Study On Morphology And Biodiversity Of Biofilm Of River Oder

During heavy polluated river self-purification process, biofilm plays an important role. A biofilm is a complex aggregation of micro?organisms growing on a solid substrate. In the river system, biofilm is considered to be steadier than the plankton type community. Because of their position at the interface between the substratum and the water, biofilm play a fundamental role not only in the self-purification process, also for various biogeochemical cycles and dynamics of the aquatic ecosystems.In this dissertation, biofilm morphology, dynamic development and structure of microbial community of biofilm was studied with the help of combination of Scanning Electronic microscope (SEM) and X-Ray (XRF),CARD-FISH and DGGE as the analysis method. Iron-and Manganese-oxidizing bacteria were also isolated from the biofilm of river Oder, their phylogeny and characters were determined. The following conclusions were achieved:Element analysis of biofilm showed that the main composed metal elements of biofilm were amorphous iron and manganese. Iron-and Manganese-oxidizing bacteria could form 1mm size brown color micro-colonies in the bilfilm within 24h. Ultra-structure observation of biofilm illustrated the existent of bacillus with special EPS matrix like a cave. Other EPS-forming bacteria such as sheath bacteria, planctomyces, and budding bacteria with appendage ability were also found.The phylogeny characters of iron-and manganese-oxidizing bacteria isolated from the river Oder biofilm illustrated that all isolated bacteria belong toβ-prokaryote, those isolated bacteria belong to five clusters, the nearest relative of those cluster are Comamonadaceae bacterium MWH55, Leptothrix dischophora,Leptothrix mobilis, Ideonella sp., Spherotilus natant. Some isolated bacteria have self-coagulate ability. Carbon source utilization detected through BIOLOG micro-plate illustrated that sugar, carboxylic acid and amino acid could be utilized. Some bacteria could form complicated branch-like nest structure, most branches were covered by iron- and manganese-oxides.CARD-FISH was applied to the river Oder biofilm to study the microbial community composition, dynamic development and spatial distribution in the biofilm. Beta-prokaryote were determined to be dominant bacteria of the biofilm from Anglerteich and Mummert. As the age of biofilm increased, Eubacteria percentage increased also in the Anglerteich and Mummert biofilm. For the 7days old biofilm, alpha-,beta-,gamma- prokaryote percentage were higher in the Anglerteich biofilm than in the Mummert biofilm. For the 15 days old biofilm, except the increased percentage of gamma-prokaryote, alpha-and beta-prokaryote percentage were lower in the Anglerteich biofilm than in the Mummert biofilm. CARD-FISH result of the microbial community spatial distribution of 24h,7d,15d old biofilm showed that community of 24h age biofilm could only hybridized with beta-probe. For the 7d age biofilm, most eubacteria in Anglerteich biofilm were long chain sheath bacteria. Morphology and relationship of Alpha-prokaryote in Anglerteich biofilm were more diverse and complicated than that in Mummert biofilm, the parasitize-like structure of caulobacter or hyphomicrobium sessile on sheath bacteria was founded. Beta-probe hybridized mainly with sheath bacteria in the 7d age Anglerteich and Mummert biofilm. Gamma-probe hybridized mainly with long filament bacteria in the 7d age Anglerteich biofilm, while with coccus and rod bacteria in the in the 7d age Mummert biofilm. For the 15d age Anglerteich biofilm, eubacteria were composed of spirillum, bacillus and sheath bacteria, while in the 15d age Mummert biofilm, bacillus were dominant bacteria among the eubacteria. Beta-prokaryote were seldom in Anglerteich biofilm while were in great amount in Mummert biofilm, typical curve structure of Leptothrix discophora give the signal with beta-probe in the 15d age Mummert biofilm.DGGE experimental process was optimized. DNA extraction kit was determined to be Fast DNA? SPIN Kit for Soil. Primers of 16S rRNA PCR amplification were selected to be P2/P3. DGGE fingerprint profile showed there was common species existed in Anglerteich and Mummert biofilm, the quantity changed as seasonal alternation. Season and water quality affect the microbial community of river Oder biofilm.