A Low-Cost Ecofriendly Oxidation Process to Manufacture High-Performance Polymeric Biosurfactants Derived from Municipal Biowaste.

Biosurfactants account for about 12% of the global value of the surfactant market, which is currently dominated by synthetic surfactants obtained from fossil sources. Yet, the production of biosurfactants from renewable feedstock is bound to increase, driven by the increasing pressure from both society and governments for chemistry-based industries to become more ecofriendly and economically sustainable. A photo-chemical oxidation process is reported here, yielding new biosurfactants from urban biowaste in water that perform as a solvent and terminal oxidant reagent at room temperature without the addition of conventional oxidants and catalysts. Products with 200-500 kDa molecular weight are obtained. They lower the surface tension of water down to 34 mN/m at 0.5-2 g/L concentration. The estimated cost is rather low (0.1-1.5 EUR/kg), which is competitive with the cost of synthetic surfactants but much lower than the cost of the best-performing bacterial surfactants. For the implementation of the photo-chemical oxidation process at the industrial level, the results suggest that the new biosurfactants obtained in the present work may not reach the performance level of the best-performing bacterial surfactants capable of lowering the surface tension of water down to 28 mN/m. Yet, the biosurfactants produced by the photo-chemical process have a greater chance of being marketed on large scales.

Enhanced low-cost lipopeptide biosurfactant production by Bacillus velezensis from residual glycerin.

Biosurfactants (BSFs) are molecules produced by microorganisms from various carbon sources, with applications in bioremediation and petroleum recovery. However, the production cost limits large-scale applications. This study optimized BSFs production by Bacillus velezensis (strain MO13) using residual glycerin as a substrate. The spherical quadratic central composite design (CCD) model was used to standardize carbon source concentration (30 g/L), temperature (34 °C), pH (7.2), stirring (239 rpm), and aeration (0.775 vvm) in a 5-L bioreactor. Maximum BSFs production reached 1527.6 mg/L of surfactins and 176.88 mg/L of iturins, a threefold increase through optimization. Microbial development, substrate consumption, concentration of BSFs, and surface tension were also evaluated on the bioprocess dynamics. Mass spectrometry Q-TOF-MS identified five surfactin and two iturin isoforms produced by B. velezensis MO13. This study demonstrates significant progress on BSF production using industrial waste as a microbial substrate, surpassing reported concentrations in the literature.

A comprehensive review of biosurfactant production and its uses in the pharmaceutical industry.

Biosurfactants are naturally occurring, surface-active chemicals generated by microorganisms and have attracted interest recently because of their numerous industrial uses. Compared to their chemical equivalents, they exhibit qualities that include lower toxic levels, increased biodegradable properties, and unique physiochemical properties. Due to these traits, biosurfactants have become attractive substitutes for synthetic surfactants in the pharmaceutical industry. In-depth research has been done in the last few decades, demonstrating their vast use in various industries. This review article includes a thorough description of the various types of biosurfactants and their production processes. The production process discussed here is from oil-contaminated waste, agro-industrial waste, dairy, and sugar industry waste, and also how biosurfactants can be produced from animal fat. Various purification methods such as ultrafiltration, liquid-liquid extraction, acid precipitation, foam fraction, and adsorption are required to acquire a purified product, which is necessary in the pharmaceutical industry, are also discussed here. Alternative ways for large-scale production of biosurfactants using different statistical experimental designs such as CCD, ANN, and RSM are described here. Several uses of biosurfactants, including drug delivery systems, antibacterial and antifungal agents, wound healing, and cancer therapy, are discussed. Additionally, in this review, the future challenges and aspects of biosurfactant utilization in the pharmaceutical industry and how to overcome them are also discussed.

Assessment of Phenanthrene Degradation Potential by Plant-Growth-Promoting Endophytic Strain Pseudomonas chlororaphis 23aP Isolated from Chamaecytisus albus (Hacq.) Rothm.

