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Phylogenetic tree based on the neighbour-joining algorithm of 16S rRNA gene sequences, showing the position of strain BH1 T and closely related species. Sequence accession numbers used are shown in parentheses. Bootstrap values higher than 50 % are indicated at branch-points. Zymobacter palmae T109 T was used as an outgroup. Bar, 1 % sequence divergence.
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A Gram-negative, heterotrophic, aerobic, non-endospore-forming, peritrichously flagellated and motile bacterial strain, designated BH1(T), was isolated from samples of rusticles, which are formed in part by a consortium of micro-organisms, collected from the RMS Titanic wreck site. The strain grew optimally at 30-37°C, pH 7.0-7.5 and in the presenc...
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... of phylogenetic neighbours and the calcula- tion of pairwise 16S rRNA gene sequence similarities were achieved using the EzTaxon server (http://www.eztaxon. org/; Chun et al., 2007). Phylogenetic analysis based on the neighbour-joining algorithm revealed that strain BH1 T was included in the cluster of species of the genus Halomonas (Fig. 1). The most closely related type strains were H. neptunia (98.6 % 16S rRNA sequence similarity), H. variabilis (98.4 %), H. boliviensis (98.3 %) and H. sulfidaeris (97.5 %). Other closely related type strains were Halomonas alkaliphila (96.5 % sequence similarity), Halomonas hydro- thermalis (96.3 %), Halomonas gomseomensis (96.3 %), H. ...
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... closely related type strains were Halomonas alkaliphila (96.5 % sequence similarity), Halomonas hydro- thermalis (96.3 %), Halomonas gomseomensis (96.3 %), H. venusta (96.3 %) and Halomonas meridiana (96.2 %). The maximum-likelihood and maximum-parsimony methods resulted in highly similar tree topologies ( Supplementary Fig. S1), confirming the phylogenetic cluster formed by strain BH1 T and species of the genus Halomonas. Based on these data, the new isolate would belong to group 2 of the two phylogenetic groups defined for the genus Halomonas (Arahal et al., 2002a; de la Haba et al., 2010a). ...
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... Halomonas sp. strain TGOS-10 was recently found to share 100% 16S rRNA sequence identity with Halomonas strains TG39 [48] and MCTG39a [53], and 99% sequence identity to Halomonas titanicae BH1 [54]. Despite the genetic similarities and comparable growing conditions between the strains, there were, however, some major differences in emulsification and chemical composition (discussed below). ...
In this study, we characterize the exopolymer produced by Halomonas sp. strain TGOS-10 –one of the organisms found enriched in sea surface oil slicks during the Deepwater Horizon oil spill. The polymer was produced during the early stationary phase of growth in Zobell’s 2216 marine medium amended with glucose. Chemical and proton NMR analysis showed it to be a relatively monodisperse, high-molecular-mass (6,440,000 g/mol) glycoprotein composed largely of protein (46.6% of total dry weight of polymer). The monosaccharide composition of the polymer is typical to that of other marine bacterial exopolymers which are generally rich in hexoses, with the notable exception that it contained mannose (commonly found in yeast) as a major monosaccharide. The polymer was found to act as an oil dispersant based on its ability to effectively emulsify pure and complex oils into stable oil emulsions—a function we suspect to be conferred by the high protein content and high ratio of total hydrophobic nonpolar to polar amino acids (52.7:11.2) of the polymer. The polymer’s chemical composition, which is akin to that of other marine exopolymers also having a high protein-to-carbohydrate (P/C) content, and which have been shown to effect the rapid and non-ionic aggregation of marine gels, appears indicative of effecting marine oil snow (MOS) formation. We previously reported the strain capable of utilising aromatic hydrocarbons when supplied as single carbon sources. However, here we did not detect biodegradation of these chemicals within a complex (surrogate Macondo) oil, suggesting that the observed enrichment of this organism during the Deepwater Horizon spill may be explained by factors related to substrate availability and competition within the complex and dynamic microbial communities that were continuously evolving during that spill.
