Future distribution of Arctic char Salvelinus alpinus in Sweden under climate change: effects of temperature, lake size and species interactions

Novel communities will be formed as species with a variety of dispersal abilities and environmental tolerances respond individually to climate change. Thus, models projecting future species distributions must account for species interactions and differential dispersal abilities. We developed a species distribution model for Arctic char Salvelinus alpinus, a freshwater fish that is sensitive both to warm temperatures and to species interactions. A logistic regression model using lake area, mean annual air temperature (1961-1990), pike Esox lucius and brown trout Salmo trutta occurrence correctly classified 95?% of 467 Swedish lakes. We predicted that Arctic char will lose 73?% of its range in Sweden by 2100. Predicted extinctions could be attributed both to simulated temperature increases and to projected pike invasions. The Swedish mountains will continue to provide refugia for Arctic char in the future and should be the focus of conservation efforts for this highly valued fish.     

Spatio-temporal trends of PCBs in the Swedish freshwater environment 1981–2012

Polychlorinated biphenyls (PCBs) have been monitored in perch (Perca fluviatilis), pike (Esox lucius), and Arctic char (Salvelinus alpinus) in reference lakes since the late 1960s. Temporal trends and spatial patterns are currently monitored in nine and 32 lakes, respectively. Overall, PCB concentrations are decreasing. However, this is not consistent for all congeners across all lakes and species. Perch has comparatively low PCB concentrations relative to suggested target levels, but individual congener concentrations in some lakes are concerningly high. No temporal trend is seen for CB-118 and CB-153 in perch, but significant decreasing trends exist for Arctic char and pike, for which monitoring started earlier than for perch. The lower/higher chlorinated congener ratio decreased over time in most lakes, indicating fewer new emissions. CB-118 and CB-153 concentrations in perch show spatial gradients across Sweden, with higher concentrations found near urban/industrial areas.     

Seafood from a changing Arctic

We review current knowledge about climate change impacts on Arctic seafood production. Large-scale changes in the Arctic marine food web can be expected for the next 40–100 years. Possible future trajectories under climate change for Arctic capture fisheries anticipate the movement of aquatic species into new waters and changed the dynamics of existing species. Negative consequences are expected for some fish stocks but others like the Barents Sea cod (Gadus morhua) may instead increase. Arctic aquaculture that constitutes about 2% of global farming is mainly made up of Norwegian salmon (Salmo salar) farming. The sector will face many challenges in a warmer future and some of these are already a reality impacting negatively on salmon growth. Other more indirect effects from climate change are more uncertain with respect to impacts on the economic conditions of Arctic aquaculture.     

Enhanced UV-B and Elevated CO<Subscript>2</Subscript> Impacts Sub-Arctic Shrub Berry Abundance,Quality and Seed Germination

This study investigated the effects of long-term-enhanced UV-B, and combined UV-B with elevated CO₂ on dwarf shrub berry characteristics in a sub-arctic heath community. Germination of Vaccinium myrtillus was enhanced in seeds produced at elevated UV-B, but seed numbers and berry size were unaffected. Elevated UV-B and CO₂ stimulated the abundance of V. myrtillus berries, whilst UV-B alone stimulated the berry abundance of V. vitis-idaea and Empetrum hermaphroditum. Enhanced UV-B reduced concentrations of several polyphenolics in V. myrtillus berries, whilst elevated CO₂ increased quercetin glycosides in V. myrtillus, and syringetin glycosides and anthocyanins in E. hermaphroditum berries. UV-B × CO₂ interactions were found for total anthocyanins, delphinidin-3-hexoside and peonidin-3-pentosidein in V. myrtillus berries but not E. hermaphroditum. Results suggest positive impacts of UV-B on the germination of V. myrtillus and species-specific impacts of UV-B × elevated CO₂ on berry abundance and quality. The findings have relevance and implications for human and animal consumers plus seed dispersal and seedling establishment.     

