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Interest in enzymes capable of neutralizing various mycotoxins is quite high. The methods used for the screening and selection of enzymes that catalyze the detoxification of mycotoxins should be sensitive and fast. However toxic compounds can be generated under the action of such enzymes. Thus, the assessment of the overall reduction in the toxic properties of reaction media towards bioluminescent bacteria seems to be the most reasonable control method allowing a quick search for the effective enzymatic biocatalysts. The influence of a wide range of mycotoxins and glucanases, which hydrolyze toxins with different chemical structures, on the analytical characteristics of luminescent photobacteria as a biosensing element has been studied. Different glucanases (β-glucosidase and endoglucanase) were initially selected for reactions with 10 mycotoxins based on the results of molecular docking which was performed in silico with 20 mycotoxins. Finally, the biorecognizing luminescent cells were used to estimate the residual toxicity of reaction media with mycotoxins after their interaction with enzymes. The notable non-catalytic decrease in toxicity of media containing deoxynivalenol was revealed with luminous cells for both types of tested glucanases, whereas β-glucosidase provided a significant catalytic detoxification of media with aflatoxin B2 and zearalenone at pH 6.0. [ABSTRACT FROM AUTHOR]

Photorhabdus spp. are the only known terrestrial bioluminescent bacteria. We show that the bioluminescence produced by these bacteria reduces scavenging activity on the insect cadavers they colonize. Photorhabdus spp. are the symbiont of the insect pathogenic nematodes Heterorhabditis spp. Together they kill insects and colonize the cadaver. The function of their bioluminescence has been the subject of debate, but here for the first time we demonstrate an ecological benefit. In our experiments, fewer Photorhabdus temperata -infected cadavers than uninfected cadavers were scavenged, but only in dark conditions where their bioluminescence would be visible. This was the case both in the field and in laboratory experiments with Lehmannia valentiana slugs (the primary scavengers found in our field tests). We also show that L. valentiana is innately deterred from scavenging on uninfected cadavers in proximity to light imitating the bioluminescence of Photorhabdus, indicating that luminescence can be a deterrent independent of chemical cues. We propose a multimodal defence where bioluminescence works together with the chemical defences also produced by Photorhabdus to deter scavengers, such as slugs, from feeding on the host cadaver, with the potential for aposematism. [ABSTRACT FROM AUTHOR]

Photorhabdus spp. are the only known terrestrial bioluminescent bacteria. We show that the bioluminescence produced by these bacteria reduces scavenging activity on the insect cadavers they colonize. Photorhabdus spp. are the symbiont of the insect pathogenic nematodes Heterorhabditis spp. Together they kill insects and colonize the cadaver. The function of their bioluminescence has been the subject of debate, but here for the first time we demonstrate an ecological benefit. In our experiments, fewer Photorhabdus temperata -infected cadavers than uninfected cadavers were scavenged, but only in dark conditions where their bioluminescence would be visible. This was the case both in the field and in laboratory experiments with Lehmannia valentiana slugs (the primary scavengers found in our field tests). We also show that L. valentiana is innately deterred from scavenging on uninfected cadavers in proximity to light imitating the bioluminescence of Photorhabdus, indicating that luminescence can be a deterrent independent of chemical cues. We propose a multimodal defence where bioluminescence works together with the chemical defences also produced by Photorhabdus to deter scavengers, such as slugs, from feeding on the host cadaver, with the potential for aposematism.

Bioluminescent bacteria in the form of a cell suspension for on‐site hazard analysis are not suitable as in vivo luminescence in free cells fluctuates and may lead to erroneous results. Furthermore, the culture broth cannot be stored for long durations to continue sensing analytes as the luminescence ceases over time. Factors that affect luminescence response include growth dynamism, and ambient environmental conditions. The present study investigated the effect of storage conditions such as temperature (25 ± 2°C, room temperature; 4°C; and −20°C) and ambient aqueous environment (M1: sucrose, 1.02 M; M2, bioluminescent media [tryptone, 10 g L−1; NaCl, 28.5 g L−1; MgCl2.7H2O, 4.5 g L−1; CaCl2, 0.5 g L−1; KCl 0.5 g L−1; yeast extract, 1 g L−1; H2O, 1 L]; M3, bioluminescent media and 95% glycerol, 1:1 ratio) on the luminescence emission from the calcium alginate‐immobilized Photobacterium phosphoreum (Sb) against the cells in free suspension for an extended period. The results indicated that both the parameters that were undertaken markedly affected the luminescence. In the study, Sb showed an enhanced luminescence emission than the control up to 18.5‐fold and for a prolonged period which can be efficiently utilized for rapid biosensing of hazardous materials. [ABSTRACT FROM AUTHOR]

According to the World Health Organization, antimicrobial resistance (AMR) is one of the top ten global public health threats, justifying the need for new effective antimicrobials for biomedical applications [...]

