scholarly journals Bioremediation of Hexavalent Chromium by Chromium Resistant Bacteria Reduces Phytotoxicity

2020 ◽  
Vol 17 (17) ◽  
pp. 6013
Author(s):  
Shanewaz Hossan ◽  
Saddam Hossain ◽  
Mohammad Rafiqul Islam ◽  
Mir Himayet Kabir ◽  
Sobur Ali ◽  
...  
Keyword(s):  
Bacterial Biomass ◽  
Dry Weight ◽  
Sem Analysis ◽  
Luria Bertani ◽  
Isotherm Models ◽  
Resistant Bacteria ◽  
Infrared Analysis ◽  
Relative Reduction ◽  
Tannery Effluent ◽  
Luria Bertani Broth

Chromium (Cr) (VI) has long been known as an environmental hazard that can be reduced from aqueous solutions through bioremediation by living cells. In this study, we investigated the efficiency of reduction and biosorption of Cr(VI) by chromate resistant bacteria isolated from tannery effluent. From 28 screened Cr(VI) resistant isolates, selected bacterial strain SH-1 was identified as Klebsiella sp. via 16S rRNA sequencing. In Luria–Bertani broth, the relative reduction level of Cr(VI) was 95%, but in tannery effluent, it was 63.08% after 72 h of incubation. The cell-free extract of SH-1 showed a 72.2% reduction of Cr(VI), which indicated a higher activity of Cr(VI) reducing enzyme than the control. Live and dead biomass of SH-1 adsorbed 51.25 mg and 29.03 mg Cr(VI) per gram of dry weight, respectively. Two adsorption isotherm models—Langmuir and Freundlich—were used for the illustration of Cr(VI) biosorption using SH-1 live biomass. Scanning electron microscopy (SEM) analysis showed an increased cell size of the treated biomass when compared to the controlled biomass, which supports the adsorption of reduced Cr on the biomass cell surface. Fourier-transform infrared analysis indicated that Cr(VI) had an effect on bacterial biomass, including quantitative and structural modifications. Moreover, the chickpea seed germination study showed beneficial environmental effects that suggest possible application of the isolate for the bioremediation of toxic Cr(VI).

scholarly journals Biosorption and enzymatic reduction of hexavalent chromium by chromium resistant bacteria ameliorate phytotoxicity

2019 ◽  
Author(s):  
Shanewaz Hossan ◽  
Mohammad Rafiqul Islam ◽  
Mir Himayet Kabir ◽  
Sobur Ali ◽  
Md Shafiqul Islam ◽  
...  
Keyword(s):  
Hexavalent Chromium ◽  
Reduction Rate ◽  
Dry Weight ◽  
Luria Bertani ◽  
Resistant Bacteria ◽  
Relative Reduction ◽  
Toxic Heavy Metals ◽  
Tannery Effluents ◽  
Dead Biomass ◽  
Enzymatic Reduction

Abstract Background: Chromium (Cr) (VI) is one of the toxic heavy metals and environmental hazards. Alleviating the levels of contaminants in the environment is imperative, and studying the bioremediation of Cr via reduction or biosorption is an indispensable approach to this cause. In this study, we investigated the efficiency of reduction and biosorption of Cr(VI) by chromate resistant bacteria isolated from tannery wastewater. Results: From screening, 28 Cr resistant bacteria were selected, and only two isolates, SH-1 and SH-2, were found as potential candidates for the reduction of Cr(VI). Post 16s rRNA sequencing, SH-1 isolate was identified to be Klebsiella sp and SH-2 isolate as Lysinibacillus sp. SH-1 could tolerate up to 2000 mg/L of Cr(VI) whereas, SH-2 could tolerate up to 1500 mg/L of Cr(VI). In Luria-Bertani media containing 100 mg/L of Cr(VI), the relative reduction level was 95% (SH-1) and 88.77% (SH-2) but their reduction rate was 63.08% (SH-1) and 49.89% (SH-2) of Cr(VI), respectively in the tannery effluents after 72h period of incubation. In the presence of Cr(VI) at a concentration of 10 mg/L Cr(VI), the cell-free extracts of pre-grown SH-1 and SH-2 showed a reduction of 72.2% and 33%, respectively. This reduction indicates the production or the activity of Cr reducing enzyme being higher in these two isolates than that of control in the presence of Cr(VI). In biosorption study, live and dead biomass of SH-1 biosorbed 51.25 mg and 29.03 mg chromium per gram dry weight, respectively. However, 28.83 mg and 27.65 mg chromium per gram dry weight were biosorbed by live and dead biomass of SH-2, respectively. Both the Langmuir model -for monolayer adsorption- and Freundlich model -for adsorption characteristics for the heterogeneous surface- were suitable for describing biosorption of Cr(VI) by SH-1 live biomass. The chickpea seed germination study confirmed the beneficial environmental effect of Cr(VI) reduction by these two isolates. Conclusion: The bacterial isolates can be exploited for their potential for reduction and biosorption of toxic hexavalent chromium in biological treatment of hexavalent chromium-containing wastes.

