Community Structure of Ammonia-Oxidizing Bacteria During Long-term Fertilizer Application in the Loess Plateau
|Keywords||AOB Community structure Long-term fertilization DGGE Loess Plateau|
Farm Ecosystem term fertilization makes artificial soil characteristics change occurred , and different manure management practices in changing soil carbon, nitrogen and other nutrients characteristics of the time, changed the microbial properties. Ammonia -oxidizing bacteria are involved nitrification of ammonia oxidation process is the first step , but also its rate-limiting step , is to support the global nitrogen cycle important biological processes , microbial ecology study them as one of the species in the model , received wide attention . In this paper, PCR-DGGE method for encoding ammonia monooxygenase α- subunit gene amoA , 29 years on the Loess Plateau fertilization of farmland ecosystems of ammonia oxidizing bacteria were studied, analyzed the ammonia oxidizing bacteria communities structure and diversity of different inorganic and organic fertilizer response . Experiment consists of six treatment : CK, no fertilizer ; N, N fertilizer annually ; NP, annual nitrogen and phosphate ; M, manure applied annually ; MNP, manure applied annually , nitrogen, phosphorus ; SNP, straw and fertilizer applied annually , 2 phosphate was applied once . DGGE profiles showed that the MNP and SNP balanced fertilization treatment , ammonia-oxidizing bacterial diversity than any other treatment is high. In addition, the maturity of wheat , with no N fertilizer treatment compared to the oxidation of ammonia nitrogen can increase bacterial community structure . Our results also show that different growth stages of wheat and soil at different depths on the community structure of ammonia-oxidizing bacteria have a significant impact . Filling period ( May ) diversity index was significantly higher than the jointing stage ( April ) and maturity ( June ) (P lt; 0.05), especially in May, the highest diversity index MNP process , and as the soil depth increases, the reduction of ammonia oxidizing bacteria diversity . Phylogenetic analysis showed nitrosated snail genus cluster 3 in all treatments have an absolute advantage , but there are very few appear Nitrosomonas spp . These results suggest that the Loess Plateau farmland ecosystem , long-term different fertilization management systems on soil ammonia oxidizing bacteria have different effects on community structure and composition of ammonia-oxidizing bacterial community in different growth stages of crops and soil depth are closely between linked.