Biology and management of two important <Emphasis Type="Italic">Conyza</Emphasis> weeds: a global review

Weed management is one of the prime concerns for sustainable crop production. Conyza bonariensis and Conyza canadensis are two of the most problematic, noxious, invasive and widespread weeds in modern-day agriculture. The biology, ecology and interference of C. bonariensis and C. canadensis have been reviewed here to highlight pragmatic management options. Both these species share a unique set of biological features, which enables them to invade and adapt a wide range of environmental conditions. Distinct reproductive biology and an efficient seed dispersal mechanism help these species to spread rapidly. Ability to interfere strongly and to host crop pests makes these two species worst weeds of cropping systems. These weed species cause 28–68 % yield loss in important field crops such as soybean and cotton every year. These weeds are more prevalent in no-till systems and, thus, becoming a major issue in conservation agriculture. Cultural practices such as crop rotations, seed rate manipulation, mulching, inter-row tillage and narrow row spacing may provide an effective control of these species. However, such methods are not feasible and applicable under all types of conditions. Different herbicides also provide a varying degree of control depending on crop, agronomic practices, herbicide dose, application time and season. However, both these species have evolved resistance against multiple herbicides, including glyphosate and paraquat. The use of alternative herbicides and integrated management strategies may provide better control of herbicide-resistant C. bonariensis and C. canadensis. Management plans based on the eco-biological interactions of these species may prove sustainable in the future.     

<Emphasis Type="Italic">Ailanthus Altissima</Emphasis> and <Emphasis Type="Italic">Phragmites Australis</Emphasis> for chromium removal from a contaminated soil

The comparative effectiveness for hexavalent chromium removal from irrigation water, using two selected plant species (Phragmites australis and Ailanthus altissima) planted in soil contaminated with hexavalent chromium, has been studied in the present work. Total chromium removal from water was ranging from 55 % (Phragmites) to 61 % (Ailanthus). After 360 days, the contaminated soil dropped from 70 (initial) to 36 and 41 mg Cr/kg (dry soil), for Phragmites and Ailanthus, respectively. Phragmites accumulated the highest amount of chromium in the roots (1910 mg Cr/kg_{(dry tissue)}), compared with 358 mg Cr/kg_{(dry tissue)} for Ailanthus roots. Most of chromium was found in trivalent form in all plant tissues. Ailanthus had the lowest affinity for Cr^VI reduction in the root tissues. Phragmites indicated the highest chromium translocation potential, from roots to stems. Both plant species showed good potentialities to be used in phytoremediation installations for chromium removal.     

Challenges in assessing biological recovery from acidification in Swedish lakes

Since the 1980s, Swedish lakes have in general become less acidified. Assessment of biological recovery is, however, hampered by poor pre-acidification data, confounding effects of climate change, and few lakes with annual sampling of fish and other organisms. Only three critically acidified, but non-limed, lakes had two decades of fish monitoring. The lakes had not yet recovered to pre-industrial chemical targets. Fish had low species richness compared to other organism groups. Roach (Rutilus rutilus) and/or European perch (Perca fluviatilis) were the dominant fish species, and the acid-sensitive roach had been lost from one of the lakes. Calcium decreased, possibly approaching pre-acidification concentrations, but exceeded minimum levels needed to sustain some Daphnia species. High or increasing levels of total organic carbon, likely due to reduced acidification and climate change, might influence the biological communities in unexpected ways, for example, facilitating more frequent occurrence of the invasive algae Gonyostomum semen.     

Development of a real-time polymerase chain reaction assay for the detection of the invasive Mediterranean fanworm, <Emphasis Type="Italic">Sabella spallanzanii</Emphasis>, in environmental samples

The Mediterranean fanworm, Sabella spallanzanii Gmelin 1791, was first detected in the Southern Hemisphere in the 1990s and is now abundant in many parts of southern Australia and in several locations around northern New Zealand. Once established, it can proliferate rapidly, reaching high densities with potential ecological and economic impacts. Early detection of new S. spallanzanii incursions is important to prevent its spread, guide eradication or control efforts and to increase knowledge on the species’ dispersal pathways. In this study, we developed a TaqMan probe real-time polymerase chain reaction assay targeting a region of the mitochondrial cytochrome oxidase I gene. The assay was validated in silico and in vitro using DNA from New Zealand and Australian Sabellidae with no cross-reactivity detected. The assay has a linear range of detection over seven orders of magnitude with a limit of detection reached at 12.4 × 10^?4 ng/μL of DNA. We analysed 145 environmental (water, sediment and biofouling) samples and obtained positive detections only from spiked samples and those collected at a port where S. spallanzanii is known to be established. This assay has the potential to enhance current morphological and molecular-based methods, through its ability to rapidly and accurately identify S. spallanzanii in environmental samples.     

