Characterization of Heavy-Metal-Removal Bacteria From The Persian Gulf

The study was carried out to isolate and screen high heavy metals resistant bacteria from Persian Gulf and enclosed industrial areas within 241,000 km2. A total of 35 heavy metal resistant bacteria strains were identified from sediment and water samples collected. The resistance and biological capacity of the isolated bacteria were tested in a new formulated media, minimal salt solution (M.S.S), that mimics seawater. Isolated bacteria responded to media supplemented in range 0.5 to 2 mM of Zn, Cd, Cu and Pb by showing a prolonged lag phase and by decreasing growth rate. Bacteria isolates, in the form of free or immobilized cells, are able to remove lead, copper, zinc and cadmium from solution. Removal of lead and cadmium from solution by some bacteria was very efficient, about 120 mglg dry weight as high as 90%. Isolates tested presented distinct uptake capacities and the best results were obtained for Delftia tsuruhatensis and Pseudornonas AU3411 respectively.The diversity of isolated bacteria was examined by the phylogenetic analysis of 16s rRNA gene sequences. The phylogenetic analyses of the sequences revealed seven main taxonomic lineages. The phylogenetic tree illustrated discrimination between isolated bacteria from wastewater, industrials areas and marine environment. Some Pseudornonas strains isolated from marine environment were well differentiated from those of industrial wastewater. Members of the genera Delftia and Bacterium formed a monophyletic group within the subdivision of the class. There was a clear differentiation between two groups of Pseudornonas and other groups of bacteria in the phylogenetic tree. The isolated bacteria were tested for the occurrence of plasmid using the modified alkaline lysate method. The study revealed that the frequency of the occurrence of plasmid in the heavy metals resistance bacteria was more than in the common bacteria. Multiple forms of plasmids were observed in 66% of the plasmidcarrying strains. Isolates bacteria from industrials wastewater showed the highest plasmid incidence (84.6%). In the marine environment there was a slightly higher incidence of plasmid in bacteria isolated from sediments (55.5%) compared to the water sample of the same origin (53.8%). Scanning Electron Microscope (SEM) analyses showed Pseudornonas sp. accumulated heavy metals in the cell wall and along the external cell surfaces. This suggested that heavy metals uptake involves both surface phenomena and diffusion. Energy Dispersive X-ray (EDX) analysis confirmed heavy metals on the bacteria cell surface which was reported by SEM

Detection of plasmids in heavy metal resistance bacteria isolated from the Persian Gulf and enclosed industrial areas

Several heavy metal resistant bacterial strains were isolated from sediment and water samples collected from the Persian Gulf and enclosed industrial areas. All the isolated bacteria were identified by 16S rRNA gene sequencing. Isolated bacteria were tested for the presence of plasmids using the modified alkaline lysate method. The method was effective for identification and characterization of plasmids of different sizes without the use of highly toxic chemicals. The study revealed that the frequency of the occurrence of plasmids in heavy metal resistant bacteria was more than that in the common bacteria. The study also demonstrated that about 66% of isolated bacteria carried large (38-62kb) and/or small sized (4- >2 kb) plasmids. The highest plasmid incidence (84.6%) was detected from industrial wastewater bacteria. A slightly higher incidence of plasmids occurred in bacteria isolated from marine sediments (55.5%) compared to that of the marine water (53.8%). The findings suggested that plasmids are highly ubiquitous and predominant in most heavy metal resistant bacteria. Removal of lead and cadmium from solution by some of these bacteria was very efficient, approximately 120 mg/g dry weightas high as 90%. The isolates tested, presented distinct uptake capacities and the best results were obtained for Delftia tsuruhatensis and Pseudomonas AU3411 respectively

Screening and identification of efficient strain in selenium oxyanions sorption in order to biological wastewater treatment

