Synthetic Biocides Research Articles

Biosurfactants: Eco-Friendly and Innovative Biocides against Biocorrosion.

Corrosion influenced by microbes, commonly known as microbiologically induced corrosion (MIC), is associated with biofilm, which has been one of the problems in the industry. The damages of industrial equipment or infrastructures due to corrosion lead to large economic and environmental problems. Synthetic chemical biocides are now commonly used to prevent corrosion, but most of them are not effective against the biofilms, and they are toxic and not degradable. Biocides easily kill corrosive bacteria, which are as the planktonic and sessile population, but they are not effective against biofilm. New antimicrobial and eco-friendly substances are now being developed. Biosurfactants are proved to be one of the best eco-friendly anticorrosion substances to inhibit the biocorrosion process and protect materials against corrosion. Biosurfactants have recently became one of the important products of bioeconomy with multiplying applications, while there is scare knowledge on their using in biocorrosion treatment. In this review, the recent findings on the application of biosurfactants as eco-friendly and innovative biocides against biocorrosion are highlighted.

A triclosan-resistance protein from the soil metagenome is a novel enoyl-acyl carrier protein reductase: Structure-guided functional analysis.

The synthetic biocide triclosan targets enoyl-acyl carrier protein reductase(s) (ENR) in bacterial type II fatty acid biosynthesis. Screening and sequence analyses of the triclosan resistome from the soil metagenome identified a variety of triclosan-resistance ENRs. Interestingly, the mode of triclosan resistance by one hypothetical protein was elusive, mainly due to a lack of sequence similarity with other proteins that mediate triclosan resistance. Here, we carried out a structure-based function prediction of the hypothetical protein, herein referred to as FabMG, and invivo and invitro functional analyses. The crystal structure of FabMG showed limited structural homology with FabG and FabI, which are also involved in type II fatty acid synthesis. Invivo complementation and invitro activity assays indicated that FabMG is functionally a FabI-type ENR that employs NADH as a coenzyme. Variations in the sequence and structure of FabMG are likely responsible for inefficient binding of triclosan, resulting in triclosan resistance. These data unravel a previously uncharacterized FabMG, which is prevalent in various microbes in triclosan-contaminated environments and provide mechanistic insight into triclosan resistance.

Investigation of finishing of leather for inside parts of the shoes with a natural biocide

The prevention of decrease of quality caused by microbial activity in footwear materials entails the use of biocides. However, these substances may pose a hazard to humans and to the natural environment. The paper presents the results of antimicrobial effect investigation for cowhide leather treated with oregano oil. In these studies oil was applied by spraying onto the finished leather surface and examined to determine its antimicrobial activity by using the Agar Diffusion Plate Test. These results were compared with those where a cowhide leather was treated with oil at the stage of fatliquoring. In addition, the oregano oil toxicity level was assessed and compared with biocides used in the tanning industry. Introducing oregano oil into the leather at the stage of fatliquoring provides a better antimicrobial effect than by spraying, however hygienic finishing of leather can be obtained by introducing oil into the raw material by these both methods. The oregano oil is characterised by the lowest number of hazards and toxicity as compared with commercial biocides. The use of essential oils as natural biocides in the tanning industry seems to be especially important and suitable solution considering the harmful effects of synthetic biocides to humans and the environment.

Control of contaminants in the in vitro establishment of Guadua latifolia

ABSTRACT The Amazonian bamboo forests are located in an important region of high biodiversity in Brazil, Peru and Bolivia, forming the largest native bamboo forest reserve in the world. However, the bamboos from these forests have characteristics that hinder their propagation. This study aimed to evaluate the biocide action of a plant preservative mixture for controling contaminants, during the in vitro establishment of Guadua latifolia (Bonpl.) Kunth, a species native to the region. Nodal segments were cultured in a semi-solid medium containing Plant Preservative Mixture (PPMTM), at the concentrations of 0; 1; 2; and 3 mL L-1, and supplemented with 2 mg L-1 of 6-benzylaminopurine. The analyzed variables were number of shoots, percentage of bacterial and fungal contamination, and shoot survival. The treatments with the synthetic biocide were efficient in controlling the in vitro contamination caused by bacteria and fungi (Fusarium sp.), also presenting the highest survival rate of regenerated shoots. For the in vitro establishment of this native bamboo species, the use of 2 mL L-1 of PPMTM is recommended.

