Responses of the marine bacterium Pseudomonas fluorescens to an excess of heavy metals: Physiological and biochemical aspects

Abstract

A Pseudomonas fluorescens strain was isolated from oxic marine sediments obtained from the strand zone of the St Anne Bay (a moderately metal-contaminated site to the west of Cherbourg harbour). The strain, which exhibited a high tolerance to metal contamination when cultivated (minimal inhibitory concentration=950 microM [62 mg L(-1)] for Zn, 660 microM [42 mg L(-1)] for Cu, and 505 microM [57 mg L(-1)] for Cd), was further characterized by its physiological and biochemical responses to metal additions to the culture medium. Bacterial growth was significantly disturbed by 380 microM Zn (25 mg L(-1)), 315 microM Cu (20 mg L(-1)) and 90 microM Cd (10 mg L(-1)). The Zn-containing alkaline phosphatase was studied as an intoxication biomarker. Its activity was stimulated (+9%) by an excess of Zn, but inhibited by Cd (-55%) and Cu (-10%), these two elements could displace the native Zn or/and disturb the enzyme 3D-structure. Bacterial O(2) consumption was recorded as a global physiological response to metal stress. This parameter dropped with increasing Cd and Cu contamination (-49% and -45%, respectively, at 20 mg L(-1)). By contrast, Zn increased O2 consumption (approximately +40% for the different tested concentrations). The proteomes of bacteria grown in the presence or absence of 20 mg metal L(-1) were characterized by 2D-gel electrophoresis. The number of spots exhibiting a difference in intensity between the contaminated sample and the control was 65, 68, and 103, for Zn, Cu and Cd, respectively. Among them, 45, 61 and 82 spots respectively appeared de novo or increased in intensity, indicative of metal-stimulated synthesis, particularly for Cu and Cd. In summary, whereas Cd and Cu treatments both stressed cells and slowed down primary metabolism to differing extents, Zn has a stimulating action on several physiological and biochemical parameters.

Protein expression from zooplankton communities in a metal contaminated NW mediterranean coastal ecosystem

“…This field presents two coexisting approaches: the first involves analysing proteins from microorganisms cultured under specific environmental conditions, the second involves the recovery and analysis of proteins directly sampled from the marine environment (Nunn and Timperman, 2007). According to the first approach, some studies have been carried out on pure cultures of marine microorganisms such as the bacterium Pseudomonas fluorescens (Poirier et al, 2008), the cyanobacterium Prochlorococcus marinus (Pandhal et al, 2007), the phytoplankton Alexandrium (Chan et al, 2005(Chan et al, , 2006Lee and Lo, 2008;Wang et al, 2008), Prorocentrum (Chan et al, 2002(Chan et al, , 2004, Lingulodinium polyedrum (Akimoto et al, 2004), and the zooplankton Calanus finmarchicus (Hansen et al, 2007). According to the second approach, proteomic studies have taken place in marine environments to sample targeted organisms, such as the zooplankton species Acartia tonsa (Tartarotti and Torres, 2009) and Eurytemora affinis (Kimmel and Bradley, 2001), as the fish Paralichthys olivaceus (Ling et al, 2009;Zhu et al, 2006) or the bivalve Mytilus (Manduzio et al, 2005;Mosquera et al, 2003;Ronzitti et al, 2008).…”

Copper and cadmium: responses inPseudomonas putidaKT2440

“…We used a proteomics approach to identify the proteins responding to Cd and Cu in KT2440 because this technique was successful in studies of Cd interacting with Escherichia coli (Ferianc et al 1998) and Pseudomonas fluorescens (Poirier et al 2008). However, proteomics is in part limited by protein extractability and abundance as well as overlap of proteins on the electrophoresis gels.…”

Study of the Toxic effect of new Cadmium ( II) complex [ CdL2]. 1/2H2O on GPT and ALP activity in some organs of female mice comparable with anitumor drug Cyclophosphamide (CP)

“…(1) No mortality was observed during the three days treatment period in the mice treated to three concentrations of cadmium complex (II). There is a clear association between the mice treatment with cadmium ( II) complex and the significant depletion of GPT activity at most doses in different tissues compared to cyclophosphamide could be attributed to the increased the permeability of the cell as well as the direct effect of the heavy metal on tissues [10]. Rikabi and Jawad [14] showed the damging effect of cadmium in the liver manifestested by an increase of AST,ALT and ALP, which specific marker of the liver cell damge .…”

“…Transition metal complexes with dithiocarbamates as a ligands have been extensively investigated and were of interest in many fields ;as flotation agents and as antifungal agents [9]. Enzymes are biochemical macromolecules that catalyst accelerate metabolic processes of organoisms , thus a slight variation in enzyme activity would affect the organism [10]. Poirier et al ,[11] , studied the effect cadmium(II) in marine bacterium Pseudomonas ----phenyl-1 ,2,4-traizole -3dithiocarbamato hydrazide ] cadmium ( II) hydra ( 0.5 ) ] on the activity levels of ( GPT and ALP in the liver , kidney and lung tissues of female albino mice were assessed on three doses after three days of the treatment comparable with anticancer drug cyclophosphamide.…”