Lake Michigan Water Research Articles

Polyaniline-metal oxide coatings for biocidal applications: Mechanisms of activation and deactivation

Metal oxide (MO) coatings (e.g. TiO2, ZnO, and CuO) have shown great promise to inactivate pathogenic bacteria, maintain self-cleaning surfaces, and prevent infectious diseases spread via surface contact. Under light illumination, the antibacterial performance of photoactive MO coatings is determined by reactive oxygen species (ROS) generation. However, several drawbacks, such as photo-corrosion and rapid electron-hole recombination, hinder the ROS production of MO coatings and diminish their antibacterial efficiency. In this study, we employed polyaniline (PANI), an inexpensive and easy-to-synthesize conductive polymer, to fabricate polyaniline-metal oxide composite (PMC) films. The antibacterial performance of PMC films was tested using E. coli as the model bacterium and Lake Michigan water (LMW) as the background medium and revealed enhanced antibacterial performance relative to MO coatings alone (approximately 75–90 % kill of E. coli by PMC coatings in comparison to 20–40 % kill by MO coatings), which is explained by an increase in the ROS yields of PMC. However, with repeated use, the antibacterial performance of the PMC coatings is diminished due to deprotonation of the PANI in the neutral/slightly basic aqueous environment of LMW. Overall, PANI can enhance the antibacterial performance of MO coatings, but efforts need to be directed to preserve or regenerate PMC stability under environmental conditions and applications.

Out of oxygen: Stratification and loading drove hypoxia during a warm, wet, and productive year in a Great Lakes estuary

Hypolimnetic hypoxia, or low oxygen in bottom waters, impairs ecosystem services of freshwater lakes and estuaries globally. Both hypoxia incidence and intensity are increasing around the world due to eutrophication and climate change. As the hypolimnion becomes hypoxic and ultimately anoxic, sediment-bound legacy phosphorus is released. Water column mixing due to large storm events or fall turnover entrains these nutrients to the surface, causing harmful algal blooms. To assess the dynamics of hypoxia throughout the growing season, we evaluated Muskegon Lake, where hypoxia recurs annually, utilizing high-frequency time-series data from the Muskegon Lake Observatory (MLO) buoy (https://www.gvsu.edu/wri/buoy/), biweekly nutrient sampling, and seasonal respiration experiments during 2021. While water-column stratification set the stage for hypolimnetic hypoxia, frequent wind-mixing events, and episodic intrusions of cold, oxygenated, upwelled Lake Michigan waters intermittently reduced the thickness or intensity of the hypoxic zone. Respiration experiments revealed that riverine and surface organic matter inputs contributed most to hypolimnetic hypoxia in the spring, whereas surface inputs did so during summer, and riverine inputs during fall, indicating seasonally variable sources drive hypoxia. Biweekly measurements indicated increased soluble reactive phosphorus in the hypolimnion during anoxia via internal phosphorus loading from the sediment with the potential for fueling surface blooms with net export of soluble reactive phosphorus and total phosphorus to nearshore Lake Michigan. Our findings on the role of seasonally changing temperature, loading, phytoplankton production, hypolimnetic respiration, and internal phosphorus loading in shaping hypoxia dynamics have relevance to similarly afflicted ecosystems in the Great Lakes Basin.

A Flexible Anti-Biofilm Hygiene Coating for Water Devices.

