Study On Soil Bacterial Diversity Of Alpine Meadow In The Eastern Qilian Mountains

In this study, three types of shrub grassland and three types of meadow had been selected: Rhododendron fruticosa shrub land, Salix cupularis fruticosa shrub land, Dasiphoru fruticosa shrub land, Polygonum viviparum grassland, Grass grassland and Kobresia grassland. Microbiological and molecular biological methods had been applied, to study on the species diversity of soil microbial, the diversity of physiological metabolism and the community function diversity of soil microbial. The results were as follows:1 The species diversity of soil culturable bacteria50 kinds of alpine grassland soil bacteria, which had been preserved in laboratory and isolated, had been observed and described the morphological and cultural characteristics. And the genomic DNA of these bacteria had been extracted for 16SrDNA identification, which aim to establish phylogenetic status. 29 bacteria strains had been identified respevtively: Bacillaceae, Bacillus sp., Arthrobacter sp., Paenibacillus sp., Sporosarcina sp., Brevibacillus laterosorus, Bacillus weihenstephanensis, Bacillus pumilus, Bacillus aquimaris, Bacillus cereus, and Bacillus simplex.2 Physiological and metabolic diversity of soil culturable bacteriaFive bacteria which had been isolated from the soil of alpine grassland had been selected for estimating their motility and using ability of various carbon resources and nitrogen resources as well as decomposition of large molecular substances. The obtained results were as follows: HX4, HX3, HY1-1 and NX3 had obvious motility, but HY6 was inconspicuous; There were differences among the utilization ability and degree of inorganic nitrogen or organic nitrogen, such as nitrate and protein, as well as various carbon resources in five bacteria .It was proved that those bacteria had certain selectivity and played different roles in the decomposition and utilization of animal and plant debris and leavings in the grassland soil.3 Study on soil microbial community metabolic functional diversityBy utilization of Biolog ECO PlateTM system with 31-carbon-substrate, this paper analysised soil microbial metabolic functional diversity of 6 types of alpine grassland. The results showed that: (1) By comparing scrub and grassland, total carbon utilization kinetic characteristics of soil microbial community under scrub and grassland indicated that the used amount of carbon substrates by soil microbial community increased with time; before cultured 144h, scrub>grassland, and when to 168h, the grassland>scrub; principal component analysis of utilized carbon substrate type by soil microbial community showed that the efficiency of utilization of carbon substrate were different under scrub and grassland and that the main used kinds of carbon substrate were 6 carboxylic acids,5 amino acids and 5 carbohydrate,16 carbon substrate in total; the comparison of soil microbial community metabolic functional diversity under scrub and grassland indicated that the difference of both Shannon index and the Eveness(EH) were significant(P<0.05),but there was no obvious difference between the richness(R)(P>0.05). (2) By comparing 3 kinds of scrub, the capability of utilization of sole carbon substrate by soil microbial community under 3 kinds of scrub were as follows: Dasiphoru fruticosa shrub land>Salix cupularis fruticosa shrub land>Rhododendron fruticosa shrub land; principal component analysis of utilized carbon substrate type by soil microbial community showed that the efficiency of utilization of carbon substrate are different under 3 kinds of scrub and that the main used kinds of carbon substrate are 9 carboxylic acids, 6 carbohydrate and 4 polymer,19 carbon substrate in total; the comparison of soil microbial community metabolic functional diversity under 3 kinds of scrub indicated that the difference of both the richness(R) and the Eveness(EH) were significant(P<0.05),but Shannon index was extremely significant (P<0.01). (3) By comparing 3 kinds of grassland, the capability of utilization of sole carbon substrate by soil microbial community under 3 kinds of grassland were as follows: Polygonum viviparum grassland>Kobresia grassland>Grass grassland; principal component analysis of utilized carbon substrate type by soil microbial community showed that the efficiency of utilization of carbon substrate are different under 3 kinds of grassland and that the main used kinds of carbon substrate were 9 carboxylic acids, 7 carbohydrate, 6 amino acids and 4 polymer; the comparison of soil microbial community metabolic functional diversity under 3 kinds of grassland indicated that the difference of between Shannon index, the richness(R) and the Eveness(EH) were extremely significant(P<0.01).