Transcriptional Difference of Deep-Sea Microorganisms under Different Sampling Methods

The metabolic potential
and activity of deep-sea microbes have
not been fully explored by meta-transcriptomics using the samples
obtained by different sampling methods. Here, we report active deep-sea
microbes obtained by the methods of multiple in situ nucleic acid
collection (MISNAC), in situ microbial filtration and fixation (ISMIFF),
in situ microbial filtration without fixation (ISMIFU), and the Niskin
bottle at a 1038 m depth in the South China Sea. Higher biodiversity
and different dominant active microbial taxa in the metatranscriptomes
were detected in the MISNAC and ISMIFF samples compared with the other
two approaches. The transcriptional profiles of 40 conserved genes
were similar between the MISNAC and ISMIFF samples, while the expression
of a quarter of these genes was not detected in the ISMIFU sample.
Genes related to the CO oxidation and nitrification processes were
highly transcribed in the MISNAC and ISMIFF transcriptomes, whereas
those for chemotaxis and low-oxygen adaptation were highly transcribed
in the Niskin samples. Overall, our result highlights the importance
of in situ sampling and preservation for more precise quantification
of the ecological function of active deep-sea microbiomes.