Effect of heavy metals on tissue-specific antioxidant response in Indian major carps

Concentrations of heavy metals (Cu, Ni, Zn, Cd and Pb) were measured in sediments, water and liver and kidney tissues of three Indian major carps (Labeo rohita, Catla catla and Cirrhinus cirrhosus), belonging to two different weight groups (250 and 500 g), collected from ponds at two different sites (Nalban bheri and Diamond Harbour). The tissues were analysed for the levels of different antioxidant defence systems such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GRd), glutathione S-transferase (GST), glutathione (GSH) and malondialdehyde (MDA). Concentrations of all the metals were significantly higher (P < 0.05) in sediment, water and the tissues from Nalban bheri compared to those in Diamond Harbour. Metal concentrations were the lowest in C. cirrhosus, which increased with an increase in fish weight, and the liver accumulated higher amount of metals than the kidney. Activities of all enzymatic and non-enzymatic antioxidant parameters except GPx and GRd were significantly higher (P < 0.05) in the tissues from Nalban bheri than those in Diamond Harbour. Significant multicollinearity was found in the values of SOD, CAT, GST, GRd, GPx and MDA with Pb, Cu and Ni in all three fish species at Nalban and with Cd in L. rohita and C. catla. Principal component analysis results revealed that stress response in a polluted site was directly regulated by an amalgamation of GSH profile and the levels of MDA in a synchronized manner. The study indicated a tissue-specific and species-specific difference for heavy metal-induced oxidative stress response in fish and a correlation between different heavy metals and individual oxidative stress markers.     

Physiological and biochemical responses of <Emphasis Type="Italic">Machilus ichangensis</Emphasis> Rehd. et Wils and <Emphasis Type="Italic">Taxus chinensis</Emphasis> (Pilger) Rehd. to elevated O<Subscript>3</Subscript> in subtropical China

Considerable researches have documented the negative effects of ozone on woody species in North America and Europe; however, little is known about how woody tree species respond to elevated O₃ in subtropical China, and most of the previous studies were conducted using pot experiment. In the present study, Machilus ichangensis Rehd. et Wils (M. ichangensis) and Taxus chinensis (Pilger) Rehd. (T. chinensis), evergreen tree species in subtropical China, were exposed to non-filtered air (NF), 100 nmol mol^?1 O₃ (E1) and 150 nmol mol^?1 O₃ (E2), in open-top chambers under field conditions from 21st March to 2nd November 2015. In this study, O₃ fumigation significantly reduced net photosynthesis rate (Pn) in M. ichangensis in the three measurements and in T. chinensis in the last measurement. Also, non-stomatal factors should be primarily responsible for the decreased Pn. O₃ fumigation-induced increase in malondialdehyde, superoxide dismutase, and reduced ascorbic acid levels indicated that antioxidant defense mechanism had been stimulated to prevent O₃ stress and repair the oxidative damage. Yet, the increase of antioxidant ability was not enough to counteract the harm of O₃ fumigation. Because of the decrease in CO₂ assimilation, the growth of the two tree species was restrained ultimately. The sensitivity of the two tree species to O₃ can be determined: M. ichangensis > T. chinensis. It suggests a close link between the rising O₃ concentrations and the health risk of some tree species in subtropics in the near future.     

Endogenous <Emphasis Type="Italic">trans</Emphasis>-zeatin content in plants with different metal-accumulating ability: a field survey

A field survey was conducted to evaluate soil metal pollution and endogenous trans-zeatin content in the leaves of plants growing at six sites in a metal-polluted area located in Gejiu, Yunnan, China. Five plant species were collected, and the physicochemical properties and concentrations of five metals in the soil were analyzed. The trans-zeatin content in plant leaves was measured by high-performance liquid chromatography. Based on the Nemerow pollution index, the six sites were classified into four levels of pollution (i.e., low, medium, high, and severely high). The degree of soil metal pollution was cadmium (Cd) > arsenic (As) > lead (Pb) > zinc (Zn) > copper (Cu). The leaf trans-zeatin content in Pteris vittata (an arsenic hyperaccumulator) increased significantly by 98.6 % in soil with a severely high level of pollution compared with soil at a low level of pollution. However, in non-hyperaccumulators Bidens pilosa var. radiata and Ageratina adenophora, a significant decrease in leaf trans-zeatin content of 35.6 and 87.6 %, respectively, was observed. The leaf trans-zeatin content in Artemisia argyi also decreased significantly by 73.6 % in high metal-polluted soil compared with that in medium metal-polluted soil. Furthermore, significant correlations were observed between leaf trans-zeatin content in Pteris vittata and As, Pb, and Cd concentrations in the soil; however, either no correlation or a negative one was observed in the other plant species. Therefore, a high content of trans-zeatin in the leaves of Pteris vittata may play an important role in its normal growth and tolerance to metals.     