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Current chemical analysis approaches for contaminants have failed to reveal their biotoxicity. Moreover, conventional bioassays are time consuming and exhibit poor repeatability. In this study, we performed the acute toxicity detection of various contaminants (chromium (Cr), cadmium (Cd), lead (Pb), arsenic (As), mercury (Hg), tin (Sn), nickel (Ni), and bisphenol A (BPA)) with four bioluminescent bacteria (Vibrio qinghaiensis Q67, V. fischeri, Photobacterium phosphoreum T3, and P. phosphoreum 502) using a rapid, flexible, and low‐cost bioassay. We found that the temperature affected the bacterial luminescence, and freeze‐dried cells exhibited sensitive toxic responses to contaminants. Indeed, the optimized protectants containing 12% (w/v) trehalose, 4% sucrose, and 2% sorbitol displayed better luminescence and toxic sensitivity. Furthermore, freeze‐dried powders of these strains were prepared and subjected to acute toxicity detection. The results showed that all contaminants exhibited acute toxicity toward Q67, but the other strains did not show obvious response to nickel and tin. The relative half‐maximal effective concentration (EC50) values of BPA, Cr, Cd, Pb, As, Hg, Ni, and Sn to Q67 were 0.674, 1.313, 11.137, 5.921, 4.674, 0.911, 5.941, and 54.077 mg/L, respectively. In addition, the EC50 values of contaminants toward different strains were suggested to be statistically significant. Freeze‐dried Q67 exhibited toxic responses to more contaminants than the other bioluminescent strains; therefore, Q67 was selected to be more suitable than the other strains for single and mixture toxicity detection tests. Compared with other strains, Q67 was more appropriate for the rapid screening of the mixture toxicity of contaminants in samples as a nonspecific screening sensor before the use of standard analysis approaches. [ABSTRACT FROM AUTHOR]

In this study, the silver nanoparticles (AgNPs) were extracellularly synthesized using a bioluminescent bacterium, Vibriocampbellii, and characterized their functional properties and morphological nature by UV–Vis spectroscopy, X-ray diffraction (XRD), Fourier transformed infrared spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM–EDS), and atomic force microscopy (AFM). Further, the synthesized AgNPs were analyzed for their antibacterial and antioxidant activity (2,2-diphenyl-1-picrylhydrazyl (DPPH), and hydrogen peroxide) in in vitro method. The antibacterial activity of AgNPs was tested against pathogenic bacteria such as Aeromonas hydrophila MTCC 1739, Klebsiellapneumoniae MTCC 4030, Klebsiellaoxytoca MTCC 3030, and Pseudomonasaeruginosa MTCC 1934. Characterization studies revealed that the synthesized AgNPs were poly-dispersed, spherical shaped with various size ranges, and exhibited as crystalline in nature. The assay of antibacterial activity showed the synthesized AgNPs strongly inhibited the tested pathogenic bacterial growth. Also, the AgNPs showed good antioxidant activity by strong scavenging actions on DPPH (61.88%) and hydrogen peroxide (53.48%) free radicals. Overall results demonstrated that AgNPs could be used in the pharmaceutical field due to their good antibacterial and antioxidant activity. [ABSTRACT FROM AUTHOR]

Background and objectiveThe development and feasibility of a novel nanocrystalline yttria-stabilized-zirconia (nc-YSZ) cranial implant has been recently established. The purpose of what we now call "window to the brain (WttB)" implant (or platform), is to improve patient care by providing a technique for delivery and/or collection of light into/from the brain, on demand, over large areas, and on a chronically recurring basis without the need for repeated craniotomies. WttB holds the transformative potential for enhancing light-based diagnosis and treatment of a wide variety of brain pathologies including cerebral edema, traumatic brain injury, stroke, glioma, and neurodegenerative diseases. However, bacterial adhesion to the cranial implant is the leading factor for biofilm formation (fouling), infection, and treatment failure. Escherichia coli (E. coli), in particular, is the most common isolate in gram-negative bacillary meningitis after cranial surgery or trauma. The transparency of our WttB implant may provide a unique opportunity for non-invasive treatment of bacterial infection under the implant using medical lasers.Study design/materials and methodsA drop of a diluted overnight culture of BL21-293 E. coli expressing luciferase was seeded between the nc-YSZ implant and the agar plate. This was followed by immediate irradiation with selected laser. After each laser treatment the nc-YSZ was removed, and cultures were incubated for 24 hours at 37 °C. The study examined continuous wave (CW) and pulsed wave (PW) modes of near-infrared (NIR) 810 nm laser wavelength with a power output ranging from 1 to 3 W. During irradiation, the temperature distribution of nc-YSZ surface was monitored using an infrared thermal camera. Relative luminescence unit (RLU) was used to evaluate the viability of bacteria after the NIR laser treatment.ResultsAnalysis of RLU suggests that the viability of E. coli biofilm formation was reduced with NIR laser treatment when compared to the control group (P

Growing concerns about water pollution and its potentially harmful effects on human being have stimulated serious efforts to develop reliable biological monitoring techniques. The bioluminescent analysis is one of the most promising approaches for the biomonitoring of the environment, due to the sensitivity of the luminescent system to even micro quantities of the pollutants. The aim of the current study was to assess the petroleum compounds toxicity using Vibrio fischeri bacterium. The growth pattern of the bacterium was determined in photobacterium broth using the optical density measurement at 600 nm, which showed the optimum growth time of 16-18 hours after inoculation. In this research, the effects of environmental parameters such as temperature, pH and various concentrations of oil on the growth and luminescence of Vibrio fischeri were examined. The results revealed that the optimum growth conditions of the bacterium after 16 hours included the temperature of 25 °C and pH 7. Besides, the growth and luminescence intensity of Vibrio fischeri were a function of total petroleum hydrocarbon concentrations in the medium, which were significantly reduced in oil concentrations by more than 4% w/v. Therefore, the Vibrio fischeri could, therefore, have the potential for monitoring of petroleum pollutants in the aqueous media.