scholarly journals β-Lactams and Florfenicol Antibiotics Remain Bioactive in Soils while Ciprofloxacin, Neomycin, and Tetracycline Are Neutralized

2011 ◽  
Vol 77 (20) ◽  
pp. 7255-7260 ◽  
Author(s):  
Murugan Subbiah ◽  
Shannon M. Mitchell ◽  
Jeffrey L. Ullman ◽  
Douglas R. Call
Keyword(s):  
High Performance ◽  
Selective Pressure ◽  
Luria Bertani ◽  
Resistant Bacteria ◽  
Antibiotic Resistant ◽  
Content Type ◽  
Adsorption Mechanisms ◽  
E Coli ◽  
Luria Bertani Broth ◽  
Contamination Levels

ABSTRACTIt is generally assumed that antibiotic residues in soils select for antibiotic-resistant bacteria. This assumption was tested by separately adding 10 different antibiotics (≥200 ppm) to three soil-water slurries (silt-loam, sand-loam, and sand; 20% soil [wt/vol]) and incubating mixtures for 24 h at room temperature. The antibiotic activity of the resultant supernatant was assessed by culturing a sensitiveEscherichia colistrain in the filter-sterilized supernatant augmented with Luria-Bertani broth. We found striking differences in the abilities of supernatants to suppress growth of the indicatorE. coli. Ampicillin, cephalothin, cefoxitin, ceftiofur, and florfenicol supernatants completely inhibited growth while bacterial growth was uninhibited in the presence of neomycin, tetracycline, and ciprofloxacin supernatants. High-performance liquid chromatography (HPLC) analysis demonstrated that cefoxitin and florfenicol were almost completely retained in the supernatants, whereas tetracycline and ciprofloxacin were mostly removed. Antibiotic dissipation in soil, presumably dominated by adsorption mechanisms, was sufficient to neutralize 200 ppm of tetracycline; this concentration is considerably higher than reported contamination levels. Soil pellets from the tetracycline slurries were resuspended in a minimal volume of medium to maximize the interaction between bacteria and soil particles, but sensitive bacteria were still unaffected by tetracycline (P= 0.6). Thus, residual antibiotics in soil do not necessarily exert a selective pressure, and the degree to which the pharmaceutical remains bioactive depends on the antibiotic. Efforts to control antibiotic contamination would be better directed toward compounds that retain biological activity in soils (e.g., cephalosporins and florfenicol) because these are the antibiotics that could exert a selective pressure in the environment.

scholarly journals Insight into the Metabolic Profiles of Pb(II) Removing Microorganisms

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 4008
Author(s):  
Carla Cilliers ◽  
Evans M. N. Chirwa ◽  
Hendrik G. Brink
Keyword(s):  
Liquid Chromatography ◽  
High Performance ◽  
Microbial Consortium ◽  
Luria Bertani ◽  
Nutrient Concentrations ◽  
Batch Experiments ◽  
Metabolic Study ◽  
Luria Bertani Broth ◽  
Tandem Mass Spectroscopy ◽  
Insight Into

The objective of the study was to gather insight into the metabolism of lead-removing microorganisms, coupled with Pb(II) removal, biomass viability and nitrate concentrations for Pb(II) bioremoval using an industrially obtained microbial consortium. The consortium used for study has proven to be highly effective at removing aqueous Pb(II) from solution. Anaerobic batch experiments were conducted with Luria-Bertani broth as rich growth medium over a period of 33 h, comparing a lower concentration of Pb(II) with a higher concentration at two different nutrient concentrations. Metabolite profiling and quantification were conducted with the aid of both liquid chromatography coupled with tandem mass spectroscopy (UPLC-HDMS) in a “non-targeted” fashion and high-performance liquid chromatography (HPLC) in a “targeted” fashion. Four main compounds were identified, and a metabolic study was conducted on each to establish their possible significance for Pb(II) bioremoval. The study investigates the first metabolic profile to date for Pb(II) bioremoval, which in turn can result in a clarified understanding for development on an industrial and microbial level.

