Distribution Patterns of Iron-Oxidizing Zeta- and Beta-Proteobacteria From Different Environmental Settings at the Jan Mayen Vent Fields

Iron oxidizers are widespread in marine environments and play an important role in marine iron cycling. However, little is known about the overall distribution of iron oxidizers within hydrothermal systems, including settings with little hydrothermal activity. Moreover, the extent to which different phylogenetic groups of iron oxidizers exhibit niche specialization toward different environmental settings, remains largely unknown. Obtaining such knowledge is critical to unraveling the impact of the activity of iron oxidizers and how they are adapted. Here, we used 16S rRNA sequencing to characterize the distribution of iron oxidizers in different environmental settings within the Jan Mayen hydrothermal vent fields (JMVFs). Putative iron oxidizers affiliated to Zetaproteobacteria and Betaproteobacteria were detected within iron mounds, bottom seawater, basalt surfaces, and surface layers of sediments. The detected iron oxidizers were compared to sequence types previously observed in patchily distributed iron mats associated with diffuse venting at the JMVFs. Most OTUs of iron oxidizers reoccurred under different environmental settings, suggesting a limited degree of niche specialization. Consequently, most of the detected iron oxidizers seem to be generalists with a large habitat range. Our study highlights the importance of gathering information about the overall distribution of iron oxidizers in hydrothermal systems to fully understand the role of this metabolic group regarding cycling of iron. Furthermore, our results provide further evidence of the presence of iron-oxidizing members of Betaproteobacteria in marine environments

Microbiology and production hygiene in the fish meal industry

Rapporten gir en grunnleggende innføring i mikroorganismenes systematiske inndeling, reproduksjon og forhold til miljøfaktorer som temperatur, fuktighet og næringstilgang. De mest aktuelle patogene bakterier som kan forekomme i fiskemel er beskrevet med data om toleranser og krav. Den naturlige flora av mikroorganismer i fiskeråstoff er varmesensitiv og blir inaktivert i koker. Floraen i fiskemel har en annen sammensetning og stammer fra smittekilder i produksjonslinjen etter koker. Smittekildene er belegg med produktkontakt i maskiner og transportører. Smittemåte og aktuelle forebyggende tiltak er beskrevet. Rapporten oppsummerer mikrobiologiske krav til fiskemel, herunder regelbundne krav som er basis for godkjenning av ferdigvarepartier, retningslinjer og kundekrav. Rapporten beskriver prøvetaking og analyseprinsipper som benyttes ifm. mikrobiologiske undersøkelser. Virksomhetenes forskriftsmessige plikter ifm. mikrobiologi og produktsikkerhet er oppsummert og det er beskrevet metoder for dekontaminering av varer som ikke kan omsettes pga. hygienesvikt.The report provides a basic introduction to microbiology and production hygiene in fish meal factories, with emphasis on contamination routes and preventive measures. The intrinsic microbial flora of raw fish is heat sensitive and readily inactivated by thermal treatment in the cooker. The flora associated with finished fishmeal is markedly different and originates from contaminated product deposits or surfaces in the process machinery after the cooker. The report summarizes basic legal requirements related to hygiene and product safety in food and feed processing facilities. The report also describes methods used in microbiological examinations, and microbiological standards and guidelines applicable to fishmeal. Methods for large-scale decontamination of products and process machinery are briefly described.publishedVersio

Mikrobiologi og produksjonshygiene i fiskemelindustrien

Rapporten gir en grunnleggende innføring i mikroorganismenes systematiske inndeling, reproduksjon og forhold til miljøfaktorer som temperatur, fuktighet og næringstilgang. De mest aktuelle patogene bakterier som kan forekomme i fiskemel er beskrevet med data om toleranser og krav. Den naturlige flora av mikroorganismer i fiskeråstoff er varmesensitiv og blir inaktivert i koker. Floraen i fiskemel har en annen sammensetning og stammer fra smittekilder i produksjonslinjen etter koker. Smittekildene er belegg med produktkontakt i maskiner og transportører. Smittemåte og aktuelle forebyggende tiltak er beskrevet. Rapporten oppsummerer mikrobiologiske krav til fiskemel, herunder regelbundne krav som er basis for godkjenning av ferdigvarepartier, retningslinjer og kundekrav. Rapporten beskriver prøvetaking og analyseprinsipper som benyttes ifm. mikrobiologiske undersøkelser. Virksomhetenes forskriftsmessige plikter ifm. mikrobiologi og produktsikkerhet er oppsummert og det er beskrevet metoder for dekontaminering av varer som ikke kan omsettes pga. hygienesvikt

The distribution of Zetaproteobacterial OTUs (ZetaOtus) at Loihi Seamount, Southern Mariana Trough (SMT), South Pacific Ocean (SPO) (Vailulu’u Seamount, Tonga Arc, East Lau Spreading Center, Kermadec Arc) and Mid-Atlantic Ridge (MAR) (TWVF, Snake pit, Rainbow, TAG).