Inhibition of microbial influenced corrosion on carbon steel ST37 using biosurfactant produced by Bacillus sp.

Microbial influenced corrosion that associated with biofilm has been one of the major problem in industry. It causes damage to equipment and infrastructure because of rapid material deterioration and often resulting in pipeline failures. Pipeline failures can lead to large economic losses and environmental problems. Synthetic chemical biocides are commonly used to prevent corrosion but are not effective against preformed biofilm on pipes and toxic to the environment. A new antimicrobial is being developed by using biosurfactant produced by indigenous oil reservoir bacteria Bacillus sp. to prevent and eradicate biofilm. This study aims to determine minimum inhibitory concentration (MIC), minimum biofilm inhibitory concentration (MBIC), and minimum biofilm eradication concentration for 50% eradication (MBEC50) of biosurfactant against biofilm forming bacteria isolated from oil resevoir, its effect on biofilm community structure and its ability to inhibit the corrosion rate of Carbon Steel ST37. MIC, MBIC, and MBEC50 were determined using broth macrodillution technique, biofilm community structure were analyzed using total plate count method, and corrosion rate of steel were determined using weight loss method. Biofilm and corroded steel surface was also visualized using SEM-EDS. From this study, it is revealed that MIC, MBIC, and MBEC50 values respectively are 62.5; 31.25; and 500 μg ml−1. Biosufactant is able to inhibit Pseudomonas sp. 1 and Pseudomonas sp. 2 attachment to Carbon Steel ST37 surface and also able to eradicate preformed biofilm on steel surface. This study also showed the reduction of corrosion rate in Carbon Steel ST 37 as a result of biosurfactants treatment; from 4.56 × 10−4 mm year−1 to 3.31 × 10−4 mm year−1 based on MBIC value and from 5.18 × 10−5 mm year −1 to 2.7 × 10−5 mm year−1 after biofilm eradication at MBEC value. The results showed that biosurfactant in this study could be a good candidate for a new anti-corrosion agent.

Plant secondary metabolites against arthropods of medical importance

Natural compounds of botanical origin are increasingly being investigated for the development of novel biocides. Intensive use of synthetic biocides and the confined array of chemical classes in use has led to the buildup of unwanted residues and to parasites’ adaptive responses and resistance. Meanwhile, the geographic and host ranges of arthropod vectors and vector-borne diseases are broadening. In an effort to develop “friendly” biocidal compounds for the environment and human health, plant secondary metabolites originating in a number of botanical families could be engaged. This mini-review compiles the recently available knowledge on plant secondary metabolites exhibiting biocidal properties and provides a brief overview on their activity against arthropods with a focus on toxic and repellent properties. The selected examples show that it is valuable to consider plants as a promising source for new products development to support the fight against arthropods related to human health. Finally, we outline the biocides regulatory framework in the European Union (EU) and pinpoint some issues of concern regarding the development of low risk biocides. Plant secondary metabolites acting against arthropods of medical importance

Short-chain diamines are the physiological substrates of PACE family efflux pumps

Acinetobacter baumannii has rapidly emerged as a major cause of gram-negative hospital infections worldwide. A. baumannii encodes for the transport protein AceI, which confers resistance to chlorhexidine, a widely used antiseptic. AceI is also the prototype for the recently discovered proteobacterial antimicrobial compound efflux (PACE) family of transport proteins that confer resistance to a range of antibiotics and antiseptics in many gram-negative bacteria, including pathogens. The gene encoding AceI is conserved in the core genome of A. baumannii, suggesting that it has an important primordial function. This is incongruous with the sole characterized substrate of AceI, chlorhexidine, an entirely synthetic biocide produced only during the last century. Here we investigated a potential primordial function of AceI and other members of the PACE family in the transport of naturally occurring polyamines. Polyamines are abundant in living cells, where they have physiologically important functions and play multifaceted roles in bacterial infection. Gene expression studies revealed that the aceI gene is induced in A. baumannii by the short-chain diamines cadaverine and putrescine. Membrane transport experiments conducted in whole cells of A. baumannii and Escherichia coli and also in proteoliposomes showed that AceI mediates the efflux of these short-chain diamines when energized by an electrochemical gradient. Assays conducted using 8 additional diverse PACE family proteins identified 3 that also catalyze cadaverine transport. Taken together, these results demonstrate that short-chain diamines are common substrates for the PACE family of transport proteins, adding to their broad significance as a novel family of efflux pumps.