The Effect of Modifier on Properties of Bamboo Powder/High-Density Polyethylene Composites

2019 ◽  
Vol 69 (4) ◽  
pp. 313-321
Author(s):  
Xiaoxia Hu ◽  
Zhenghao Chen ◽  
Yang Cao ◽  
Zhangjing Chen ◽  
Shuangbao Zhang ◽  
...  
Keyword(s):  
High Density Polyethylene ◽  
Dry Weight ◽  
Weight Percent ◽  
Sem Analysis ◽  
High Density ◽  
Hydroxyl Groups ◽  
Plastic Composites ◽  
Bamboo Powder ◽  
Plastic Matrix ◽  
Polyethylene Composites

Abstract The focus of this study was to observe the properties of bamboo plastic composites modified with a self-made modifier, 18 acyl-dopamine (0, 0.25, 0.50, 0.75, 1.00, and 1.25 weight percent [wt%] based on the dry weight of bamboo powder). The effects of the modifier were demonstrated by measures of mechanical properties, water absorption, thermal stability, and scanning electron microscopy (SEM). The results revealed that 18 acyl-dopamine could be used as an effective modifier of bamboo powder/high-density polyethylene composites. When the modifier was increased, the toughness of the composite deteriorated, and the strength and rigidity improved. This indicated that when the dosage became higher, the compatibilization became stronger, and the toughening effect became worse. Based on the experimental data, a small dosage modifier acted as a toughening agent; as the dosage increased to 1.0 wt%, the compatibility began to appear. The modifier reacted with the hydroxyl groups on the surface of the bamboo powder, which caused the bamboo powder to absorb less water, so the thickness expansion rate was lowest at 1.25 wt%. The pyrolysis peak of bamboo powder and plastic showed a tendency to be close to each other, indicating that the interface was improving. Based on the equation of Flynn-Wall-Ozawa, as the dosage of the modifier increased from 0.50 to 1.25 wt%, the apparent activation energy also increased. The SEM analysis showed the binding between bamboo powder and the plastic matrix was strongest when the modifier dosage was 1.25 wt%.

scholarly journals EVALUASI HEMATOTOKSIK SECARA IN VITRO NANOPARTIKEL ZnS HASIL REDUKSI BIOMATRIKS Eschericia coli

2020 ◽  
Vol 23 (3) ◽  
pp. 82-84
Author(s):  
Lisa Kurniati ◽  
Andi Arjuna ◽  
Sukamto S Mamada
Keyword(s):  
Escherichia Coli ◽  
Luria Bertani ◽  
Luria Bertani Broth

Nanopartikel ZnS merupakan material semi konduktor yang memiliki sifat unik dan manfaat yang besar dibidang kesehatan, terutama sebagai antibakteri dan biomarker kanker. Walaupun demikian, informasi mengenai toksisitas dari nanopartikel ZnS masih sangat terbatas. Oleh karena itu, pada penelitian ini telah dilakukan evaluasi hematotoksisitas secara in vitro nanopartikel ZnS hasil reduksi biomatriks Escherichia coli. Penyiapan nanopartikel ZnS diawali dengan pencampuran dispersi ZnSO4 konsentrasi 200 bpj ke dalam medium Luria Bertani Broth (LBB) yang ditumbuhi E.Coli  sebagai bioreduktor. Produk yang dihasilkan dikarakterisasi dengan uji photolimunisence (PL) dan spektrofotometri pada rentang panjang gelombang 250-700 nm. Hasilnya, nanopartikel ZnS berpendar biru dan diidentifikasi pada λmax 288 nm dengan absorbansi 0,905. Partikel yang dihasilkan kemudian didispersikan dengan variasi volume 30 µl, 40 µl, 50 µl pada larutan tyrod. Data persentase hemolisis secara berturut-turut adalah 32%, 39%, 22%, 0% (kontrol negatif) dan 100% (kontrol positif). Sehingga dapat disimpulkan bahwa nanopartikel ZnS hasil reduksi E.coli memberikan efek toksik terhadap sel darah merah

scholarly journals Antimicrobial and Antibiofilm Properties of Graphene Oxide on Enterococcus faecalis

