Marine sponges are major habitat-forming organisms in coastal benthic communities and have an ancient origin in evolution history. Here, we report significant accumulation of polyphosphate (polyP) granules in three common sponge species of the Caribbean coral reef. The identity of the polyP granules was confirmed by energy-dispersive spectroscopy (EDS) and by the fluorescence properties of the granules. Microscopy images revealed that a large proportion of microbial cells associated with sponge hosts contained intracellular polyP granules. Cyanobacterial symbionts cultured from sponges were shown to accumulate polyP. We also amplified polyphosphate kinase (ppk) genes from sponge DNA and confirmed that the gene was expressed. Based on these findings, we propose here a potentially important phosphorus (P) sequestration pathway through symbiotic microorganisms of marine sponges. Considering the widespread sponge population and abundant microbial cells associated with them, this pathway is likely to have a significant impact on the P cycle in benthic ecosystems.phosphorus sequestration | sponge | microbial symbionts | polyphosphate

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Algal biofuels represent one of the most promising means of sustainably replacing liquid fuels. However, significant challenges remain before alga-based fuels become competitive with fossil fuels. One of the largest challenges is the ability to harvest the algae in an economical and low-energy manner. In this article, we describe the isolation of a bacterial strain, Bacillus sp. strain RP1137, which can rapidly aggregate several algae that are candidates for biofuel production, including a Nannochloropsis sp. This bacterium aggregates algae in a pH-dependent and reversible manner and retains its aggregation ability after paraformaldehyde fixation, opening the possibility for reuse of the cells. The optimal ratio of bacteria to algae is described, as is the robustness of aggregation at different salinities and temperatures. Aggregation is dependent on the presence of calcium or magnesium ions. The efficiency of aggregation of Nannochloropsis oceanica IMET1 is between 70 and 95% and is comparable to that obtained by other means of harvest; however, the rate of harvest is fast, with aggregates forming in 30 s.

SummaryThe earthworm Eisenia fetida harbours Verminephrobacter eiseniae within their excretory nephridia. This symbiont is transferred from the parent into the egg capsules where the cells are acquired by the developing earthworm in a series of recruitment steps. Previous studies defined V. eiseniae as the most abundant cell type in the egg capsules, leaving approximately 30% of the bacteria unidentified and of unknown origin. The study presented here used terminal restriction fragment length polymorphism analysis together with cloning and sequencing of 16S rRNA genes to define the composition of the bacterial consortium in E. fetida egg capsules from early to late development. Newly formed capsules of E. fetida contained three bacterial types, a novel Microbacteriaceae member, a Flexibacteriaceae member and the previously described V. eiseniae. Fluorescent in situ hybridization (FISH) using specific and general rRNA probes demonstrated that the bacteria are abundant during early development, colonize the embryo and appear in the adult nephridia. As the capsules mature, Herbaspirillum spp. become abundant although they were not detected within the adult worm. These divergent taxa could serve distinct functions in both the adult earthworm and in the egg capsule to influence the competitive ability of earthworms within the soil community.

dense Plakortis tissue. Symbioses with both Plakortis spp. were documented from an early recruit stage through adulthood. Spicule measurements conducted on symbiotic versus free-living X. deweerdtae revealed significantly smaller spicule sizes for symbiotic individuals, suggesting a cost in terms of silicon availability, or a benefit in terms of a lower investment in skeleton synthesis for support. This study reveals new specialized symbiotic associations between distantly related sponge genera that likely represent an alternative strategy of adaptation for life in reef caves and mesophotic reefs.