Studies On Soil Microbial Community And Functional Strains Of Mountain Brown Soil And Yellow-brown Soil In Wolong Nature Reserve

Based on the forest vegetation of deciduous broad-leaved and mixed coniferousbroadleaved forest in Wolong Nature Reserve in Sichuan Province, the thesis conducts asystematic study of the distribution of the soil microbial,obtain pure culture isolates andobtaincellulose, lignin, phosphate solubilization, nitrogen fixation by using of selectivemedium tochoose functional microorganism.It aims to testify the activity of the four kinds of bacteria,conduct physiological and biochemical experiments, study themorphological features, and havea feature analysis of the bacteria of cellulose and lignin. And then applied research on thedecomposition of cellulose and lignin ability of two bacteria, and achieved good result, laid thefoundation for the agricultural and forestry wastes utilization, obtained from the strains withthe potentially economical strains of bacteria strains.By the separate analysis of the soil micro flora in the two kinds of forest vegetation, theresearch obtains296strains of bacteria,196strains of fungi,165strains of actinomycetes. Allmicroorganisms were vertically distributed, litter layer>A layer>B layer>C layer, litterlayer>0~20cm layer>20~40cm layer, the number of bactria>the number of actinomycetes>thenumber of fungus. As the vegetation species differin the two kinds of forest, the compositionand the feature of the litter fall differ as well. Therefore, the distribution of the soilmicroorganism differs, with the number of microorganism in broad-leaved forest>the numberof microorganism in mixed coniferousbroad-leaved forest.By the selective screening of the269strains of bactria,196strains of fungus,165strainsof actinomycete, the study obtains9strains of bactria,35strains of fungus,and52strains ofactinomycete that decompose cellulose;5strains of azotobacter;7strains of bactria,60strainsof fungus,10strains of actinomycete that decompose lignin;110strains of bactria,59strains offungus, and56strains of actinomycete that have phosphate solubilization activity. It can beseen that the bacteria groups with different functions, species with very different, phosphatesolubilization bacteria can be transformed into an invalid phosphorus, available phosphorus, and to provide phosphorus for woodland and tree growth required, the forest vegetationbettergrowth. Cellulose decomposing bacteria and lignin decomposing bacteria can dry litterinto humic acid, carbohydrates and other dissolved organic matter for forest use, was the mainsource of tree carbon and energy source plays an important role in forest soil carbon cycle, andmorphological composition of the organic matter and soil physical properties, chemicalproperties and biological properties are closely related.The phosphorus solubilizing capability of the phosphobacteria liquid culture shows thatLK3-1FH(1) strains in solid plate on phosphorus dissolving the largest circle, with a5.041D/dvalue. In liquid shaking flask, phosphorus solubilizing capability in liquid shaking flask turnsto be the maximum,the content of available phosphorus in785and865mg/L respectivelywhich proves that the diameter of the phosphorus dissolving circle and the colony (of thebacteria) of the diameter ratio and the corresponding strain medium phosphorus content wasclosely related. Thus validating the phosphorus dissolving circle diameter and the colonydiameter ratio can be used as a qualitative index for whether the strains can dissolvephosphorus and how good of the ability. Also, the strains phosphorus solubilization capabilityand the pH values of the culture solution is negative correlation with each other. That is to say,as the pH value decreased, the strains of phosphorus solubilizing capability enhancement. Butthe strains which was reduced most of the pH value, don’t necessarily have the strongestphosphorus solubilizing capability.The determination of the enzyme activity of FPA and CMCcse by9strain cellulolyticbacteria shows that the strains of LK1-2FH(2) and LK1-2A(1) behave more actively. Afteranalyzing the condition of enzyme production of the two strains, the study f-ound thattemperature, time, initial pH value, inoculation quantity, shaker speed and other factors play agreat role in enzyme production. And temperature and initial pH value affect the enzymeproduction in a greater way. The orthogonal test of conditions of the two strains of enzymeproduction study said that the best culture conditionfor the temperature is30℃,the pH value6.0, the time4d, the inoculation quantity6%,the shaker speed150r/min. Under the above condition, the CMC enzyme of LK1-2A(1)and filter paper enzyme activity respectively are15.69U and12.78U.By the analysis of the experiment result of morphological features and physiological andbiochemical experiments, the study can initially make sure that the strains of LK1-2FH(2),LK1-2A(1), LK2-3C(2) and LK1-2FH(3) are bacillus subtilis; the strains of京09WL8�'�京09WL27are azotobacter; the strains of LK3-1FH(1), ZK3-1FH(1), LK1-1C(1)、LK2-1A(4),LK3-3A(1), LK3-3FH(2), LK1-1FH(2), ZK2-3FH(1), LK3-1A(1), ZK1-2C(2) and LK2-1C(2)are Gram-negative bacteremia; the strains of ZK2-2FH(1), ZK2-2B(1), LK2-1C(3), LK3-2C(1),ZK2-1C(1) and ZK2-3C(1) are psedomonas; and the strains of09WL9are acinetobacter.The testifying of ligninase showed that Lignin peroxidase LiP, Manganese peroxidaseMnPand laccase Lac of the strains of LK2-1C(3) are the highest, with124u/mL，342u/mL，67u/mLrespectively. The strains of LK2-1C3and LK1-2A(1) has a high biodegra-bity over camelliashell.On the tenth day, the weight-loss ratio of camellia shell are31.2%and37.3%. Weight lossrate were increased by25%,31.1%.