism in inhibiting agricultural diseases and pests is a novel biological control method, getting an increasing concern for its prominent advantages such as high efficiency, great convenience and environmental friendliness.This paper did a research on the biological activity of a biocontrol strain Streptomyces sp. TD-1 preserved by the laboratory and found that the volatile organic compounds released by its wheat seed culture were able to inhibit the growth of a variety of plant pathogenic fungi belonging to Fusarium, Aspergillus, Alternaria and Penicillium. Streptomyces sp. TD-1 fumigant activity was studied in vitro and in vivo with Fusarium moniliforme as the indicator strain; constituents of Streptomyces sp. TD-1 volatiles were identified by means of GC/MS; inhibition of volatile organic compounds on Meloidogyne incognita survival and hatch ability as well as the susceptibility of infected tomato cultivars were also studied, providing a foundation for the development and application of effective biofumigants from Streptomyces resource.The additional components to Streptomyces sp. TD-1 wheat seed medium and culturing conditions were optimized for the strongest inhibition effect on the growth of F. moniliforme by single factor experiments and orthogonal design:soybean powder 1%, K2HPO4 0.1%, inoculum 10%, bottling amount 50 g/250mL, fumigant dose 20 g, corresponding inhibition rate 58.32%,157.26% higher than the original.The optimal drying and rehydration conditions were:drying temperature 40 ℃, rehydration solution 3% sucrose and mass ratio of dried material to liquid 1:1, able to reduce antifungal activity loss during drying process to the greatest extent; compared to the inoculated corn ear with no treatment, the moldy degree of fumigated counterparts was obviously alleviated, moldy time significantly delayed and the more fumigant dose was, the less corn sensory quality changed.60 kinds of substances were detected by GC/MS, including terpenes, aromatic hydrocarbons, aldehydes, alcohols, phenols, ethers and so on. Dimethyl disulfide, cycloheptatriene, (-)-myrtenal, p-cymene, patchouli alcohol, β-eudesmol, cis-1,4-dimethyl adamantane, 1H-indene, hydrogenated naphthol, cyclodecadiene, cubebene, cycloisolongifolene and some others all may play a potential role in inhibiting various fungal growth.Streptomyces sp. TD-1 was also found to have fumigation activity against Meloidogyne incognita:all J2 dead in 8 days; eggs hatching rate only 17.98%, more than half remaining dormant; disease severity of root-knot nematode infected tomato cultivars was well alleviated with 5% Streptomyces sp. TD-1 fumigant in the soil.