Objectives:The purpose of this study is to evaluate the effects of heavy metals (Zn2+, Pb2+, Hg2+, Cd2+) toxicity in a real-time biosensor which is based on measuring the attenuation of light intensity emitted by Vibrio fischeri. Methods:The inhibition test included four heavy metals and the spiked effluent wastewater. The toxicity of the test samples was assessed by freeze-dried bacteria (Vibrio fischeri NRRL-B-11177). The pH of the samples was adjusted to 7±0.2 before conducting the toxicity tests in oder to eliminate potential pH effects. The results obtained from the real-time biosensor that can be measuring the toxicity of the samples as a function of the emitted light. within a short period time (2 min). And then EC20 and EC50 values was estimated from inhibition curves. Results and Discussion:In case of the inhibition test for dilluents of heavy metals, EC20 values were estimated as < 0.2 mg/L for Zn(II), 0.45 mg/L for Hg(II), 0.58 mg/L for Cd(II) and 1.95 mg/L for Pb(II) and EC50 values were estimated as 0.25 mg/L for Zn(II), 0.5~1.0 mg/L for Hg(II), 1.38 mg/L for Cd(II) and 3.76 mg/L for Pb(II). The sensitivity ranking of heavy metals was in order as Zn(II) > Hg(II), > Cd(II) > Pb(II). In case of the inhibition test for the spiked effluent wastewater, EC20 values were estimated as 0.38 mg/L for Hg(II), 0.58 mg/L for Zn(II), 1.45 mg/L for Pb(II) and 1.95 mg/L for Cd(II) and EC50 values were estimated as 0.53 mg/L for Hg(II), 1.13 mg/L for Zn(II), 6.44 mg/L for Pb(II) and 7.82 mg/L for Cd(II). The sensitivity ranking of the spiked effluent wastewater was in order as Hg(II) > Zn(II) > Pb(II) > Cd(II). Compared to the Emssion Limit Value (ELV) in Korea, the EC20 value of Zn(II) was found to be lower than ELV so that it was suitable for screening of Zn(II) as to meet the criteria of effluent wastewater. However, the other EC20 value of heavy metals can be used to control the unit processes and avoid accidental discharge. Conclusions:The assessment of the toxicity of four heavy metals and spiked samples with them was performed in this study, by real-time biosensor using bioluminescent bacteria. The EC20 value of the spiked sample with Zn(II) has been found to be 0.58 mg/L lower than its ELV so that it was considered as a suitable screening for determining whether or not to exceed the permissible limit value. The use of real-time biosensor is required in combination with physicochemical analyses for an integrated screening of the industrial effluent properties.

This article discusses the potential environmental hazards of silver-chitosan nanocomposites (nAgCSs). These nanocomposites are synthesized by reducing AgNO3 with trisodium citrate and coating them with low molecular-weight chitosan. The toxicity of these nanocomposites was tested on the bacterium Vibrio fischeri and microcrustaceans Daphnia magna and Thamnocephalus platyurus. The results showed that the nanocomposites were more toxic to the microcrustaceans than to the bacterium. The study concludes that chitosan-silver nanocomposites may pose a hazard to aquatic organisms and should be handled accordingly. [Extracted from the article]

The internal surface of the animal gastrointestinal tract is covered by microbial biofilms. They play an important role in the development and functioning of the host organism and protect it against pathogens. Microbial communities of gastrointestinal biofilms are less elucidated than luminal microbiota. Therefore, the studies of biofilm formation by gastrointestinal microorganisms are a topical issue. For the first time, we report the formation of a biofilm in vitro by the strains of bioluminescent bacteria isolated from the intestines of marine fish. These bacteria exhibit co-aggregation and tend to attach to solid surfaces. The attachment of cells is accompanied by appearance of the pili. Then, we observed the formation of microcolonies and the production of extracellular polymer substances (EPSs) connecting bacterial cells into an integrated system. The presence of acidic polysaccharides is shown in the EPS when using the ruthenium red staining. Acidic polysaccharides in this matrix is a biochemical evidence of microbial biofilms. On the fibers of the polymer matrix, these bacteria form the "mushroom body"-type structures. Matured biofilms exhibit a specific three-dimensional architecture with pores and channels formed by cells and EPS. We also demonstrated the formation of a biofilm by binary culture of the luminous enterobacterium Kosakonia cowanii and a Gram-positive Macrococcus sp. The data obtained help to understand the role of these bacteria in the intestines of fish. They lead to a new study in the field of investigation of the intestinal microbiome of fish. [ABSTRACT FROM AUTHOR]

Protecting the quality of lake watersheds by preventing and reducing their contamination is an effective approach to ensure the sustainability of the drinking water supply. In this study, acute toxicity assessment was conducted on the basis of acute bioluminescence inhibition assay using the marine bacterium Vibrio fischeri as the test organism and Luoma Lake drinking water source in East China as the research target. The suitable ranges of environmental factors, including pH value, organic matter, turbidity, hardness, and dissolved oxygen of water samples were evaluated for the toxicity testing of bioluminescent bacteria. The physicochemical characteristics of water samples at the selected 43 sites of Luoma Lake watershed were measured. Results showed that the variations in pH value (7.31–8.41), hardness (5–20 °d) and dissolved oxygen (4.44–11.03 mg/L) of Luoma Lake and its main inflow and outflow rivers had negligible impacts on the acute toxicity testing of V. fischeri. The luminescence inhibition rates ranged from −11.21% to 10.80% at the 43 sites. Pearson's correlation analysis in the experiment revealed that temperature, pH value, hardness, and turbidity had no correlation with luminescence inhibition rate, whereas dissolved oxygen showed a weak statistically positive correlation with a Pearson correlation coefficient of 0.455 (p < 0.05). [ABSTRACT FROM AUTHOR]