Polycyclic aromatic hydrocarbons (PAHs) are common xenobiotics that are detrimental to the environment and human health. Bacterial endophytes, having the capacity to degrade PAHs, and plant growth promotion (PGP) may facilitate their biodegradation. In this study, phenanthrene (PHE) utilization of a newly isolated PGP endophytic strain of Pseudomonas chlororaphis 23aP and factors affecting the process were evaluated. The data obtained showed that strain 23aP utilized PHE in a wide range of concentrations (6-100 ppm). Ethyl-acetate-extractable metabolites obtained from the PHE-enriched cultures were analyzed by gas chromatography-mass spectrometry (GC-MS) and thin-layer chromatography (HPTLC). The analysis identified phthalic acid, 3-(1-naphthyl)allyl alcohol, 2-hydroxybenzalpyruvic acid, α-naphthol, and 2-phenylbenzaldehyde, and allowed us to propose that the PHE degradation pathway of strain 23aP is initiated at the 1,2-, 3,4-carbon positions, while the 9,10-C pathway starts with non-enzymatic oxidation and is continued by the downstream phthalic pathway. Moreover, the production of the biosurfactants, mono- (Rha-C8-C8, Rha-C10-C8:1, Rha-C12:2-C10, and Rha-C12:1-C12:1) and dirhamnolipids (Rha-Rha-C8-C10), was confirmed using direct injection-electrospray ionization-mass spectrometry (DI-ESI-MS) technique. Changes in the bacterial surface cell properties in the presence of PHE of increased hydrophobicity were assessed with the microbial adhesion to hydrocarbons (MATH) assay. Altogether, this suggests the strain 23aP might be used in bioaugmentation-a biological method supporting the removal of pollutants from contaminated environments.

Fungal bioproducts for petroleum hydrocarbons and toxic metals remediation: recent advances and emerging technologies.

Petroleum hydrocarbons and toxic metals are sources of environmental contamination and are harmful to all ecosystems. Fungi have metabolic and morphological plasticity that turn them into potential prototypes for technological development in biological remediation of these contaminants due to their ability to interact with a specific contaminant and/or produced metabolites. Although fungal bioinoculants producing enzymes, biosurfactants, polymers, pigments and organic acids have potential to be protagonists in mycoremediation of hydrocarbons and toxic metals, they can still be only adjuvants together with bacteria, microalgae, plants or animals in such processes. However, the sudden accelerated development of emerging technologies related to the use of potential fungal bioproducts such as bioinoculants, enzymes and biosurfactants in the remediation of these contaminants, has boosted fungal bioprocesses to achieve higher performance and possible real application. In this review, we explore scientific and technological advances in bioprocesses related to the production and/or application of these potential fungal bioproducts when used in remediation of hydrocarbons and toxic metals from an integral perspective of biotechnological process development. In turn, it sheds light to overcome existing technological limitations or enable new experimental designs in the remediation of these and other emerging contaminants.

Comparative study on antimicrobial activity of mono-rhamnolipid and di-rhamnolipid and exploration of cost-effective antimicrobial agents for agricultural applications.

BACKGROUND: Chemical pesticides have defects in crop diseases control, such as narrow antimicrobial spectrum, chemicals residue risk and harm to farmland ecosystem. Antimicrobial agents from microbial sources are highly interested in agriculture. Studies showed that rhamnolipid biosurfactants possessed certain antimicrobial activity. The structural differences in rhamnolipid inevitably affect their activities. But the antimicrobial effect of mono-rhamnolipid and di-rhamnolipid is unknown. Rhamnolipid with unique structure can be produced using specific microbial cell factory. RESULTS: Different types of rhamnolipid were produced from different Pseudomonas aeruginosa strains. Rha-C10-C10 and Rha-Rha-C10-C10 were the main homologues in the separated mono-rhamnolipid and di-rhamnolipid, respectively. Both mono-rhamnolipid and di-rhamnolipid exhibited certain antimicrobial activity against the tested microbial strains, especially the fungi and Gram-positive bacteria. But mono-rhamnolipid was superior to di-rhamnolipid, with inhibition zone diameters larger than 25 mm and inhibition rate higher than 90%. The IC50 values of mono-rhamnolipid were lower than 5 mg/L against the tested bacterium and fungus, whereas the IC50 values of di-rhamnolipid were ranged from 10 mg/L to 20 mg/L. Mono-rhamnolipid stimulated the tested strains to generate higher level of intracellular ROS. Mono-rhamnolipid exhibited better antimicrobial activity to the potential agricultural pathogens, such as Alternaria alternata, Pantoea agglomerans and Cladosporium sp. The mono-rhamnolipid crude extract of strain P. aeruginosa SGΔrhlC can replace the separated mono-rhamnolipid. After 50 times dilution, the fermentation broth of the mono-rhamnolipid producing strain SGΔrhlC exhibited equal antimicrobial effect to mono-rhamnolipid (200 mg/L). Prospects of mono-rhamnolipid were also discussed for antimicrobial applications in agriculture. CONCLUSIONS: This work discovered that mono-rhamnolipid was superior to di-rhamnolipid on antimicrobial activity for agricultural applications. Mono-rhamnolipid is an excellent candidate for agricultural biocontrol. The knockout strain P. aeruginosa SGΔrhlC is an excellent microbial cell factory for high producing mono-rhamnolipid. Its mono-rhamnolipid crude extract and its diluted fermentation broth are cost-effective antimicrobial agents. This work provided new insights to develop green and efficient antimicrobial agents for agricultural applications.

