[Effect of temperature on the eubacteria associated with marine sponge Pachychalina sp].

Unlabelled: Temperature is important factor affecting the bacterial diversity.

Objective: In order to disclose the effect of temperature on the diversity of microorganisms.

Methods: The diversity of microorganisms associated with the sponge Pachychilina sp. at 16 degrees C and 30 degrees C of the seawater in the Gulf of Zhanjiang was examined by a restriction fragment length analysis termed ARDRA (amplified rDNA restriction analysis) and 16S rRNA-encoding DNA (rDNA) sequence analysis. The computer-aided clustering was performed after separate restriction analysis with enzymes Hae III.

Results: By this method, 100 cloned 16S rDNA fragments were clustered into a total of 34 different groups at 16 degrees C and 32 different groups at 30 degrees C. Hae III ARDRA patterns showed different among eubacteria living at different temperature degree, whereas the whole communities of eubacteria were not changed distinctly. Screening 60 clones by sequence analysis suggested vast majority of eubacteria related to alpha, gamma, delta subclasses of the class Proteobacteria, some related to sulfur bacteria, desulfobacter, and hydrocarbon utilizing bacteria, minority belonging to actinomyceten at 16 degrees C and 30 degrees C. Alpha subclass of the class Proteobacteria were the predominant bacteria at 30 degrees C, and gamma-Proteobacteria were predominant bacteria at 16 degrees C, additionally sulfur bacteria and desulfobacter were mainly attributed to chilly-enduring bacteria. Sequence analysis of clones with an identical ARDRA pattern confirmed that members of an ARDRA group were closely related to each other.