Biofilm, as a form of the microbial community in nature, represents an evolutionary adaptation to the influence of various environmental conditions. In nature, the largest number of microorganisms ...occur in the form of multispecies biofilms. The ability of microorganisms to form a biofilm is one of the reasons for antibiotic resistance. The creation of biofilms resistant to various contaminants, on the other hand, improves the biological treatment process in wastewater treatment plants. Heavy metals cannot be degraded, but they can be transformed into non-reactive and less toxic forms. In this process, microorganisms are irreplaceable as they interact with the metals in a variety of ways. The environment polluted by heavy metals, such as wastewater, is also a source of undiscovered microbial diversity and specific microbial strains. Numerous studies show that biofilm is an irreplaceable strategy for heavy metal removal. In this review, we systematize recent findings regarding the bioremediation potential of biofilm-forming microbial species isolated from diverse wastewaters for heavy metal removal. In addition, we include some mechanisms of action, application possibilities, practical issues, and future prospects.
Wastewater often contains an increased amount of mercury and, at the same time, resistant microorganisms. During wastewater treatment, a biofilm of indigenous microorganisms is often unavoidable. ...Therefore, the objective of this research is to isolate and identify microorganisms from wastewater and investigate their ability to form biofilms for possible application in mercury removal processes.
The resistance of planktonic cells and their biofilms to the effects of mercury was investigated using Minimum Biofilm Eradication Concentration-High Throughput Plates. The formation of biofilms and the degree of resistance to mercury were confirmed in polystyrene microtiter plates with 96 wells. Biofilm on AMB Media carriers (Assisting Moving Bad Media) was quantified using the Bradford protein assay. The removal of mercury ions by biofilms formed on AMB Media carriers of selected isolates and their consortia was determined by a removal test in Erlenmeyer flasks simulating MBBR.
All isolates in planktonic form showed some degree of resistance to mercury. The most resistant microorganisms (Enterobacter cloacae, Klebsiella oxytoca, Serratia odorifera, and Saccharomyces cerevisiae) were tested for their ability to form biofilms in the presence and absence of mercury, both in polystyrene plates and on ABM carriers. The results showed that among planktonic forms, K. oxytoca was the most resistant. A biofilm of the same microorganisms was more than 10-fold resistant. Most consortia biofilms had MBEC values > 100,000 μg/mL. Among individual biofilms, E. cloacae showed the highest mercury removal efficiency (97.81% for 10 days). Biofilm consortia composed of three species showed the best ability to remove mercury (96.64%–99.03% for 10 days).
This study points to the importance of consortia of different types of wastewater microorganisms in the form of biofilms and suggests that they can be used to remove mercury in wastewater treatment bioreactors.
The presence of heavy metals (HMs) in the environment represents a serious environmental problem. In this regard, this work was conceived with the aim of finding, among indigenous microorganisms, the ...species and their combinations with the best biosorption activity for the following HMs: zinc, lead, cadmium, copper, and nickel. The experiment was carried out in several steps: (1) isolation and identification of microbial strains from the Central Effluent Treatment Plant’s wastewater; (2) studying the interaction of microorganisms and the ability to form biofilms in 96-well plates; (3) testing the resistance of biofilms to HMs; (4) testing the growth of biofilms on AMB media carriers in the presence of HMS; and (5) biosorption assay. The selected strains used in this study were:
Enterobacter cloacae, Klebsiella oxytoca, Serratia odorifera
, and
Saccharomyces cerevisiae
. The best biofilm producers in control medium were
K. oxytoca
/
S. odorifera
(KS), followed by
K. oxytoca
/
S. odorifera/S. cerevisiae
(KSC), and
E. cloacae/K. oxytoca
/
S. odorifera
(EKS) after 10 days of incubation. Mixed cultures composed of three species showed the highest resistance to the presence of all tested metals. The best biosorption capacity was shown by KSC for Cu
2+
(99.18%), followed by EKS for Pb
2+
(99.14%) and Cd
2+
(99.03%),
K. oxytoca
for Ni
2+
(98.47%), and
E. cloacae
for Zn
2+
(98.06%). This research offers a novel approach to using mixed biofilms for heavy metal removal processes as well as its potential application in the bioremediation of wastewater.