Biofilm is a microbiome complex comprising different bacterial colonies that typically adhere to device surfaces in water, which causes serious medical issues such as indwelling infections and outbreaks. Here, we developed a non-nanoparticle, flexible anti-biofilm hygiene coating consisting of lithocholic acid (LCA), zinc pyrithione (Zn), and cinnamaldehyde (Cn) (named as LCA-Zn-Cn) that largely prevents the bacteria adhesion to various water device surfaces such as stainless steel and glass through a synergistic mechanism. The existing chelated groups on LCA and Cn attract plenty of bacteria via hydrophobic interaction. Both the bactericidal reaction by grafting biocidal groups from both LCA and Cn and the bacteriostatic reaction by inhibiting cell division via zinc ions (Zn) lead to a largely improved bacteria/biofilm prevention. The antibacterial performance was assessed by using the JIS Z 2801/ISO 22196 method. The designed LCA-Zn-Cn coating displayed log10 reduction of 4.23 (99.9% reduction) of E. coli and log10 reduction of 3.51 (99.8% reduction) of E. faecalis on stainless steel, which are much higher than the control samples, demonstrating a promising colonization inhibition. In parallel, the polysulfone encapsulated beads also showed >99% reduction efficiency in batch and >97-98% reduction efficiency in continuous column tests using the Lake Michigan water. Due to the strong cross-linked configuration, the coating still showed >90.9% bacterial reduction after 3000 abrasion cycles and over 99.9% bacteria reduction after a high flow velocity of 1.99 m/s test, which confirmed the enhanced mechanical durability. By applying either spray or dip-coating, the designed polymer composite can be coated on a variety of irregular water devices with mass production using an auto-controlled robot arm.

Responses to Lake Michigan water level rise: Trends in exposed sand cover at North Avenue Beach, Chicago

From 2013 to 2020, water levels in Lake Michigan rose from an all-time low to the highest levels observed in nearly four decades, causing shoreline changes throughout the Great Lakes. These changes are particularly noticeable at North Avenue Beach in Chicago, an artificial beach where federal, state, and city agencies have mitigated rising waters by importing sand and constructing groins. Using spring season aerial imagery from 2012 to 2020, we calculated beach area for each year and compared sand cover loss between years to water level change per the USGS station located just south of the study area. Analysis reveals year-to-year loss in sand cover since 2013, with the largest single-year change occurring between 2018 and 2019. An inverse relationship with a slight lag exists between water level and these beach area changes. We calculated sand-groin distances from 2000 to 2020 to identify north–south effects. Of the six beach cells separated by groins, the northernmost two cells failed over the study period, and experienced the largest individual sand-groin distance losses. We modeled inundation to investigate whether the sand loss was explainable by lake level change alone, with particular attention given to hardened shoreline implemented north of the beach in 2015. Observed sand cover loss markedly exceeded predictions from the inundation modeling. In addition to water level changes, a local response to shoreline modification and obstruction of sediment transport at this site may influence sand cover.

Impact of Lake Michigan water level rise on complex bidirectional flow in the Chicago Area Waterway System (CAWS)

In the past decade, continuously rising water levels in Lake Michigan have been threatening lakefront areas, especially in metropolitan regions like the Greater Chicago area. This provides the motivation to analyze the impact that high lake levels have on the Chicago Area Waterway System (CAWS). As the only primary free connection between the CAWS and Lake Michigan, the Calumet Area waterway subsystem plays a key and unique role. In this work, a numerical model covering the Calumet subsystem and having Lake Michigan as a boundary condition, is set up, calibrated, and validated using limited field observations. It is found that the Calumet subsystem has become bidirectional, where both discharge and flow directions are controlled by lake levels. When lake levels are below −0.15 m (-0.5 ft, Chicago City Datum, CCD), the discharge in the Grand Calumet River is around zero, with water flowing along its east branch towards Indiana. When lake levels are above +0.46 m (+1.5 ft, CCD), the flow reverses direction and drains west into Illinois. In 2020, the mean lake-level was at +1.07 m (+3.5 ft, CCD), and the base discharge in the Grand Calumet River was approximately 8.5 m3/s (300 ft3/s). The higher Lake Michigan’s level is, the larger the discharge would be into Illinois. Potential impact of this extra discharge on Lake Michigan Diversion Accounting (LMDA) of the State of Illinois and flood management in the Chicago Sanitary and Ship Canal (CSSC), is analyzed; while the nature of the bidirectional flows is characterized with the intent of shedding light on this complex phenomenon.