Proximate composition and mineral contents in the body wall of two species of sea cucumber from Oman Sea

The proximate composition and mineral contents of Stichopus horrens and Holothuria arenicola from Chabahar Bay were analyzed and investigated. During the present study, we aimed to demonstrate the nutritive value. The approximate percent composition of moisture, protein, fat, and ash were 92.8, 3.47, 0.4, and 3.33% in S. horrens and 93, 4.4, 0.6, and 2% in H. arenicola, respectively. Atomic absorption spectrophotometry of the ashes indicated the body wall of two species of sea cucumbers contained higher amounts of both macro minerals (92.5 mg/100 g Mg in S. horrens and 115 mg/100 g Mg in H. arenicola; 106.25 mg/100 g Ca in S. horrens and 83.25 mg/100 g Ca in H. arenicola) and trace elements (521.781 mg/100 g Fe in S. horrens; 60.354 mg/100 g Fe in H. arenicola, and 0.096 mg/100 g Zn in S. horrens; 0.04 mg/100 g Zn in H. arenicola). For both species, there were high content of protein and essential mineral. Also, they have low content of fat in the body wall of two species in the experiment.     

Metals and PCB levels in some edible marine organisms from the Ionian Sea: dietary intake evaluation and risk for consumers

Concentrations of some metals (Cd, Cu, As, Hg, Pb) and polychlorinated biphenyls (PCBs) were investigated in edible marine organisms from different trophic levels and feeding behaviour like bivalve molluscs (Mytilus galloprovincialis and Chlamys glabra), gastropod molluscs (Hexaplex trunculus) and some commercial species of fish (Trachurus trachurus, Boops boops, Sarpa salpa and Gobius niger). These species were collected in the first inlet of the Mar Piccolo of Taranto (Ionian Sea, Southern Italy), classified as ‘Site of National Interest’ established by National Law 426 (1998) and included in the ‘National Environmental Remediation and Restoration Projects’. The aim of this work was to investigate contamination levels and public health risks, associated with consuming seafood harvested from these areas. Moreover, in this study, was also estimated the weekly intake in children and adults, both for metals and PCBs. In comparison with the permissible limits set by EC Regulations, Cd and Pb levels were over the limit in the H. trunculus (in all sampling stations) and in the fish T. trachurus respectively. PCBs were over the legal limit in all sampled species with the exception of M. galloprovincialis (station 1), C. glabra and the herbivorous fish S. salpa. In the fish T. trachurus, for example, the concentration of six target PCBs was about five times higher than the EC limit. The estimated intakes of those trace elements included in this study through seafood consumption by the population exceed the provisional tolerable weekly intake recommended by the Joint FAO/WHO Expert Committee on Food Additives for Cd and Hg in the H. trunculus and T. trachurus, especially in children. Moreover, hazard quotience (HQ) for Hg and Cd was >1 in the children for T. trachurus and H. trunculus consumption. As regard non-dioxin-like PCB (NDL-PCB), the estimated intake were always above the ‘provisional guidance value’ (70 ng/kg body weight) Arnich et al. (Regul Toxicol Pharm 54: 287–2, 2009) for all sampled organism. Thus, health risks due to the dietary Hg, Cd and PCBs intake, especially for children, cannot be excluded. Therefore, an extended remediation programme is necessary to safeguard marine ecosystem, human health and, not less important, the economic activities, in the Taranto marine area.     

