Biogenic Production Research Articles

Tracking sources of PM10 emissions and deposition in the industrial city of Ostrava, Czech Republic: A carbonaceous δ13C-based approach

The sources of airborne particulate matter (PM10) emissions in Ostrava, Czech Republic, were investigated. Emphasis was placed on their organic carbon (OC) and elemental carbon (EC) contents, and their carbon stable isotope composition, δ13C. Emission sources were identified using OC-δ13C and concentration values. To track the extent of long-term deposition, these sources were also identified using the black carbon (BC) δ13C values of soil samples. At all sampling sites, wind flow is predominantly (65–80%) bidirectional in either SW-NE or NE-SW trajectories. Source apportionment along these dominant airflow trajectories was calculated from an isotopic 13C mass balance, and according to differences in the OC content and δ13C values of PM10. Determined emission sources are: (i) combustion of Silesian hard coal (δ13C = −24.5‰); (ii) local Ostrava coal combustion (δ13C = −25.5 to −26‰), automotive emissions (δ13C = −26.5‰), and biogenic particles (δ13C = −28 to −28.5‰). Winter emissions (mean OC concentrations from 12 to 25 μg m−3) originated mostly from coal combustion (80%) in domestic and industrial point sources. Differences were ascribed to automotive emissions. Ostrava is located near the Czech-Polish border, transboundary emissions are transported under a southbound wind flow that transported from 40 to 80% of the collected PM10. Summer emissions were lower (mean OC concentration from 6 to 8 μg m−3). Automotive emissions accounted for up to 40%, whilst biogenic production accounted for 60%. Absence of 13C isotope data of secondary OC (SOC 1.2–1.5 μg m−3) increases uncertainty in our source apportionment in summer; when SOC could comprise >20% of total OC. Contribution of SOC to the winter-measured OC is much lower (5–10%), and has no significant effect on mass balances. The upper soil layer analyses revealed long-term deposition of the same emissions sources. We conclude that the stable δ13C isotope values of OC and EC are useful for discriminating against local sources of PM10 pollution in relatively small urban areas, containing discrete polluting sources. Such a simplified approach can be easily standardized and implemented to manage regulatory compliances in the increasingly commoditized carbon offset market.

Biogenic Production of Thiosulfate from Organic and Inorganic Sulfur Substrates for Application to Gold Leaching

Gold mining and processing is an activity with large environmental impact due to the low concentration of gold in ore deposits and chemical resistance to most chemicals. Over 75% of gold is leached from ores using cyanide, however less toxic lixiviants have been proposed in the literature. Thiosulfate is one of these alternative reagents, but high reagent consumption has slowed acceptance in mining operations. Reducing the cost and impact of thiosulfate production is a way to reduce the cost of reagent consumption during leaching. The objective of this study was to evaluate the feasibility of leaching gold from ore with biogenic thiosulfate. Biogenic thiosulfate was produced using a marine methylotroph bacterium from three substrates: sodium sulfide, elemental sulfur, and dimethyl sulfide for application in bioleaching. The different substrates were evaluated to determine conversion efficiency from the sulfur source to biogenic thiosulfate and verified by titration and ion chromatography. Optimal conditions for conversion to thiosulfate were determined to be in the range of pH = 7–8, 25–30 °C, with sodium sulfide as a substrate in a sealed system to prevent sulfide from escaping as hydrogen sulfide gas. An oxide gold ore with a grade of 4.02 g/t was selected as a gold source for leaching experiments. The leaching of gold using the biogenic thiosulfate was compared with chemical thiosulfate solutions under experimental conditions of pH = 9.5, 50 mg/L copper, 500 RPM mixing, and 0.1 L/min air. The efficiency of gold bioleaching was measured using flame atomic absorption spectroscopy and fire assay. Gold extraction efficiencies ranging from 20–60% were achieved using the biogenic thiosulfate, and 27–77% with sodium thiosulfate solutions, respectively. It was concluded that the sodium sulfide substrate was best for producing higher biogenic thiosulfate concentrations and leaching efficiency.