... The negative correlation between Pseudomonas and differential functions may be related to competitive pressure in bacterial communities. The reason for the negative correlation between Halomonas and differential functions may be that Halomonas was a halophilic bacteria that require a high-salt environment to functioning stably (Sanchez-Porro et al. 2010). ...
Currently, there is limited understanding of the structures and variabilities of bacterial communities in oil-contaminated soil within shale gas development. The Changning shale gas well site in Sichuan province was focused, and high-throughput sequencing was used to investigate the structures of bacterial communities and functions of bacteria in soil with different degrees of oil pollution. Furthermore, the influences of the environmental factors including pH, moisture content, organic matter, total nitrogen, total phosphorus, oil, and the biological toxicity of the soil on the structures of bacterial communities were analyzed. The results revealed that Proteobacteria and Firmicutes predominated in the oil-contaminated soil. α-Proteobacteria and γ‐Proteobacteria were the main classes under the Proteobacteria phylum. Bacilli was the main class in the Firmicutes phylum. Notably, more bacteria were only found in CN-5 which was the soil near the storage pond for abandoned drilling mud, including Marinobacter, Balneola, Novispirillum, Castellaniella, and Alishewanella. These bacteria exhibited resilience to higher toxicity and demonstrated proficiency in oil degradation. The functions including carbohydrate transport and metabolism, energy metabolism, replication, recombination and repair replication, signal transduction mechanisms, and amino acid transport and metabolism responded differently to varying concentrations of oil. The disparities in bacterial genus composition across samples stemmed from a complex play of pH, moisture content, organic matter, total nitrogen, total phosphorus, oil concentration, and biological toxicity. Notably, bacterial richness correlated positively with moisture content, while bacterial diversity showed a significant positive correlation with pH. Acidobacteria exhibited a significant positive correlation with moisture content. Litorivivens and Luteimonas displayed a significant negative correlation with pH, while Rhizobium exhibited a significant negative correlation with moisture content. Pseudomonas, Proteiniphilum, and Halomonas exhibited positive correlations not only with organic matter but also with oil concentration. Total nitrogen exhibited a significant positive correlation with Taonella and Sideroxydans. On the other hand, total phosphorus showed a significant negative correlation with Sphingomonas. Furthermore, Sphingomonas, Gp6, and Ramlibacter displayed significant negative correlations with biological toxicity. The differential functions exhibited no significant correlation with environmental factors but displayed a significant positive correlation with the Proteobacteria phylum. Aridibacter demonstrated a significant positive correlation with cell motility and cellular processes and signaling. Conversely, Pseudomonas, Proteiniphilum, and Halomonas were negatively correlated with differential functions, particularly in amino acid metabolism, carbohydrate metabolism, and membrane transport. Compared with previous research, more factors were considered in this research when studying structural changes in bacterial communities, such as physicochemical properties and biological toxicity of soil. In addition, the correlations of differential functions of communities with environmental factors, bacterial phyla, and genera were investigated.
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... Their native microflora encompasses sulfate-reducing bacteria (SRB), sulfur-oxidizing bacteria, iron-related bacteria (IRB), heterotrophic aerobic and denitrifying bacteria, archaea, and marine fungi/Actinomycetes (Cullimore et al., 2002). In 2010, the novel strain Halomonas titanicae BH1, a flagellated gram-negative bacillus, was isolated from them (Sánchez-Porro et al., 2010). Origins for this consortium include microbe-laden sediments excavated by Titanic's wreck impacting the seafloor, seeded by thermohaline circulation from serpentinization sites such as the Lost City and Menez Gwen hydrothermal fields at the mid-Atlantic ridge. ...
