Bacterial Communities Inhabiting the Sponge Biemna fortis, Sediment and Water in Marine Lakes and the Open Sea

Experimental and modeling studies of the effects of nanoclay on the oil behaviors in a water-sand system

When oil is released into the oceans, spilled oil may get to the shoreline driven by wind and wave. This study comprehensively explored the effects of bentonite nanoclay on the oil behaviors in a water-sand system from both experimental and modeling perspectives. Four factors including nanoclay concentration, temperature, salinity, and pH have been studied. The increasing nanoclay concentration resulted in the decrease in remaining oil on sand. Higher temperature and salinity were associated with less residual oil on sand in the presence of nanoclay. The lower residual oil on sand with coexisting nanoclay was found to be at pH 7. The factorial analysis results indicated that the nanoclay concentration showed the most significant impact among these factors. Miscibility modeling results showed an increasing temperature was favorable to the nanoclay miscibility. Moreover, the effect of nanoclay on oil behavior was further revealed through the dynamic simulation, in which it can be seen the nanoclay could penetrate into oil droplets and promote the oil detachment from solid substrate. The results of this study can help understand the role of fine particles in the fate and transport of oil on shoreline and support the risk assessment and response planning after oil spill.

Exploring the effects of microalgal biomass on the oil behavior in a sand-water system

This study focused on the impact of microalgal biomass on the oil behavior in a sand-water system. The microalgal biomass was characterized, and the interaction between microalgal biomass and oil was analyzed through Fourier transform infrared (FTIR) spectroscopy. The effects of different conditions including microalgal biomass dose, pH, temperature, and salinity on the oil behavior were investigated. A two-level factorial analysis was also used to further explore the interactions of these conditions. The microalgal biomass was found to be the most influential parameter for the residual crude oil on sand. Higher microalgal biomass dose resulted in less residual oil on sand. The remaining oil decreased with increasing solution pH from 4 to 7, and an increase of remaining oil was observed when the pH was further increased above 7. In addition, temperature and salinity could affect the removal of crude oil in the presence of microalgal biomass. Increasing the temperature could result in less residual oil on sand and there was higher oil removal at the high salinity. The effects of microalgal biomass on the oil behavior could also be impacted by environmental conditions. The results of this study indicate that the presence of algae in the oiled shoreline can be considered in the comprehensive evaluation of spill risk and prediction of oil fate.

Diversity of a bacterial community associated with Cliona lobata Hancock and Gelliodes pumila (Lendenfeld, 1887) sponges on the South-East coast of India

Marine sponges are sources of various bioactive metabolites, including several anticancer drugs, produced mainly by sponge-associated microbes. Palk Bay, on the south-east coast of India, is an understudied, highly disturbed reef environment exposed to various anthropogenic and climatic stresses. In recent years, Palk Bay suffered from pollution due to the dumping of untreated domestic sewage, effluents from coastal aquaculture, tourism, salt pans, cultivation of exotic seaweeds, and geogenic heavy-metal pollution, especially arsenic, mercury, cadmium, and lead. Low microbial-abundant sponge species, such as Gelliodes pumila and Cliona lobata, were found to be ubiquitously present in this reef environment. Triplicate samples of each of these sponge species were subjected to Illumina MiSeq sequencing using V3–V4 region-specific primers. In both C. lobata and G. pumila, there was an overwhelming dominance (98 and 99%) of phylum Candidatus Saccharibacteria and Proteobacteria, respectively. The overall number of operational taxonomic units (OTUs) was 68 (40 and 13 OTUs unique to G. pumila and C. lobata, respectively; 15 shared OTUs). Alphaproteobacteria was the most abundant class in both the sponge species. Unclassified species of phylum Candidatus Saccharibacteria from C. lobata and Chelotivorans composti from G. pumila were the most abundant bacterial species. The predominance of Alphaproteobacteria also revealed the occurrence of various xenobiotic-degrading, surfactant-producing bacterial genera in both the sponge species, indirectly indicating the possible polluted reef status of Palk Bay. Studies on sponge microbiomes at various understudied geographical locations might be helpful in predicting the status of reef environments.

Geographical location and habitat predict variation in prokaryotic community composition of Suberites diversicolor

Purpose

Marine lakes are unique habitats that house diverse assemblages of benthic and planktonic organisms including endemic species. In this study, we aimed to assess to what extent geographical location (Berau versus Papua) and the degree of marine lake connectivity (relatively open versus closed) to the surrounding marine environment structures the prokaryotic community composition of the sponge species Suberites diversicolor.

Methods

Sponge specimens were sampled in five marine lakes in Borneo and Papua and one open sea habitat in Taiwan.

Result

Prokaryotic communities of S. diversicolor were dominated by members assigned to the Proteobacteria (particularly Alphaproteobacteria and Gammaproteobacteria) and Cyanobacteria, which together made up from 78 to 87% of sequences in all samples. The dominant operational taxonomic units (OTUs) in most samples, OTUs 1 and 3, were both assigned to the alphaproteobacterial order Rhodospirillales with OTU-1 dominant in the marine lakes of Berau and Papua and OTU-3 in Taiwan. OTU-3 was also largely absent from Papuan samples but present in all Berau samples. Compositionally, S. diversicolor samples clustered according to geographical location with the main axis of variation separating marine lake samples collected in Berau from those collected in Papua and the second axis of variation separating open sea samples collected in Taiwan from all marine lake samples. In addition, our results suggest that the degree of lake connectivity to the open sea also influences prokaryotic composition.