Automobile service station waste assessment and promising biological treatment alternatives: a review.

Unprecedented growth in the automobile sector has led to an increased number of automobile service stations across all major cities especially in the developing countries. These service stations release huge amounts of waste that contain objectionable levels of oil and grease (O&G) and heavy metals, amongst other environmentally toxic compounds. Not much literature is available on the hazardous nature, public health concerns, and sustainable treatment options of such an industrial waste. This review throws light on the nuisances caused by the automobile industry waste, the various conventional and promising physical-chemical remediation measures adopted, and the scope of bioremediation for the same. Work on the use of microbial enzymes such as lipases and microbial surface-active agents (biosurfactants) as emerging promising candidates for the bioremediation of metals and O&G contaminated automobile service centre wastewater and soil are especially highlighted in this review article. The adoption of constructed wetlands and regular scientific monitoring of service sector are the aspects that would prove to be critical in sustainable and ecological automobile service station waste management. Stricter environment regulations, along with the growing ecological and environmental awareness, call for stringent monitoring of the service station waste and its treatment in an environmentally sustainable manner. This review can effectively aid in revealing potential hazards of this industrial sectors and in policy making for effective environmental monitoring.

Trends in mitigation of industrial waste: Global health hazards, environmental implications and waste derived economy for environmental sustainability.

Majority of industries, in order to meet the technological development and consumer demands generate waste. The untreated waste spreads out toxic and harmful substances in the environment which serves as a breeding ground for pathogenic microorganisms thus causing severe health hazards. The three industrial sectors namely food, agriculture, and oil industry are among the primary organic waste producers that affect urban health and economic growth. Conventional treatment generates a significant amount of greenhouse gases which further contributes to global warming. Thus, the use of microbes for utilization of this waste, liberating CO2 offers an indispensable tool. The simultaneous production of value-added products such as bioplastics, biofuels, and biosurfactants increases the economics of the process and contributes to environmental sustainability. This review comprehensively summarized the composition of organic waste generated from the food, agriculture, and oil industry. The linkages between global health hazards of industrial waste and environmental implications have been uncovered. Stare-of-the-art information on their subsequent utilization as a substrate to produce value-added products through bio-routes has been elaborated. The research gaps, economical perspective(s), and future research directions have been identified and discussed to strengthen environmental sustainability.

Characterization and cytotoxicity assessment of biosurfactant derived from Lactobacillus pentosus NCIM 2912.