During his bio-archaeological Last Mysteries of the Titanic expedition in 2005, explorer James Cameron observed the RMS Titanic's Turkish Baths, an anoxic chamber secluded from currents deep within the wreck's remote interior, utilizing the ROV Skipper. There, Cameron discovered anomalously thin, vertical, and bifurcating rusticle formations he termed “Rustflowers.” Proposing magnetotaxis as the involved mechanism, this study analyzed rusticles salvaged from Titanic's #8 davit bitt utilizing ferromagnetic resonance, which demonstrated an asymmetric spectrum featuring prominent uniaxial over magnetocrystalline anisotropy fields of Buni = 110 mT and Bcub = −23 mT, linewidth parameters of ΔB = 200 mT, ΔBFWHM = 144 mT, ΔBhigh = 37 mT, ΔBlow = 107 mT, and asymmetry ratio of A = 0.35, and α = 0.20. These represent the established signature of biogenic magnetofossil chains synthesized by former magnetotactic bacteria, enduring within the rusticle cortex. Electron microscopy and chemical analysis identified single-domain range magnetite nanocrystals, and crystalline elemental sulfur inclusions, respectively. Chemosynthetic microbial iron oxy-hydroxide accretions guided upward along geomagnetic field lines by north-seeking magnetotaxis, under reducing conditions exhibited in Titanic's Turkish Baths, may account for the distinctive morphology of its Rustflowers; adding dimension to the bacterial application of iron assimilated from deep-sea sources, including shipwrecks.
... Selected isolates with the highest heavy metal tolerance presented a high sequence identity to the Halomonas genus, which is found in a great variety of saline environments. From sea water to salt flats like the athalassohaline environment of Salar de Uyuni in Bolivia [9,[22][23][24]. This genus is comprised of halophilic and halotolerant Gramnegative aerobic bacteria [25]. ...
The Bolivian Altiplano has an ongoing history of heavy metal pollution due to years of uncontrolled mining in this region. Heavy metals are a threat to natural environments such as lakes and soils with cultural and economic importance for the local communities. The extreme environmental conditions of the Bolivian Altiplano translate into alkaline soils with high concentration of minerals, high radiation and considerable daily temperature oscillations. Halophilic and halotolerant microorganisms isolated from such environments have interesting biotechnological applications including bioremediation of metal polluted waters and soils. Here, bacterial strains from the Bolivian Altiplano were characterized and biosorption capacity evaluated for three heavy metals (Pb +2 , Cd +2 and Zn +2) in variable concentrations. Four strains were able to grow in multimetal medium with a final concentration of 100 mg. L-1 , with a higher tolerance to Pb +2. The four isolates were selected for further characterization and were identified as different species of Halomonas genus. The best heavy metal biosorption rates for the four isolates were found at pH 7 and 37°C. Additionally, the fastest uptake rate for all three metals was under 120 minutes in the four chosen isolates. The biosorption process was best described by Langmuir isotherm for all isolates exposed to the three metals separately. The four Halomonas isolates showed a bioremediation potential for heavy metal polluted substrates, although the highest biosorption capacity values were from isolate Ss_is3 notably for Pb +2. This study provides new information about the potential biotechnological capacities of Halomonas strains isolated from mineral soils in the Andes.
... However, the presence of B. subtilis and additional Bacillus spore-formers provide potential forward contamination routes. Further, the lower temperature limit for H. titanicae is 4 C for consistent growth which is within the known Martian temperature range [10,11,70,71]. H. titanicae resistance to UV radiation is unknown, however, the biofilm morphology can exhibit greater tolerance to UV radiation and other environmental stresses than individual cells of the same species [72]. ...
