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Abstract: Surfactants are amphiphilic compounds which can reduce surface and interfacial tensions by accumulating at the interface of immiscible fluids and increase the solubility, mobility, bioavailability and subsequent biodegradation of hydrophobic or insoluble organic compounds. Chemically synthesized surfactants are commonly used in the petroleum, food and pharmaceutical industries as emulsifiers and wetting agents. Biosurfactants produced by some microorganisms are becoming important biotechnology products for industrial and medical applications due to their specific modes of action, low toxicity, relative ease of preparation and widespread applicability. They can be used as emulsifiers, de-emulsifiers, wetting and foaming agents, functional food ingredients and as detergents in petroleum, petrochemicals, environmental management, agrochemicals, foods and beverages, cosmetics and pharmaceuticals, and in the mining and metallurgical industries. Addition of a surfactant of chemical or biological origin accelerates or sometimes inhibits the bioremediation of pollutants. Surfactants also play an important role in enhanced oil recovery by increasing the apparent solubility of petroleum components and effectively reducing the interfacial tensions of oil and water in situ. However, the effects of surfactants on bioremediation cannot be predicted in the absence of empirical evidence because surfactants sometimes stimulate bioremediation and sometimes inhibit it. For medical applications, biosurfactants are useful as antimicrobial agents and immunomodulatory molecules. Beneficial applications of chemical surfactants and biosurfactants in various industries are discussed in this review. [Copyright &y& Elsevier]

Abstract: Surfactants, both chemical and biological, are amphiphilic compounds which can reduce surface and interfacial tensions by accumulating at the interface of immiscible fluids and increase the solubility, mobility, bioavailability and subsequent biodegradation of hydrophobic or insoluble organic compounds. Investigations on their impacts on microbial activity have generally been limited in scope to the most common and best characterized surfactants. Recently a number of new biosurfactants have been described and accelerated advances in molecular and cellular biology are expected to expand our insights into the diversity of structures and applications of biosurfactants. Biosurfactants play an essential natural role in the swarming motility of microorganisms and participate in cellular physiological processes of signaling and differentiation as well as in biofilm formation. Biosurfactants also exhibit natural physiological roles in increasing bioavailability of hydrophobic molecules and can complex with heavy metals, and some also possess antimicrobial activity. Chemical- and indeed bio-surfactants may also be added exogenously to microbial systems to influence behaviour and/or activity, mimicking the latter effects of biosurfactants. They have been exploited in this way, for example as antimicrobial agents in disease control and to improve degradation of chemical contaminants. Chemical surfactants can interact with microbial proteins and can be manipulated to modify enzyme conformation in a manner that alters enzyme activity, stability and/or specificity. Both chemical- and bio-surfactants are potentially toxic to specific microbes and may be exploited as antimicrobial agents against plant, animal and human microbial pathogens. Because of the widespread use of chemical surfactants, their potential impacts on microbial communities in the environment are receiving considerable attention. [Copyright &y& Elsevier]

The high global consumption of ibuprofen and its limited elimination by wastewater treatment plants (WWTPs), has led to the contamination of aquatic systems by this common analgesic and its metabolites. The potentially negative environmental and public health effects of this emerging contaminant have raised concerns, driving the demand for treatment technologies. The implementation of bacteria which mineralize organic contaminants in biopurification systems used to decontaminate water or directly in processes in WWTPs, is a cheap and sustainable means for complete elimination before release into the environment. In this work, an ibuprofen-mineralizing bacterial strain isolated from sediments of the River Elbe was characterized and assayed to remediate different ibuprofen-polluted media. Strain RW412, which was identified as Sphingopyxis granuli , has a 4.48 Mb genome which includes plasmid sequences which harbor the ipf genes that encode the first steps of ibuprofen mineralization. Here, we confirm that these genes encode enzymes which initiate CoA ligation to ibuprofen, followed by aromatic ring activation by a dioxygenase and retroaldol cleavage to unequivocally produce 4-isobutylcatechol and propionyl-CoA which then undergo further degradation. In liquid mineral salts medium, the strain eliminated more than 2 mM ibuprofen within 74 h with a generation time of 16 h. Upon inoculation into biopurification systems, it eliminated repeated doses of ibuprofen within a few days. Furthermore, in these systems the presence of RW412 avoided the accumulation of ibuprofen metabolites. In ibuprofen-spiked effluent from a municipal WWTP, ibuprofen removal by this strain was 7 times faster than by the indigenous microbiota. These results suggest that this strain can persist and remain active under environmentally relevant conditions, and may be a useful innovation to eliminate this emerging contaminant from urban wastewater treatment systems. Image 1 • Sphingopyxis granuli RW412 removes ibuprofen from biopurification systems. • RW412 avoids the accumulation of ibuprofen metabolites in biopurification systems. • RW412 bioaugmentation removes ibuprofen from WWTP effluents. • Structures of intermediates ibuprofenyl-CoA and 4-isobutylcatechol are resolved. Ibuprofen mineralization by Sphingopyxis granuli RW412 was characterized molecularly and the strain assayed to remediate ibuprofen from different artificially polluted media. [ABSTRACT FROM AUTHOR]

