The Character And Diversity Of Culturable Bacteria Under Vegetation Restoration In The Soil Of Tibetan Plateau

The Qinghai-Tibet Plateau is one of the areas that exotic the most abundant natural resources on the roof of the world.This area is most sensitive to global climate change,and hence the ecological environment there has been severely damaged as a result of frequent human activities in recent years.Vegetation restoration on ecological damaged areas has gained its popularity among scholars owing to its economical properties and non-secondary-pollutants production.Plants and microorganism are closely related,and they jointly promote a verity of biochemical reactions and energy flow in soil.Microorganism plays a significant role in soil and participates in various chemical reactions,and is a sensitive indicator to detect changes in climate and soil environment,however,less is known about counts of soil culturable bacteria and the diversity.In this research,soil from native plots(without vegetation destruction),from restored plots(by planting single species of Elymus nutans,Leymus secalinus,Roegneria thoroldiana,Poa crymophila,mixed sowing of Elymus nutans + Poa crymophila)and from natural recovery plots(no seeding)was sampled(7 treatments in total)in alpine steppe of the Qinghai-Tibet Plateau to investigate counts of soil culturable bacteria and the diversity under different restoration methods.The physiological and biochemical characteristics,together with bioactivity of extracellular enzyme of these strains were studied,which provides ecological parameters for counts of culturable bacteria under varied restoration methods,and a scientific basis for plant restoration as well as potential applications of regional microbial resources.The results are as follows:1.The counts of culturable bacteria in soil varied under different restoration methods,from 1.147×105 to 1.671×106CFU(colony forming unit)per gram of soil.And all vegetation restoration methods increased the counts of culturable bacteria in soil compared to natural recovery method.2.27276 bacterial strains were isolated and characterized based on DNA extraction,PCR amplification,sequencing and blast analysis.The results showed that these strains belong to 6 Phylum,namely Actinobacteria,Bacteroidetes,Firmicutes,?-Proteobacteria,?-Proteobacteria and ?-Proteobacteria.Actinobacteria and ?-Proteobacteria were the dominant phylum under all 7 treatments,and Bacteroidetes,?-Proteobacteria,Firmicutes and ?-Proteobacteria were also isolated.But the species were different in all 7 treatments,indicating that plant restoration changes diversity of soil culturable bacteria.3.Psychrotrophs bacteria(growth range in 20 ? to 37 ?)was the dominant among culturable bacteria in soil under different restoration methods.It was mainly consisted with lipase-production bacterial(48.19%),followed by amylase-production and protease-production bacterial,least was produce cellulase-production bacterial.It grew well in neutral to slightly alkaline(pH 7-9)medium,in which the salt concentration was less than 7%.