Noteworthy properties of biosurfactant (BS) are fascinating scientific fraternity to explore them for food, medicinal, cosmetic, or pharmaceutical etc. applications. Newer products intended for pharmaceutical purposes are mandatory to go through pragmatic evaluation protocols. BS, being less cytotoxic, offers an ideal candidature for widespread applications in the healthcare sector. The goal of the current study was the isolation, physico-chemical characterization, and safety assessment of cell-associated biosurfactant (CABS) from Lactobacillus pentosus NCIM 2912. The culture was grown in a 3-L fermentor to produce CABS from the cell pellets through procedures like centrifugation, filtration, dialysis, column chromatography, and freeze-drying. Further, physical properties like surface tension (ST), critical micelle concentration (CMC), contact angle (CA), emulsification activity, stability of emulsion (height of emulsion, the extent of coalescence, and appearance), and ionic character of CABS were evaluated. Analytical characterization through TLC, FTIR, NMR, and GC-MS was carried out. The physico-chemical characterization revealed CABS as an anionic, multicomponent glycolipopeptide having a hydrophobic chain comprising butanoic acid (C4), decanoic acid (C10), undecanoic acid (C11), tridecanoic acid (C13), hexadecenoic acid (C16), and octadecanoic acid (C18). The oil-in-water (O/W) emulsions formed by CABS with various oils (olive, sesame, soybean, coconut) were stabilized up to the 7th day of storage and were analogous with polysorbate 80 (emulsifier/defoamer used in food industries). The O/W emulsions are quite stable at room temperature with no evidence of coalescence of droplets around 1 week. The cytotoxicity of CABS was evaluated through MTT (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide) assay. Cytotoxicity study performed on the human embryonic kidney (HEK 293), mouse fibroblast ATCC L929 and human epithelial type (HEP-2) cell lines recorded viability of 90.3 ± 0.1%, 99.2 ± 0.43, and 94.3 ± 0.2% respectively. The toxicity of the BS was comparable to that of the commercially used rhamnolipid sample. Thus, CABS derived from L. pentosus NCIM 2912 pose promising applications in the pharmaceutical, food industries acquiescently. The multifunctional potential of the incredibly versatile microbial product like BS from lactic acid bacteria (LAB) certainly contributes to wider avenues for varied industries.

Biosurfactant Production from Lactobacilli: an Insight on the Interpretation of Prevailing Assessment Methods.

Biosurfactants constitute amphiphilic molecules, receiving increased attention as environmentally benign, biodegradable alternatives to substitute for the petroleum derived counterparts in food, pharmaceutical and cosmetics applications. However, their high production cost hinders industrial production. In this study, fifty GRAS lactobacilli strains were screened for their ability to produce biosurfactants, implementing different substrates. Cheese whey permeate (CWP) was also assessed as a low-cost and inherent lactobacilli substrate, aiming to mitigate its polluting impact, expand valorization strategies, alleviate costs deriving from commercial supplements and enhance overall sustainability. Surface tension, emulsification activity (E24) and oil displacement were deployed to identify the most promising candidates. Results reveal surface tension as the most robust method and underline the effect of substrate on biosurfactant synthesis. Likewise, this study indicates the fundamental role of including the final fermentation substrate (CWP) during strain selection to avoid misinterpretation of results and enhance subsequent bioprocess integration.

Bioconversion of Food Waste to produce Industrial-scale Sophorolipid Syrup and Crystals: dynamic Life Cycle Assessment (dLCA) of Emerging Biotechnologies.

Bioconversion of food waste into sophorolipid-based biosurfactants is a promising emerging technology. It is important to evaluate the environmental impacts associated with the latest advancements in sophorolipid production as it matures to maximize sustainability on scale-up. This study takes a dynamic Life Cycle Assessment (dLCA) approach to address the inherent uncertainties and evaluate the environmental performances. It demonstrates the dLCA framework by conducting the new traversal of food waste-derived industrial-scale sophorolipid production, with the combination of Techno-Economic Analysis (TEA). A systematic investigation of the environmental-economic implications of the two pathways to produce SL crystals and syrup. The global warming potential (GWP) for 1 kg of SL crystals and syrup was 7.9 kg CO2 eq. and 5.7 kg CO2 eq., respectively. The Ashby-like charts based on the LCA and TEA results at the pilot plant highlighted the trade-offs between systemic environmental costs and economic benefits for design decisions.

Analysis of the Genome of the Heavy Metal Resistant and Hydrocarbon-Degrading Rhizospheric Pseudomonas qingdaonensis ZCR6 Strain and Assessment of Its Plant-Growth-Promoting Traits.