A Great Conversation With Dr. James Corbett

A Great Conversation With Dr. James Corbett

Combined toxicity of nano-CuO/nano-TiO2 and CuSO4/nano-TiO2 on Escherichia coli in aquatic environments under dark and light conditions

Copper(II) oxide nanoparticles (n-CuO) and copper(II) sulfate (CuSO4), commonly used in industrial and agricultural applications, are released in substantial amounts to the environment where they may then interact in unexpected ways with other materials such as engineered nanomaterials (ENM). In this study, we assessed the combined effects of their interaction with titanium(IV) dioxide nanoparticles (n-TiO2), a widely used ENM, on the ATP levels and cell membrane integrity of Escherichia coli in a natural aqueous medium (Lake Michigan water). Under dark conditions, we observed that n-TiO2 addition had negligible effects on copper toxicity, except in the case of higher doses of CuSO4 where n-TiO2 attenuated bacterial stress effects presumably by the adsorption of copper ions at the n-TiO2 surface. However, an opposite effect was observed under exposure to simulated solar irradiation (SSI) with synergistic stress occurring in mixtures of n-TiO2 with either CuSO4 or n-CuO. Enhanced photoactivity (as measured by methylene blue decay) in both CuSO4/n-TiO2 and n-CuO/n-TiO2 mixtures compared to single-component solutions explains the amplified stress effects of the mixtures under SSI, but we were unable to directly measure an increase in the production of reactive oxygen species (ROS) in the mixtures. Under environmental conditions that include light exposure, then, Cu/n-TiO2 mixtures exert amplified cellular stress exceeding that expected based on individual component effects.

Coastal geomorphic response to seasonal water-level rise in the Laurentian Great Lakes: An example from Illinois Beach State Park, USA

Hydrodynamic processes, such as fluctuating water levels, waves, and currents, shape coastlines across timescales ranging from minutes to millennia. In large lacustrine systems, such as the Laurentian Great Lakes, the role of water level in driving long-term (centuries to millennia) coastal evolution is well understood. However, additional research is needed to explore short-term (weeks to months) beach geomorphic response to fluctuating water level. Developing a process-focused understanding of how water level fluctuations shape coastal response across these shorter time scales is imperative for coastal management. Here, we present measurements of geomorphic response along a lacustrine beach ridge plain to seasonal water level fluctuations during a decadal high-stand in Lake Michigan water level. Frequent topographic change measurements revealed high spatial and temporal variability in geomorphic response to rising lake level. Sites immediately downdrift of shore protection began to erode immediately as lake level increased. The co-occurrence of peak seasonal lake levels and a modest increase in wave energy resulted in erosion and overwash at sites that resisted erosion during the initial seasonal rise in lake level. None of the sites in this study returned to their initial morphology following seasonal lake level rise. Given that peak water levels were nearly identical in 2017 and 2018, yet the majority of erosion at our sites occurred in 2017, we postulate that erosion associated with seasonal lake level rise is primarily a function of the change in annual maximum water level from year to year, rather than solely the elevation of the water level.

Bosea psychrotolerans sp. nov., a psychrotrophic alphaproteobacterium isolated from Lake Michigan water.

Three strains of a Gram-stain negative bacterium were isolated from Lake Michigan water. 16S rRNA gene sequence analysis revealed that strain 1131 had sequence similarities to Bosea vaviloviae LMG 28367T, Bosea lathyri LMG 26379T, Bosea lupini LMG 26383T, Bosea eneae CCUG 43111T, Bosea vestrisii CCUG 43114T and Boseamassiliensis CCUG 43117T of 99.8, 99.1, 98.4, 98.4, 98.4 and 98.2 %, respectively. The average nucleotide identity value between strain 1131T and Bosea vaviloviae Vaf-18T was 93.4 % and the DNA relatedness was 38 %. The primary cellular fatty acids of strain 1131T were C16 : 1ω7c and C18 : 1ω7c. The primary polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine. The major compound in the quinone system was ubiquinone Q-10 and in the polyamine pattern sym-homospermidine was predominant. Additional phenotypic characteristics included growth at 5-35 °C, pH values of pH 5.5-8.0, a salt tolerance range of 0.0-1.2 % (w/v), and production of an unknown water soluble brown pigment. After phenotypic, chemotaxonomic and genomic analyses, this isolate was identified as a novel species for which the name Bosea psychrotolerans is proposed. The type strain is 1131T (NRRL B-65405=LMG 30034).