<p>The figure is based on ZetaHunter analysis of MAR sequences (This study, [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0185008#pone.0185008.ref014" target="_blank">14</a>]), as well as information from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0185008#pone.0185008.ref011" target="_blank">11</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0185008#pone.0185008.ref035" target="_blank">35</a>].</p

Microbial analysis of <i>Zetaproteobacteria</i> and co-colonizers of iron mats in the Troll Wall Vent Field, Arctic Mid-Ocean Ridge

<div><p>Over the last decade it has become increasingly clear that <i>Zetaproteobacteria</i> are widespread in hydrothermal systems and that they contribute to the biogeochemical cycling of iron in these environments. However, how chemical factors control the distribution of <i>Zetaproteobacteria</i> and their co-occurring taxa remains elusive. Here we analysed iron mats from the Troll Wall Vent Field (TWVF) located at the Arctic Mid-Ocean Ridge (AMOR) in the Norwegian-Greenland Sea. The samples were taken at increasing distances from high-temperature venting chimneys towards areas with ultraslow low-temperature venting, encompassing a large variety in geochemical settings. Electron microscopy revealed the presence of biogenic iron stalks in all samples. Using 16S rRNA gene sequence profiling we found that relative abundances of <i>Zetaproteobacteria</i> in the iron mats varied from 0.2 to 37.9%. Biogeographic analyses of <i>Zetaproteobacteria</i>, using the ZetaHunter software, revealed the presence of ZetaOtus 1, 2 and 9, supporting the view that they are cosmopolitan. Relative abundances of co-occurring taxa, including <i>Thaumarchaeota</i>, <i>Euryarchaeota</i> and <i>Proteobacteria</i>, also varied substantially. From our results, combined with results from previous microbiological and geochemical analyses of the TWVF, we infer that the distribution of <i>Zetaproteobacteria</i> is connected to fluid-flow patterns and, ultimately, variations in chemical energy landscapes. Moreover, we provide evidence for iron-oxidizing members of <i>Gallionellaceae</i> being widespread in TWVF iron mats, albeit at low relative abundances.</p></div

NMDS plot of the iron mat communities on class level.

<p>Blue squares indicate samples from the rift valley and red triangles indicate samples from the rift margin. Dots indicate major microbial classes and have a radius proportional to overall relative abundance. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0185008#pone.0185008.s003" target="_blank">S3 Fig</a> for a plot based on OTU-level comparisons.</p

Proposed model on how fluid flow patterns and geobiological factors shape energy landscapes and microbial community composition in different regions within the TWVF.

<p>(1) High-temperature fluids venting through the chimneys and flowing through sediments in the vicinity of the chimneys are formed deep inside the crust and have high concentrations of sulphide as well as moderate concentrations of methane and hydrogen. Iron concentrations are low due to precipitation of pyrite inside the crust. White microbial mats are abundant on and around the active chimneys and have relative abundances of sulphide oxidizers and methane oxidizers that are consistent with communities predicted from energy models considering mixing of high-temperature fluids with seawater [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0185008#pone.0185008.ref001" target="_blank">1</a>]. (2) Rare-earth element analyses suggest that hydrothermal fluids flowing through iron mats in the rift margin, have the same source as the high-temperature fluids flowing through the chimneys (not published). However, subseafloor precipitation of sulphides lead to conditions where Fe(II), leaching out from minerals or produced by iron reducers, is more stable and forms the basis for the development of iron deposits inhabited by low abundances of FeOB on the seafloor. Yet, high abundances of methanotrophs and methanogens are indicative of a microbial degradation of organic matter with organics as the main source of energy under this setting. Accumulation of organic carbon in the rift margin may partly be a result of transport of biomass from the most active hydrothermal areas down towards the rift valley. (3) As suggested by rare-earth element analysis, fluids circulating through the rift valley belong to a shallow circulation system that is separated from the high-temperature fluids [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0185008#pone.0185008.ref017" target="_blank">17</a>]. Sulphate is therefore not reduced to sulphide abiotically, and lower amounts of Fe(II) precipitate in the crust. This forms the basis for conditions on the seafloor with relatively high densities of potential energy from iron oxidation, as reflected by communities with high relative abundances of FeOB. SOB = sulphur-oxidizing bacteria, MA = methanogenic archaea, MOB = methanotrophic bacteria, FeOB = iron-oxidizing bacteria.</p

Class-level taxonomic composition of iron mat communities.

<p>Numbers above each bar represent inverse Simpson diversity indices for each sample. ‘Unclassified Bacteria’–Bacteria not classified on class-level. ‘Other’–All sequences not falling into any of the listed taxonomic groups.</p