The Pseudomonas qingdaonensis ZCR6 strain, isolated from the rhizosphere of Zea mays growing in soil co-contaminated with hydrocarbons and heavy metals, was investigated for its plant growth promotion, hydrocarbon degradation, and heavy metal resistance. In vitro bioassays confirmed all of the abovementioned properties. ZCR6 was able to produce indole acetic acid (IAA), siderophores, and ammonia, solubilized Ca3(PO4)2, and showed surface active properties and activity of cellulase and very high activity of 1-aminocyclopropane-1-carboxylic acid deaminase (297 nmol α-ketobutyrate mg-1 h-1). The strain degraded petroleum hydrocarbons (76.52% of the initial hydrocarbon content was degraded) and was resistant to Cd, Zn, and Cu (minimal inhibitory concentrations reached 5, 15, and 10 mM metal, respectively). The genome of the ZCR6 strain consisted of 5,507,067 bp, and a total of 5055 genes were annotated, of which 4943 were protein-coding sequences. Annotation revealed the presence of genes associated with nitrogen fixation, phosphate solubilization, sulfur metabolism, siderophore biosynthesis and uptake, synthesis of IAA, ethylene modulation, heavy metal resistance, exopolysaccharide biosynthesis, and organic compound degradation. Complete characteristics of the ZCR6 strain showed its potential multiway properties for enhancing the phytoremediation of co-contaminated soils. To our knowledge, this is the first analysis of the biotechnological potential of the species P. qingdaonensis.

Microbial biosurfactants: A broad analysis of properties, applications, biosynthesis, and techno-economical assessment of rhamnolipid production.

Biosurfactants are surface-active molecules originated from renewable resources, which are produced by microbial fermentation or chemical/enzymatic catalysis. These molecules present important advantages as compared to petrochemical surfactants, given their resistance to extreme conditions, biodegradability, specificity, and environmental compatibility. Besides that, the high production costs hinder its commercialization. In this way, this article aimed to analyze microbial biosurfactants production, focusing on the optimization of metabolic pathways and production processes, to identify key aspects and provide alternatives to allow a cost-effective production at industrial scale. This was achieved by a broad analysis of biosurfactants properties, applications, and biosynthetic pathways (in terms of yield, cofactors, and energy), in addition to an assessment of production-associated costs. As a result of the present extensive data survey and analysis, key production aspects are disclosed. The metabolic pathway yield analysis demonstrated that production of biosurfactants can be significantly improved (highest theoretical yield was 0.47 gbiosurfactant /gsubstrate ) by the use of biomolecular engineering techniques to generate optimized synthetic pathways. With an alternative proposed pathway for surfactin, yield was improved and imbalance in cofactors and ATP was reduced. Analysis of productive costs indicated that to make rhamnolipids commercial production feasible, the main efforts should focus on lowering substrate costs as well as the identification of energy-efficient unit operations to lower electricity cost, since these parameters accounted for 19.36 and 78.22%, respectively, of the production costs. The data generated by this analysis highlight the need for multidisciplinary collaboration to make rhamnolipids economically feasible, including biomolecular engineering and process intensification.

Guiding environmental sustainability of emerging bioconversion technology for waste-derived sophorolipid production by adopting a dynamic life cycle assessment (dLCA) approach.

Microbial biosurfactants are surface-active molecules that are naturally produced by a range of microorganisms. They have certain advantages over chemical surfactants, such as lower toxicity, higher biodegradability, anti-tumor, and anti-microbial properties. Sophorolipids (SLs) in particular are one of the most promising biosurfactants, as they hold the largest share of the biosurfactant market. Currently, researchers are developing novel approaches for SL production that utilize renewable feedstocks and advanced separation technologies. However, challenges still exist regarding consumption of materials, enzymes, and electricity, that are primarily fossil based. Researchers lack a clear understanding of the associated environmental impacts. It is imperative to quantify and optimize the environmental impacts associated with this emerging technology very early in its design phase to guide a sustainable scale-up. It is necessary to take a collaborative perspective, wherein life cycle assessment (LCA) experts work with experimentalists, to quantify environmental impacts and provide recommendations for improvements in the novel waste-derived SL production pathways. Studies that have analyzed the environmental sustainability of microbial biosurfactant production are very scarce in literature. Hence, in this work, we explore the possibility of applying LCA to evaluate the environmental sustainability of SL production. A dynamic LCA (dLCA) framework that quantifies the environmental impacts of a process in an iterative manner, is proposed and applied to evaluate SL production. The first traversal of the dLCA was associated with the selection of an optimal feedstock, and results identified food waste as a promising feedstock. The second traversal compared fermentation coupled with alternative separation techniques, and highlighted that the fed-batch fermentation of food waste integrated with the in-situ separation technique resulted in less environmental impacts. These results will guide experimentalists to further optimize those processes, and improve the environmental sustainability of SL production. Resultant datasets can be iteratively used in subsequent traversals to account for technological changes and mitigate the corresponding impacts before scaling up.