Removal ratio of gaseous toluene and xylene transported from air to root zone via the stem by indoor plants

This work was designed to investigate the removal efficiency as well as the ratios of toluene and xylene transported from air to root zone via the stem and by direct diffusion from the air into the medium. Indoor plants (Schefflera actinophylla and Ficus benghalensis) were placed in a sealed test chamber. Shoot or root zone were sealed with a Teflon bag, and gaseous toluene and xylene were exposed. Removal efficiency of toluene and total xylene (m, p, o) was 13.3 and 7.0 μg·m^?3·m^?2 leaf area over a 24-h period in S. actinophylla, and was 13.0 and 7.3 μg·m^?3·m^?2 leaf area in F. benghalensis. Gaseous toluene and xylene in a chamber were absorbed through leaf and transported via the stem, and finally reached to root zone, and also transported by direct diffusion from the air into the medium. Toluene and xylene transported via the stem was decreased with time after exposure. Xylene transported via the stem was higher than that by direct diffusion from the air into the medium over a 24-h period. The ratios of toluene transported via the stem versus direct diffusion from the air into the medium were 46.3 and 53.7 % in S. actinophylla, and 46.9 and 53.1 % in F. benghalensis, for an average of 47 and 53 % for both species. The ratios of m,p-xylene transported over 3 to 9 h via the stem versus direct diffusion from the air into the medium was 58.5 and 41.5 % in S. actinophylla, and 60.7 and 39.3 % in F. benghalensis, for an average of 60 and 40 % for both species, whereas the ratios of o-xylene transported via the stem versus direct diffusion from the air into the medium were 61 and 39 %. Both S. actinophylla and F. benghalensis removed toluene and xylene from the air. The ratios of toluene and xylene transported from air to root zone via the stem were 47 and 60 %, respectively. This result suggests that root zone is a significant contributor to gaseous toluene and xylene removal, and transported via the stem plays an important role in this process.     

2,3,7,8-TCDD-mediated toxicity in peripheral blood mononuclear cells is alleviated by the antioxidants present in <Emphasis Type="Italic">Gelidiella acerosa</Emphasis>: an in vitro study

Seaweeds have been used as a source of traditional medicine worldwide for the treatment of various ailments, mainly due to their ability to quench the free radicals. The present study aims at evaluating the protective effect of methanolic extract of Gelidiella acerosa, an edible red seaweed against 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced toxicity in peripheral blood mononuclear cells (PBMC). For evaluating the protective effect of G. acerosa, PBMC were divided into four groups: vehicle control, TCDD (10 nM), TCDD?+?G. acerosa (300 μg/ml), and G. acerosa alone treated. Scavenging of intracellular reactive oxygen species (ROS) induced by TCDD was assessed by the dichloro-dihydro-fluorescein diacetate (DCFH-DA) method. Alterations at macromolecular level were quantified through lipid peroxidation (LPO) level, protein carbonyl content (PCC) level, and comet assay. The cellular morphology upon TCDD toxicity and G. acerosa treatment was obtained by light microscopy and histopathological studies. The chemical composition present in the methanolic extract of G. acerosa was determined by gas chromatography-mass spectrometry (GC-MS) analysis. The results reveal that 10 nM TCDD caused significant (P?<?0.05) reduction in cell viability (94.10?±?0.99), and treatment with 300 μg/ml extract increased the cell viability (99.24?±?0.69). TCDD treatment resulted in a significant increase in the production of ROS, LPO (114?±?0.09), and PCC (15.13?±?1.53) compared to the control, whereas co-treatment with G. acerosa significantly (P?<?0.05) mitigated the effects. Further, G. acerosa significantly (P?<?0.05) prevented TCDD-induced genotoxicity and cell damage. GC-MS analysis showed the presence of n-hexadecanoic acid (retention time (RT) 13.15), cholesterol (RT 28.80), α-d-glucopyranose, 4-O-α-d-galactopyranosyl (RT 20.01), and azulene (RT 4.20). The findings suggest that G. acerosa has a strong protective ability against TCDD-induced cytotoxicity, oxidative stress, and DNA damage.     

Assessment of trace metal contamination in the sea cucumber (<Emphasis Type="Italic">Holothuria tubulosa</Emphasis>) and sediments from the Dardanelles Strait (Turkey)

This study was performed to determine the concentrations of some trace metals (Cd, Cu, Pb, Ni, Zn, and Fe) in Holothuria tubuosa (Gmelin, 1788) belonging to Echinoderm species and in sediments that they live at three different stations (Gelibolu, Umur Bey/Lapseki, and Dardanos) on Dardanelles Strait between April 2013 and March 2014. The mean trace metal concentrations determined in H. tubulosa and sediment were as follows: Cd 0.18 mg/kg, Cu 2.43 mg/kg, Pb 2.09 mg/kg, Ni 14.58 mg/kg, Zn 16.86 mg/kg, and Fe 73.46 mg/kg and Cd 0.70 mg/kg, Cu 5.03 mg/kg, Pb 14.57 mg/kg, Ni 27.15 mg/kg, Zn 54.52 mg/kg, and Fe 3779.9 mg/kg, respectively. It was detected that the statistical difference between trace metals determined seasonally in muscle tissue of H. tubulosa was significant (p?>?0.05). As a result of the study, it was detected that H. tubulosa is a bioindicator species in determining Ni trace metal in sediment. The results were compared to the limit values of National and International Food Safety, and it was detected that Cd and Ni concentrations measured in sediment were above LEL of Ni and Cd concentrations according to Sediment Quality Guidelines.     