Introduction: Selenium is an element with antioxidant activities that plays roles in thyroid hormone homeostasis, immunity and also fertility. Nevertheless, selenium toxicity (selenosis) causes problems for humans such as abnormalities of the nervous system, gastrointestinal problems and hair loss. Thus, this study was performed with the aim of bacterial biosorbent isolation in order to remove selenium contaminant from wastewater. Materials and methods: In this research, at first using modified Luria- Bertani agar (mLBA) medium with certain concentration of sodium selenate salt, isolation of bacterial isolates was done from three collected wastewater and sludge samples from Khouzestan industrial factories. After determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), the sorption capacity and the percentage of metal removal efficiency (%RE) were investigated by atomic absorption spectrophotometer using metabolically active and inactive samples belonging to an efficient isolate. Identification was performed by morphological, biochemical and molecular methods. Results: Among 73 attained bacterial isolates at the first stage, 8 selenate oxyanion resistant isolates were gathered. Among these, AMS1-S8 isolate with MIC= 600­mM and MBC= 1200­mM were selected for more studies. Attained results in sorption mechanism determination stage showed that the sorption capacity in metabolically active sample is more than the inactive samples. Based on the identification results, it is revealed that this isolate belongs to the Enterobacter genus. This isolate is deposited as accession JQ965667 in the GeneBank database. Discussion and conclusion: The results showed that active biomass of selected isolate, have most sorption capacity and %RE and among the other isolates, have high partial resistance against selenate. Therefore, it can be a relatively ideal option for the bioremediation of polluted environments

Morphological variability of Liza aurata (Risso, 1810), along the southern Caspian Sea

Morphological variability of Liza aurata (Risso, 1810), was studied in traditional morphometric measurements in 25 morphological characters from 90 specimens in three fishery areas in the southern Caspian Sea (Guilan, Mazandaran and Golestan). Univariate analysis of variance showed significant differences between the means of the three groups for 22 out of 25 standardized morphometric measurements. In discriminant function analysis (DFA), the proportion of individuals correctly classified into their original groups was 100%. Principal component analysis results (PCA) for morphometric data indicated that samples of Guilan and Mazandaran showed high degree of overlap and these two regions were highly different from Golestan. The dendrogram derived from cluster analysis showed that the samples of L. aurata from Guilan and Mazandaran had same clade while both were obviously distinct from Golestan

Screening, isolation and study of antifungal activity of marine actinomycetes from Deylam nearshore sediments

Background: Marine actinomycetes, gram positive bacteria, have been prolific sources of novel secondary metabolites with a range of biological antibacterial activities. Marine sediments are potential sources for isolation of novel actinomycetes yielding new products and are recognized as source of novel antibiotic. In this study, we reported the isolation, characterization and antifungal activities of 8 actinomycetes isolated from Deylam nearshore sediments. Materials and Methods: The marine soil sediment samples were collected from Deylam nearshore at the depth of 10 cm. The treated samples were serially diluted and used starch casein agar as a culture medium. Morphological and biochemical characterization of isolated strain was carried out by using standard methods. Antifungal assay of the bacterial extracts was performed using standard well diffusion assay. Results: In this study, 8 marine actinomycetes were isolated from Deylam near shore sediments according to their morphology. All of isolate was belonged to Streptomyces genus. Differential analyses results for catalase and Gram test were positive for all isolates, the positive isolates for TSI, simmon citrate and ornitin decarboxylase were 1, 2 and 5 respectively, all isolates were negative for lysine decarboxylase, VP, MR and indol test, SIM test results showed that all isolates were non-motile, one isolate was produced H2S and some isolates formed pigmented colony. Most isolates showed antifungal activity against tested pathogenic fungi. Conclusion: Results of this investigation revealed that the marine actinomycetes of Deylam nearshore sediments were potent source of bioactive compounds with antifungal activity

CYP1A gene expression as a basic factor for fipronil toxicity in Caspian kutum fish