The use of low-cost brewery waste product for the production of surfactin as a natural microbial biocide.

Surfactin has potential as next generation antibiofilm agent to combat antimicrobial resistance against emerging pathogens. However, the widespread industrial applications of surfactin is hampered by its high production cost. In this work, surfactin was produced from Bacillus subtilis using a low-cost brewery waste as a carbon source. The strain produced 210.11 mg  L - 1 after 28 h. The antimicrobial activity was observed against all tested strains, achieving complete inhibition for Pseudomonas aeruginosa, at 500  µ g mL - 1 . A growth log reduction of 3.91 was achieved for P. aeruginosa while, Staphylococcus aureus and Staphylococcus epidermidis showed between 1 and 2 log reductions. In the anti-biofilm assays against P. aeruginosa, the co-incubation, anti-adhesive and disruption showed inhibition, where the greatest inhibition was observed in the co-incubation assay (79.80%). This study provides evidence that surfactin produced from a low-cost substrate can be a promising biocide due to its antimicrobial and anti-biofilm abilities against pathogens.

Production, formulation and cost estimation of a commercial biosurfactant.

Due to their amphipathic nature, biosurfactants are multifunctional molecules that have considerable potential in several industries, especially the petroleum industry. In this study, the commercial production of a biosurfactant from Pseudomonas cepacia CCT6659 grown on industrial waste was investigated in a semi-industrial 50-L bioreactor for use in the removal of hydrocarbons from oily effluents. A concentration of 40.5 g/L was achieved in the scale up and the surface tension was reduced to 29 mN/m. The biosurfactant was formulated with an added preservative, tyndallization and the combination of fluent vaporization plus the preservative. Formulated biosurfactant samples were stored for 120 days. Tensioactive properties and stability were evaluated with different pH values, temperatures and salt concentrations. The commercial biosurfactant obtained with all formulation methods demonstrated good stability, with tolerance to a wide range of pH values as well as high temperature and high salinity, enabling application in extreme environmental conditions, as it occurs in industrial plants. The biosurfactant proved to be economically viable for large-scale application, as demonstrated by the cost of the product, estimated at around US$ 0.14-0.15/L and US$ 0.02/g for the formulated and the isolated biosurfactant, respectively. Both products were applied in an oil-fired thermoelectric plant for the treatment of oily effluents and removed up to 100% of the oil. Therefore, this biosurfactant is suitable for application under extreme conditions, such as in the petroleum industry, and can be produced at a more attractive price compared to other commercially available products on the market.

Performance of Bacillus subtilis on fibrous biomass sugar hydrolysates in producing biosurfactants and techno-economic comparison.

Surfactin and fatty acetyl glutamate (FA-Glu) were produced by Bacillus subtilis in 5-L fermentor. In a previous 50-mL shake flask study, sugar hydrolysates from soy hull, alfalfa and switchgrass were shown to support the growth of Bacillus strains. It was observed that glucose content and availability of hexose and pentose sugars in the hydrolysates played an important role in determining growth and product concentration. Growth, economic efficiency and product concentration of biosurfactants was compared in fermentations conducted in 5-L stirred tank bioreactor, on biomass hydrolysate-based growth media. Highest bacterial growth absorbance for surfactin and FA-Glu producing strains were at 3.5 and 3.3 absorbance units, respectively, for switchgrass hydrolysate media. Highest concentrations of products were observed in soy hull hydrolysate media (2.9 g/L and 0.28 g/L for surfactin and FA-Glu). Techno-economic analysis of the 5-L fermentations on the three biomasses showed surfactin cost estimate to be $6.63/kg for 97% pure product.