Morus Alba Leaf Extract-Based Biogenic Production of Silver Nanoparticles: Characterization, Antibacterial, and Antiviral Evaluation

Morus Alba Leaf Extract-Based Biogenic Production of Silver Nanoparticles: Characterization, Antibacterial, and Antiviral Evaluation

Acumulación de selenio por Lactobacillus aislados de leches fermentadas comerciales: concentración mínima inhibitoria y cambios cinéticos de crecimiento

Selenium is essential for human health; however, recommended daily intake is not always met. Thus, studies have been carried out on the biogenic production of more bioavailable selenium. It has been demonstrated that certain lactobacilli can metabolize inorganic selenium to transform it into selenoamino acids. This study aimed to add selenium on  Lactobacillus casei Shirota and Lactobacillus johnsonii La1, isolated from commercial dairy products through an MRS media fermentation enriched with Na2SeO3 to determine the minimum inhibitory concentration, the changes in the kinetics growth, and the selenium bioaccumulation. The minimum inhibitory concentration (MIC) was determined using the Talmadge and Fitch method. Kinetic changes were calculated by modeling the growth curve, and an inductively coupled plasma (ICP) assay was used to determine selenium accumulation by the cell. The MIC of Na2SeO3 was higher than 190 mg/L in both bacteria, and kinetic changes showed faster growth when media was not enriched. Selenium absorption of 64.50 % was found for Lb. casei Shirota and 75.78 % for Lb. johnsonii La1. Obtained results demonstrated that these lactic acid bacteria bacteria are a potential ingredient in functional food processing to their ability to accumulate selenium.

Effectiveness of Snail Slime in the Green Synthesis of Silver Nanoparticles

The development of green, low cost and sustainable synthetic routes to produce metal nanoparticles is of outmost importance, as these materials fulfill large scale applications in a number of different areas. Herein, snail slime extracted from Helix Aspersa snails was successfully employed both as bio-reducing agent of silver nitrate and as bio-stabilizer of the obtained nanoparticles. Several trials were carried out by varying temperature, the volume of snail slime and the silver nitrate concentration to find the best biogenic pathway to produce silver nanoparticles. The best results were obtained when the synthesis was performed at room temperature and neutral pH. UV–Visible Spectroscopy, SEM-TEM and FTIR were used for a detailed characterization of the nanoparticles. The obtained nanoparticles are spherical, with mean diameters measured from TEM images ranging from 15 to 30 nm and stable over time. The role of proteins and glycoproteins in the biogenic production of silver nanoparticles was elucidated. Infrared spectra clearly showed the presence of proteins all around the silver core. The macromolecular shell is also responsible of the effectiveness of the synthesized AgNPs to inhibit Gram positive and Gram negative bacterial growth.

Extremophilic Microorganisms for the Green Synthesis of Antibacterial Nanoparticles.

The biogenic synthesis of nanomaterials, i.e., synthesis carried out by means of living organisms, is an emerging technique in nanotechnology since it represents a greener and more eco-friendly method for the production of nanomaterials. In this line, in order to find new biological entities capable of biogenic synthesis, we tested the ability of some extremophilic microorganisms to carry out the biogenic production of AgNPs and SeNPs. Silver NPs were produced extracellularly by means of the thermophilic Thermus thermophilus strain SAMU; the haloalkaliphilic Halomonas campaniensis strain 5AG was instead found to be useful for the synthesis of SeNPs. The structural characterization of the biogenic nanoparticles showed that both the Ag and Se NPs possessed a protein coating on their surface and that they were organized in aggregates. Moreover, both types of NPs were found be able to exert an interesting antibacterial effect against either Gram-positive or Gram-negative species. This study confirmed that extremophilic microorganisms can be considered valuable producers of biologically active nanoparticles; nevertheless, further experiments must be performed to improve the synthesis protocols in addition to the downstream processes.