In this research paper, the total phenols (TP), flavonoids (TF), and tannins (TT) content in the acetone and ethyl acetate extracts of Najas marina L. and the identification and quantification of ...phenolic acids and flavonoids from the ethyl acetate extract were performed. Antioxidant, antimicrobial, and antibiofilm properties of the mentioned extracts were investigated in vitro. The genotoxic potential was analyzed in cultured human peripheral blood lymphocytes (PBL). The TP and TF content was higher in the ethyl acetate extract, dominated by quercetin (172.4 µg mg-1) and ferulic acid (22.74 µg mg-1), while the TT content was slightly higher in the acetone extract. Both extracts tested showed limited antioxidant effects compared to ascorbic acid. The strongest antibacterial activity was observed with Gram-positive bacteria, particularly Staphylococcus aureus (MIC and MMC at 0.31 mg ml-1) and S. aureus ATCC 25923 (MIC at <0.02 mg ml-1), while antifungal activity was limited. Both extracts tested showed better activity on preformed biofilms. Acetone extract had no genotoxic activity but showed significant genoprotective activity against mitomycin C-induced DNA damage in cultured PBLs. Results of our research demonstrate the potential for the development of plant-based antibacterial and biofilm agents.
A series of new 3d metal complexes with 5-chloro-quinolin-8-ol (ClQ), Mn(ClQ)2 (1), Fe(ClQ)3 (2), Co(ClQ)2(H2O)2 (3), Ni(ClQ)2(H2O)2 (4), Cu(ClQ)2 (5), Zn(ClQ)2(H2O)2 (6), Mn(ClQ)3·DMF (7) and ...Co(ClQ)3·DMF·(EtOH)0.35 (8) (DMF=N,N-dimethylformamide), has been synthesized and characterized by elemental analysis, IR spectroscopy and TG–DTA thermal analysis. X-ray structure analysis of 7 and 8 revealed that these molecular complexes contain three chelate ClQ molecules coordinated to the central atoms in a deformed octahedral geometry and free space between the complex units is filled by solvated DMF and ethanol molecules. Antimicrobial activity of 1–6 was tested by determining the minimum inhibitory concentration and minimum microbicidal concentration against 12 strains of bacteria and 5 strains of fungi. The intensity of antimicrobial action varies depending on the group of microorganism and can be sorted: 1>ClQ>6>3/4>2>5. Complexes 1–6 exhibit high cytotoxic activity against MDA-MB, HCT-116 and A549 cancer cell lines. Among them, complex 2 is significantly more cytotoxic against MDA-MB cells than cisplatin at all tested concentrations and is not cytotoxic against control mesenchymal stem cells indicating that this complex seems to be a good candidate for future pharmacological evaluation. Interaction of 1–6 with DNA was investigated using UV–VIS spectroscopy, fluorescence spectroscopy and agarose gel electrophoresis. The binding studies indicate that 1–6 can interact with CT-DNA through intercalation; complex 2 has the highest binding affinity. Moreover, complexes 1–6 inhibit the catalytic activity of topoisomerase I.
M(ClQ)2 (M=Mn (1), Cu (5)), Fe(ClQ)3 (2), M(ClQ)2(H2O)2 (M=Co (3), Ni (4), Zn (6)), Mn(ClQ)3·DMF (7) and Co(ClQ)3·DMF·(EtOH)0.35 (8) (ClQ=5-chloro-quinolin-8-ol) were characterized by IR/UV–VIS spectroscopy, thermal analysis, crystallography (7, 8) and biological testing (1–6, ClQ) (antimicrobial activity, cytotoxicity, DNA binding, topoisomerase I inhibition). Display omitted
•Eight 3d complexes with 5-chloro-quinolin-8-ol (ClQ) are characterized.•Complexes interact with DNA by intercalative binding mode.•Complexes target topoisomerase I as mildly effective topoisomerase inhibitors.•Fe(ClQ)3 complex is highly active against human breast MDA-MB cancer cell line.•Fe(ClQ)3 complex is not cytotoxic against control mesenchymal stem cells.