In situ downstream strategies for cost-effective bio/surfactant recovery.

Since 60-80% of total costs of production are usually associated with downstream collection, separation, and purification processes, it has become advantageous to investigate how to replace traditional methods with efficient and cost-effective alternative techniques for recovery and purification of biosurfactants. In the traditional techniques, large volumes of organic solvents are usually used for increasing production cost and the overall environmental burden. In addition, traditional production and separation methods typically carried out in batch cultures reduce biosurfactant yields due to product inhibition and lower biosurfactants activity as a result of interaction with the organic solvents used. However, some in situ recovery methods that allow continuous separation of bioproducts from culture broth leading to an improvement in yield production and fermentation efficiency. For biosurfactants commercialization, enhancement of product capacity of the separation methods and the rate of product removal is critical. Recently, interest in the integration of separation methods with a production step as rapid and efficient techniques has been increasing. This review focuses on the technology gains and potentials for the most common methods used in in situ product removal: foam fractionation and ultrafiltration, especially used to recover and purify two well-known biosurfactants: glycolipids (rhamnolipids) and lipopeptides (surfactins).

Can Sophorolipids prevent biofilm formation on silicone catheter tubes?

Given the impact of biofilms in health care environment and the increasing antibiotic resistance and/or tolerance, new strategies for preventing that occurrence in medical devices are obligatory. Thus, biomaterials surface functionalization with active compounds can be a valuable approach. In the present study the ability of the biosurfactants sophorolipids to prevent biofilms formation on silicone rubber aimed for medical catheters was investigated. Sophorolipids produced by Starmerella bombicola, identified by HPLC-MS/MS were used to cover silicone and surface characterization was evaluated through contact angle measurements and FTIR-ATR. Results revealed that sophorolipids presence on silicone surface decreased the hydrophobicity of the material and biofilm formation of Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922. Antibiofilm activity was evaluated through different methods and was more pronounced against S. aureus. Furthermore, biocompatibility of silicone specimens with HaCaT cells was also obtained. From this study it was possible to conclude that sophorolipids seem to be a favourable approach for coating silicone catheters. Such compounds may represent a novel source of antibiofilm agents for technological development passing through strategies of permanent functionalization of surfaces.

Polycyclic aromatic hydrocarbon-contaminated soils: bioaugmentation of autochthonous bacteria and toxicological assessment of the bioremediation process by means of Vicia faba L.

Two bacterial strains, Achromobacter sp. (ACH01) and Sphingomonas sp. (SPH01), were isolated from a heavily polycyclic aromatic hydrocarbon (PAH)-contaminated soil (5431.3 ± 102.3 ppm) for their capacity to use a mixture of anthracene, pyrene, phenanthrene and fluorene as sole carbon sources for growth and for the capacity to produce biosurfactants. The two strains were exploited for bioaugmentation in a biopile pilot plant to increase the bioavailability and the degradation of the residual PAH contamination (99.5 ± 7.1 ppm) reached after 9 months of treatment. The denaturing gel gradient electrophoresis (DGGE) profile of the microbial ecology of the soil during the experimentation showed that the bioaugmentation approach was successful in terms of permanence of the two strains in the soil in treatment. The bioaugmentation of the two bacterial isolates positively correlated with the PAH depletion that reached 7.9 ± 2 ppm value in 2 months of treatment. The PAH depletion was assessed by the loss of the phyto-genotoxicity of soil elutriates on the model plant Vicia faba L., toxicological assessment adopted also to determine the minimum length of the decontamination process for obtaining both the depletion of the PAH contamination and the detoxification of the soil at the end of the process. The intermediate phases of the bioremediation process were the most significant in terms of toxicity, inducing genotoxic effects and selective DNA fragmentation in the stem cell niche of the root tip. The selective DNA fragmentation can be related to the selective induction of cell death of mutant stem cells that can compromise offsprings.