Growing concerns about water pollution and its potentially harmful effects on human being have stimulated serious efforts to develop reliable biological monitoring techniques. The bioluminescent analysis is one of the most promising approaches for the biomonitoring of the environment, due to the sensitivity of the luminescent system to even micro quantities of the pollutants. The aim of the current study was to assess the petroleum compounds toxicity using Vibrio fischeri bacterium. The growth pattern of the bacterium was determined in photobacterium broth using the optical density measurement at 600 nm, which showed the optimum growth time of 16-18 hours after inoculation. In this research, the effects of environmental parameters such as temperature, pH and various concentrations of oil on the growth and luminescence of Vibrio fischeri were examined. The results revealed that the optimum growth conditions of the bacterium after 16 hours included the temperature of 25 °C and pH 7. Besides, the growth and luminescence intensity of Vibrio fischeri were a function of total petroleum hydrocarbon concentrations in the medium, which were significantly reduced in oil concentrations by more than 4% w/v. Therefore, the Vibrio fischeri could, have the potential for monitoring of petroleum pollutants in the aqueous media. [ABSTRACT FROM AUTHOR]

Bioluminescence is an emission of cold light by enzyme driven reaction within certain living organisms. The most abundant and widely distributed light emitting organisms are luminescent bacteria. Such organisms are either found as freeliving in the ocean or in symbiotic relationship with the marine host. To employ bioluminescence in environmental monitoring, isolation of bioluminescent bacteria from the two different marine samples (sea water sample and various organs of squid and fish) were collected from different sites of Veraval seashore and fish markets located nearby seashore respectively. The marine organisms used in the study were 20-25 days old. Cultivation media that were used for isolation were sea water agar (SWA), luminous agar (LA) and nutrient agar (NA); out of which SWA proved to be the most suitable medium for their growth and luminescence. No bioluminescent bacterium was found in water samples and total five bioluminescent bacteria were isolated from five different organs of fish and squid each. Out of these five isolates, two were selected based on their maximum light intensity. These two isolates, PBS1 and PBF1, were further characterized biochemically. PBS1 was able to utilize glucose, galactose, maltose and were tested positive for catalase and oxidase tests. Similar results were obtained in case of PBF1 except it was tested positive for urease urea but was unable to utilize glucose. Both isolates thrived at neutral pH and showed maximum bioluminescence. Effect of NaCl concentration on luminescence revealed that the two isolates were not able to grow in media devoid of NaCl and the luminescence was found to be maximum at 3 % (w/v) NaCl supplementation. [ABSTRACT FROM AUTHOR]

Dyes from different sources often behave with mostly toxic properties when they enter the aquatic ecosystem. The main sources of these toxic substances causing problems in the aquatic ecosystem are wastewaters of the textile and dye industries. The aim of this study was to examine the change of acute toxicity values of wastewaters containing dyestuff depending on time and color parameters. In this study, an acute toxicity test was conducted for 30 seconds, which is shorter than the time specified in the original Microtox test protocol. Thus, the results of the original Microtox Basic Test (BT), Microtox Color Correction Procedure recommended by the manufacturer (BT-CC), and the Microtox Basic Test-30 seconds (sBT) were compared, taking into account the effect of time and color parameters. There is a statistically significant difference between two groups: sBT and BT, and sBT and BT-CC (F = 4.919; p<0.01). The results of sBT have been obtained more rapid and more sensitively than other acute toxicity tests. The sBT, which is time-saving and gives correct result might provide some guidance as a pre-screening test and might be used in routine monitoring. [ABSTRACT FROM AUTHOR]

The management of ocular infections is challenging due to poor drug bioavailability and vehicle related adverse effects associated with current antibiotic eye drops. Semifluorinated alkanes (SFAs) are reportedly well-tolerated on the ocular surface and can enhance ocular drug bioavailability. Therefore, an SFA-based azithromycin suspension (SFA-AZM) was prepared and its antibacterial efficacy was compared to that of marketed azithromycin eye drops by monitoring the growth of bioluminescent Staphylococcus aureus in ex vivo ocular tissues. Corneal and conjunctival distribution of hydrophobic fluorescent dye particles from an SFA suspension (SFA-BODIPY) resulted in preferential dye localisation in the epithelial layers of both tissues. However, corneal dye absorption was significantly lower than conjunctival absorption, likely due to limited adhesion of suspended dye particles to the corneal compared to the conjunctival epithelium. In line with the dye distribution results, bacterial colonisation in the conjunctiva reduced significantly upon application of SFA-AZM with the efficacy being greater than or at least equal to the marketed azithromycin eye drops. In the cornea, all tested azithromycin eye drops reduced the rate of bacterial growth with similar efficacy. Overall, the SFA-AZM suspension tested here may provide a safe and effective alternative for the management of ocular infections by enhancing conjunctival drug absorption and thus drug efficacy. [ABSTRACT FROM AUTHOR]