Five new complexes of the palladium(II) ion (C1-C5) having the general formula (PdL
)Cl
with some 2-aminothiazoles (L1-L5), where L1 = 2-amino-4-(3,4-difluorophenyl)thiazole, L2 = ...2-amino-5-methyl-4-phenylthiazole, L3 = 2-amino-4-phenylthiazole, L4 = 2-amino-4-(4-chlorophenyl)thiazole, and L5 = 2-amino-4-(2,4-difluorophenyl)thiazole, have been synthesized and characterized by elemental microanalysis and infrared,
H NMR and
C NMR spectroscopy. The
antimicrobial activity of the five ligands and the corresponding Pd(II) complexes is investigated. Testing is performed by the microdilution method and the minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC) have been determined. Testing is conducted against 11 microorganisms (nine strains of pathogenic bacteria and two yeast species). The tested ligands and palladium(II) complexes show selective, high and moderate activity. There is a difference in antimicrobial activity between the ligands and the corresponding palladium(II) complexes. The complexes have significant anti-staphylococcal activity and activity on
which is better than the positive control. The interactions of newly synthesized palladium(II) complexes with calf thymus DNA (CT-DNA) were investigated using UV-Vis absorption and fluorescence spectroscopy. Analysis of UV-absorption and fluorescence spectra indicates the formation of a complex between the palladium(II) complexes and DNA. The high values of intrinsic binding constants,
, of the order 10
M
and Stern-Volmer quenching constants,
, of the order 10
M
indicated very good binding of all complexes to CT-DNA. Also, the new Pd(II) complexes show high cytotoxic activity towards the human prostate cancer cell line and insignificant activity towards non-cancerous human fibroblasts. Future research could additionally explore the biological activity of Pd(II) complexes presented in this paper and investigate the possibility of their implementation in clinical practice.
In this study, four hybrid organic-inorganic compounds (8-H2Q)2PdCl4 (1), (H2ClQ)2PdCl4 (2), (H2NQ)2PdCl4 (3) and (H2MeQ)2PdCl4·2H2O (4) (where 8-H2Q = 8-hydroxyquinolinium, ...H2ClQ = 5-chloro-8-hydroxyquinolinium, H2NQ = 5-nitro-8-hydroxyquinolinium and H2MeQ = 2-methyl-8-hydroxyquinolinium) were synthesized through organic cation modulation. Single-crystal X-ray structure analysis of compounds 1 and 3 indicates that their structures are planar and consist of PdCl42− anions and 8-H2Q or H2NQ cations, respectively. Both ionic components are held together through ionic interactions and hydrogen bonds forming infinite chains linked through π-π interactions to form 2D structures. Furthermore, NMR spectroscopy, UV–Vis spectroscopy, elemental analysis, and FT-IR spectroscopy were used to explore the synthesized compounds. The DNA interaction, antimicrobial activity, antiproliferative activity, and radical scavenging effect of the compounds were evaluated. The hybrid compounds and their free ligands can interact with the calf thymus DNA via an intercalation mode involving the insertion of the aromatic chromophore between the base pairs of DNA; compound 1 has the highest binding affinity. Moreover, they have high antimicrobial efficacy against the tested 14 strains of microorganisms with minimum inhibitory concentration values ranging from <1.95 to 250 μg/mL. The antiproliferative activity of the compounds was investigated against three different cancer cell lines, and their selectivity was verified on mesenchymal stem cells. Compounds 1 and 2 displayed selective and high cytotoxicity against human lung and breast cancer cells and showed moderate cytotoxicity against colon cancer cells. Accordingly, they might be auspicious candidates for future pharmacological investigations in lung and breast cancer research.
Four (H2XQ)2PdCl4 complexes (H2XQ = 8-hydroxyquinolinium cation and its derivatives) were synthesized and characterized by structure analysis, IR, UV-VIS, NMR and elemental analyses, and their interaction to DNA, antitumor, antimicrobial and antiradical activities were evaluated. Display omitted
•Four hybrid organic-inorganic complexes were synthesized and characterized.•They are selectively cytotoxic against A549, HCT116 and MDA-MB-231 cells.•Complexes exhibit high antimicrobial efficacy.•The radical scavenging experiments reveal relatively low antioxidant properties.•The complexes interact with DNA via an intercalation mode.
