| Actinomycetes are important producers of antibiotics. Isolation of novel bioactivecompound-producing actinomycetes is a fundamental work for research and development ofnew drugs. For extensive studies, it has become increasingly difficult in finding novelbioactive actinomycetes using regular technique. In this context, new isolation methods,alternative ecosystems and exploring the distribution of antagonistic actinomycetes are threeeffective ways to improve the isolation efficiency. Qin Mountains is a natural geographic andclimatic boundary between North and South China and possessing diverse biologicalresources. The previous studies of microorganisms in Qin Mountains were mainly focused onthe surface soils. Knowledge is less regarding distribution of microorganisms, especiallyactinomycetes, in other habitats including root zone soil, root surface soil and root of plants.The reserve and distribution of actinomycete resources in Qin Mountains is still unclear. It ishelpful for the protection and utilization of actinomycete resources in Qin Mountains to studythe microbial flora and evaluate the antagonistic potential of actinomycetes in differenthabitats in this area. Taibai Mountain, the highest peak of Qin Mountains, possesses thecomplete vegetation belts in Qin Mountains. To this end, the present paper mainly exploredthe actinomycete flora and distribution of antagonistic actinomycete in five habitats, includingbarks, saxicolous lichens, moss soils, root zone of alpine meadow plants and root field of trees,as well as three isolation methods of soil actinomycetes on the north side of Taibai Mountain.Additionally, the present study analyzed the bacterial and fungal flora in these five habitats.The main results are listed as follows:1. Effect of three new methods on the isolation of soil actinomycetesMicrowave irradiation increased culturable actinomycete counts, species numbers andantagonistic isolates numbers in tested soils, while adding CaCl2to isolation medium andoligotrophy showed reverse effect. Compared to the control, some actinomycetes isolatesbelonging to genus of Streptomyces and Streptosporangium were isolated in all of the threetreatments. Additionally, microwave irradiation was helpful for the isolation of Nocardia spp.and Lentzea spp. Adding CaCl2to isolation medium and oligotrophy were helpful for the isolation of Micromonospora spp. Adding CaCl2to isolation medium was also helpful for theisolation of Nonomuraea spp.2. Biological distribution of actinomycetesTaibai Mountain is possessing rich diverse of actinomycete, in which was mainlyStreptomyces spp. In tested tree barks, there were19dominant actinomycetes speciesbelonging to5genera, in which Streptomyces setonii, Streptomyces cyaneofuscatus andNocardiopsis umidischolae were distributed widely. In saxicolous lichens, there were42dominant actinomycetes species belonging to10genera, in which Streptomyces cirratus,Streptomyces avidinii, Streptomyces griseorubiginosus, Streptomyces vinaceusdrappus andStreptomyces spororaveus were distributed widely. In moss soils, there were28dominantactinomycetes species belonging to2genera, in which Streptomyces cirratus andStreptomyces avidinii were distributed widely. In root zone soils of alpine meadow plants,there were17dominant actinomycetes species belonging to3genera, in which Streptomycescirratus, Streptomyces humidus, Streptomyces spiroverticillatus and Streptomyces avidiniiwere distributed widely. In root field of trees, there were21dominant actinomycetes speciesbelonging to4genera, in which Streptomyces prunicolor, Streptomyces setonii andStreptomyces spiroverticillatus were distributed widely. The diversity of dominantactinomycetes in saxicolous lichens was richest, while in moss soils was poorest in the5tested habitats.3. Antagonistic resource of actinomycetesTaibai Mountain is possessing rich diverse of antagonistic actinomycete resources. Theantagonistic activities were studied using4typical bacterial and fungal species and11plantpathogens. The results showed that about56%of the isolates showed antagonistic activities,including162broad-spectrum antagonistic isolates and plenty of isolates which couldstrongly inhibit G+and G-bacteria.(1) In tested tree barks, about54%of actinomycete isolates cultured from barks showedantagonistic activities. Number of antagonistic isolates in broadleaf tree barks was more thanthat in coniferous tree barks. The reserve of antagonistic actinomycetes and broad-spectrumantagonistic actinomycetes in bark of Quercus aliena var. acuteserrata were more than thoseof other tree species. The reserve of strong antagonistic actinomycetes in bark of Betulaalbo-sinensis var. septentrionalis was more than those of other tree species.