Rflp Analysis Of The Red Soil Ammonia Oxidizing Bacteria-specific 16s Rdna Clone Library

Ammonia-oxidizing bacteria (AOB) are chemolitho-autotrophs and widely exist in most environments. These organisms are unique in their ability to live upon the sole energy source from converting ammonia to nitrite. They are also responsible for the rate-limiting step of nitrification in a wide variety of environments, making them important in the global cycling of nitrogen. Hitherto, domestic researches on AOB are mainly about active sludge, sewage processor and so on, while investigations of AOB community structure in soils especially acidic soils are seldom reported.The diversity and community structure of AOB in red soil sample was mainly studied in this paper. MPN method was used to account the number of AOB in red soil and AOB culture medium was used to enrich AOB from red soil. The community diversity of soil sample was investigated by a culture-independent 16S rRNA gene-based cloning approach. Direct, indirect and a new method were used to extract the total DNA of red soil and the indirect-extracted DNA was used as PCR template owing to its stable PCR result. Clone library was constructed from the PCR amplification with primers specific to16S rDNA gene sequences products. Phylotypes were defined by performing a restriction fragment length polymorphism analysis of 16S rRNA gene sequences with the enzymes Rsa I and Hha I. Main phylotypes were picked up and sequenced. Results of sequence blast in GenBank indicated that there were lots of AOB-like sequences in the library using indirect extraction method. Results also showed Nitrosomonas sp. was dominant phylotype in the library constructed with 16S rDNA PCR amplification from enrichment culture DNA extracted by direct extraction method.