The present work was undertaken to determine the total phenol, flavonoid and tannin content in five extracts of Origanum vulgare growing wild in southwest Serbia as well as to evaluate antioxidant ...and antimicrobial activity towards 29 strains of human pathogenic and food spoilage bacteria and fungi. In order to define a chemotype of this O. vulgare, chemical composition of essential oil was determined. The major compounds were: sabinene, terpinen-4-ol, 1.8 cineole, γ-terpinene and caryophyllene oxide. The concentrations of total phenols were examined using Folin–Ciocalteu reagent and the obtained values ranged from 84.5 to 235 mg GA/g. By using aluminium chloride method, the concentrations of flavonoids were obtained and the values ranged from 57.1 to 132 mg RU/g. In determining the amount of tannins, the method with butanol–HCl reagent was used and the obtained values were between 1.25 and 4.02 mg CCh/g. Antioxidant activity was evaluated by measuring the scavenging capacity of extracts on DPPH. Tested extracts expressed strong scavenger activity with IC50 values between 34.5 and 86 μg/ml. The ethanol extract was the most active. The strongest antibacterial activity, determined by microdilution method, was detected on G+ bacteria such as Bacillus species and Staphylococcus aureus, obtaining minimal inhibitory concentration (MIC) 0.16 mg/ml while antifungal activity was moderate with MICs between 2.5 and 20 mg/mL.
•We determined chemical composition of essential oils.•We examined five different extracts of aerial parts from oregano.•All extracts showed significant antimicrobial effect.•Good antioxidative activity.
This study compares the effect of heavy metals (Hg
2+
, Cu
2+
, and Pb
2+
) on the
Rhodotorula mucilaginosa
and
Saccharomyces boulardii
biofilm and planktonic cells. A MBEC
TM
-HTP assay was used to ...test the levels of tolerance to heavy metals. The minimum inhibitory concentration (MICp) and minimum lethal concentration (MLCp) of the
R. mucilaginosa
and
S. boulardii
planktonic cells were determined, as well as minimum biofilm eradication concentration (MBEC). Metal removal efficiency was determined by batch biosorption assay. Previous studies had focused on heavy metal tolerance and removal efficiency of planktonic cells from
Rhodotorula
species only. Hence, our study presents and compares results for metal tolerance and removal efficiency of the
R. mucilaginosa
planktonic cells and biofilm. Biofilm tolerance was higher than the planktonic cells. The
R. mucilaginosa
planktonic cells showed the tolerance in the presence of Hg
2+
(MICp 0.08 mM), Cu
2+
(MICp 6.40 mM), and Pb
2+
(MICp 3.51 mM), while the
S. boulardii
planktonic cells only tolerated Pb
2+
(MICp 0.43 mM). The
R. mucilaginosa
biofilm showed the highest tolerance in the presence of Hg
2+
(MBEC >0.31 mM), Cu
2+
(MBEC >12.81 mM), Pb
2+
(MBEC >7.12 mM), and obtained results were confirmed by fluorescence microscopy.
S. boulardii
did not show potential in biofilm formation. The
R. mucilaginosa
biofilm exhibited better efficiency in removal of all tested metals than the planktonic cells. Metal removal efficiency was in the range from 4.79–10.25% for planktonic cells and 91.71–95.39% for biofilm.
The objective of this study is to develop a feedforward neural network (FNN) model to predict the dissolved oxygen in the Gruža Reservoir, Serbia. The neural network model was developed using ...experimental data which are collected during a three years. The input variables of the neural network are: water pH, water temperature, chloride, total phosphate, nitrites, nitrates, ammonia, iron, manganese and electrical conductivity. Sensitivity analysis is used to determine the influence of input variables on the dependent variable. The most effective inputs are determined as pH and temperature, while nitrates, chloride and total phosphate are found to be least effective parameters. The Levenberg–Marquardt algorithm is used to train the FNN. The optimal FNN architecture was determined. The FNN architecture having 15 hidden neurons gives the best choice. Results of FNN models have been compared with the measured data on the basis of correlation coefficient (
r), mean absolute error (MAE) and mean square error (MSE). Comparing the modelled values by FNN with the experimental data indicates that neural network model provides accurate results.