In ovo injection of probiotics has been of interest for achieving early health benefits. However, there is limited research demonstrating where bacteria could migrate within the embryo after injection. The objective of this study was to evaluate bacterial colonization or migration after in ovo injection of broiler embryo with bioluminescent Escherichia coli. Injection using 106 CFU/mL nonpathogenic E. coli was applied to amniotic and air cell regions on day 18 of incubation. On days 18, 19, 20, and 21 the amnion, skin, lung, gastrointestinal tract (GIT), bursa, and spleen were collected. On day 21, the GIT was separated into crop, duodenum, jejunum, ileum, and ceca sections. All tissues were visualized using anin vivo imaging system to confirm the presence of bioluminescent E. coli. Samples were homogenized, 10-fold serially diluted, and spread onto appropriate agar to determine bacterial loads in all tissues. Results indicated that eggs injected into the amnion had significantly high numbers of E. coli cells in all tissues compared to air cell injected and control treatments 2 h post-injection (P < 0.0001). E. coli was also found on the lungs, spleen, and bursa of eggs injected either in the amnion or air cell (P < 0.05). Results indicated that in ovo injection into the amnion was more efficient than air cell injection, yielding a higher bacterial concentration in the evaluated tissues, specifically the ileum and ceca. Future research using bioluminescent probiotic bacteria may establish sites of preference for different probiotics leading to site-specific application that can maximize their overall impact when in ovo injected. [ABSTRACT FROM AUTHOR]

Novel sensitive analytical agents that can be used for simple, affordable, and rapid analysis of mycotoxins are urgently needed in scientific practice, especially for the screening of perspective bio-destructors of the toxic contaminants. We compared the characteristics of a rapid quantitative analysis of different mycotoxins (deoxynivalenol, ochratoxin A, patulin, sterigmatocystin, and zearalenone) using acetyl-, butyrylcholinesterases and photobacterial strains of luminescent cells in the current study. The best bioindicators in terms of sensitivity and working range (μg/mL) were determined as follows: Photobacterium sp. 17 cells for analysis of deoxynivalenol (0.8–89) and patulin (0.2–32); Photobacterium sp. 9.2 cells for analysis of ochratoxin A (0.4–72) and zearalenone (0.2–32); acetylcholinesterase for analysis of sterigmatocystin (0.12–219). The cells were found to be more sensitive than enzymes. The assayed strains of photobacterial cells ensured 44%–83% lower limit of detection for deoxynivalenol and sterigmatocystin as compared to the previously known data for immobilized luminescent cells, and the range of working concentrations was extended by a factor of 1.5–3.5. Calibration curves for the quantitative determination of patulin using immobilized photobacteria were presented in this work for the first time. This calibration was applied to estimate the enzyme efficiency for hydrolyzing mycotoxins using zearalenone and His6-tagged organophosphorus hydrolase as examples.

Accomplishing the Italian law to verify honey quality is onerous, because it requires measuring many chemical and physical parameters. On the contrary, bioluminescence-based analytical methods allow for rapid and inexpensive analysis. Bioluminescence has never been applied before to verify honey adulteration. The application of chemometrics to analytical methods based on bioluminescence has been here explored for this scope. Several honey samples were prepared, in which sugar syrup was added without exceeding legal limits: in this case, univariate analysis prescribed by the law cannot reveal the fraud. All samples were subjected to measurements of parameters prescribed by the law and also to bioluminescence analysis, executed using the Vibrio fischeri bacterium, one of the most common bioluminescent bacteria. Principal components analysis, linear discriminant analysis, and partial least square regression were applied to discriminate sugar-added honeys with respect to natural honeys, both by regulated physicochemical parameters and by bioluminescence ones. The feasibility of combining bioluminescence and multivariate analysis for a rapid screening of honey authenticity was demonstrated. [ABSTRACT FROM AUTHOR]

Abstract Antimicrobial photodynamic therapy (aPDT) is an effective way to combat infectious diseases and antibiotic resistance. Photosensitizer is a key factor of aPDT and has triggered extensive research interest. In this study, a new asymmetric Zn(II) phthalocyanine mono-substituted with a triazatricyclodecane moiety (compound 3) and its cationic N -methylated derivative (compound 4) were synthesized. Their photodynamic antimicrobial activities were evaluated using bioluminescent bacterial strains. Compound 3 showed phototoxicity only toward the Gram-positive bacteria, whereas the cationic derivative compound 4 exhibited strong anti-bacterial activity against both Gram-positive and Gram-negative strains. These bacterial species were eradicated (>4.0 logs or 99.99% killing) at appropriate concentrations of compound 4 with 12.7 J/cm2 of red light, demonstrating compound 4 as a potent aPDT agent. Graphical abstract A new asymmetric zinc phthalocyanine conjugated with triazatricyclodecane (3) was synthesized. Upon methylation to compound 4 , the agent exhibited potent anti-bacterial activity with an IC 50 value at nano-molar range and >4 logs reduction of bacteria load. Unlabelled Image Highlights • A new asymmetric triazatricyclodecane substituted zinc phthalocyanine was prepared. • The compound had strong antibiotic efficacy on S. aureus , but weak effect on E. coli. • Further cationization led to potent anti-bacterial activity against both S. aureus and E. coli. • The cationic compound eliminated >4 logs of bacteria at micromolar concentration. • A new and rapid method using bioluminescent bacteria was adopted in anti-bacterial assay. [ABSTRACT FROM AUTHOR]

In this work, PM 10 samples previously subjected to thorough chemical speciation and receptor modelling, have been investigated for their bio-toxicity using an inhibition test based on bacterial luminescence modulation when in contact with airborne particulate samples. The variation of light emission intensity from a luminescent bacteria strain, the Photobacterium phosphoreum , is proposed as an efficient proxy for the quantification of bio-toxic effects induced by airborne particulate matter. PM 10 samples characterized by definite levels of pollutants from the pertaining air shed were found to induce a decrease in the bacterial bioluminescence intensity, expressed as percentage of Inhibition Ratio (IR%). This behaviour suggests the decay of this energy-consuming activity because of a toxic effect. Cluster analysis on chemical composition and IR% data provides evidence of a statistically significant association between the adverse effects on living cells and the range of specific chemical species in PM 10 . [ABSTRACT FROM AUTHOR]

