Abstract

Different water masses have distinct natural physical and chemical properties, which may influence the bacterial community structure. In the western pacific on both sides of the Luzon strait, which is covered with three water masses including the South China Sea (SCS) water mass, the Kuroshio water mass and the SCS-Kuroshio transition water mass, we selected 11 stations to estimate the spatial variation of surface water bacterial community composition using denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction (PCR)-amplified bacterial 16S ribosomal deoxyribonucleic acid (DNA) gene fragments and interpreted the results; its relationship with physical and chemical factors based on multivariate statistical analysis. A total of 343 bands at 105 different positions were detected in DGGE profiles and 18 distinct DGGE bands were sequenced. Sequence analysis revealed that most of the phylotypes were typical marine uncultured bacteria, and predominant bacteria came from three major phyla; Proteobacteria, Actinobacteria and Cyanobacteria. Apparent phylotype richness near the Luzon strait area varied between 24 and 35 bands (mean 31). Similarity and cluster analysis indicate that the distribution and composition of bacterial community at transition area were more affected by the SCS water mass than Kuroshio current. Redundancy analysis (RDA) revealed that temperature, salinity and the concentration of nitrate accounted for a significant amount of the variability in the bacterial community composition (P=0.004, P=0.014 and P=0.038, respectively, P<0.05).

Key words: Bacterial community composition, spatial distribution, Luzon strait; Kuroshio Current, denaturing gradient gel electrophoresis (DGGE), redundancy analysis (RDA).

Abbreviation

SCS, South China Sea; DGGE, denaturing gradient gel electrophoresis; PCR, polymerase chain reaction; RDA, redundancy analysis; CTD, conductivity-temperature-depth; DCA, detrended correspondence analysis; PAH,polycyclic aromatic hydrocarbons; NCBI, national center for biotechnology information; MVSP, multivariate statistical    package;   UPGMA,   unweighted   pair-group method with arithmetic mean; BLAST, basic local alignment search tool; TAE,Tris–acetate– ethylene diamine tetraacetic acid; dNTP, deoxyribonucleotide triphosphate; EDTA, ethylene diamine tetraacetic acid; rDNA, ribosomaldeoxyribonucleic acid; UV, ultraviolet; DNA, deoxyribonucleic acid; PCR-DGGE,polymerase chain reaction-denaturing gradient gel electrophoresis.