Spectral Detection of Nanophase Iron Minerals Produced by Fe(III)-Reducing Hyperthermophilic Crenarchaea.

Mineral transformations by two hyperthermophilic Fe(III)-reducing crenarchaea, Pyrodictium delaneyi and Pyrobaculum islandicum, were examined using synthetic nanophase ferrihydrite, lepidocrocite, and akaganeite separately as terminal electron acceptors and compared with abiotic mineral transformations under similar conditions. Spectral analyses using visible-near-infrared, Fourier-transform infrared attenuated total reflectance (FTIR-ATR), Raman, and Mössbauer spectroscopies were complementary and revealed formation of various biomineral assemblages distinguishable from abiotic phases. The most extensive biogenic mineral transformation occurred with ferrihydrite, which formed primarily magnetite with spectral features similar to biomagnetite relative to a synthetic magnetite standard. The FTIR-ATR spectra of ferrihydrite bioreduced by P. delaneyi also showed possible cell-associated organics such as exopolysaccharides. Such combined detections of biomineral assemblages and organics might serve as biomarkers for hyperthermophilic Fe(III) reduction. With lepidocrocite, P. delaneyi produced primarily a ferrous carbonate phase reminiscent of siderite, and with akaganeite, magnetite and a ferrous phosphate phase similar to vivianite were formed. P. islandicum showed minor biogenic production of a ferrous phosphate similar to vivianite when grown on lepidocrocite, and a mixed valent phosphate or sulfate mineral when grown on akaganeite. These results expand the range of biogenic mineral transformations at high temperatures and identify spacecraft-relevant spectroscopies suitable for discriminating mineral biogenicity.

The relevance of coastal sediment budgets to management of sandy wave-dominated shorelines, a case study of Twofold Bay, southeastern Australia

Coastal compartments provide a framework for considering sediment budgets by defining the boundaries between adjacent beaches or sections of coast with a common sediment source. Here we present Twofold Bay as an ideal field laboratory to test the coastal compartment management approach, and in particular, note the relevance of long-term coastal evolution to shorter term planning timescales. Twofold Bay on the New South Wales south coast, Australia, contains four main beaches (Aslings, Boydtown, Whale and Fisheries Beaches) and associated barrier systems. We present a range of existing geological and geomorphic information combined with new field data which demonstrate considerable variation in the Holocene evolution and sediment budget of these adjacent beaches. These data show three broad sediment types exist within Twofold Bay and its beach systems: Type 1 is a mature quartz-rich sand derived from the shelf. Type 2 is a fine carbonate-rich sand from local biogenic production, and Type 3 is a coarse-fine angular feldspathic sand sourced from the Towamba River which drains to Twofold Bay via the southern end of Whale Beach. Newly available high-resolution topography and bathymetry as well as sediment thickness maps, have enabled shoreface geometry and basement topography to be estimated seaward of each beach and reveal considerable variability between sites helping explain past shoreline behaviour. Several new optically stimulated luminescence (OSL) ages for Boydtown Beach, combined with existing ages, confirm two distinct phases of shoreline progradation, initially at 0.16 m/yr, and then over the past ∼1500 years, at 0.65 m/yr. The increase in progradation rate reflects sediment supply from the Towamba River via Whale Spit. While these two beaches have become interconnected, Aslings Beach and Fisheries Beach are dominated by sediment Type 1 and Type 2 respectively and have different evolutionary histories with Aslings Beach forming a stationary barrier while Fisheries has prograded at 0.15 m/yr over the past ∼4300 years according to a new set of OSL ages. The Holocene evolution of these four adjacent beaches has resulted from their differing sediment sources and budgets and is in accord with several available datasets of decadal shoreline changes. These results demonstrate that spatial variation in shoreline behaviour is driven by differences in sediment budget and that just as adjacent beaches have behaved differently in the past, so will they in the future. Understanding these drivers of shoreline change is imperative to effective coastal management and planning in the context of projected future sea-level rise and other anthropogenic pressures.