Pseudomonas Diversity Within Urban Freshwaters.

Freshwater lakes are home to bacterial communities with 1000s of interdependent species. Numerous high-throughput 16S rRNA gene sequence surveys have provided insight into the microbial taxa found within these waters. Prior surveys of Lake Michigan waters have identified bacterial species common to freshwater lakes as well as species likely introduced from the urban environment. We cultured bacterial isolates from samples taken from the Chicago nearshore waters of Lake Michigan in an effort to look more closely at the genetic diversity of species found there within. The most abundant genus detected was Pseudomonas, whose presence in freshwaters is often attributed to storm water or runoff. Whole genome sequencing was conducted for 15 Lake Michigan Pseudomonas strains, representative of eight species and three isolates that could not be resolved with named species. These genomes were examined specifically for genes encoding functionality which may be advantageous in their urban environment. Antibiotic resistance, amidst other known virulence factors and defense mechanisms, were identified in the genome annotations and verified in the lab. We also tested the Lake Michigan Pseudomonas strains for siderophore production and resistance to the heavy metals mercury and copper. As the study presented here shows, a variety of pseudomonads have inhabited the urban coastal waters of Lake Michigan.

New pollutant identified in homes, environment

Likely used as a flame retardant or plasticizer in electrical and electronic equipment, tri(2,4-di-tert-butylphenyl) phosphate has been identified in dust from an electronic-waste-recycling facility as well as in residential dust and Lake Michigan water and sediments (Environ. Sci. Technol. 2018, DOI: 10.1021/acs.est.8b02939). The research team that identified the compound was led by Marta Venier of Indiana University’s School of Public & Environmental Affairs. The compound may also reach the environment via oxidation of tri(2,4-di-tert-butylphenyl) phosphite, which is used in plastics to protect them from degradation during extrusion, sterilization, or storage. No systematic toxicity assessments have been published for the compound, say the researchers who identified it in the dust and other samples. The researchers estimate exposure to be 571 ng/kg of body weight per day for electronic-waste-recycling workers, and household exposure of 536 ng/kg of body weight per day for adults and 7,550 ng/kg for todd...

Attenuation of Microbial Stress Due to Nano-Ag and Nano-TiO2 Interactions under Dark Conditions

Engineered nanomaterials (ENMs) are incorporated into thousands of commercial products, and their release into environmental systems creates complex mixtures with unknown toxicological outcomes. To explore this scenario, we probe the chemical and toxicological interactions of nanosilver (n-Ag) and nanotitania (n-TiO2) in Lake Michigan water, a natural aqueous medium, under dark conditions. We find that the presence of n-Ag induces a stress response in Escherichia coli, as indicated by a decrease in ATP production observed at low concentrations (in the μg L-1 range), with levels that are environmentally relevant. However, when n-Ag and n-TiO2 are present together in a mixture, n-TiO2 attenuates the toxicity of n-Ag at and below 20 μg L-1 by adsorbing Ag+(aq). We observe, however, that toxic stress cannot be explained by dissolved silver concentrations alone and, therefore, must also depend on silver associated with the nanoscale fraction. Although the attenuating effect of n-TiO2 on n-Ag's toxicity is limited, this study emphasizes the importance of probing the toxicity of ENM mixtures under environmental conditions to assess how chemical interactions between nanoparticles change the toxicological effects of single ENMs in unexpected ways.