While life on Mars has not been found, Earth-based microorganisms may contaminate the Red Planet during rover expeditions and human exploration. Due to the survival advantages conferred by the biofilm morphology to microorganisms, such as resistance to UV and osmotic stress, biofilms are particularly concerning from a planetary protection perspective. Modeling and data from the NASA Phoenix mission indicate that temporary liquid water might exist on Mars in the form of high salinity brines. These brines could provide colonization opportunities for terrestrial microorganisms brought by spacecraft or humans. To begin testing for potential establishment of microbes, results are presented from a simplified laboratory model of a Martian saline seep inoculated with sediment from Hailstone Basin, a terrestrial saline seep in Montana (USA). The seep was modeled as a sand-packed drip flow reactor at room temperature fed media with either 1 M MgSO4 or 1 M NaCl. Biofilms were established within the first sampling point of each experiment. Endpoint 16S rRNA gene community analysis showed significant selection of halophilic microorganisms by the media. Additionally, we detected 16S rRNA gene sequences highly similar to microorganisms previously detected in two spacecraft assembly cleanrooms. These experimental models provide an important foundation for identifying microbes that could hitch-hike on spacecraft and may be able to colonize Martian saline seeps. Future model optimization will be vital to informing cleanroom sterilization procedures.
... Nevertheless, the temperature range for the growth of strain ANRCS81 is 2 to 45°C, which is far broader than the growth temperature for most Halomonas species (58-61), such as H. titanicae BH1 and Halomonas axialensis (23,62). Temperature directly affects the stability of biological molecules, which is the core environmental factor that microorganisms must address through the adaptation process (12,63,64). ...
... Our data support a common adaptation strategy that allows strain ANRCS81 to cope simultaneously with HHP and other stresses. The genes involved in the common adaptation, as mentioned above, are the core genes in Halomonas (23,(71)(72)(73). Therefore, the adaptation strategy developed by strain H. titanicae ANRCS81 is expected to be generally observed in Halomonas. ...
Microorganisms have successfully predominated deep-sea ecosystems, while we know little about their adaptation strategy to multiple environmental stresses therein, including high hydrostatic pressure (HHP). Here, we focused on the genus Halomonas, one of the most widely distributed halophilic bacterial genera in marine ecosystems and isolated a piezophilic strain Halomonas titanicae ANRCS81 from Antarctic deep-sea sediment. The strain grew under a broad range of temperatures (2 to 45°C), pressures (0.1 to 55 MPa), salinities (NaCl, 0.5 to 17.5%, wt/vol), and chaotropic agent (Mg2+, 0 to 0.9 M) with either oxygen or nitrate as an electron acceptor. Genome annotation revealed that strain ANRCS81 expressed potential antioxidant genes/proteins and possessed versatile energy generation pathways. Based on the transcriptomic analysis, when the strain was incubated at 40 MPa, genes related to antioxidant defenses, anaerobic respiration, and fermentation were upregulated, indicating that HHP induced intracellular oxidative stress. Under HHP, superoxide dismutase (SOD) activity increased, glucose consumption increased with less CO2 generation, and nitrate/nitrite consumption increased with more ammonium generation. The cellular response to HHP represents the common adaptation developed by Halomonas to inhabit and drive geochemical cycling in deep-sea environments. IMPORTANCE Microbial growth and metabolic responses to environmental changes are core aspects of adaptation strategies developed during evolution. In particular, high hydrostatic pressure (HHP) is the most common but least examined environmental factor driving microbial adaptation in the deep sea. According to recent studies, microorganisms developed a common adaptation strategy to multiple stresses, including HHP, with antioxidant defenses and energy regulation as key components, but experimental data are lacking. Meanwhile, cellular SOD activity is elevated under HHP. The significance of this research lies in identifying the HHP adaptation strategy of a Halomonas strain at the genomic, transcriptomic, and metabolic activity levels, which will allow researchers to bridge environmental factors with the ecological function of marine microorganisms.
... Halomonas titanicae BH1 type strain was isolated from rusticlesis collected from the RMS Titanic wreck site [1]. It is a Gram-negative, heterotrophic, aerobic rod, and motile bacterium. ...