Biological–physical oceanographic coupling influencing particulate organic matter in the South Yellow Sea

Using total suspended matter (TSM), particulate organic carbon (POC), and particulate nitrogen data, this study investigated the potential vertical POC flux and transport in the South Yellow Sea (SYS). The biogenic production and resuspension fraction (i.e., the proportion of resuspended particles in TSM) were estimated using an ecosystem model and a vertical mixing model. They were verified against reported sediment trap and primary productivity data. The estimates of resuspension fraction showed substantial uncertainty of 50% in summer likely owing to the potential errors of model parameter estimation and the influence of other unexplored biophysical processes such as biological degradation, upwelling, and monsoons; however, the estimates of resuspension fraction showed less uncertainty in other seasons (<20%). Few previous studies have considered the specific influence of resuspension on the dynamics and budget of particulate organic matter (POM) in the SYS. This study proposed a reasonably simple and effective method to address this issue, which was applied to systematic examination of the variation of vertical POM flux with the change of coupled biological–physical oceanographic processes along the Subei coast and in the SYS central basin. The influence of horizontal transport from the Subei coast to the central basin may cause an overestimation of >10% of the resuspension fraction. It will be necessary to acquire additional field data covering a larger spatiotemporal scale to establish an integrated network of the SYS carbon budget.

Nitrate Application in Mitigation of SRB Activity and Biogenic Sulfide Production

Nitrate Application in Mitigation of SRB Activity and Biogenic Sulfide Production

Valorization of Parkia biglobosa wastewater for novel biofabrication of Ag/TiO2 nanoparticles with potent action against MDR strains and nanotextile application

In this work, we report for the first time, the biogenic production of silver-titanium oxide alloy nanoparticles (Ag/TiO2 NPs) via wastewater from fermented beans of locust beans plant (Parkia biglobosa) with potent antimicrobial activities using as-prepared nanoparticles and fabric functionalized with the nanoparticles. The deep brown colloidal solution of Ag/TiO2 NPs absorbed at 400 nm with a single peak that signifies the formation of bimetallic nanoparticles. The characteristic peaks of 3898–3900, 3493–3506 and 1773–1775 cm−1 obtained through Fourier Transform Infrared spectroscopic investigations showed the involvement of proteins and phenolics in the synthesis of Ag/TiO2 NPs. The transmission electron microscopic measurement of the nearly spherical-shaped nanoparticles revealed size range of 11.40–28.93 nm with crystalline structure in the selected area electron diffraction (SAED) image. The energy-dispersive X-ray pattern showed prominence of silver, oxygen and titanium in the colloidal solution. The synthesized Ag/TiO2 NPs inhibited the growth of strains of multi-drug resistant bacteria such as Klebsiella oxytoca, Pseudomonas aeruginosa, Staphylococcus aureus, Proteus mirabilis, Klebsiella pneumoniae, and Escherichia coli as well as fungal isolates that included Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus and Fusarium solani. Similarly, the antimicrobial potency of the fabrics functionalized with Ag/TiO2 NPs NPs was remarkable with antibacterial activities (15–24 mm) and complete suppression of the growth of A. niger. This novel antimicrobial agent can be explored for textile and biomedical applications in the control of drug resistant isolates to engender good health and wellbeing (SDG 3).

Biogenic Methane Accumulation and Production in the Jurassic Low-Rank Coal, Southwestern Ordos Basin

