Microplastic-antifouling paint particle contamination alters microbial communities in surrounding marine sediment.

Paint used to coat surfaces in aquatic environments often contain biocides to prevent biofouling, and as these coatings degrade, antifouling paint particles (APPs) end up in aquatic, and especially marine, sediments. However, it is currently unclear what further influence APPs in the sediment have on biotic communities or processes. This study investigates how a variety of commercially-available APPs effect the marine microbial community by spiking different laboratory-manufactured APPs to sediment. Following exposure for 30 and 60 days, APPs caused a clear and consistent effect on the bacterial community composition as determined by 16S metabarcoding. This effect was strongest between 0 and 30 days, but continues to a lesser extent between 30 and 60 days. APPs appear to inhibit the highly diverse, but in general rarer, fraction of the community and/or select for specific community members to become more dominant. 71 antifouling-presence and 454 antifouling-absence indicator taxa were identified by indicator analysis. The difference in the level of classification in these two indicator groups was highly significant, with the antifouling-presence indicators having much higher percentage sequence identity to cultured taxa, while the antifouling-absence indicators appear to be made up of undescribed taxa, which may indicate that APPs act as a proxy for general anthropogenic influence or that APP contamination selects for taxa capable of being cultured. Given the clear and consistent effect APPs have on the surrounding sediment microbial community, further research into how APPs affect sediment functional processes and how such effects scale with concentration is recommended to better assess the wider consequences of these pollutants for marine biogeochemical cycles in the future. SYNOPSIS: Microplastic-paint particles are commonly found in marine sediment but little is known about how these, especially antifouling, paint particles affect sediment microbial communities. This study demonstrates that antifouling paint particles fundamentally alter sediment microbial communities.

Microcapillary sampling of Baltic Sea copepod gut microbiomes indicates high variability among individuals and the potential for methane production.

The paradox of methane oversaturation in oxygenated surface water has been described in many pelagic systems and still raises the question of the source. Temora sp. and Acartia sp. commonly dominate the surface and subsurface waters of the central Baltic Sea. It is hypothesised that their gut microbiome at least partly contributes to the methane anomaly in this ecosystem. However, the potential pathway for this methane production remains unclear. Using a microcapillary technique, we successfully overcame the challenge of sampling the gut microbiome of copepods <1 mm. 16S rRNA gene amplicon sequencing revealed differences among the dominant bacterial communities associated with Temora sp. (Actinobacteria, Betaproteobacteria and Flavobacteriia) and Acartia sp. (Actinobacteria, Alphaproteobacteria and Betaproteobacteria) and the surrounding water (Proteobacteria, Cyanobacteria and Verrucomicrobia), but also intraspecific variability. In both copepods, gut-specific prokaryotic taxa and indicative species for methane production pathways (methanogenesis, dimethylsulfoniopropionate or methylphosphonate) were present. The relative abundance of archaea and methanogens was investigated using droplet digital polymerase chain reaction and showed a high variability among copepod individuals, underlining intra- and interspecific differences in copepod-associated prokaryotic communities. Overall, this work highlights that the guts of Temora sp. and Acartia sp. have the potential for methane production but are probably no hotspot.

Sulfate-reducing bacteria-dominated biofilms that precipitate ZnS in a subsurface circumneutral-pH mine drainage system.

The microbial diversity of ZnS-forming biofilms in 8 degrees C, circumneutral-pH groundwater in tunnels within the abandoned Piquette Zn, Pb mine (Tennyson, Wisconsin, USA) has been investigated by molecular methods, fluorescence in situ hybridization (FISH), and cultivation techniques. These biofilms are growing on old mine timbers that generate locally anaerobic zones within the mine drainage system. Sulfate-reducing bacteria (SRB) exclusively of the family Desulfobacteriaceae comprise a significant fraction of the active microbiota. Desulfosporosinus strains were isolated, but could not be detected by molecular methods. Other important microbial clusters belonged to the beta-, gamma-, and epsilon-Proteobacteria, the Cytophaga/Flexibacter/Bacteroides-group (CFB), Planctomycetales, Spirochaetales, Clostridia, and green nonsulfur bacteria. Our investigations indicated a growth dependence of SRB on fermentative, cellulolytic, and organic acid-producing Clostridia. A few clones related to sulfur-oxidizing bacteria were detected, suggesting a sulfur cycle related to redox gradients within the biofilm. Sulfur oxidation prevents sulfide accumulation that would lead to precipitation of other sulfide phases. FISH analyses indicated that Desulfobacteriaceae populations were not early colonizers in freshly grown and ZnS-poor biofilms, whereas they were abundant in older, naturally established, and ZnS-rich biofilms. Gram-negative SRB have been detected in situ over a period of 6 months, supporting the important role of these organisms in selective ZnS precipitation in Tennyson mine. Results demonstrate the complex nature of biofilms responsible for in situ bioremediation of toxic metals in a subsurface mine drainage system.

