Effects of lead on tolerance, bioaccumulation, and antioxidative defense system of green algae, Cladophora

https://doi.org/10.1016/j.ecoenv.2014.11.007Get rights and content

Highlights

  • Low concentrations of Pb2+ accelerate Cladophora growth.

  • The total soluble sugar content of Cladophora was affected by Pb2+ treatment.

  • The peroxidase(POD) and metallothionein(MT) help Cladophora to survive in Pb-contaminated environments.

  • The malondialdehyde (MDA) activity of Cladophora gradually increased as Pb2+ concentration increased.

  • Cladophora can accumulate Pb, the adsorption on Cladophora is not a simple surface adsorption.

Abstract

Effects of various concentrations (0.5, 1.0, 2.5, 5.0, 7.5, and 10.0 mg/L) of lead (Pb2+) on the growth, bioaccumulation, and antioxidative defense system of green algae, Cladophora, was investigated. Low concentrations of Pb2+ accelerated Cladophora growth, but concentrations of 10.0 mg/L and above inhibited the growth because of the hinderance to photosynthesis. The total soluble sugar content of Cladophora was affected by Pb2+ treatment, but the protein content showed no significant changes. The malondialdehyde (MDA) content and peroxidase(POD) activity of Cladophora gradually increased whereas superoxide dismutase(SOD) decreased with Pb2+ concentrations. Catalase (CAT) activity exhibited no significant changes following Pb2+ treatment. Pb2+ accumulated in Cladophora and that the lead content in Cladophora was correlated with POD growth, MDA, and Metallothionein (MT). POD and MT play a role in the survival of Cladophora in Pb-contaminated environments. This study suggests that Cladophora can be a choice organism for the phytoremediation of Pb-polluted coastal areas.

Introduction

Heavy metal pollution is a worldwide problem (Chehregani et al., 2009). Anthropogenic inputs of pollutants, such as heavy metals (HM), into the marine environment have significantly increased within the past few years (Doney, 2010). Rivers contained highest concentrations of arsenic, cadmium, copper, mercury, and zinc. Mean concentrations of Cu, Zn, Cr, Pb, and Cd were higher than background concentrations determined for the areas (Xu et al., 2014). Lead (Pb) is one of the most common and dangerous environmental contaminants (Needleman, 2004), it in the environment can be hazardous to the health and well-being of most living species,so,estimating the toxic-effect of Pb(II) and removed it from waters and the environment is important.

Acute and chronic bioassays were conducted to determine the effects of copper, lead, and zinc mixtures on Ceriodaphnia dubia and Daphnia carinata (Cooper et al., 2009). On five marine microalgae with the same biovolume quantity (Tetraselmis chuii, Rhodomonas salina, Chaetoceros sp., Isochrysis galbana (T-iso) and Nannochloropsis gaditana) 72-h exposure toxicity tests with copper and lead were performed. For both metals, 72-h EC50s showed T. chuii as the most tolerant and R. salina as one of the most sensitive (Debelius et al., 2009). Antioxidant enzymes, such as SODs, CAT, POD, and MDA participate in antioxidant protection processes. (Alvarez et al., 2012). Trinchella et al. (2013) investigated Cd, Pb, and metallothionein (MT) contents in cultivated mussels (Mytilus galloprovincialis) in the Gulf of Naples, Southern Italy to evaluate MT content as a powerful index of the HM exposure of examined tissues.

Bioremediation is an effective and low-cost interesting technology for HM (Chehregani et al., 2009). Biosorption onto living or non-living biomass, such as fungi, bacteria, yeast, moss, aquatic plants, and algae (Tien, 2002, Akar and Tunali, 2006, Sari and Tuzen, 2008, Wang and Chen, 2009), can be a feasible method for Pb(II) removal. Juknys et al. (2012) examined the effects of HM on the oxidative stress and growth of spring barley. Major green algae can be particularly useful (Hamdy, 2000, Pavasant et al., 2006) because they are fairly abundant in many regions of the world, as well as efficiently minimize secondary wastes and can be utilized as low-cost materials (Bulgariu and Bulgariu, 2012, Montazer-Rahmati et al., 2011). Bulgariu and Bulgariu (2013) reported the sorption of Pb(II) onto a mixture of algae waste biomass and anion exchanger resin in a packed-bed column. Sarada et al. (2014) analyzed the biosorption trend of biosorbent Caulerpa fastigiata (macroalgae) biomass to remove toxic HM ion Pb (II) from a solution; the resulting sorption data were consistent with various isotherm models, such as the Freundlich model.The metal-binding capacity of these algae can be attributed to the presence of polysaccharides, proteins, and lipids on the cell wall surface (Uncun et al., 2003). Cladophora is one of the most important components of freshwater biota and serves an important function in aquatic ecosystems. With the use of Cladophora as the biosorbent material, and aims to determine the basis for the physiological response to Pb exposure, but there are few study about these.