Geological conditions are the key for coalbed methane (CBM) accumulation and production. However, the geological feature of CBM accumulation and production in the Jurassic of Ordos Basin lacks systematic and detailed evaluation, resulting in poor CBM production in this area. This study has determined the genetic types of gas according to geochemistry characteristics of the gas, the geological factors to control CBM accumulation and production performance were revealed, and a comprehensive method was established to evaluate favorable areas based on 32 sets of CBM well production data from Jurassic Yan’an Formation. The results show the coal macerals are rich in inertinite (41.13~91.12%), and the maximum reflectance of vitrinite (Ro,max) in coal is 0.56~0.65%. According to gas compositions and carbon isotopes analysis, the δ13C(CH4) is less than −55‰, and the content of heavy hydrocarbon is less than 0.05%. The value of C1/(C2 + C3) is 6800~98,000, that is, the CBM is a typical biogenic gas of low-rank coal. The CBM accumulation model is the secondary biogenic on the gentle slope of the basin margin, in which gas content is closely related to buried depth and hydrodynamic environment, i.e., the high gas content areas are mainly located in the groundwater weak runoff zone at the burial depth of 450 m~650 m, especially in the syncline. Meanwhile, gas production mainly depends on the location of the structure. The high gas production areas of vertical wells were distributed on the gentle slope with high gas content between anticline and syncline, and the horizontal wells with good performance were located near the core of the syncline. According to the above analysis combined with the random forest model, the study area was divided into different production favorable areas, which will provide a scientific basis for the CBM production wells.

Spatiotemporal distribution and environmental control factors of halocarbons in the Yangtze River Estuary and its adjacent marine area during autumn and spring

The oceanic production and release of volatile halocarbons (VHCs) to the atmosphere play a vital role in regulating the global climate. In this study, seasonal and spatial variations in VHCs, including trichlorofluoromethane (CFC-11), methyl iodide (CH3I), dibromomethane (CH2Br2), and bromoform (CHBr3), and environmental parameters affecting their concentrations were characterized in the atmosphere and seawater of the Yangtze River Estuary and its adjacent marine area during two cruises from October 17 to October 26, 2019 and from May 12 to May 25, 2020. Significant seasonal variations were observed in the atmosphere and seawater because of seasonal differences in the prevalent monsoon, water mass (Yangtze River Diluted Water), and biogenic production. VHCs concentrations were positively correlated with Chl-a concentrations in the surface water during autumn. The average sea-to-air fluxes of CH3I, CH2Br2, and CHBr3 in autumn were 19.7, 4.0, and 7.6 nmol m−2 d−1, respectively, while those in spring were 6.3, 6.4, and −3.6 nmol m−2 d−1. In the ship-based incubation experiments, ocean acidification and dust deposition had no significant effects on VHCs concentrations. The concentrations of CH2Br2 and CHBr3 were significantly positively correlated with phytoplankton biomass under lower pH condition (M3: pH 7.9). This result indicated that CH2Br2 and CHBr3 concentrations were mainly related to the biological release.

In Vivo Analgesic, Anti-Inflammatory, and Anti-Diabetic Screening of Bacopa monnieri-Synthesized Copper Oxide Nanoparticles.

