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Ocean warming is killing corals, but heat-tolerant populations exist; if protected, they could replenish affected reefs naturally or through restoration. Palau's Rock Islands experience consistently higher temperatures and extreme heatwaves, yet their diverse coral communities bleach less than those on Palau's cooler outer reefs. Here, we combined genetic analyses, bleaching histories and growth rates of Porites cf. lobata colonies to identify thermally tolerant genotypes, map their distribution, and investigate potential growth trade-offs. We identified four genetic lineages of P. cf. lobata. On Palau's outer reefs, a thermally sensitive lineage dominates. The Rock Islands harbor two lineages with enhanced thermal tolerance; one of which shows no consistent growth trade-off and also occurs on several outer reefs. This suggests that the Rock Islands provide naturally tolerant larvae to neighboring areas. Finding and protecting such sources of thermally-tolerant corals is key to reef survival under 21st century climate change. A thermally-tolerant lineage of Porites lobata is identified from the Rock Islands of Palau. [ABSTRACT FROM AUTHOR]

Reef-building corals form a symbiotic association with photosynthetic dinoflagellates of the family Symbiodiniaceae. This symbiosis is crucial for the maintenance of coral reefs. In this work, we evaluate the effect of light conditions on the transcriptomic response of Symbiodinium CCMR0100 (ITS2 type A4), isolated from the Southwestern Atlantic Ocean endemic Mussismilia braziliensis. We obtained a total of 36,224 transcripts (N50 = 1007 bases, mean GC = 55.7%; ~25 Gb of assembled bases). We observed ecologically relevant transcripts encoding i. the complete antioxidant enzymatic system, ii. the recently described algal dimethylsulfoniopropionate (DMSP) lyase, and iii. The Mycosporine-like aminoacids (MAA) biosynthesis pathway. Cultures maintained in dark and light conditions yielded different transcriptomic profiles, and 48 transcripts were differentially expressed between these treatments. Expression of cytochrome P450 was inhibited by light, suggesting that endoplasmic reticulum monooxygenase activity might play a role in light-independent coral bleaching. Light conditions also triggered the induction of transcripts associated to chromatin condensation and mitosis, consistent with the light dependent progression of Symbiodiniaceae cell cycle. The repression of transcripts associated to the phosphatidylinositol (PI) signaling pathwaysuggests this pathway shall be related to light-induced morphological changes in Symbiodiniaceae cell. [ABSTRACT FROM AUTHOR]

The Brazilian endemic scleractinian corals, genus Mussismilia, are among the main reef builders of the South Atlantic and are threatened by accelerating rates of disease. To better understand how holobiont microbial populations interact with corals during health and disease and to evaluate whether selective pressures in the holobiont or neutral assembly shape microbial composition, we have examined the microbiota structure of Mussismilia corals according to coral lineage, environment, and disease/health status. Microbiota of three Mussismilia species ( Mussismilia harttii, Mussismilia hispida, and Mussismilia braziliensis) was compared using 16S rRNA pyrosequencing and clone library analysis of coral fragments. Analysis of biological triplicates per Mussismilia species and reef site allowed assessment of variability among Mussismilia species and between sites for M. braziliensis. From 173,487 V6 sequences, 6,733 coral- and 1,052 water-associated operational taxonomic units (OTUs) were observed. M. braziliensis microbiota was more similar across reefs than to other Mussismilia species microbiota from the same reef. Highly prevalent OTUs were more significantly structured by coral lineage and were enriched in Alpha- and Gammaproteobacteria. Bacterial OTUs from healthy corals were recovered from a M. braziliensis skeleton sample at twice the frequency of recovery from water or a diseased coral suggesting the skeleton is a significant habitat for microbial populations in the holobiont. Diseased corals were enriched with pathogens and opportunists ( Vibrios, Bacteroidetes, Thalassomonas, and SRB). Our study examines for the first time intra- and inter-specific variability of microbiota across the genus Mussismilia. Changes in microbiota may be useful indicators of coral health and thus be a valuable tool for coral reef management and conservation. [ABSTRACT FROM AUTHOR]

Strains of hyperthermophilic anaerobic hydrothermal vent archaea maintained in the culture collection assembled by Holger Jannasch at the Woods Hole Oceanographic Institution between 1984 and 1998 were identified and partially characterized by Denaturing Gradient Gel Electrophoresis, 16S rRNA gene sequencing, and by growth tests at different temperatures and on different organic carbon and nitrogen sources. All strains were members of the genera Thermococcus and Pyrococcus. The greatest phylogenetic diversity was found in strains from a single Guaymas Basin core isolated by serial dilution from four different depth horizons of heated sediment incubated at the corresponding in situ temperatures. In contrast, geographically distinct vent locations and sample materials yielded a lower diversity of isolates when enriched under uniform temperature regimes and without prior dilution of the source material. [ABSTRACT FROM AUTHOR]

Culture contamination, end-product toxicity, and energy efficient product recovery are long-standing bioprocess challenges. To solve these problems, we propose a high-pressure fermentation strategy, coupled with in situ extraction using the abundant and renewable solvent supercritical carbon dioxide (scCO2), which is also known for its broad microbial lethality. Towards this goal, we report the domestication and engineering of a scCO2-tolerant strain of Bacillus megaterium, previously isolated from formation waters from the McElmo Dome CO2 field, to produce branched alcohols that have potential use as biofuels. After establishing induced-expression under scCO2, isobutanol production from 2-ketoisovalerate is observed with greater than 40% yield with co-produced isopentanol. Finally, we present a process model to compare the energy required for our process to other in situ extraction methods, such as gas stripping, finding scCO2 extraction to be potentially competitive, if not superior. End-product toxicity, culture contamination, and energy efficient product recovery are long-standing issues in bioprocessing. Here, the authors address these problems using a fermentation strategy that combines microbial production of branched alcohols with supercritical carbon dioxide extraction. [ABSTRACT FROM AUTHOR]

Cyanobacterial harmful algal blooms (cyanoHABs) appear to be increasing in frequency on a global scale. The Cyanobacteria in blooms can produce toxic secondary metabolites that make freshwater dangerous for drinking and recreation. To characterize microbial activities in a cyanoHAB, transcripts from a eutrophic freshwater reservoir in Singapore were sequenced for six samples collected over one day-night period. Transcripts from the Cyanobacterium Microcystis dominated all samples and were accompanied by at least 533 genera primarily from the Cyanobacteria, Proteobacteria, Bacteroidetes and Actinobacteria. Within the Microcystis population, abundant transcripts were from genes for buoyancy, photosynthesis and synthesis of the toxin microviridin, suggesting that these are necessary for competitive dominance in the Reservoir. During the day, Microcystis transcripts were enriched in photosynthesis and energy metabolism while at night enriched pathways included DNA replication and repair and toxin biosynthesis. Microcystis was the dominant source of transcripts from polyketide and non-ribosomal peptide synthase (PKS and NRPS, respectively) gene clusters. Unexpectedly, expression of all PKS/NRPS gene clusters, including for the toxins microcystin and aeruginosin, occurred throughout the day-night cycle. The most highly expressed PKS/NRPS gene cluster from Microcystis is not associated with any known product. The four most abundant phyla in the reservoir were enriched in different functions, including photosynthesis (Cyanobacteria), breakdown of complex organic molecules (Proteobacteria), glycan metabolism (Bacteroidetes) and breakdown of plant carbohydrates, such as cellobiose (Actinobacteria). These results provide the first estimate of secondary metabolite gene expression, functional partitioning and functional interplay in a freshwater cyanoHAB. [ABSTRACT FROM AUTHOR]