Lung cancer mortality and exposure to synthetic metalworking fluid and biocides: controlling for the healthy worker survivor effect

ObjectivesSynthetic metalworking fluids (MWFs), widely used to cool and lubricate industrial machining and grinding operations, have been linked with increased risk of several cancers. Estimates of their relation with lung...

Lauroyl Arginate Ethyl Blocks the Iron Signals Necessary for Pseudomonas aeruginosa Biofilm Development.

Pseudomonas aeruginosa is a ubiquitous gram-negative bacterium capable of forming a biofilm on living and non-living surfaces, which frequently leads to undesirable consequences. We found that lauroyl arginate ethyl (LAE), a synthetic non-oxidizing biocide, inhibited biofilm formation by P. aeruginosa at a sub-growth inhibitory concentration under both static and flow conditions. A global transcriptome analysis was conducted using a gene chip microarray to identify the genes targeted by LAE. In response to LAE treatment, P. aeruginosa cells up-regulated iron acquisition and signaling genes and down-regulated iron storage genes. LAE demonstrated the capacity to chelate iron in an experiment in which free LAE molecules were measured by increasing the ratio of iron to LAE. Furthermore, compared to untreated cells, P. aeruginosa cells treated with LAE exhibited enhanced twitching motility, a phenotype that is usually evident when the cells are starved for iron. Taken together, these results imply that LAE generated iron-limiting conditions, and in turn, blocked iron signals necessary for P. aeruginosa biofilm development. As destroying or blocking signals leading to biofilm development would be an efficient way to mitigate problematic biofilms, our findings suggest that LAE can aid in reducing P. aeruginosa biofilms for therapeutic and industrial purposes.

Comparative Analysis of Irish Potato (Solanum tuberosum L.) Production in the Farming Sectors that Emerged from Zimbabwe’s Radical Land Reform of 2000

Irish potato production in Zimbabwe can be traced back to the early 1900s. Large-scale commercial farmers dominated production until the early 2000s. Potato is the most important horticultural crop and has been declared a strategic national food security crop in 2012. In 2000, the Fast Track Land Reform Programme completely restructured commercial agriculture and potato farming. A product of the agrarian reforms, the A2 and A1 resettlement growers, started growing potato. The A1 resettlement model has individually owned cropping land and shared grazing, while A2 resettlement comprises of self-contained farm units. A survey was conducted to characterise potato growers, mainly to understand the current potato production systems and to assess the impact of the landmark reform programme on potato farming. Four production systems, large-scale commercial, communal area, A2 resettlement and A1 resettlement, were identified, and two main growing agro-ecological zones, the Highveld and Eastern Nyanga Highlands. In 1961–2013, significant positive trends for annual planted area, average yield and total production were observed. In terms of yield, Zimbabwe is fourth in southern Africa with an average yield of 17 t ha−1 in the 2009–2013 period. Large-scale commercial and A2 resettlement systems were well-mechanised, and growers owned large land holdings ranging from an average of 165–1600 and 31–390 ha across the different areas, respectively, with average potato areas of 11 and 8 ha, respectively. A1 resettlement and communal area growers owned an average of 4 and 3 ha cropping area, respectively, with average potato areas of 0.4 and 1.1 ha, respectively. Input use was significantly different among the production systems. High synthetic fertiliser and biocide use was observed.