(2) In saxicolous lichens, about66%of actinomycetes in saxicolous lichens showedantagonistic activities. The reserve of antagonistic actinomycetes and broad-spectrumantagonistic actinomycetes in saxicolous lichens from lower elevations were more than thosefrom higher elevations. The reserve of antagonistic actinomycetes in starch-utilizing group was highest, while the isolation possibility of antagonistic actinomycetes inoligotrophy-tolerant group was highest.(3) In moss soils, about49%of the isolates in moss soils showed antagonistic activities.The reserve of antagonistic actinomycetes and broad-spectrum antagonistic actinomycetes inmoss soils from lower elevations were more than those from higher elevations. The reserve ofantagonistic actinomycetes in glucose-utilizing group was highest, while the isolationpossibility of antagonistic actinomycetes in chitin-utilizing group was highest.(4) In root zone soils of alpine meadow plants, about47%of actinomycete isolates inroot zone soils of six grasses showed antagonistic activities. The reserve of antagonisticactinomycete resource in root zone soils of Saussurea japonica and Pedicularis plicataMaxim were higher than that of other grass species. Number of broad-spectrum antagonisticactinomycetes in root zone of Delphinium grandiflorum was highest. The reserve ofantagonistic actinomycetes in glucose-utilizing group was highest.(5) In root field of trees, about62%of isolates in root field of trees showed antagonisticactivities. Number of antagonistic isolates in root field of broadleaf trees was more than thatin coniferous trees. The reserve of strong antagonistic actinomycetes in root field of Quercusaliena var. acuteserrata was highest.3. Bacterial and fungal flora(1) In the five habitats, there were44dominant bacterial species belonging to18genera,in which was mainly Pseudomonas spp. For tree barks, the18dominant bacterial specieswere belonging to6genera, in which P. libanensis, Brevibacterium frigoritolerans,Flavobacterium aquidurense and P. Costantinii were distributed widely. For saxicolouslichens, the17dominant bacterial species were belonging to9genera, in which Bacillusmycoides, P. brenneri and P. Orientalis were distributed widely. For moss soils, there were10dominant bacterial species were belonging to7genera, in which Flavobacteriumhercynium and P. Mandelii were distributed widely. For root zone soils of grasses, the8dominant bacterial species were belonging to4genera, in which P. frederiksbergensis, P.mandelii, P. psychrophila and Flavobacterium hercynium were distributed widely. For rootfield of trees, the8dominant bacterial species were belonging to4genera, in which Bacillusdrentensis, Bacillus mycoides and Flavobacterium hercynium were distributed widely. Amongthe5tested habitats, the diversity of dominant bacteria in saxicolous lichens was richest,while in root zone soils of alpine meadow plants and root fields of trees were poorer thanother habitats.(2) In the five habitats, there were44dominant fungal species belonging to18genera.For tree barks, the9dominant fungal species were belonging to8genera, in which Cladosporium Cladosporioides and Cryptococcus albidus were distributed widely. Forsaxicolous lichens, the13dominant fungal species were belonging to10genera, in whichDebaryomyces hansenii and Cryptococcus albidus were distributed widely. For moss soils,the10dominant fungal species were belonging to8genera, in which Mucor Hiemalis,Sydowia Polyspora and Trichocladium asperum were distributed widely. For root zone soilsof grasses, the4dominant fungal species were belonging to3genera: Mucor Hiemalis,Fusarium acuminatum, Fusarium tricinctum and D. hansenii. For root field of trees, the6dominant fungal species were belonging to5genera, in which Cryptococcus albidus andLecythophora mutabilis were distributed widely. The diversity of dominant fungi insaxicolous lichens was richest, while in root zone soils of alpine meadow plants was poorestin the5tested habitats.(3) A novel bacterial species, named Paenibacillus quercus sp. nov., was isolated fromroot surface soil of Quercus aliena var. acuteserrata.Innovations of this paper:(1) Systematically studied the microbial flora and identified the dominant species in treebarks, saxicolous lichens and moss soils, root zone soil of alpine meadow plants and root fieldof trees for the first time, which provided scientific basis for the investigation, preservationand utilization of microbial resources in Qin Mountains.(2) Systematically explored the biological distribution and evaluated the antagonisticpotentiality of actinomycetes in5habitats in the north side of Taibai Mountain for the firsttime. The results drew clear pictures of resources distribution and exploring route, whichcould diminish the blindness and contingency to isolate novel antibiotic producingactinomycetes.(3) Isolated a novel bacterial species, which was named Paenibacillus quercus sp. nov. |
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