The advent of high-throughput sequencing technologies in recent years has revealed the unexpected presence of genus Photobacterium within the chicken meat spoilage ecosystem. This study was undertaken to decipher the occurrence, the growth patterns and the genotypic biodiversity of Photobacterium phosphoreum on chicken breast fillets stored aerobically at 4 °C through conventional microbiological methods and molecular techniques. Samples were periodically cultured on marine broth agar (MA; supplemented with meat extract and vancomycin) for the enumeration of presumptive bioluminescent Photobacterium spp. In total, 90 bioluminescent bacteria were recovered from the initial (time of first appearance), middle and end stages of storage. Concomitantly, 95 total psychrotrophic/psychrophilic bacteria were isolated from the same medium to assess the presence and diversity of non-luminous photobacteria. Genetic diversity between bioluminescent isolates was assessed with two PCR-based DNA fingerprinting methods, i.e. RAPD and rep-PCR. Moreover, the characterization of selected bacterial isolates at the genus and/or species level was performed by sequencing of the 16S rRNA and/or gyr B gene. Bioluminescent bacteria were scarcely encountered in fresh samples at population levels of ca. 2.0 log CFU/g, whilst total psychrotrophic/psychrophilic bacteria were found at levels of ca. 4.4 log CFU/g. As time proceeded and close to shelf-life end, bioluminescent bacteria were encountered at higher populations, and were found at levels of 5.3 and 7.0 log CFU/g in samples from the second and third batch, respectively. In the first batch their presence was occasional and at levels up to 3.9 log CFU/g. Accordingly, total psychrotrophic/psychrophilic bacteria exceeded 8.4 log CFU/g at the end of storage, suggesting the possible underestimation of bioluminescent populations following the specific cultivation conditions. Sequence analysis assigned bioluminescent isolates to Photobacterium phosphoreum , while genetic fingerprinting revealed high intra-species variability. Respectively, total psychrotrophs/psychrophiles were assigned to genera Pseudomonas , Shewanella , Psychrobacter , Acinetobacter , Vibrio and Photobacterium. Non-luminous photobacteria were not identified within the psychrotrophs/psychrophiles. Results of the present study reveal the intra- and inter-batch variability on the occurrence and growth responses of P. phosphoreum and highlight its potential role in the chicken meat spoilage consortium. • Insights into genetic variability of bioluminescent photobacteria in refrigerated chicken breast fillets. • P. phosphoreum levels varied within and between batches in fresh and spoiled samples. • P. phosphoreum population was found at levels potentially connected with spoilage processes. • Non-luminous photobacteria were not detected in spoilage microbiota. [ABSTRACT FROM AUTHOR]

We describe an antibacterial assay based on bioluminescence of two Gram negative bacteria, Photorhabdus luminescens and transformed Escherichia coli, which can be used as a real-time measurement of antibacterial activity in insect haemolymph. This method is based on the production of the bioluminescence signal depending on the viability of bacterial cells. We observed a significant rapid dose-dependent decrease in bioluminescence using both bacterial species, and Bombyx mori or Galleria mellonella haemolymph, which was confirmed by the decrease in bacterial viability determined by plating. The humoral origin of the antibacterial activity observed in whole haemolymph was confirmed for haemolymph plasma without haemocytes. Antibacterial activity directed against Gram negative bacteria was recorded in unaffected insect larvae as well as after septic injury; increased antibacterial activity of haemolymph was detected in the latter case confirming the inducibility of antimicrobial agents. We think it is likely that this method could be widely used for determining antibacterial activity in insects and other invertebrates.

A biosensitive element in the form of bacterial Photobacterium phosphoreum cells immobilized in poly(vinyl alcohol) cryogel was tested for the determination of different mycotoxins under discrete and flow-through analysis conditions. The immobilized bioluminescent cells made it possible to quantify the presence of Ochratoxin A, Sterigmatocystin, Zearalenone, and Deoxynivalenon in aqueous media in a wide range of their concentrations (0.017−56 mg/L, 0.010−33 mg/L, 0.009−14 mg/L, and 0.026−177 mg/L, respectively) via measuring the quenching of cell luminescence. The flow conditions allowed the analysis sensitivity to be improved by an order of magnitude in terms of detected concentrations. Using the immobilized luminescent bacterial cells, we have shown the possibility of evaluating the efficiency of the mycotoxins’ hydrolysis under the action of enzymes. In this way, a 94 ± 4.5% efficiency of Zearalenone hydrolysis with hexahistidine-containing organophosphorus hydrolase for 1h-long treatment of the mycotoxin solution (100 mg/L) was shown.