Ecological and Economic Tools for Assessing Efficiency of Physicochemical Wastewater Treatment Methods

Ecological and economic characteristics of wastewater treatment processes are studied by the example of assessment of effectiveness of synthetic and natural adsorbents and biocide flocculants. The norms for the maximum allowable discharge are calculated taking account of the achieved wastewater treatment quality indexes. Calculations of ecological hazard index that determines the adverse effect of highly concentrated wastewaters on the environment are presented. The effectiveness of nature protection measures for reducing the inflicted damage is shown.

Comparison of the efficacy of natural-based and synthetic biocides to disinfect silicone and stainless steel surfaces.

New biocidal solutions are needed to combat effectively the evolution of microbes developing antibiotic resistance while having a low or no environmental toxicity impact. This work aims to assess the efficacy of commonly used biocides and natural-based compounds on the disinfection of silicone and stainless steel (SS) surfaces seeded with differentStaphylococcus aureusstrains. Minimum inhibitory concentration was determined for synthetic (benzalkonium chloride-BAC, glutaraldehyde-GTA,ortho-phthalaldehyde-OPA and peracetic acid-PAA) and natural-based (cuminaldehyde-CUM), eugenol-EUG and indole-3-carbinol-I3C) biocides by the microdilution method. The efficacy of selected biocides at MIC, 10 × MIC and 5500 mg/L (representative in-use concentration) on the disinfection of sessileS. aureuson silicone and SS was assessed by viable counting. Silicone surfaces were harder to disinfect than SS. GTA, OPA and PAA yielded complete CFU reduction of sessile cells for all test concentrations as well as BAC at 10 × MIC and 5500 mg/L. CUM was the least efficient compound. EUG was efficient for SS disinfection, regardless of strains and concentrations tested. I3C at 10 × MIC and 5500 mg/L was able to cause total CFU reduction of silicone and SS deposited bacteria. Although not so efficient as synthetic compounds, the natural-based biocides are promising to be used in disinfectant formulations, particularly I3C and EUG.

Assessing cypermethrin penetration in Pinus sylvestris wood products by immuno-electron microscopy

The preservative efficacy of organic biocidal products is strongly related to their capacity of penetration and retention within wood tissues. The specific detection of the pyrethroid insecticide cypermethrin is currently obtained after extraction followed by chemical analysis by chromatography techniques. However, visualizing the insecticide molecule within the wood structure requires specific probes together with microscopy techniques. Therefore, the aim of the present work was to prepare a polyclonal antibody directed against cypermethrin and to implement it on Pinus sylvestris wood samples treated with technical cypermethrin. The antibody was tested on cypermethrin-impregnated wood, and the specific recognition of the insecticide was visualized by transmission electron microscopy (TEM). The immunogold-TEM assay evidenced the capacity of the synthetic biocide active substance to penetrate in the wood. The depth of penetration was measured on sections taken at increasing distances from the coated surface of the wood. Under the present conditions of application, cypermethrin was shown to penetrate up to the 6- to 9-mm zone below the surface. Such results correlated with chemical analyses carried out by GC-ECD after extraction. In addition, the immuno-TEM investigation allowed visualizing, for the first time at the ultrastructure scale of resolution, that cypermethrin was able to diffuse within the secondary wood cell walls. The scarce labeling of the compound middle lamella shows that the chemical does not diffuse freely in this part of the cell walls. The results suggest that the adsorption within the cell walls is an essential factor for the retention of cypermethrin and for its permanence in treated wood products.

Field evaluation of the effectiveness of mesh crop covers for the protection of potatoes from tomato potato psyllid

Tomato potato psyllid (TPP; Bactericera cockerelli) is a serious pest of solanaceous crops in New Zealand. Control of TPP is currently dominated by synthetic biocides, although this method is curative and does not always prevent transmission of TPP-vectored plant diseases. This study evaluated mesh crop covers as non-chemical alternatives for controlling TPP in potato crops. Over two growing seasons in Canterbury, New Zealand, potatoes growing under mesh covers were found to have reduced numbers of TPP nymphs and adults, increased tuber size, increased overall yield and enhanced storage potential compared with uncovered plots. There was also a slight reduction in potato blight spores under mesh, and the actual occurrence of blight was slightly reduced in one trial. The results of this study indicate that mesh crop covers could provide a viable option for potato growers who wish to protect their crops from TPP without using chemical insecticides.

