Study Of The Tidal-flat Area Mangrove Bacterial Diversity From Zhanjiang

Mangrove is a transition special ecological system between the land and the seawater,which located in tropical and subtropical coast intertidal zone. Due to its unique growthenvironment, mangrove become the dwelled places of many species, containing many extremelyunique microorganism resources. Mangrove beaches bacteria are one of the most important partof the mangrove microbes.We collected samples from Zhanjiang Gaoqiao mangrove national reserve area inSeptember2010, and aim to preliminary investigate the species and variation of communitystructure of the mangrove bacteria in the tidal-flat area. From different tidal zone (low, middle,high) and different soil layer (0~5cm,20~30cm),30soil samples have been collected. Allbacteria strains were isolated from each soil sample, and some of them were identified. The16SrDNA diversity of V3area of bacteria was studied by directly extracting bacteria DNA frommangrove soil and employing polymerase chain reaction and denaturing grade gelelectrophoresis (DGGE) technology. The soil water contents, pH, N, P, K contents and heavymetals contents were determined and there effects on the number of bacteria were studies. Themajor results are as follows:1. The number of bacteria from each soil sample was tested by plate dilution assay andshowed that: middle tidal zone> high tidal zone> low tidal zone, the number in turn is:1.76×10~7,1.65×10~7,1.51×10~7cfu/g.fw.90strains of the bacteria from the samples of three tidelevels were isolated by the pure culture method. From the phylogenetic tree of14representativestrains being subordinated to11species, which distributed in two groups of bacteria: Firmacutesand Gammaproteobacteria. One of the most advantage for community was the genus Bacillus(71.4%).2. The16S rDNA V3area of bacteria in30mangrove soil samples was studied by directlyextracting bacteria DNA from mangrove soil and employing polymerase chain reaction anddenaturing grade gel electrophoresis (DGGE) technology. Use Quantity-One software analysedthe band quantity and gray of the DGGE map, and indagated the bacteria richness index (S),diversity index (H), the homogeneous degree (EH). The results showed that: each index of30mangrove soil samples was different, and with a trend of: middle tidal zone> high tidal zone> low tidal zone, surface soil layer> deep soil layer.3. We got61sequences after cloning and sequencing the predominant bands and greatvariability bands, which were recovered by the DGGE map of the30mangrove soil samples.And the16S rDNA gene sequence similarities ranged from94%~100%, most of the61sequences were phylogenetically close to Proteobacterium, Firmicutes, Actinobacteria,Chloroflexi, Bacteroidetes, Thermodesulfobacteria and Division rchae-bacteria. Uneultured bacteriasequenees presented85%, and the most predominant bands was identified by Bacillus.Our results showed that61sequences represented19genera: Bacillus, Roseobacter,Paracoccus, Pelagibacter, Pantoea agglomerans, Methylomicrobium, actinobacterium,Eubacterium, Corynebacterium, Geobacter, Photobacterium, Chelativorans, Bacteroidaceae,Vibrio, Psychrobacter, Virgibacillus, Enterobacter cloacae, Myxobacterium and Sphingomonas.Thus it can be seen that there was a high diversity of marine bacteria of idal-flat area fromZhanjiang.