Purpose: The present study aims to develop five Gram-negative bacteria expressing bacterial luciferase for use to evaluate the influence of different antibiotics on bacterial bioluminescence.Procedures: The pBBR-lux plasmid was introduced into five Gram-negative bacteria; the bioluminescent signals and colony-forming unit (CFU)/ml of all the bioluminescent strains were monitored with six antibiotics at various concentrations.Results: Dose-dependent bioluminescence signals can be used for rapid bacterial antibiotic susceptibility test (AST). All five bioluminescent bacterial strains have similar bioluminescence and CFU enhancement at sub-minimum inhibitory concentration (MIC) of six different antibiotics.Conclusion: The bioluminescent signals and CFU enhancement at sub-MIC antibiotic concentrations should be of value in the research of new antibiotic drugs and bioluminescent imaging. [ABSTRACT FROM AUTHOR]

Secretory phospholipasesA2 (sPLA2s) form a large family of structurally related enzymes widespread in nature. Herein, we studied the inhibitory effects of sPLA2s from Vipera lebetina (VLPLA2), Vipera berus berus (VBBPLA2), and Naja naja oxiana (NNOPLA2) venoms on (i) human platelets, (ii) four different bacterial strains (gram-negative Escherichia coli and Vibrio fischeri; gram-positive Staphylococcus aureus and Bacillus subtilis) and (iii) five types of cancer cells (PC-3, LNCaP, MCF-7, K-562 and B16-F10) in vitro. sPLA2s inhibited collagen-induced platelet aggregation: VBBPLA2 IC50 = 0.054, VLPLA2 IC50 = 0.072, NNOPLA2 IC50 = 0.814 μM. p-Bromophenacylbromide-inhibited sPLA2 had no inhibitory action on platelets. 36.17 μM VBBPLA2 completely inhibited the growth of gram-positive Bacillus subtilis whereas no growth inhibition was observed towards gram-negative Escherichia coli. The inhibitory action of sPLA2s (~0.7 μM and ~7 μM) towards cancer cells depended on both venom and cell type. VBBPLA2 (7.2 μM) inhibited significantly the viability of K-562 cells and the cell death appeared apoptotic. The sPLA2s exhibited no inhibitory effect towards LNCaP cells and some effect (8%–20%) towards other cells. Thus, already sub-μM concentrations of sPLA2s inhibited collagen-induced platelet aggregation and from the current suite of studied svPLA2s and test cells, VBBPLA2 was the most growth inhibitory towards Bacillus subtilis and K-562 cells.

Artificial sweeteners have become increasingly controversial due to their questionable influence on consumers’ health. They are introduced in most foods and many consume this added ingredient without their knowledge. Currently, there is still no consensus regarding the health consequences of artificial sweeteners intake as they have not been fully investigated. Consumption of artificial sweeteners has been linked with adverse effects such as cancer, weight gain, metabolic disorders, type-2 diabetes and alteration of gut microbiota activity. Moreover, artificial sweeteners have been identified as emerging environmental pollutants, and can be found in receiving waters, i.e., surface waters, groundwater aquifers and drinking waters. In this study, the relative toxicity of six FDA-approved artificial sweeteners (aspartame, sucralose, saccharine, neotame, advantame and acesulfame potassium-k (ace-k)) and that of ten sport supplements containing these artificial sweeteners, were tested using genetically modified bioluminescent bacteria from E. coli. The bioluminescent bacteria, which luminesce when they detect toxicants, act as a sensing model representative of the complex microbial system. Both induced luminescent signals and bacterial growth were measured. Toxic effects were found when the bacteria were exposed to certain concentrations of the artificial sweeteners. In the bioluminescence activity assay, two toxicity response patterns were observed, namely, the induction and inhibition of the bioluminescent signal. An inhibition response pattern may be observed in the response of sucralose in all the tested strains: TV1061 (MLIC = 1 mg/mL), DPD2544 (MLIC = 50 mg/mL) and DPD2794 (MLIC = 100 mg/mL). It is also observed in neotame in the DPD2544 (MLIC = 2 mg/mL) strain. On the other hand, the induction response pattern may be observed in its response in saccharin in TV1061 (MLIndC = 5 mg/mL) and DPD2794 (MLIndC = 5 mg/mL) strains, aspartame in DPD2794 (MLIndC = 4 mg/mL) strain, and ace-k in DPD2794 (MLIndC = 10 mg/mL) strain. The results of this study may help in understanding the relative toxicity of artificial sweeteners on E. coli, a sensing model representative of the gut bacteria. Furthermore, the tested bioluminescent bacterial panel can potentially be used for detecting artificial sweeteners in the environment, using a specific mode-of-action pattern.

Bioluminescent bacteria in the form of a cell suspension for on-site hazard analysis are not suitable as in vivo luminescence in free cells fluctuates and may lead to erroneous results. Furthermore, the culture broth cannot be stored for long durations to continue sensing analytes as the luminescence ceases over time. Factors that affect luminescence response include growth dynamism, and ambient environmental conditions. The present study investigated the effect of storage conditions such as temperature (25 ± 2°C, room temperature; 4°C; and -20°C) and ambient aqueous environment (M1: sucrose, 1.02 M; M2, bioluminescent media [tryptone, 10 g L -1 ; NaCl, 28.5 g L -1 ; MgCl 2 .7H 2 O, 4.5 g L -1 ; CaCl 2 , 0.5 g L -1 ; KCl 0.5 g L -1 ; yeast extract, 1 g L -1 ; H 2 O, 1 L]; M3, bioluminescent media and 95% glycerol, 1:1 ratio) on the luminescence emission from the calcium alginate-immobilized Photobacterium phosphoreum (S b ) against the cells in free suspension for an extended period. The results indicated that both the parameters that were undertaken markedly affected the luminescence. In the study, S b showed an enhanced luminescence emission than the control up to 18.5-fold and for a prolonged period which can be efficiently utilized for rapid biosensing of hazardous materials., (© 2023 John Wiley & Sons Ltd.)