Efficacy of triclosan as an antimicrobial hand soap and its potential impact on antimicrobial resistance: a focused review.

Triclosan is a synthetic biocide found in many household products, including antimicrobial hand soap. Levels of triclosan have been found throughout the environment and in human urine, blood, and even breast milk. Increasing levels of exposure to triclosan have led to concerns over the development of resistance to triclosan and cross-resistance to other antimicrobials. We performed a literature search to assess whether the widespread use of triclosan displays a favorable benefit: risk ratio, defined by evaluation of triclosan's efficacy as an antimicrobial hand soap and its potential effect on the development of antimicrobial resistance. Data from laboratory-based studies regarding the efficacy of triclosan are conflicting, although well-designed studies suggest no significant difference in efficacy over nonantimicrobial soap. In addition, when triclosan was introduced in a community setting, no beneficial effects were observed on the reduction of infections over nonantimicrobial soap. Resistance to triclosan and cross-resistance to antimicrobials have been consistently demonstrated in laboratory settings, although overall resistance rates and cross-resistance rates in the community setting are low. Based on the available evidence, the risk of potential antimicrobial resistance outweighs the benefit of widespread triclosan use in antimicrobial soaps.

Pore size criteria of mesh crop covers for the exclusion of tomato-potato psyllid (Bactericera cockerelli)

Control methods for tomato-potato psyllid (TPP; Bactericera cockerelli) are currently dominated by the use of synthetic biocides. A non-chemical alternative for TPP management is crop mesh, which forms a physical barrier between crop and pest. This study examined the ability of TPP adults to penetrate, or lay eggs through, 22 commercially available crop meshes using a laboratory bioassay. Adult TPP were prevented from moving through the mesh if the mesh complied with any one of the following criteria: shortest pore length <0.55 mm; longest pore length <0.60 mm; diagonal length <0.85 mm; area <0.3 mm2. Eggs were found on foliage only when TPP adults had penetrated the mesh, suggesting that eggs could not be laid through the mesh. The results indicate that crop meshes may provide non-chemical control for TPP that can be used by organic growers, and producers attempting to reduce chemical inputs as part of integrated pest management.

Comparative surface antimicrobial properties of synthetic biocides and novel human apolipoprotein E derived antimicrobial peptides

Medical device infection remains a major clinical concern. Biocidal compounds have been incorporated into medical device materials ideally to inhibit bacterial colonisation whilst exhibiting relatively low cytotoxicity. We compared the antibacterial activity, anti-biofilm efficacy and cytotoxicity of a novel peptide derivative of human apolipoprotein E (apoEdpL-W) to that of commonly used biocides, before and after coating onto a range of standard polymers. Since the antimicrobial function of most biocides frequently involves associations with cellular membranes, we have also studied the detailed interactions of the test antimicrobials with phospholipid bilayers, using the quartz crystal microbalance device combined with dual-polarisation interferometry. ApoEdpL-W displayed broad-spectrum antibacterial activity and marked efficacy against nascent Staphylococcus aureus biofilms. Compounds showed better antimicrobial activity when combined with hydrogel materials than with non-porous materials. The membrane interactions of apoEdpL-W were most similar to that of PHMB, with both agents appearing to readily bind and insert into lipid bilayers, possibly forming pores. However apoEdpL-W showed lower cytotoxicity than PHMB, its efficacy was less affected by the presence of serum, and it demonstrated the highest level of biocompatibility of all the biocides, as indicated by our measurement of its antimicrobial biocompatibility index. This work shows the potential of apoEdpL-W as an effective antiseptic coating agent.