This study focuses on bioaccumulation and the tolerance, and antioxidative defense system of Cladophora under Pb2+ stress. The first is to assess the toxicity of lead, and use a certain antioxidant enzymes, MT of Cladophora as biomarkers for detecting toxic lead in water. The second objective is to research the potential bioaccumulation and the tolerance of Cladophora to Pb(II). The advantages of using naturally growing aquatic algae for metal removal and biological monitoring that is an effective and low-cost interesting technology.

Section snippets

Algae cultivation and preparation

The Cladophora was collected from rivers in Hefei in Anhui Province, China. The rivers where the species were isolated are not contaminated by metals. After isolation and purification, the plants were enlarged cultivated in a sterilized natural water, then selected Cladophora plants with superior uniform traits for the experiments. The samples were grown in a sterilized medium at 25 °C and kept under an illumination intensity ranging from 3000 lx to 4000 lx (with a light:dark photoperiod of 12:12 

Effects of Pb2+ on Cladophora growth

Fig. 1a shows the RGR of Cladophora after treatment with various concentrations of Pb2+. The chlorophyll a in Cladophora is shown in Fig. 1b.

Fig. 1a shows that Pb2+ greatly influences Cladophora growth. When Pb2+ concentration is below 1.0 mg/L, the RGR of Cladophora is higher than the control (7.88% versus 9.48%, respectively). The results clearly show that low concentrations (<1.0 mg/L) of Pb2+ accelerate Cladophora growth. At concentrations below ≤7.5 mg/L, Pb2+ has no significant inhibitory

Conclusion

Low Pb2+ concentrations accelerated the growth of Cladophora, whereas Pb2+ concentrations increases to 10.0 mg/L inhibited its growth. The photosynthesis of Cladophora decreased under Pb2+ stress.

Pb2+ treatment affected the content of total soluble sugar in Cladophora, but not its protein content. The experimental results also showed that Cladophora can accumulate Pb. The results of the correlation analyzes demonstrated that the Pb content in Cladophora was significantly correlated with POD,

Acknowledgements

This research is completed, under the financial aid of the National Science-Technology Support Plan Projects (2012BAD14B00). Funding for this study was provided by Nature Fund of Anhui Province of China (070411025) also.

References (49)

  • FatimaR.A. et al.

    Certain antioxidant enzymes of Allium cepa as biomarkers for the detection of toxic heavy metals in wastewater

    Sci. Total Environ.

    (2005)
  • FridovichI.

    Superoxide anion radical, superoxide dismutase and related matters

    J. Biol. Chem.

    (1997)
  • KlaassenC.D. et al.

    Metallothionein protection of cadmium toxicity

    Toxicol. Appl. Pharmacol.

    (2009)
  • MaityS. et al.

    Metallothionein responses in the earthworm Lampito mauritii (Kinberg) following lead and zinc exposure: a promising tool for monitoring metal contamination

    Eur. J. Soil Biol.

    (2011)
  • Montazer-RahmatiM.M. et al.

    Kinetics and equilibrium studies on biosorption of cadmium, lead, and nickel ions from aqueous solutions by intact and chemically modified brown algae

    J. Hazard. Mater.

    (2011)
  • PavasantP. et al.

    Biosorption of Cu2+, Cd2+, Pb2+ and Zn2+ using dried marine green macroalga Caulerpa lentillifera

    Bioresour. Technol

    (2006)
  • Pawlik-Skowron′skaB.

    Correlations between toxic Pb effects and production of Pb-induced thiol peptides in the microalga Stichococcus bacillaris

    Environ. Pollut.

    (2002)
  • SariA. et al.

    Biosorption of Pb(II) and Cd(II) from aqueous solution using green alga (Ulva lactuca)

    J. Hazard. Mater.

    (2008)
  • SimonielloP. et al.

    Responses to cadmium intoxication in the liver of the wall lizard Podarcis sicula

    Comp. Biochem. Physiol. Part C: Pharmacol. Toxicol.

    (2010)
  • TienC.T.

    Biosorption of metal ions by fresh water algae with different surface characteristics

    Process Biochem.

    (2002)
  • WangJ. et al.

    Biosorbents for heavy metals removal and their future

    Biotechnol. Adv.

    (2009)
  • AlmelC. et al.

    Heavy metal, total arsenic, and inorganic arsenic contents of algae food products

    J. Agric. Food Chem.

    (2002)
  • ArnonD.I.

    Copper enzymes in isolated chloroplasts polyphenoloxidase in Beta vulgaris

    J. Plant Physiol.

    (1949)
  • BenavidesM.P. et al.

    Cadmium toxicity in plants

    Braz. J. Plant Physiol.

    (2005)
  • Cited by (88)

    View all citing articles on Scopus
    View full text