Study On Actinomycete Resources From Desert And Saline-Alkali Soil In Xinjiang Province

Xinjiang located in eurasia hinterland, the territory is very vast, special and diversiform ecological environment gestates special and diversiform microbial resources, so it has great researching and developing value. Study on actinomycete resources from desert and saline-alkali soil in part of region of Xinjiang, which has important significance for law of actinomycete biodiversity in this kind of habitat and promoting exploition of extreme microbial resources, meanwhile, which provide theoretical basis for exploition of extreme actinomycete resources.25 soil samples from desert and saline-alkali soil in Turpan,Kuala,Aksu,Kashgar,Ili and Khotan ect.of Xinjiang were collected, by means of testing soil basic properties analysis the law of ecological distribution of actinomycete, 632 strains of actinomycetes were obtained. Taking common plant pathogens and animal pathogens as organism, which damage seriously in agricultural production and animal husbandry culture, we screened excellent antagonistic actinomycetes, and used polyphasic taxonomy technique to identify parts of strains of actinomycetes which had special morphology and excellent antagonistic effect, meanwhile, preliminary discussed isolation method of actinomycete.The main conclusions were drawed by our research:1. Ecological background of experimental soil and composition of actinomycetes populationsExperimental soil organic matter average contents were lower than middle level, solonetz soils > gravel solonetz soils > sand saline soils > sand soils and average contents were 6.54 21.83,3.75 26.23,2.42 11.31,1.75 8.36 g·kg^-1 respectively; available nutrients contents varied slightly, available nitrogen,available phosphorus,available potassium average contents were 26.37 78.30 mg·kg^-1,7.89 13.30 mg·kg^-1,156.11 431.37 mg·kg^-1 respectively; Soil pH value varied around 8; Soil total salt of solonetz soils,gravel solonetz soils,sand saline soils and sand soils average contents were 0.46 2.64,0.28 0.65,2.96 80.12,0.20 1.46 g·kg^-1 respectively, and average contents were highest in sand saline soils.605 strains of actinomycetes were obtained, and 533 strains were Streptomyces, Streptomyces accounted for 88.1 % of total actinomycetes, Streptomyces could be classified into 12 kinds and Cinerogriseus was the dominant group. There were 72 strains of other genera, and accounted for 11.9 % of total actinomycetes, they could be classified into Nocardia,Micromonospora and Indeterminate genera, Nocardia was the dominant genera.The statistical analysis showed that the positively significant correlation were found out between the contents of soil available phosphorus and the quantities and species of soil actinomycetes, the contents of soil available nitrogenous were correlated with the quantities of soil actinomycetes positively, the contents of soil total salt were correlated with the the quantities and species of soil actinomycetes negatively, soil organic matter and available phosphorus had most effect on the quantities and the species of soil actinomycetes.2. Discussion of isolation method of actinomyceteThe results showed that the quantities and species of actinomycetes were the most when thermal treatment (100℃×1 h); There were the most of the quantities of actinomycetes after the treatment of 6 % peptone solution, but species were the least, the quantities of actinomycetes were in second place after 0.05 % SDS solution, while there were many species; On the improved Gauze No.1 agar,humic acid agar and yeast ext- asparagine agar, the quantities of actinomycetes without inhibitor were higher than with inhibitor, and the species of actinomycetes without inhibitor also greater than or equal to with inhibitor; Streptomyces still were main genera and Griseorubroviolaceus was the dominant group, Nocardia was the dominant other genera.3. Study on the antagonistic activity of actinomycetes in the experimental soil199 strains of antagonistic actinomycetes were screened from 632 strains of actinomycetes, 31.5 % of the test strains had antagonistic activity. In all actinomycetes which antagonized bacteria, actinomycetes which antagonized G⁺ bacteria were more than which antagonized G- bacteria; In all actinomycetes which antagonized fungi, actinomycetes which antagonized pathogenic fungi were more than which antagonized common fungi. Antimicrobial activity of antagonistic actinomycetes was higher, antagonistic actinomycetes which antimicrobial activity was high and mediate accounted for over 90 % of antagonistic actinomycetes. In 33 strains of antagonistic actinomycetes with broad spectrum, antagonistic actinomycetes with broad spectrum which could antagonize four test organisms were more relative,which accounted for 69.7 % of antagonistic actinomycetes with broad spectrum; In 16 strains of antagonistic actinomycetes with high activity, there were 11 strains of antagonistic actinomycetes with high activity, which could antagonize two test organisms meanwhile, 11 strains of antagonistic actinomycetes with high activity accounted for 68.8 % of antagonistic actinomycetes with high activity.By means of antagonistic test in Petri dish, 6 strains were screened, which could antagonize Streptococcus agalactiae, bovine and Staphylococcus aureus, swine very well, strain No. of these 6 strains was 0425,0601,0708,0720,1504 and 2425 respectively, range of antagonistic ring was D≥15 mm, in addition, 14 strains were screened, which could antagonize Phytophthora capsici very well, range of antagonistic ring was D≥20 mm.4. Polyphasic taxonomy of special and antagonistic actinomycetesBy means of observing morphology and culture characteristics, combined with physiological characteristics, the strains of were all Streptomyces, which produced special antibacterial activity substance, and the strains with special form of morphology and culture characteristics were all different, they could not be classified status; According to chemistrical component of cell, cell wall of the strains which produced special antibacterial activity substance included LL-DAP, and cell wall of the strains with special form included meso-DAP or without DAP.The measured sequence of 16S rDNA were compared with the sequence in GenBank, the strain 2202 was Streptomyces, which produced special antibacterial activity substance, the strains with special form 0425,0710,2012,2044 and 2509 were Streptomyces, genetic relationship with Verrucosispora of the strains 1604 and 1511 were more nearly than with Actinoplanes, the strain 2207 was classified Catellatospora in phylogenetic level, and the strain 0910 was classified Streptosporangium in phylogenetic level, but if want to determine the taxonomic status further, complete sequence must be measured, or even by means of DNA-DNA homology analysis , that is DNA-DNA molecular hybridization in vitro.This research revealed that the law of ecological distribution of actinomycete from desert and saline-alkali soil in Xinjiang, enriched actinomycete resources from desert and saline-alkali soil; established antimicrobial spectrum of actinomycete resources in this kind of habitat, obtained parts of excellent antagonistic actinomycetes which had potential application value in agricultural production and animal husbandry culture, which laid the foundations for further application and production; used polyphasic taxonomy technique to identify parts of strains of actinomycetes which had special morphology and excellent antagonistic effect, and determined the taxonomic status objectively, which provided precious data for further research and application on these strains.