Phylogenetic diversity of the dddP gene for dimethylsulfoniopropionate-dependent dimethyl sulfide synthesis in mangrove soils.

The dddP gene encodes an enzyme that cleaves dimethylsulfoniopropionate (DMSP) into dimethyl sulfide (DMS) plus acrylate and has been identified in various marine bacteria and some fungi. The diversity of dddP genes was investigated by culture-independent PCR-based analysis of metagenomic DNA extracted from 4 mangrove soils in Southern China. A phylogenetic tree of 144 cloned dddP sequences comprised 7 groups, 3 of which also included dddP genes from previously identified Ddd(+) (DMSP-dependent DMS production) bacteria.

Phylogenetic diversity of nitrogen-fixing bacteria and the nifH gene from mangrove rhizosphere soil.

Nine types of nitrogen-fixing bacterial strains were isolated from 3 rhizosphere soil samples taken from mangrove plants in the Dongzhaigang National Mangrove Nature Reserve of China. Most isolates belonged to Gammaproteobacteria Pseudomonas, showing that these environments constituted favorable niches for such abundant nitrogen-fixing bacteria. New members of the diazotrophs were also found.