Dataset Information

Bacterial community structure and metabolic potential in microbialite-forming mats from South Australian saline lakes.

ABSTRACT: Microbialites are sedimentary rocks created in association with benthic microorganisms. While they harbour complex microbial communities, Cyanobacteria perform critical roles in sediment stabilisation and accretion. Microbialites have been described from permanent and ephemeral saline lakes in South Australia; however, the microbial communities that generate and inhabit these biogeological structures have not been studied in detail. To address this knowledge gap, we investigated the composition, diversity and metabolic potential of bacterial communities from different microbialite-forming mats and surrounding sediments in five South Australian saline coastal lakes using 16S rRNA gene sequencing and predictive metagenome analyses. While Proteobacteria and Bacteroidetes were the dominant phyla recovered from the mats and sediments, Cyanobacteria were significantly more abundant in the mat samples. Interestingly, at lower taxonomic levels, the mat communities were vastly different across the five lakes. Comparative analysis of putative mat and sediment metagenomes via PICRUSt2 revealed important metabolic pathways driving the process of carbonate precipitation, including cyanobacterial oxygenic photosynthesis, ureolysis and nitrogen fixation. These pathways were highly conserved across the five examined lakes, although they appeared to be performed by distinct groups of bacterial taxa found in each lake. Stress response, quorum sensing and circadian clock were other important pathways predicted by the in silico metagenome analysis. The enrichment of CRISPR/Cas and phage shock associated genes in these cyanobacteria-rich communities suggests that they may be under selective pressure from viral infection. Together, these results highlight that a very stable ecosystem function is maintained by distinctly different communities in microbialite-forming mats in the five South Australian lakes and reinforce the concept that 'who' is in the community is not as critical as their net metabolic capacity.

SUBMITTER: Nguyen STT

PROVIDER: S-EPMC9311741 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:Although it is recognized that acidification of freshwater systems results in decreased overall species richness of plants and animals, little is known about the response of aquatic microbial communities to acidification. In this study we examined bacterioplankton community diversity and structure in 18 lakes located in the Adirondack Park (in the state of New York in the United States) that were affected to various degrees by acidic deposition and assessed correlations with 31 physical and chemical parameters. The pH of these lakes ranged from 4.9 to 7.8. These studies were conducted as a component of the Adirondack Effects Assessment Program supported by the U.S. Environmental Protection Agency. Thirty-one independent 16S rRNA gene libraries consisting of 2,135 clones were constructed from epilimnion and hypolimnion water samples. Bacterioplankton community composition was determined by sequencing and amplified ribosomal DNA restriction analysis of the clone libraries. Nineteen bacterial classes representing 95 subclasses were observed, but clone libraries were dominated by representatives of the Actinobacteria and Betaproteobacteria classes. Although the diversity and richness of bacterioplankton communities were positively correlated with pH, the overall community composition assessed by principal component analysis was not. The strongest correlations were observed between bacterioplankton communities and lake depth, hydraulic retention time, dissolved inorganic carbon, and nonlabile monomeric aluminum concentrations. While there was not an overall correlation between bacterioplankton community structure and pH, several bacterial classes, including the Alphaproteobacteria, were directly correlated with acidity. These results indicate that unlike more identifiable correlations between acidity and species richness for higher trophic levels, controls on bacterioplankton community structure are likely more complex, involving both direct and indirect processes.

Project description:Biosurfactants are surface-active biomolecules with great applicability in the food, pharmaceutical and oil industries. Endospore-forming bacteria, which survive for long periods in harsh environments, are described as biosurfactant producers. Although the ubiquity of endospore-forming bacteria in saline and hypersaline environments is well known, studies on the diversity of the endospore-forming and biosurfactant-producing bacterial genera/species in these habitats are underrepresented.In this study, the structure of endospore-forming bacterial communities in sediment/mud samples from Vermelha Lagoon, Massambaba, Dois Rios and Abraão Beaches (saline environments), as well as the Praia Seca salterns (hypersaline environments) was determined via denaturing gradient gel electrophoresis. Bacterial strains were isolated from these environmental samples and further identified using 16S rRNA gene sequencing. Strains presenting emulsification values higher than 30 % were grouped via BOX-PCR, and the culture supernatants of representative strains were subjected to high temperatures and to the presence of up to 20 % NaCl to test their emulsifying activities in these extreme conditions. Mass spectrometry analysis was used to demonstrate the presence of surfactin.A diverse endospore-forming bacterial community was observed in all environments. The 110 bacterial strains isolated from these environmental samples were molecularly identified as belonging to the genera Bacillus, Thalassobacillus, Halobacillus, Paenibacillus, Fictibacillus and Paenisporosarcina. Fifty-two strains showed emulsification values of at least 30%, and they were grouped into 18 BOX groups. The stability of the emulsification values varied when the culture supernatants of representative strains were subjected to high temperatures and to the presence of up to 20% NaCl. The presence of surfactin was demonstrated in one of the most promising strains.The environments studied can harbor endospore-forming bacteria capable of producing biosurfactants with biotechnological applications. Various endospore-forming bacterial genera/species are presented for the first time as biosurfactant producers.

Dataset Information

Bacterial community structure and metabolic potential in microbialite-forming mats from South Australian saline lakes.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets