Changing microspatial patterns of sulfate-reducing microorganisms (SRM) during cycling of marine stromatolite mats

• Published in: International journal of molecular sciences Vol. 15; no. 1; pp. 850 - 877
• Main Authors: Petrisor, Alexandru I, Szyjka, Sandra, Kawaguchi, Tomohiro, Visscher, Pieter T, Norman, Robert Sean, Decho, Alan W
• Format: Journal Article
• Language: English
• Published: Switzerland Molecular Diversity Preservation International (MDPI) 09.01.2014; MDPI AG
• Subjects: 35SO42− silver-foil; AHLs; Bacteria - classification; Bacteria - isolation & purification; Bacteria - metabolism; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; biofilms; CaCO3; Caseins - chemistry; chemical signals; Cluster Analysis; dsrA probe; EPS; Geographic Information Systems; Geologic Sediments - microbiology; microbial mats; microspatial; Phylogeny; RNA, Small Untranslated - chemistry; sulfate-reducing microorganisms; Sulfates - chemistry; Sulfates - metabolism; Sulfite Reductase (NADPH) - genetics; Sulfite Reductase (NADPH) - metabolism
• ISSN: 1422-0067; 1422-0067
• DOI: 10.3390/ijms15010850

Microspatial arrangements of sulfate-reducing microorganisms (SRM) in surface microbial mats (~1.5 mm) forming open marine stromatolites were investigated. Previous research revealed three different mat types associated with these stromatolites, each with a unique petrographic signature. Here we focused on comparing "non-lithifying" (Type-1) and "lithifying" (Type-2) mats. Our results revealed three major trends: (1) Molecular typing using the dsrA probe revealed a shift in the SRM community composition between Type-1 and Type-2 mats. Fluorescence in-situ hybridization (FISH) coupled to confocal scanning-laser microscopy (CSLM)-based image analyses, and 35SO4(2-)-silver foil patterns showed that SRM were present in surfaces of both mat types, but in significantly (p < 0.05) higher abundances in Type-2 mats. Over 85% of SRM cells in the top 0.5 mm of Type-2 mats were contained in a dense 130 µm thick horizontal layer comprised of clusters of varying sizes; (2) Microspatial mapping revealed that locations of SRM and CaCO3 precipitation were significantly correlated (p < 0.05); (3) Extracts from Type-2 mats contained acylhomoserine-lactones (C4- ,C6- ,oxo-C6,C7- ,C8- ,C10- ,C12- , C14-AHLs) involved in cell-cell communication. Similar AHLs were produced by SRM mat-isolates. These trends suggest that development of a microspatially-organized SRM community is closely-associated with the hallmark transition of stromatolite surface mats from a non-lithifying to a lithifying state.