Filimonas aurantiibacter sp. nov., an orange-pigmented bacterium isolated from lake water and emended description of the genus Filimonas

A Gram-stain-negative bacterium was isolated from Lake Michigan water. 16S rRNA gene sequence analysis revealed that strain 1458T had a sequence similarity to Filimonas lacunae YT21T, Sediminibacterium goheungense HME7863T, Parasegetibacter terrae SGM2-10T, Sediminibacterium ginsengisoli DCY13T, Terrimonas ferruginea DSM 30193T, Lacibacter cauensis NJ-8T, Flavihumibacter solisilvae 3-3T, Parasegetibacter luojieneis RHYL-37T, Vibrionimonas magnilacihabitans MU-2T and Parafilimonas terrae 5GHs7-2T with values of 93.4, 92.3, 91.9, 91.9, 91.8, 91.6, 91.6, 91.6, 91.5 and 90.4 %, respectively. The primary cellular fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH, iso-C15 : 1G and summed feature 3 (iso-C15 : 0 2-OH/C16 : 1ω7c). The primary polar lipids were phosphatidylethanolamine and an unidentified polar lipid only detectable after total polar lipid staining. The quinone system was menaquinone MK-7, and in the polyamine pattern, sym-homospermidine was predominant. Additional phenotypic characteristics included growth at 15 to 40 °C and pH 5.0 to 8.0, a salt tolerance range of 0 to 2.0 % (w/v), production of orange cell-bound pigment flexirubin, and gliding motility. After phenotypic, chemotaxonomic and molecular analyses, strain 1458T was identified as a novel species of the genus Filimonas, for which the name Filimonas aurantiibacter sp. nov. is proposed. The type strain is 1458T (=NRRL B-65305T=LMG 29039T). An emended description of the genus Filimonas is also provided.

Distribution of Sediment Measurements in Lake Michigan as a Case Study: Implications for Estimating Sediment and Water Interactions in Eutrophication and Bioaccumulation Models

Lake Michigan, the sixth largest freshwater lake in the world by surface area, was utilized as a water body for assessment. Field data collected at sampling sites throughout the lake in an intensive monitoring effort were utilized for evaluation of the distribution of sediment measurements. An assessment of sediment nutrient and carbon measurements within Lake Michigan was completed to recognize strata resulting from the hydrodynamics of the system. Nonparametric comparison tests revealed that significant differences exist between measurements of sediment nutrients and organic carbon in the lake using strata based upon water column depth (all results demon-strated a p < 0.05, α = 0.05). Cross-validation analysis was applied to the field-collected samples, revealing that large errors occur when estimating sediment flux of carbon or nutrients at a given location in the lake without considering stratification of the distributions of these measurements. Errors in estimating sediment concentrations of nutrients and carbon specific to a location in the lake demonstrated a statistically significant increase when stratification of sediment measurements wasn’t employed among sites. For example, distributions of errors in estimating all nutrients and organic carbon concentrations, whereby distance squared inverse interpolation methods were applied, demonstrated a statistically significant increase in absence of stratification (all p < 0.001, α = 0.05). These results have implications for characterization, monitoring, and modeling sediment and water interaction as related to eutrophication, as well as to contaminant exposure and bioaccumulation for chemicals within Lake Michigan and large water bodies where stratification of the sediment based upon physics of the system exists.

Global and regional contributions to total mercury concentrations in Lake Michigan water

The Lake Michigan mercury mass balance model, LM2-Mercury, which was calibrated to a comprehensive data set collected from Lake Michigan during 1994–1995, was applied to predict long-term total mercury concentrations in lake water for different mercury loading and air concentration scenarios. The model predictions (volume-weighted, lakewide average total mercury concentrations) appear to be comparable to the available independent measurements from 2005 through 2013. The forecast based on the constant condition scenario, where conditions representative of 1994–1995 were held constant, shows that total mercury concentrations in the lake are near steady-state. The model was used to investigate the relative importance of different global versus regional impact scenarios on total mercury concentrations in Lake Michigan. The results suggest that mercury from global sources could contribute between 30% and 70% of total mercury water concentrations in Lake Michigan. Results for declining global emission scenarios modeled, based on both high and low global contribution estimates and information on mercury emission trends from current observations and the literature, indicate that total mercury concentrations in the water column in Lake Michigan will continue to decrease.