Various water samples were successfully evaluated using a panel of different recombinant bioluminescent bacteria and estrogenic activity analysis. The bioluminescent bacteria strains induced by oxidative (superoxide radical or hydroxyl radical), protein damage, cell membrane damage, or cellular toxicity were used. Estrogenic activities were examined by using the yeast strain BY4741, which carries the β-galactosidase reporter gene under the control of the estrogen-responsive element (ERE). A total of 14 samples from three wastewater treatment plants, one textile factory, and seawater locations in Tunisia were analyzed. A wide range of bio-responses were described. Site/sample heterogeneity was prevalent, in combination with generally high relative bioluminescence scores for oxidative stress (OH•). Estrogenic activity was detected at all sites and was particularly elevated at certain sites. Our perspectives include the future exploration of the variation detected in relation to treatment plant operations and environmental impacts. In conclusion, this new multi-experimental method can be used for rapid bio-response profile monitoring and the evaluation of environmental samples spanning a wide range of domains. This study confirms that bio-reactive wastewater treatment plant (WWTP) effluents are discharged into seawater, where they may impact coastal populations. [ABSTRACT FROM AUTHOR]

Nanosized inorganic metal oxides, such as TiO 2 , ZnO, γ -Al 2 O 3 , are proposed as heterogeneous catalysts for the oxidative degradation of chemical warfare agents (CWA), particularly of organosulfur toxic agents, into oxidised products with reduced toxicity. The morphology, structural and textural properties of the catalysts were investigated. Furthermore, their catalytic properties were evaluated in the oxidative abatement of (2-chloroethyl)ethylsulfide, CEES, a simulant of sulfur mustard (blistering CWA). Their performance was also compared to a conventional decontamination powder and a commercial Nb 2 O 5 sample. The metal oxides powders were then employed in the active oxidative decontamination of CEES from a cotton textile substrate, mimicking a real contamination occurrence. Remarkable results in terms of abatement and degradation into desired products were recorded, achieving good conversions and decontamination efficiency with Nb 2 O 5 , TiO 2 and γ -Al 2 O 3 , under very mild conditions, with hydrogen peroxide (as aqueous solution or as urea-hydrogen peroxide adduct), at room temperature and ambient pressure. In the aim of a real on-field use, the potential environmental impact of these solids was also evaluated by bioluminescence toxicity tests on reference bacteria ( Photobacterium leiognathi Sh1), showing a negligible negative impact for TiO 2 , γ -Al 2 O 3 , and Nb 2 O 5 . A major biotoxic effect was only found for ZnO. [ABSTRACT FROM AUTHOR]

To prevent the attachment of bacteria to implant surfaces, the 1D zinc oxide nanowire-coating has been successfully developed on material surfaces by using a custom-made hydrothermal approach. The chemical nature, surface topography and wettability of spike-like 1D ZnO nanowire-coating are comprehensively investigated. The anti-adhesive and antimicrobial properties of 1D nanowire-coating are tested against Staphylococcus aureus , Pseudomonas aeruginosa and Escherichia coli by using in vitro live/dead staining and scanning electron microscopy. We find that the adhesion of bacteria can be reduced via the special spike-like topography and that the release of Zn 2+ ions can help suppress the growth of attached bacteria. Furthermore, the antimicrobial effect is also evaluated under in vivo conditions by using a rat model infected with bioluminescent S. aureus . The amount of live bacteria in the rat implanted with a nanowire-coated sample is less than that of the control at various time points. Hence, it is believed that the nanowire-coated material is promising for application in orthopaedic implantation after the long-term animal studies have been completed. [ABSTRACT FROM AUTHOR]

ABSTRACT When found in excess, phosphorus (P) has been linked to surface water eutrophication. As a result, adsorbents are now used in P remediation efforts. However, possible secondary toxicological impacts on the use of new materials for P removal from surface water have not been reported. This study evaluated the toxicity of adsorbent materials used in the removal of P from surface water including: fly ash, bottom ash, alum sludge, a proprietary mix of adsorbents, and a proprietary engineered material. Toxicity screening was conducted by performing solid-liquid extractions (SLEs) followed by the bacterial bioluminescence inhibition test with a Microtox® M500. Of the materials tested, the samples extracted at lower pH levels demonstrated higher toxicity. The material exhibiting the most toxic response was the iron and aluminum oxide coated engineered material registering a 66-67% 15-min EC50 level for pH 4 and 5 SLEs, respectively. However, for SLEs prepared at pH 7, toxic effects were not detected for this engineered material. Fly ash and bottom ash demonstrated between 82 and 84% 15-min EC50 level, respectively, for pH 4 SLE conditions. Dried alum sludge and the proprietary mix of adsorbents were classified as having little to no toxicity. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 489-495, 2016. [ABSTRACT FROM AUTHOR]

This study assesses the comparative sensitivity and possibility of obtaining fast results of various methods of biotesting for several surfactants: Tween 85, sodium dodecyl sulfate (SDS), Fairy dishwashing gel, and Mif washing powder. The following test organisms are used for the study: luminescent bacteria Photobacterium phosphoreum (Beijerinck), preparation of Ecolum luminescent bacteria, unicellular algae Scenedesmus quadricauda (G.M. Smith), infusorian Paramecium caudatum (Ehrenberg), and crustacean Daphnia magna (Straus). It has been revealed that Fairy dishwashing gel possesses the strongest toxicity against the studied test objects. Daphnia and algae are most sensitive to the effects of Fairy and SDS, protozoan and luminescent bacteria are most sensitive to SDS, and Ecolum is most sensitive to Mif washing powder. The tested aquatic organisms and Ecolum are most tolerant to the effect of Tween 85. [ABSTRACT FROM AUTHOR]