... They are slightly to moderately halophilic and oligotrophic organisms [4]. H. titanicae BH1 strain showed an ability to grow in media with 0.5-25% NaCl with no growth in the absence of NaCl [1], which reflects an ability to tolerate osmotic stress fluctuations. Generally, to cope with osmotic stress halophilic microorganisms deploy multiple strategies to regulate their internal osmotic pressure through the accumulation of organic or inorganic compatible solutes [5][6][7] citing (i) The primary response to osmotic stress: the early response consists of water influx either in or out of the cells through dedicated membrane channels called aquaporin. ...
... H. titanicae BH1 bacterium was isolated from a sample of rusticles collected from the RMS Titanic wreck site [1]. BH1 is Gram-negative cell, heterotrophic, aerobic rod, and motile by peritrichous flagella. ...
Here, we report the osmoadaptation strategies adopted by the halotolerant species Halomonas titanicae BH1(T) inferred from genome sequence analysis. BH strain was isolated in 2010 from a rusticated sample collected in 1991 from the wreck of the Titanic, genome deposited in the database under the accession number (CP059082.1). It showed a high salt tolerance ranging from 0.5 to 25% NaCl (w/v) (optimal growth at 10% NaCl) with no growth in the absence of NaCl. The phylogenomic analysis showed that the BH1 strain is more closely related to the Halomonas sedementi QX-2, a strain isolated from deep-sea sediments. The RAST (Rapid Annotation using Subsystem Technology) annotation revealed divergent mechanisms involved in the primary and secondary response to osmotic stress citing protein implicated in potassium transport, periplasmic glucan synthesis, choline and betaine upake system, biosynthesis of glycine-betaine, ectoine, and proline. These findings provide an overview of the osmoadaptive mechanisms of H. titanicae BH1, and could offer helpful information to future biotechnological applications like osmolyte synthesis and related applications.
... Previous experimental studies performed under aerobic conditions at 4 • C using a medium made of artificial seawater and seafloor massive sulfide slabs have reported bacterial phylotypes related to Halomonas, Marinobacter, Methylophaga, and Pseudomonas (Kato et al., 2015). The dominant genus Marinobacter, involved in iron oxidation (Edwards et al., 2003b), and the genus Halomonas, affiliated with acidproducing bacteria (Sanchez-Porro et al., 2010), were both adhered to the slabs, which probably contribute to release of Zn from sulfide minerals. In our laboratory enrichment, we found that three genera, Pseudomonas, Paracoccus, and Alcanivorax from the slab were effectively enriched and eventually attached to the metal sulfide powder (Figures 1, 2), indicating their potential for iron or sulfur oxidation and interaction between cells and sulfide minerals (Napieralski et al., 2021). ...
The genus Alcanivorax is common in various marine environments, including in hydrothermal fields. They were previously recognized as obligate hydrocarbonoclastic bacteria, but their potential for autotrophic carbon fixation and Fe(II)-oxidation remains largely elusive. In this study, an in situ enrichment experiment was performed using a hydrothermal massive sulfide slab deployed 300 m away from the Wocan hydrothermal vent. Furthermore, the biofilms on the surface of the slab were used as an inoculum, with hydrothermal massive sulfide powder from the same vent as an energy source, to enrich the potential iron oxidizer in the laboratory. Three dominant bacterial families, Alcanivoraceae , Pseudomonadaceae , and Rhizobiaceae , were enriched in the medium with hydrothermal massive sulfides. Subsequently, strain Alcanivorax sp. MM125-6 was isolated from the enrichment culture. It belongs to the genus Alcanivorax and is closely related to Alcanivorax profundimaris ST75FaO-1 T (98.9% sequence similarity) indicated by a phylogenetic analysis based on 16S rRNA gene sequences. Autotrophic growth experiments on strain MM125-6 revealed that the cell concentrations were increased from an initial 7.5 × 10 ⁵ cells/ml to 3.13 × 10 ⁸ cells/ml after 10 days, and that the δ ¹³ C VPDB in the cell biomass was also increased from 234.25‰ on day 2 to gradually 345.66 ‰ on day 10. The gradient tube incubation showed that bands of iron oxides and cells formed approximately 1 and 1.5 cm, respectively, below the air-agarose medium interface. In addition, the SEM-EDS data demonstrated that it can also secrete acidic exopolysaccharides and adhere to the surface of sulfide minerals to oxidize Fe(II) with NaHCO 3 as the sole carbon source, which accelerates hydrothermal massive sulfide dissolution. These results support the conclusion that strain MM125-6 is capable of autotrophic carbon fixation and Fe(II) oxidization chemoautotrophically. This study expands our understanding of the metabolic versatility of the Alcanivorax genus as well as their important role(s) in coupling hydrothermal massive sulfide weathering and iron and carbon cycles in hydrothermal fields.
