Compositon Of Culturable Microbial Physiological Groups And Identifications Of Dominant Bacteria In Soils Under Sand-fixing Plantations In Horqin Sand Land

Soil microbes are taken as an indication of environmental changes because they are sensitive to those. Microbial numbers and composition are used to assess soil quality. Plantations have different ecological effect on soil microbe. The goal of this study is to investigate effects of plantations on culturable microbial composition and dominant species in sandy soil in Kerqin, China.15soil samples under sand-fixing plantations including Caragana microphylla (12-,16-, and26-yr), wild Caragana microphylla, Salix gordeiviig (12-and26-yr), Hedysarum fruticosum(12-and26-yr), Artemisia halodendron(12-and26-yr), Pinus sylvesris var. mongolica (26-yr), Populus simonii(26-yr), Hippophae ramnoides(12-yr) and Caragana Korshinskii Kom(12-yr) were collected. Using pour plate and most probable number methods, microbiaota and microorganism quantity were examined. Main physiological groups such as ammonifier, ammonia oxidizing bacteria, aerobic autotrophic nitrogen-fixing bacteria, aerobic cellulose decomposition bacteria, anaerobic cellulose decomposition bacteria, were characterized numerically. Culturable dominant bacteria and specific bacteria were identified by microbiology and molecular biology(16S rDNA gene sequences) ways.The result indicated that bacteria were most in number followed by actinomycetes, fungi least in all soils. Ammonifier were abosolutey dominant in all soils. Few ammonia oxidizing bacteria, aerobic autotrophic nitrogen-fixing bacteria, aerobic and anaerobic cellulose decomposition bacteria were found. Microbiaota and microorganism quantity were measured. The quantity of bacteria, actinomycetes, fungi and total microorganism were found increasing with the development of plantation, and so were ammonifier, ammonia oxidizing bacteria, aerobic autotrophic nitrogen-fixing bacteria, aerobic and anaerobic cellulose decomposition bacteria. The Soil under26-yr Populus simonii contained the most bacteria, fungi actinomycetes and physiological groups.26dominant isolates were identified based on16S rDNA gene sequences associated morphology and they belonged to Arthrobacter sp., Bacillus sp., Lysobacter sp., Stenotrophomonas sp., Micrococcus sp., Microbacterium sp., Planomicrobium sp., Agromyces sp., respectively. Arthrobacter was the dominant bacteria in soils under most of plantations and suggested that soil type and climatic conditions may be main factor influencing culturable soil microorganic community and composition while plantation and time of plantation development had less effect on dominant species in sandy soil in the area.