Antibiotics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 692
Author(s):  
Cecilia Martini ◽  
Francesca Longo ◽  
Raffaella Castagnola ◽  
Luca Marigo ◽  
Nicola Maria Grande ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Enterococcus Faecalis ◽  
Antibacterial Properties ◽  
Luria Bertani ◽  
Bacterial Suspension ◽  
Adhesion Properties ◽  
High Antibacterial Activity ◽  
Luria Bertani Broth ◽  
Bacterial Film

The aim of this study was to evaluate the antibacterial properties of graphene oxide (GO) against Enterococcus faecalis in vitro conditions and when used to coat dentin surface to prevent E. faecalis adhesion. The ATCC strain of E. faecalis 29212 has been used to perform a viability test. The pellet was suspended in ultrapure water, NaCl, PBS buffer, CaCl2 and MgCl2, Luria−Bertani broth solutions. The viability was evaluated by the colony forming unit counting method. Atomic force microscopy images and the measure of surface zeta potential variation were analyzed. Dentin discs were covered with a film of GO (n = 15) or were not treated (n = 15). Bacterial suspension was added to each sample of dentine discs and microbial counts were calculated. Statistically significant differences between two groups were assessed by a two-tailed unpaired t-test. Bacteria cell morphology was investigated with scanning electron microscopy. The highest growth inhibition was obtained in ddH2O and CaCl2 solution while, in PBS and NaCl, GO had poor antibacterial efficacy with a growth enhancing effect in the latter. GO on dentin discs demonstrated high antibacterial activity. GO film has demonstrated acceptable adhesion properties to root dentin and a role in the inhibition of bacterial film proliferation and biofilm formation.

scholarly journals Effects of Bacillus thuringiensis HC-2 Combined with Biochar on the Growth and Cd and Pb Accumulation of Radish in a Heavy Metal-Contaminated Farmland under Field Conditions

2019 ◽  
Vol 16 (19) ◽  
pp. 3676 ◽  
Author(s):  
Zigang Li ◽  
Peng Wang ◽  
Xiaoyu Yue ◽  
Jingtao Wang ◽  
Baozeng Ren ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Bacillus Thuringiensis ◽  
Organic Matter Content ◽  
Dry Weight ◽  
Underlying Mechanism ◽  
Water Soluble ◽  
Field Conditions ◽  
Resistant Bacteria ◽  
Culture Solution ◽  
Rhizosphere Soils

The objective of this study was to explore the effect of heavy metal-resistant bacteria and biochar (BC) on reducing heavy metal accumulation in vegetables and the underlying mechanism. We tested Bacillus thuringiensis HC-2, BC, and BC+HC-2 for their ability to immobilize Cd and Pb in culture solution. We also studied the effects of these treatments on the dry weight and Cd and Pb uptake of radish in metal-contaminated soils under field conditions and the underlying mechanism. Treatment with HC-2, BC, and BC+HC-2 significantly reduced the water-soluble Cd (34–56%) and Pb (31–54%) concentrations and increased the pH and NH4+ concentration in solution compared with their vales in a control. These treatments significantly increased the dry weight of radish roots (18.4–22.8%) and leaves (37.8–39.9%) and decreased Cd (28–94%) and Pb (22–63%) content in the radish roots compared with the control. Treatment with HC-2, BC, and BC+HC-2 also significantly increased the pH, organic matter content, NH4+ content, and NH4+/NO3− ratio of rhizosphere soils, and decreased the DTPA-extractable Cd (37–58%) and Pb (26–42%) contents in rhizosphere soils of radish. Furthermore, BC+HC-2 had higher ability than the other two treatments to protect radish against Cd and Pb toxicity and increased radish biomass. Therefore, Bacillus thuringiensis HC-2 combined with biochar can ensure vegetable safety in situ for the bioremediation of heavy metal-polluted farmland.