Enhanced biocidal activity of Au nanoparticles synthesized in one pot using 2, 4-dihydroxybenzene carbodithioic acid as a reducing and stabilizing agent

BackgroundThe conjugation of gold nanoparticles with biocides such as natural products, oligosaccharides, DNA, proteins has attracted great attention of scientists recently. Gold NPs covered with biologically important molecules showed significant enhancement in biological activity in comparison with the activity of the free biocides. However, these reports are not very systematic and do not allow to draw definitive conclusions. We therefore embarked in a systematic study related to the synthesis and characterization of biocidal activities of Au nanoparticles conjugated to a wide variety of synthetic and natural biomolecules. In this specific report, we investigated the activity of a synthetic biocide, 2-4, Dihydroxybenzene carbodithioic acid (DHT).ResultsAu nanoparticles (NP) with a mean size of about 20 nm were synthesized and functionalized in one pot with the help of biocide 2,4-Dihydroxybenzene carbodithioic acid (DHT) to reduce HAuCl4 in aqueous solution. Conjugation of DHT with gold was confirmed by FT-IR and the amount of DHT conjugated to the Au nanoparticles was found to be 7% by weight by measuring the concentration of DHT in the supernatant after centrifugation of the Au NPs. To ascertain the potential for in vivo applications, the stability of the suspensions was investigated as a function of pH, temperature and salt concentration. Antibacterial, antifungal, insecticidal and cytotoxic activities of the Au-DHT conjugates were compared with those of pure DHT and of commercially available biocides. In all cases, the biocidal activity of the Au-DHT conjugates was comparable to that of commercial products and of DHT.ConclusionsSince the DHT concentration in the Au-DHT conjugates was only about 7%, our results indicate that conjugation to the Au NPs boosts the biocidal activity of DHT by about 14 times. The suspensions were found to be stable for several days at temperatures of up to 100°C, salt concentrations up to 4 mol/L and a pH range of 2-13.

Staphylococcus epidermidis Isolated in 1965 Are More Susceptible to Triclosan than Current Isolates

Since its introduction to the market in the 1970s, the synthetic biocide triclosan has had widespread use in household and medical products. Although decreased triclosan susceptibility has been observed for several bacterial species, when exposed under laboratory settings, no in vivo studies have associated triclosan use with decreased triclosan susceptibility or cross-resistance to antibiotics. One major challenge of such studies is the lack of strains that with certainty have not been exposed to triclosan. Here we have overcome this challenge by comparing current isolates of the human opportunistic pathogen Staphylococcus epidermidis with isolates collected in the 1960s prior to introduction of triclosan to the market. Of 64 current S. epidermidis isolates 12.5% were found to have tolerance towards triclosan defined as MIC≥0.25 mg/l compared to none of 34 isolates obtained in the 1960s. When passaged in the laboratory in the presence of triclosan, old and current susceptible isolates could be adapted to the same triclosan MIC level as found in current tolerant isolates. DNA sequence analysis revealed that laboratory-adapted strains carried mutations in fabI encoding the enoyl-acyl carrier protein reductase isoform, FabI, that is the target of triclosan, and the expression of fabI was also increased. However, the majority of the tolerant current isolates carried no mutations in fabI or the putative promoter region. Thus, this study indicates that the widespread use of triclosan has resulted in the occurrence of S. epidermidis with tolerance towards triclosan and that the adaptation involves FabI as well as other factors. We suggest increased caution in the general application of triclosan as triclosan has not shown efficacy in reducing infections and is toxic to aquatic organisms.

Application of essential oils of thyme as a natural preservative in leather tanning

The aim of this study was to investigate the possibility of using essential oils of Thymus vulgaris as an alternative preservative for chromed leather. The differences between the chemical composition of commercial and pure essential oils of thyme were determined. It was observed that these differences have an influence on the antibacterial activity of essential oils. Gram-positive bacteria were found to be more sensitive to the essential oils of thyme than Gram-negative bacteria. The bacteria Pseudomonas aeruginosa had a low sensitivity to the action of the selected essential oils of thyme, but the leather samples treated with the essential oils of thyme remained resistant to the action of these bacteria. As the main result of this study, it was concluded that the essential oil of thyme could be used as a preservation agent in the leather tanning industry. The leather preserved with 2-(thiocyanomethylthio)benzothiazole had weaker protection after four weeks compared to the samples treated with the essential oil of thyme when the amount of the used essential oil was not less than 3% of the wet-blue mass. The essential oil of thyme was the more active component in the mixture of essential oil and synthetic biocide used for the preservation of leather.