In this work, an ecofriendly approach for biogenic production of copper oxide nanoparticles (CuO-NPs) was proposed by utilizing the Bacopa monnieri leaf extract as a reducing and stabilizing agent. The synthesis of CuO-NPs was instantly confirmed by a shift in the color of the copper solution from blue to dark gray. The use of UV–visible spectroscopy revealed a strong narrow peak at 535 nm, confirming the existence of monoclinic-shaped nanoparticles. The average size of CuO-NPs was 34.4 nm, according to scanning electron microscopy and transmission electron microscopy studies. The pristine crystalline nature of CuO-NPs was confirmed by X-ray diffraction. The monoclinic form of CuO-NPs with a crystallite size of 22 nm was determined by the sharp narrow peaks corresponding to 273, 541, 698, 684, and 366 Bragg’s planes at different 2θ values. The presence of different reducing metabolites on the surface of CuO was shown by Fourier transform infrared analysis. The biological efficacy of CuO-NPs was tested against Helicobacter felis, Helicobacter suis, Helicobacter salomonis. and Helicobacter bizzozeronii. H. suis was the most susceptible strain with an inhibition zone of 15.84 ± 0.89 mm at 5 mg/mL of NPs, while the most tolerant strain was H. bizzozeronii with a 13.11 ± 0.83 mm of inhibition zone. In in vivo analgesic activity, CuO-NPs showed superior efficiency compared to controls. The maximum latency time observed was 7.14 ± 0.12 s at a dose level of 400 mg/kg after 90 min, followed by 5.21 ± 0.29 s at 400 mg/kg after 60 min, demonstrating 65 and 61% of analgesia, respectively. Diclofenac sodium was used as a standard with a latency time of 8.6 ± 0.23 s. The results observed in the rat paw edema assays showed a significant inhibitory activity of the plant-mediated CuO-NPs. The percentage inhibition of edema was 74% after 48 h for the group treated with CuO-NPs compared to the control group treated with diclofenac (100 mg/kg) with 24% edema inhibition. The solution of CuO-NPs produced 82% inhibition of edema after 21 days when compared with that of the standard drug diclofenac (73%). CuO-NPs vividly lowered glucose levels in STZ-induced diabetic mice, according to our findings. Blood glucose levels were reduced by about 33.66 and 32.19% in CuO-NP and (CuO-NP + insulin) groups of mice, respectively. From the abovementioned calculations, we can easily conclude that B. monnieri-synthesized CuO-NPs will be a potential antibacterial, anti-diabetic, and anti-inflammatory agent on in vivo and in vitro basis.

High Potential for Anaerobic Microbial Sulfur Oxidation in Oil Sands Tailings Ponds.

The biogenic production of toxic H2S gas in sulfate-rich oil sands tailings ponds is associated with strong environmental concerns. Beside precipitation into sulfide minerals and chemical re-oxidation, microbial sulfur oxidation may catalyze sulfide re-cycling but potentially contributes to acid rock drainage (ARD) generation. To evaluate the microbial potential for sulfur oxidation, we conducted a microcosm-based pilot study with tailings of an active pond. Incubations were performed under oxic and anoxic conditions, with and without KNO3 as an electron acceptor and thiosulfate as a common substrate for microbial sulfur oxidation. The highest potentials of sulfur oxidation occurred in oxic assays (1.21 mmol L−1 day−1). Under anoxic conditions, rates were significantly lower and dominated by chemical transformation (0.09 mmol L−1 day−1; p < 0.0001). The addition of KNO3 to anoxic incubations increased microbial thiosulfate oxidation 2.5-fold (0.23 mmol L−1 day−1; p = 0.0474), with complete transformation to SO42− coupled to NO3− consumption, pointing to the activity of sulfur-oxidizing bacteria (SOB) under nitrate-reducing conditions. Importantly, in the presence of KNO3, a decrease in sedimentary sulfides was associated with an increase in S0, which indicates the potential for microbially mediated oxidation of sulfide minerals and ARD generation. Furthermore, the comparative analysis of sediments from other anthropogenic aquatic habitats demonstrated high similarities with respect to viable SOB counts and corresponding activity rates.

A novel, divergent alkane monooxygenase (alkB) clade involved in crude oil biodegradation.

Alkanes are ubiquitous in marine ecosystems and originate from diverse sources ranging from natural oil seeps to anthropogenic inputs and biogenic production by cyanobacteria. Enzymes that degrade cyanobacterial alkanes (typically C15-C17 compounds) such as the alkane monooxygenase (AlkB) are widespread, but it remains unclear whether or not AlkB variants exist that specialize in degradation of crude oil from natural or accidental spills, a much more complex mixture of long-chain hydrocarbons. In the present study, large-scale analysis of available metagenomic and genomic data from the Gulf of Mexico (GoM) oil spill revealed a novel, divergent AlkB clade recovered from genomes with no cultured representatives that was dramatically increased in abundance in crude-oil impacted ecosystems. In contrast, the AlkB clades associated with biotransformation of cyanobacterial alkanes belonged to 'canonical' or hydrocarbonoclastic clades, and based on metatranscriptomics data and compared to the novel clade, were much more weakly expressed during crude oil biodegradation in laboratory mesocosms. The absence of this divergent AlkB clade in metagenomes of uncontaminated samples from the global ocean survey but not from the GoM as well as its frequent horizontal gene transfer indicated a priming effect of the Gulf for crude oil biodegradation likely driven by natural oil seeps.