Formation of sphalerite (ZnS) deposits in natural biofilms of sulfate-reducing bacteria.

Abundant, micrometer-scale, spherical aggregates of 2- to 5-nanometer-diameter sphalerite (ZnS) particles formed within natural biofilms dominated by relatively aerotolerant sulfate-reducing bacteria of the family Desulfobacteriaceae. The biofilm zinc concentration is about 10(6) times that of associated groundwater (0.09 to 1.1 parts per million zinc). Sphalerite also concentrates arsenic (0.01 weight %) and selenium (0.004 weight %). The almost monomineralic product results from buffering of sulfide concentrations at low values by sphalerite precipitation. These results show how microbes control metal concentrations in groundwater- and wetland-based remediation systems and suggest biological routes for formation of some low-temperature ZnS deposits.

New LL-diaminopimelic acid-containing actinomycetes from hypersaline, heliothermal and meromictic Antarctic Ekho Lake: Nocardioides aquaticus sp. nov. and Friedmanniella [correction of Friedmannielly] lacustris sp. nov.

Two Gram-positive, non-motile and aerobic bacteria were isolated from a water sample of the hypersaline Ekho Lake, Antarctica. The cocci or short rods grew well on oligotrophic PYGV agar of pH 7.5 and at 26 degrees C. Strains EL-17KT and EL-17AT both required thiamine and biotin, strain EL-17AT also required nicotinic acid. Carbon sources utilized by both strains were acetate, pyruvate, alpha-D-glucose, glutamate and (weakly) citrate, but succinate, malate or butyrate were utilized only by EL-17KT. Gelatin, starch and DNA were hydrolyzed, NH, was formed from peptone, and nitrate was reduced aerobically by both strains. The isolates had the same temperature tolerance for growth in the range tested (below 3 to above 33.5 degrees C) and pH range (<5.5 to >9.5) and were sensitive to chloramphenicol and penicillin G. Their cell walls contained LL-diaminopimelic acid and had a single glycine residue as interpeptide bridge. Strain EL-17AT contained glycine at position 1 of the peptide subunit (peptidoglycan type A 3gamma'). Isolates EL-17KT and EL-17AT differed in their maximum NaCl tolerance, which was 15% or 6-8%, respectively. The major fatty acid of EL-17KT was C18:1 and that of EL-17AT was ai-C15:0. The major respiratory quinones of EL-17KT and EL-17AT were MK-8(H4) and MK-9(H4), respectively. The former isolate had 69 mol% G+C, the latter had 73 mol% G+C. Comparative 16S rRNA gene sequencing revealed phylogenetic relationships of isolate EL-17KT with the genus Nocardioides, with N. pyridinolyticus and N. plantarum as the closest relatives. Phenotypic and genotypic characteristics support the description of a new species, Nocardioides aquaticus sp. nov., with EL-17KT as the type strain (= DSM 11439T). Isolate EL-17AT is related to the genus Friedmanniella, with E antarctica and E spumicola as the closest relatives. The differentiating characteristics support the description of a new species, Friedmanniella lacustris sp. nov., with EL-17AT as the type strain (= DSM 11465T).

Staleya guttiformis gen. nov., sp. nov. and Sulfitobacter brevis sp. nov., alpha-3-Proteobacteria from hypersaline, heliothermal and meromictic antarctic Ekho Lake.

Two Gram-negative, aerobic, pointed and budding bacteria were isolated from various depths of hypersaline, heliothermal and meromictic Ekho Lake (Vestfold Hills, East Antarctica). 16S rRNA gene sequence comparisons show the isolates to be phylogenetically close to the genera Sulfitobacter and Roseobacter. Cells can be motile and contain storage granules. Sulfite addition does not stimulate growth. Isolate EL-38T can produce bacteriochlorophyll a and has a weak requirement for sodium ions; polar lipids include phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine and an unidentified amino lipid, but not diphosphatidylgycerol. The dominant fatty acid is 18:1omega7c; other characteristic fatty acids are 3-OH 10:0, 3-OH 14:1, 16:0, 18:0, 18:2 and 19:1. The DNA base composition is 55.0-56.3 mol% G+C. Isolate EL-162T has an absolute requirement for sodium ions. Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine and an unidentified amino lipid are present in the polar lipids. Dominant fatty acids of this isolate are 18:1omega7c and 18:1omega9c as well as 18:2 which is present as two isomers. Other characteristic fatty acids are 3-OH 10:0, 3-OH 14:1, 16:0 and 18:0. The G+C content is 57.9-58.1 mol%. Morphological, physiological and genotypic differences from related, thus far known genera support the description of Staleya guttiformis gen. nov. and sp. nov. with EL-38T (= DSM 11458T) as the type strain and of Sulfitobacter brevis sp. nov. with the type strain EL-162T (= DSM 11443T).

