A new sensitive GC-MS-based method for analysis of dipicolinic acid and quantifying bacterial endospores in deep marine subsurface sediment

Author(s): Fang, J.
Author Affiliation(s): Primary:
Hawaii Pacific University, Kaneohe, HI, United States
Volume Title: AGU 2015 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2015; American Geophysical Union 2015 fall meeting, San Francisco, CA, Dec. 14-18, 2015. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: Marine sediments cover more than two-thirds of the Earth's surface and represent a major part of the deep biosphere. Microbial cells and microbial activity appear to be widespread in these sediments. Recently, we reported the isolation of gram-positive anaerobic spore-forming piezophilic bacteria and detection of bacterial endospores in marine subsurface sediment from the Shimokita coalbed, Japan. However, the modern molecular microbiological methods (e.g., DNA-based microbial detection techniques) cannot detect bacterial endospore, because endospores are impermeable and are not stained by fluorescence DNA dyes or by ribosomal RNA staining techniques such as catalysed reporter deposition fluorescence in situ hybridization. Thus, the total microbial cell abundance in the deep biosphere may has been globally underestimated. This emphasizes the need for a new cultivation independent approach for the quantification of bacterial endospores in the deep subsurface. Dipicolinic acid (DPA, pyridine-2,6-dicarboxylic acid) is a universal and specific component of bacterial endospores, representing 5-15 wt% of the dry spore, and therefore is a useful indicator and quantifier of bacterial endospores and permits to estimate total spore numbers in the subsurface biosphere. We developed a sensitive analytical method to quantify DPA content in environmental samples using gas chromatography-mass spectrometry. The method is sensitive and more convenient in use than other traditional methods. We applied this method to analyzing sediment samples from the South China Sea (obtained from IODP Exp. 349) to determine the abundance of spore-forming bacteria in the deep marine subsurface sediment. Our results suggest that gram-positive, endospore-forming bacteria may be the "unseen majority" in the deep biosphere.
Year of Publication: 2015
Research Program: IODP2 International Ocean Discovery Program
Key Words: 07 Marine Geology and Oceanography; Bacteria; Biochemistry; Cores; Expedition 349; International Ocean Discovery Program; Marine sediments; North Pacific; Northwest Pacific; Pacific Ocean; Sediments; South China Sea; West Pacific
Coordinates: N125500 N183400 E1170100 E1145500
Record ID: 2016064382
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by, and/or abstract, Copyright, American Geophysical Union, Washington, DC, United States