Biogenic production of silver nanoparticles from milk of Capra aegagrus hircus and mechanism of antibacterial activity on different bacteria

Biogenic production of silver nanoparticles from milk of Capra aegagrus hircus and mechanism of antibacterial activity on different bacteria

Variation in hydrogen sulfide emissions from a U.S. Midwest anaerobic dairy lagoon.

Hydrogen sulfide (H2 S) emissions from midwestern United States dairy anaerobic waste lagoons are episodic and seasonal. Emissions were modeled using an inverse diffusion model in conjunction with measured concentrations and turbulence. The potential for lagoon mixing was estimated by the Brunt frequency using a theoretical Fourier series temperature profile model constructed from measured air and lagoon temperatures. Annual H2 S emissions from the dairy parlor and holding area liquid waste, based on 318 d of measurement, were 212g m-2 or 807g head of cattle-1 . Hydrogen sulfide emissions were highest in the spring and the fall. Eleven days with emissions >7g d-1 head-1 accounted for 25% of the annual emissions. Shear mixing appeared to dominate the mixing in the lagoon when the lagoon was estimated to be nearly isothermal. Wind shear correlated with significantly greater daily mean emissions. The H2 S emissions from this lagoon appeared to result from a series of processes; biogenic production of H2 S in the sludge, H2 S-enriched bubbles rise through the lagoon by buoyancy and wind shear induced mixing, and bubbles bursting at the surface either due to desiccation of the bubbles or surface disturbances induced by wind and precipitation.

Inhibition of biogenic hydrogen sulfide produce by Sulfate Reducing Bacteria isolated from oil fields in Basra by nitrate based treatment

The present study included using of Bio Competitive Exclusion BCX technology in treatment of biogenic production of hydrogen sulfide H2S by Sulfate Reducing Bacteria SRB in batch cultures, injection of nitrate and nitrite promotes the growth of Nitrate Reducing Bacteria NRB which outcompete the Sulfate Reducing Bacteria SRB on carbon sources. Mix cultures of SRB and NRB were isolated from produce water of oil production facilities in Iraq including Nahran Omer and Al lahis oil fields. The activity of NRB and SRB were determined by measured the concentration of nitrate, nitrite and sulfide by using spectrophotometer and bacterial counts in three tube MPN technique. The results showed that NRB had a certain inhibitory effect on the growth of SRB and sulfide production under adding NRB nutrient nitrate and nitrite at all concentrations 200, 400, 600, 800 and 1000 mg/l, activity of NRB increased after treatment, all nitrate and nitrite consumption during 2 - 3 days of incubation. The highest inhibition of H2S production was at concentration 1000 mg/l of nitrate where the results showed that there was significant decrease in sulfide level and number of bacteria 34 mg/l and 34.8 cell/ ml respectively after 10 days of treatment.

Biogenic Nanoparticles: Synthesis, Characterisation and Applications

Nanotechnology plays a big part in our modern daily lives, ranging from the biomedical sector to the energy sector. There are different physicochemical and biological methods to synthesise nanoparticles towards multiple applications. Biogenic production of nanoparticles through the utilisation of microorganisms provides great advantages over other techniques and is increasingly being explored. This review examines the process of the biogenic synthesis of nanoparticles mediated by microorganisms such as bacteria, fungi and algae, and their applications. Microorganisms offer a disparate environment for nanoparticle synthesis. Optimum production and minimum time to obtain the desired size and shape, to improve the stability of nanoparticles and to optimise specific microorganisms for specific applications are the challenges to address, however. Numerous applications of biogenic nanoparticles in medicine, environment, drug delivery and biochemical sensors are discussed.