Conclusion

Although previous studies have shown that sponge-associated microbial communities tend to be stable across different geographical and environmental gradients, in the present study, both geography and local environmental conditions were significant predictors of variation in prokaryotic community composition of S. diversicolor.

Seasonal changes in the bacterial community structure of three eutrophicated urban lakes in Mexico city, with emphasis on Microcystis spp

Artificial urban lakes commonly have physicochemical conditions that contribute to rapid anthropogenic eutrophication and development of cyanobacterial blooms. Microcystis is the dominat genus in most freshwater bodies and is one of the main producter of microcystins. Using 454-pyrosequencing we characterized the bacterial community, with special emphasis on Microcystis, in three recreational urban lakes from Mexico City in both wet and dry seasons. We also evaluated some physicochemical parameters that might influence the presence of Microcystis blooms, and we associated the relative abundance of heterotrophic and autotrophic bacterial communities with their possible metabolic capacities. A total of 14 phyla, 18 classes, 39 orders, 53 families and 48 bacterial genera were identified in both seasons in the three urban lakes. Cyanobacteria had the highest relative abundance followed by Proteobacteria and Actinobacteria. Microcystis was the dominant taxon followed by Arthrospira, Planktothrix and Synechococcus. We also found heterotrophic bacteria associated with the blooms, such as Rhodobacter, Pseudomonas, Sphingomonas and, Porphyrobacter. The highest richness, diversity and dominance were registered in the bacterial community of the Virgilio Uribe Olympic Rowing-Canoeing Track in both seasons, and the lowest values were found in the Chapultepec Lake. The canonical correspondence analysis showed that dissolved oxygen and NO₃-N concentrations might explain the presence of Microcystis blooms. The metabolic prediction indicated that these communities are involved in photosynthesis, oxidative phosphorylation, methane metabolism, carbon fixation, and nitrogen and sulfur metabolism. The lakes studied had a high prevalence of Microcystis, but average values of microcystins did not exceed the maximum permissible level established by the United States Environmental Protection Agency for recreational and cultural activities. The presence of cyanobacteria and microcystins at low to moderate concentrations in the three lakes could result in ecosystem disruption and increase animal and human health risks.

Temporal Stability of Bacterial Communities in Antarctic Sponges

Marine sponges host dense, diverse, and species-specific microbial communities around the globe; however, most of the current knowledge is restricted to species from tropical and temperate waters. Only recently, some studies have assessed the microbiome of a few Antarctic sponges; however, contrary to low mid-latitude sponges, the knowledge about temporal (stability) patterns in the bacterial communities of Antarctic sponges is absent. Here, we studied the temporal patterns of bacterial communities in the Antarctic sponges Mycale (Oxymycale) acerata, Isodictya sp., Hymeniacidon torquata, and Tedania (Tedaniopsis) wellsae that were tagged in situ and monitored during three austral summers over a 24-month period. By using amplicon sequencing of the bacterial 16S rRNA gene we found that the microbiome differed between species. In general, bacterial communities were dominated by gammaproteobacterial OTUs; however, M. acerata showed the most distinct pattern, being dominated by a single betaproteobacterial OTU. The analysis at OTU level (defined at 97% sequence similarity) showed a highly stable bacterial community through time, despite the abnormal seawater temperatures (reaching 3°C) and rates of temperature increase of 0.15°C day-1 recorded in austral summer 2017. Sponges were characterized by a small core bacterial community that accounted for a high percentage of the abundance. Overall, no consistent changes in core OTU abundance were recorded for all studied species, confirming a high temporal stability of the microbiome. In addition, predicted functional pathway profiles showed that the most abundant pathways among all sponges belonged mostly to metabolism pathway groups (e.g., amino acid, carbohydrate, energy, and nucleotide). The predicted functional pathway patterns differed among the four sponge species. However, no clear temporal differences were detected supporting what was found in terms of the relatively stable composition of the bacterial communities.

The sponge microbiome within the greater coral reef microbial metacommunity

Much recent marine microbial research has focused on sponges, but very little is known about how the sponge microbiome fits in the greater coral reef microbial metacommunity. Here, we present an extensive survey of the prokaryote communities of a wide range of biotopes from Indo-Pacific coral reef environments. We find a large variation in operational taxonomic unit (OTU) richness, with algae, chitons, stony corals and sea cucumbers housing the most diverse prokaryote communities. These biotopes share a higher percentage and number of OTUs with sediment and are particularly enriched in members of the phylum Planctomycetes. Despite having lower OTU richness, sponges share the greatest percentage (>90%) of OTUs with >100 sequences with the environment (sediment and/or seawater) although there is considerable variation among sponge species. Our results, furthermore, highlight that prokaryote microorganisms are shared among multiple coral reef biotopes, and that, although compositionally distinct, the sponge prokaryote community does not appear to be as sponge-specific as previously thought.