Combined Toxicity of Nano-ZnO and Nano-TiO2: From Single- to Multinanomaterial Systems.

Previous studies on the toxicity of engineered nanomaterials (ENMs) have been primarily based on testing individual ENMs, so little is known about the interactions and combined toxicity of multiple ENMs. In this study the toxicity of chemically stable nano-TiO2 and soluble nano-ZnO was investigated individually and in combination, by monitoring bacterial cell membrane integrity and ATP levels in a natural aqueous medium (Lake Michigan water). Both nano-TiO2 and nano-ZnO damage bacterial cell membranes under simulated solar irradiation (SSI), but their phototoxicity is not additive. Nano-ZnO at 1 mg/L, for example, surprisingly eliminates the damaging effect of nano-TiO2 at 10 mg/L. This phenomenon does not correlate with reactive oxygen species production, but is explained by a reduced extent of bacteria/nano-TiO2 contact in the presence of both nano-ZnO and dissolved zinc. The presence of nano-ZnO also exerts a significant decrease in bacterial ATP levels both under SSI and in the dark, a stress effect not captured by measuring bacterial cell membrane integrity. This inhibitory effect of nano-ZnO, however, is reduced somewhat by nano-TiO2 due to the adsorption of Zn(2+). Therefore, our results reveal that nanoparticle interactions and surface complexation reactions alter the original toxicity of individual nanoparticles and that comprehensive assessments of potential ENM toxicity in the environment require careful integration of complex physicochemical interactions between ENMs and various biological responses.

PCBs refocused: Correlation of PCB concentrations in Green Bay legacy sediments with adjacent lithophilic, invasive biota

Green Bay sediments exhibit a gradient of polychlorinated biphenyl (PCB) concentrations from the mouth of the Fox River to the northern end of the bay. This study explored whether the sediment concentration gradient was reflected along Green Bay's rocky (non-depositional) eastern coast in a suspension feeder, the invasive quagga mussel (Dreissena bugensis), as well as in the main predator on quagga mussels, the invasive round goby (Neogobius melanostomus). We performed congener-specific PCB analyses on quagga mussels and round gobies collected from ten sites along the east shore of Green Bay. PCB results were compared with sediment data. Regression analyses showed that mussel tissue PCB concentrations followed sediment PCB concentrations (F1,6=16.4, P=0.007) except at two sites near Sturgeon Bay where cleaner Lake Michigan water enters in tidal pulses. Round goby PCB concentrations also followed the sediment trends (F1,7=8.17, P=0.024). However, only a weak relationship between PCB concentrations in quagga mussel and round goby was found (P=0.085), even though the species are trophically linked. Here, ontogenetic and seasonal details of round goby diet strongly influenced PCB concentrations such that in areas adjacent to high sediment PCB concentrations, fish length dictated round goby's PCB concentration (F1,14=7.46, P=0.016). Overall, our findings indicate that these exotic benthos refocus PCBs in near-shore regions in a pattern similar to that observed in sediments. Our results also highlight the need to understand trophic details in order to track contaminant bioaccumulation accurately.