Invasive alien plant species dynamics in the Himalayan region under climate change

Climate change will impact the dynamics of invasive alien plant species (IAPS). However, the ability of IAPS under changing climate to invade mountain ecosystems, particularly the Himalayan region, is less known. This study investigates the current and future habitat of five IAPS of the Himalayan region using MaxEnt and two representative concentration pathways (RCPs). Two invasive species, Ageratum conyzoides and Parthenium hysterophorus, will lose overall suitable area by 2070, while Ageratina adenophora, Chromolaena odorata and Lantana camara will gain suitable areas and all of them will retain most of the current habitat as stable. The southern Himalayan foothills will mostly conserve species ecological niches, while suitability of all the five species will decrease with increasing elevation. Such invasion dynamics in the Himalayan region could have impacts on numerous ecosystems and their biota, ecosystem services and human well-being. Trans-boundary response strategies suitable to the local context of the region could buffer some of the likely invasion impacts.     

Inhibition of residual <Emphasis Type="Italic">n</Emphasis>-hexane in anaerobic digestion of lipid-extracted microalgal wastes and microbial community shift

Converting lipid-extracted microalgal wastes to methane (CH₄) via anaerobic digestion (AD) has the potential to make microalgae-based biodiesel platform more sustainable. However, it is apparent that remaining n-hexane (C₆H₁₄) from lipid extraction could inhibit metabolic pathway of methanogens. To test an inhibitory influence of residual n-hexane, this study conducted a series of batch AD by mixing lipid-extracted Chlorella vulgaris with a wide range of n-hexane concentration (～10 g chemical oxygen demand (COD)/L). Experimental results show that the inhibition of n-hexane on CH₄ yield was negligible up to 2 g COD/L and inhibition to methanogenesis became significant when it was higher than 4 g COD/L based on quantitative mass balance. Inhibition threshold was about 4 g COD/L of n-hexane. Analytical result of microbial community profile revealed that dominance of alkane-degrading sulfate-reducing bacteria (SRB) and syntrophic bacteria increased, while that of methanogens sharply dropped as n-hexane concentration increased. These findings offer a useful guideline of threshold n-hexane concentration and microbial community shift for the AD of lipid-extracted microalgal wastes.     

Visible light photocatalytic antibacterial activity of Ni-doped and N-doped TiO<Subscript>2</Subscript> on <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> and <Emphasis Type="Italic">Escherichia coli</Emphasis> bacteria

The Ni-doped and N-doped TiO₂ nanoparticles were investigated for their antibacterial activities on Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacteria. Their morphological features and characteristics such as particle size, surface area, and visible light absorbing capacity were compared and discussed. Scanning electron microscopy, X-ray diffraction, and UV–visible spectrophotometry were used to characterize both materials. The inactivation of E. coli (as an example of Gram-negative bacteria) and S. aureus (as an example of Gram-positive bacteria) with Ni-doped and N-doped TiO₂ was investigated in the absence and presence of visible light. Antibacterial activity tests were conducted using undoped, Ni-doped, and N-doped TiO₂. The N-doped TiO₂ nanoparticles show higher antibacterial activity than Ni-doped TiO₂. The band gap narrowing of N-doped TiO₂ can induce more visible light absorption and leads to the superb antibacterial properties of this material. The complete inactivation time for E. coli at an initial cell concentration of 2.7?×?10⁴ CFU/mL was 420 min which is longer than the 360 min required for S. aureus inactivation. The rate of inactivation of S. aureus using the doped TiO₂ nanoparticles in the presence of visible light is greater than that of E. coli. The median lethal dose (LD50) values of S. aureus and E. coli by antibacterial activity under an 18-W visible light intensity were 80 and 350 mg/ml for N-doped TiO₂, respectively.