Abstract 6:2 fluorotelomer sulfonamidoalkyl betaine (6:2 FTAB) is a major component of aqueous film-forming foams (AFFFs) used for firefighting and is frequently detected, along with one of its suspected transformation products, 6:2 fluorotelomer sulfonate (6:2 FTSA), in terrestrial and aquatic ecosystems impacted by AFFF usage. Biochemical processes underlying bacterial biodegradation of these compounds remain poorly understood due to a lack of pure culture studies. Here, we characterized the water-soluble and volatile breakdown products of 6:2 FTSA and 6:2 FTAB produced using Gordonia sp. strain NB4-1Y cultures over seven days under sulfur-limited conditions. After 168 h, 99.9% of 60 μM 6:2 FTSA was degraded into ten major breakdown products, with a mol% recovery of 88.2, while 70.4% of 60 μM 6:2 FTAB was degraded into ten major breakdown products, with a mol% recovery of 84.7. NB4-1Y uses two pathways for 6:2 FTSA metabolism, with 55 mol% of breakdown products assigned to a major pathway and <1.0 mol% assigned to a minor pathway. This work indicates that rapid transformation of 6:2 FTSA and 6:2 FTAB can be achieved under controlled conditions and improves the bacterial metabolism of these compounds. Graphical abstract Unlabelled Image Highlights • Biotransformation of 6:2 FTAB & 6:2 FTSA was studied under sulfur-limiting conditions. • Gordonia sp. NB4-1Y rapidly metabolized 6:2 FTAB (70.4%) & 6:2 FTSA (99.9%). • 16 metabolites were identified using high resolution Orbitrap mass spectrometry. • Two distinct degradation pathways were utilized by Gordonia sp. NB4-1Y. • Major breakdown products included 6:2 FTCA, 6:2 FTUA, and 5:2 fluorotelomer ketone. [ABSTRACT FROM AUTHOR]

Plant growth promoting (PGP) bacterial strains possess different mechanisms to improve plant development under common environmental stresses, and are therefore often used as inoculants in soil phytoremediation processes. The aims of the present work were to study the effects of a collection of plant growth promoting bacterial strains on plant development, antioxidant enzyme activities and nutritional status of Cytisus striatus and/or Lupinus luteus plants a) growing in perlite under non-stress conditions and b) growing in diesel-contaminated soil. For this, two greenhouse experiments were designed. Firstly, C. striatus and L. luteus plants were grown from seeds in perlite, and periodically inoculated with 6 PGP strains, either individually or in pairs. Secondly, L. luteus seedlings were grown in soil samples of the A and B horizons of a Cambisol contaminated with 1.25% (w/w) of diesel and inoculated with best PGP inoculant selected from the first experiment. The results indicated that the PGP strains tested in perlite significantly improved plant growth. Combination treatments provoked better growth of L. luteus than the respective individual strains, while individual inoculation treatments were more effective for C. striatus . L. luteus growth in diesel-contaminated soil was significantly improved in the presence of PGP strains, presenting a 2-fold or higher increase in plant biomass. Inoculants did not provoke significant changes in plant nutritional status, with the exception of a subset of siderophore-producing and P-solubilising bacterial strains that resulted in significantly modification of Fe or P concentrations in leaf tissues. Inoculants did not cause significant changes in enzyme activities in perlite experiments, however they significantly reduced oxidative stress in contaminated soils suggesting an improvement in plant tolerance to diesel. Some strains were applied to non-host plants, indicating a non-specific performance of their plant growth promotion. The use of PGP strains in phytoremediation may help plants to overcome contaminant and other soil stresses, increasing phytoremediation efficiency. [ABSTRACT FROM AUTHOR]

• The microbiome of the planarian S. mediterranea consisted mainly of Betaproteobacteriales. • AgNP exposure resulted in a decrease of the genera Curvibacter and Undibacterium. • The AgNP-induced bacterial shift was more pronounced in adult organisms. • A PVP-coating had a limited effect on the planarian microbiome compared to NC-AgNPs. Silver nanoparticles (AgNPs) are widely incorporated in household, consumer and medical products. Their unintentional release via wastewaters raises concerns on their environmental impact, particularly for aquatic organisms and their associated bacterial communities. It is known that the microbiome plays an important role in its host's health and physiology, e.g. by producing essential nutrients and providing protection against pathogens. A thorough understanding of the effects of AgNPs on bacterial communities and on their interactions with the host is crucial to fully assess AgNP toxicity on aquatic organisms. Our results indicate that the microbiome of the invertebrate Schmidtea mediterranea , a freshwater planarian, is affected by AgNP exposure at the tested 10 μg/ml concentration. Using targeted amplification of the bacterial 16S rRNA gene V3–V4 region, two independent experiments on the microbiomes of adult worms revealed a consistent decrease in Betaproteobacteriales after AgNP exposure, mainly attributed to a decrease in Curvibacter and Undibacterium. Although developing tissues and organisms are known to be more sensitive to toxic compounds, three independent experiments in regenerating worms showed a less pronounced effect of AgNP exposure on the microbiome, possibly because underlying bacterial community changes during development mask the AgNP induced effect. The presence of a polyvinyl-pyrrolidone (PVP) coating did not significantly alter the outcome of the experiments compared to those with uncoated particles. The observed variation between the different experiments underlines the highly variable nature of microbiomes and emphasises the need to repeat microbiome experiments, within and between physiological states of the animal. [ABSTRACT FROM AUTHOR]