The Great Lakes Runoff Intercomparison Project Phase 1: Lake Michigan (GRIP-M)

We assembled and applied five models (one of which included three different configurations) to the Lake Michigan basin to improve our understanding of how differences in model skill at simulating total runoff to Lake Michigan relate to model structure, calibration protocol, model complexity, and assimilation (i.e. replacement of simulated discharge with discharge observations into historical simulations), and evaluate historical changes in runoff to Lake Michigan. We found that the performance among these models when simulating total runoff to the lake varied relatively little, despite variability in model structure, spatial representation, input data, and calibration protocol. Relatively simple empirical, assimilative models, including the National Oceanic and Atmospheric Administration (NOAA) Great Lakes Environmental Research Laboratory (GLERL) area ratio-based model (ARM) and the United States Geological Survey (USGS) Analysis of Flows in Networks of CHannels (AFINCH) model, represent efficient and effective approaches to propagating discharge observations into basin-wide (including gaged and ungaged areas) runoff estimates, and may offer an opportunity to improve predictive models for simulating runoff to the Great Lakes. Additionally, the intercomparison revealed that the median of the simulations from non-assimilative models agrees well with assimilative models, suggesting that using a combination of different methodologies may be an appropriate approach for estimating runoff into the Great Lakes. We then applied one assimilative model (ARM) to the Lake Michigan basin and found that there was persistent reduction in the amount of precipitation that becomes runoff following 1998, corresponding to a period of persistent low Lake Michigan water levels. The study was conducted as a first phase of the Great Lakes Runoff Intercomparison Project, a regional binational collaboration that aims to systematically and rigorously assess a variety of models currently used (or that could readily be adapted) to simulate basin-scale runoff to the North American Laurentian Great Lakes.

Chemical interactions between Nano-ZnO and Nano-TiO2 in a natural aqueous medium.

The use of diverse engineered nanomaterials (ENMs) potentially leads to the release of multiple ENMs into the environment. However, previous efforts to understand the behavior and the risks associated with ENMs have focused on only one material at a time. In this study, the chemical interactions between two of the most highly used ENMs, nano-TiO2, and nano-ZnO, were examined in a natural water matrix. The fate of nano-ZnO in Lake Michigan water was investigated in the presence of nano-TiO2. Our experiments demonstrate that the combined effects of ZnO dissolution and Zn adsorption onto nano-TiO2 control the concentration of dissolved zinc. X-ray absorption spectroscopy was used to determine the speciation of Zn in the particulate fraction. The spectra show that Zn partitions between nano-ZnO and Zn2+ adsorbed on nano-TiO2. A simple kinetic model is presented to explain the experimental data. It integrates the processes of nano-ZnO dissolution with Zn adsorption onto nano-TiO2 and successfully predicts dissolved Zn concentration in solution. Overall, our results suggest that the fate and toxicity potential of soluble ENMs, such as nano-ZnO, are likely to be influenced by the presence of other stable ENMs, such as nano-TiO2.

Proposal of Vibrionimonas magnilacihabitans gen. nov., sp. nov., a curved Gram-stain-negative bacterium isolated from lake water

A mesophilic bacterium appearing as curved rod-shaped cells was isolated from Lake Michigan water. It exhibited highest similarities with Sediminibacterium ginsengisoli DCY13(T) (94.4%); Sediminibacterium salmoneum NJ-44(T) (93.6%) and Hydrotalea flava CCUG 51397 (T) (93.1%) while similarities with other recognized species were <92.0%. The primary polar lipid was phosphatidylethanolamine, with moderate amounts of two unidentified glycolipids, three unknown polar lipids, one unknown aminophospholipid and one aminolipid. The primary respiratory quinone was MK-7 and sym-homospermidine was the primary polyamine. The major cellular fatty acids were iso-C(15 : 1)G, iso-C(15 : 0), iso-C(16 : 0) 3-OH and iso-C(17 : 0) 3-OH, with moderate amounts of iso-C(16 : 0). The presence of glycolipids differentiated the novel strains from related genera. The DNA mol% G+C content of the type strain MU-2(T) was 45.2. Results for other phenotypic and molecular analyses indicated that strain MU-2(T) is a representative of a novel genus and species for which the name Vibrionimonas magnilacihabitans is proposed. The type strain is MU-2(T) ( = NRRL B-59231 = DSM 22423).