... Considering the structural similarity of rather extended genome fragments in H. titanicae TAT1 and related strains, we suppose that they may have acquired the genetic determinants of n-alkane degradation and the corresponding metabolic pathways due to interspecies lateral gene transfer, probably from Marinobacter bacteria, for which this ability is a characteristic feature. Probably, it was this transfer that enabled H. titanicae TAT1 to adapt to life in oil-polluted water environments, distinguishing it from the type strain H. titanicae BH1 T (Sanchez-Porro et al., 2010) and other strains identified as H. titanicae that were isolated from marine environments and do not possess alkB genes. ...
... The 16S rRNA gene sequence similarity of strain SOB56 is 100% compared with H. titanicae BH1 T , which was first obtained from the RMS (Royal Mail Ship) Titanic wreck site during the Akademic Keldysn expedition in 1991 (Sánchez-Porro et al., 2010). The complete genome sequence of H. titanicae SOB56 forms a whole circle chromosome, and it is composed of 5,279,693 bp, and the calculated G + C content is 54.6%. ...
... The genome of H. Titanicae SOB56 comprised 48 genes involved in flagellar assembly, including the complete set of genes for flagellar biosynthesis and flagellar structure proteins (Figure 5). This was consistent with a previous study showing that H. titanicae BH1 exhibits motility via peritrichous flagella (Sánchez-Porro et al., 2010). Transcriptional regulators of flagellar synthesis were also identified in the genome, such as Flgm, Flia (σ 28 ), Flhc, and Flhd. ...
Halomonas bacteria are ubiquitous in global marine environments, however, their sulfur-oxidizing abilities and survival adaptations in hydrothermal environments are not well understood. In this study, we characterized the sulfur oxidation ability and metabolic mechanisms of Halomonas titanicae SOB56, which was isolated from the sediment of the Tangyin hydrothermal field in the Southern Okinawa Trough. Physiological characterizations showed that it is a heterotrophic sulfur-oxidizing bacterium that can oxidize thiosulfate to tetrathionate, with the Na2S2O3 degradation reaching 94.86%. Two potential thiosulfate dehydrogenase-related genes, tsdA and tsdB, were identified as encoding key catalytic enzymes, and their expression levels in strain SOB56 were significantly upregulated. Nine of fifteen examined Halomonas genomes possess TsdA- and TsdB-homologous proteins, whose amino acid sequences have two typical Cys-X2-Cys-His heme-binding regions. Moreover, the thiosulfate oxidation process in H. titanicae SOB56 might be regulated by quorum sensing, and autoinducer-2 synthesis protein LuxS was identified in its genome. Regarding the mechanisms underlying adaptation to hydrothermal environment, strain SOB56 was capable of forming biofilms and producing EPS. In addition, genes related to complete flagellum assembly system, various signal transduction histidine kinases, heavy metal transporters, anaerobic respiration, and variable osmotic stress regulation were also identified. Our results shed light on the potential functions of heterotrophic Halomonas bacteria in hydrothermal sulfur cycle and revealed possible adaptations for living at deep-sea hydrothermal fields by H. titanicae SOB56.