Differentiation of newly described antarctic bacterial isolates related to Roseobacter species based on 16S-23S rDNA internal transcribed spacer sequences.

The 16S-23S rDNA internal transcribed spacer (ITS) of Roseobacter denitrificans, Roseobacter litoralis, Ruegeria algicola and strains of the recently described species Antarctobacter heliothermus and Roseovarius tolerans were analysed in order to examine DNA sequence variations and to draw conclusions about inter- and intraspecific relationships. A. heliothermus included four strains with an ITS fragment length of 1092 bp. Roseovarius tolerans was described on the basis of eight strains. Five of these harboured two ITS fragments of different lengths (959 and about 1100 bp), while the others had one fragment of either 1083 bp (two strains) or 1165 bp (one strain). ITS lengths of the related species Roseobacter denitrificans, Roseobacter litoralis and Ruegeria algicola were found to be 980, 984 and 1158 bp, respectively. Phylogenetic analyses of the DNA sequences allowed species affiliation of strains with sequence length differences of > 200 bp and recognition of relationships based on a well-supported ITS tree. The strains of A. heliothermus and Roseovarius tolerans each formed a monophyletic branch and they were separated from each other by Ruegeria algicola. This species was now clearly separated from Roseobacter denitrificans and Roseobacter litoralis, which corresponded to the new genus affiliation of Ruegeria algicola. These data were additionally supported by analyses of the structure, relative position and order of genes for tRNA(Ile) and tRNA(Ala) found within the ITS of each strain. Comparative DNA sequence analyses of ITS and 16S rDNA revealed limitations, on species and strain levels, with respect to the phylogenetic resolution of the 16S rDNA due to the limited number of informative (variable) sites, while ITS sequence analyses provided more variable and sufficiently conserved positions to discriminate between strains and to reconstruct their taxonomic relationships.

Roseovarius tolerans gen. nov., sp. nov., a budding bacterium with variable bacteriochlorophyll a production from hypersaline Ekho Lake.

Eight Gram-negative, aerobic, pointed and budding bacteria were isolated from various depths of the hypersaline, heliothermal and meromictic Ekho Lake (Vestfold Hills, East Antarctica). The cells contained storage granules and daughter cells could be motile. Bacteriochlorophyll a was sometimes produced, but production was repressed by constant dim light. The strains tolerated a wide range of temperature, pH, concentrations of artificial seawater and NaCl, but had an absolute requirement for sodium ions. Glutamate was metabolized with and without an additional source of combined nitrogen. The dominant fatty acid was C18:1; other characteristic fatty acids were C18:2, C12:0 2-OH, C12:1 3-OH, C16:1, C16:0 and C18:0. The main polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylcholine. The DNA G+C base composition was 62-64 mol%. 16S rRNA gene sequence comparisons showed that the isolates were phylogenetically close to the genera Antarctobacter, 'Marinosulfonomonas', Octadecabacter, Sagittula, Sulfitobacter and Roseobacter. Morphological, physiological and genotypic differences to these previously described and distinct genera support the description of a new genus and a new species, Roseovarius tolerans gen. nov., sp. nov. The type strain is EL-172T (= DSM 11457T).

Antarctobacter heliothermus gen. nov., sp. nov., a budding bacterium from hypersaline and heliothermal Ekho Lake.

Four Gram-negative, aerobic, pointed and budding bacteria were isolated from various depths of the hypersaline, heliothermal and meromictic Ekho Lake (Vestfold Hills, East Antarctica). The cells contained storage granules and formed rosettes. Daughter cells may be motile. Growth required sodium ions. Nitrate was reduced to nitrite, and dissimilatory reduction of nitrite was possible. DNase and gelatinase were produced. Glutamate was metabolized with and without an additional source of combined nitrogen. The most abundant fatty acid was C18:1; other fatty acids present in lower concentrations were C12:1 3-OH, C16:1, C16:0, C18:0 and C19:0 cyc. The main polar lipids were phosphatidylglycerol and phosphatidylcholine. The DNA base composition was 62.3-62.8 mol% G + C. 16S rDNA sequence comparisons showed the isolates to be phylogenetically related to the genera Sagittula and Roseobacter. Morphological, physiological and genotypic differences to these and distinct characteristics supported the description of a new genus and a new species, Antarctobacter heliothermus gen. nov., sp. nov. The type strain is EL-219T (= DSM 11445T).