scholarly journals Evolution of reduced pre-adult viability and larval growth rate in laboratory populations of Drosophila melanogaster selected for shorter development time

2000 ◽  
Vol 76 (3) ◽  
pp. 249-259 ◽  
Author(s):  
N. G. PRASAD ◽  
MALLIKARJUN SHAKARAD ◽  
VISHAL M. GOHIL ◽  
V. SHEEBA ◽  
M. RAJAMANI ◽  
...  
Keyword(s):  
Growth Rate ◽  
Drosophila Melanogaster ◽  
Development Time ◽  
Larval Growth ◽  
Dry Weight ◽  
Relative Reduction ◽  
Larval Growth Rate ◽  
Laboratory Populations ◽  
The Difference ◽  
Faster Development

Four large (n > 1000) populations of Drosophila melanogaster, derived from control populations maintained on a 3 week discrete generation cycle, were subjected to selection for fast development and early reproduction. Egg to eclosion survivorship and development time and dry weight at eclosion were monitored every 10 generations. Over 70 generations of selection, development time in the selected populations decreased by approximately 36 h relative to controls, a 20% decline. The difference in male and female development time was also reduced in the selected populations. Flies from the selected populations were increasingly lighter at eclosion than controls, with the reduction in dry weight at eclosion over 70 generations of selection being approximately 45% in males and 39% in females. Larval growth rate (dry weight at eclosion/development time) was also reduced in the selected lines over 70 generations, relative to controls, by approximately 32% in males and 24% in females. However, part of this relative reduction was due to an increase in growth rate of the controls populations, presumably an expression of adaptation to conditions in our laboratory. After 50 generations of selection had elapsed, a considerable and increasing pre- adult viability cost to faster development became apparent, with viability in the selected populations being about 22% less than that of controls at generation 70 of selection.

scholarly journals Estimating High-Affinity Methanotrophic Bacterial Biomass, Growth, and Turnover in Soil by Phospholipid Fatty Acid 13C Labeling

2006 ◽  
Vol 72 (6) ◽  
pp. 3901-3907 ◽  
Author(s):  
P. J. Maxfield ◽  
E. R. C. Hornibrook ◽  
R. P. Evershed
Keyword(s):  
Mass Spectrometry ◽  
Fatty Acid ◽  
Phospholipid Fatty Acid ◽  
Bacterial Biomass ◽  
Isotope Ratio Mass Spectrometry ◽  
Dry Weight ◽  
Methane Oxidizing Bacteria ◽  
Constant Structure ◽  
Carbon Recycling ◽  
Time Point

ABSTRACT A time series phospholipid fatty acid (PLFA) 13C-labeling study was undertaken to determine methanotrophic taxon, calculate methanotrophic biomass, and assess carbon recycling in an upland brown earth soil from Bronydd Mawr (Wales, United Kingdom). Laboratory incubations of soils were performed at ambient CH4 concentrations using synthetic air containing 2 parts per million of volume of 13CH4. Flowthrough chambers maintained a stable CH4 concentration throughout the 11-week incubation. Soils were analyzed at weekly intervals by gas chromatography (GC), GC-mass spectrometry, and GC-combustion-isotope ratio mass spectrometry to identify and quantify individual PLFAs and trace the incorporation of 13C label into the microbial biomass. Incorporation of the 13C label was seen throughout the experiment, with the rate of incorporation decreasing after 9 weeks. The δ13C values of individual PLFAs showed that 13C label was incorporated into different components to various extents and at various rates, reflecting the diversity of PLFA sources. Quantitative assessments of 13C-labeled PLFAs showed that the methanotrophic population was of constant structure throughout the experiment. The dominant 13C-labeled PLFA was 18:1ω7c, with 16:1ω5 present at lower abundance, suggesting the presence of novel type II methanotrophs. The biomass of methane-oxidizing bacteria at optimum labeling was estimated to be about 7.2 � 106 cells g−1 of soil (dry weight). While recycling of 13C label from the methanotrophic biomass must occur, it is a slower process than initial 13CH4 incorporation, with only about 5 to 10% of 13C-labeled PLFAs reflecting this process. Thus, 13C-labeled PLFA distributions determined at any time point during 13CH4 incubation can be used for chemotaxonomic assessments, although extended incubations are required to achieve optimum 13C labeling for methanotrophic biomass determinations.

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