The aim of this study was to assess the effects of fipronil insecticide on the Caspian kutum fish at different levels of biological organizations and to find possible relationship between these biomarkers. Different doses of fipronil (65, 130 and 200 mg/kg) were intraperitoneally administered to the fish for 2 weeks. After 7 and 14 days of exposure, alterations in organ-somatic index, tissue and DNA structure, oxidative stress and CYP1A gene expression in gill, liver, brain and kidney were studied. Determination of these parameters in the liver showed that the degree of tissue change (DTC), comet tail, superoxide dismutase (SOD) and relative CYP1A mRNA expression increased mostly in a time dependent manner whereas in the kidney increased mostly in a dose dependent manner. These parameters in the gill increased more in time and dose dependent manner. Apart from the changes in CYP1A expression and oxidative stress, no alterations was observed in the brain. Multiple regression analysis showed that the CYP1A had the most correlation with the organ-somatic index (R2 = 0.76) and comet tail (R2 = 0.89) in the liver, and with DTC (R2 = 0.93) and oxidative stress (R2 = 0.87) in the kidney. Generally, this study showed that CYP1A gene expression can be considered as one basic factor for fipronil toxicity in this fish. However, other possible factors also should be considered for future research. Keywords: CYP1A gene, Oxidative stress, Comet assay, Fiproni

Comparison of waterborne and intraperitoneal exposure to fipronil in the Caspian white fish (Rutilus frisii) on acute toxicity and histopathology

Fipronil is an effective insecticide widely used in agriculture with potential ecotoxicological consequences. The median lethal dose (LD50) and concentration (LC50) of fipronil in 16.3 g Caspian white fish, Rutilus frisii kutum fingerlings were determined. To determine the LD50, a total of 133 fish were assigned to 19 tanks (7 fish/tank) including one control and 6 treatment groups (300, 450, 550, 650, 750, 850 mg/kg). Fish were injected intraperitoneally and monitored at 96 h. The LD50 of fipronil was 632 mg/kg suggesting it was slightly toxic to the Caspian white fish. To determine LC50, 114 fish were assigned to 19 tanks (6 fish/tank) including one control and 6 treatment groups (300, 400, 500, 600, 700, 800 μg/L). The LC50 of fipronil was 572 μg/L, which was highly toxic to the fish. The degree of tissue change (DTC) in vital organs from moribund fish exposed via waterborne exposure showed severe damage (DTC: 71 ± 52 for 700 μg/L) in the gill, including aneurisms, extensive fusion and necrosis. The fish exposed through the intraperitoneal route seemed to have severe lesions (DTC: 66 ± 50 for 750 mg/kg) in the kidney, involving hemorrhage, tubular degeneration and necrosis. The liver had no significant differences in DTC values between the two routes and showed pyknosis and sinusoid dilation. Hematoxylin and eosin staining did not show any histological alterations in the brain but nissl staining showed some alterations in distribution of purkinje cells. Generally, this study showed that the route of exposure to fipronil not only affects its acute toxicity but also determines the main target organs of toxicity and histopathological alterations in Caspian white fish. Keywords: Fipronil, Caspian white fish, Acute toxicity, Administration rout

Non-essential metals (Cd & Pb) accumulation and elimination in liver tissue of juvenile milkfish, after sublethal exposure

412-417Present study consists the bioaccumulation of cadmium and lead in young juvenile Milkfish liver (Chanos chanos). It is carried out after exposure to three sublethal concentration of each pollutants (on 1/20, 1/10 and 1/5 LC50 of 96-h LC50) for acute time 12, 24 and 96 hour and subchronic time 7, 14 and 21 days. Cadmium and lead accumulation in liver increased with exposure periods and concentration of pollutants. Compared with controls, the uptake of cadmium is much higher than that of lead. Accumulation factors showed an increase with the exposure period and an inverse relationship between the accumulation factor and exposure concentration for lead. Elimination of these two pollutants was investigated after 30 days depuration time. During the depuration phase, cadmium and lead concentration decreased