Lipopeptide Biosurfactant Research Articles

A New Bacterial Strain Producing Both of the Surfactin and Fengycin Lipopeptide Biosurfactant with Strong Emulsifications on Crude Oil.

A new lipopeptide-producing strain Cytobacillus sp. R3-1 was isolated from the production water of the Daqing oilfield in China and identified based on 16S rRNA gene sequence analyses. The strain R3-1 is capable of simultaneously producing both of the surfactin and fengycin, the two major families of the lipopeptide biosurfactant. The chemical structures of the surfactin and fengycin were confirmed by a combination of the ESI-MS, FT-IR, and amino acid analyses, and the impact of various temperatures, pH, and NaCl concentrations on the emulsifying activity (E24) was investigated. The lipopeptide biosurfactant produced by the strain R3-1 exhibited strong emulsifying activity with E24 value over 60% on crude oil and different hydrocarbons, including the cyclohexane, hexadecane, benzene, toluene, kerosene, diesel oil, and liquid paraffin. Meanwhile, it showed excellent emulsifying activity across a broad range of conditions of the temperature up to 60 °C, NaCl tolerance up to 100 g/L, and pH values between 5 and 9, which suggests that the strain R3-1 is a valuable microbial candidate for the simultaneous production of the surfactin and fengycin lipopeptide biosurfactant with strong emulsifying properties and stability under diverse environmental conditions and is a potential application in environmental bioremediation and enhanced oil recovery.

Biodegradation and high-value utilization of waste cooking oil: Strategies and mechanisms for producing lipopeptide biosurfactants using Bacillus subtilis YZQ-2

This study explored the strategies and mechanisms of Bacillus subtilis YZQ-2 in producing lipopeptide biosurfactants using waste cooking oil (WCO) as a raw material. The optimal conditions achieved a WCO utilization rate of 75.88% and a biosurfactant yield of 0.30g/L at pH 6.0, 30°C, with 20g/L WCO and 5g/L yeast extract. GC-MS analysis of degradation products at different intervals elucidated the mechanism of WCO degradation. After 72hours of fermentation, a reduction in linoleic and palmitic acid levels indicated the completion of lipid hydrolysis and the continuation of β-oxidation. The biosurfactants, identified as lipopeptides (surfactin and fengycin), exhibited stability in alkaline environments (pH 7.0-11.0) and high-salt concentration (5-45g/L). Genomic and transcriptomic analyses of Bacillus subtilis YZQ-2 revealed genes associated with biosurfactant production, which were upregulated in the presence of WCO. The differential expression values (log2 fold change) were SrfAA 3.30, SrfAB 3.31, SrfAC 3.63, FenA 2.42, FenB 2.55, FenC 1.99, FenD 2.03 and FenE 2.29, respectively. The proposed biosynthesis pathway of lipopeptides begins with the hydrolysis of WCO by lipase into glycerol and fatty acids. The glycerol is then transformed into pyruvate through glycolysis, entering the Tricarboxylic Acid cycle. Additionally, pyruvate contributes to synthesizing amino acids and branched-chain fatty acids, which serve as precursors for lipopeptide synthesis. These findings underscore the potential of WCO as a sustainable feedstock for biosurfactant production.

Scaled-up production and recovery of lipopeptide biosurfactant and its application for washing petroleum-contaminated drill cuttings

A simple and efficient fermentation strategy using chitosan-immobilized Bacillus subtilis GY19 was developed for large-scale lipopeptide production from waste glycerol and palm oil. When a fed-batch fermentation approach was employed, excessive foaming was minimized, while lipopeptide production was greater than that of conventional batch fermentation. When a 700L stirred tank fermenter with a 400L working volume was used, a lipopeptide concentration and yield of 7.55g/L and 0.190g/g of substrate, respectively, were achieved. The pilot-scale recovery process involved sequential bacterial cell removal via centrifugation, elimination of impurities through acidification of the cell-free broth, and partial purification and concentration of the lipopeptides via ultrafiltration. A 5kDa stabilized cellulose-based membrane maintained a constant permeate flux and resulted in 67.2% lipopeptide recovery. The concentrated lipopeptide retentate contained 16.8g/L lipopeptides and a surface tension of 28.82 mN/m. A biobased washing agent for the treatment of petroleum-contaminated drill cuttings was later formulated with the retentate and various vegetable oil-based surfactants via the simplex−lattice mixture design methodology. The mixture of 1% retentate and 4% fatty alcohol ethoxylate 5EO presented the greatest removal efficiency of 83.2% for drill cuttings containing 15% (w/w) total petroleum hydrocarbons. The formulation also mobilized petroleum hydrocarbons into a distinct free oil layer, which would be easy to separate and subsequently recycle. These findings demonstrate the scalability of the lipopeptide production and recovery process, while the biobased washing agent offers an environmentally friendly approach for petroleum remediation.

Solubilization and enhanced degradation of benzene phenolic derivatives-Bisphenol A/Triclosan using a biosurfactant producing white rot fungus Hypocrea lixii S5 with plant growth promoting traits.

Endocrine disrupting chemicals (EDCs) as benzene phenolic derivatives being hydrophobic partition to organic matter in sludge/soil sediments and show slow degradation rate owing to poor bioavailability to microbes. In the present study, the potential of a versatile white rot fungal isolate S5 identified as Hypocrea lixii was monitored to degrade bisphenol A (BPA)/triclosan (TCS) under shake flask conditions with concomitant production of lipopeptide biosurfactant (BS) and plant growth promotion. Sufficient growth of WRF for 5 days before supplementation of 50 ppm EDC (BPA/TCS) in set B showed an increase in degradation rates by 23% and 29% with corresponding increase in secretion of lignin-modifying enzymes compared to set A wherein almost 84% and 97% inhibition in fungal growth was observed when BPA/TCS were added at time of fungal inoculation. Further in set B, EDC concentration stimulated expression of laccase and lignin peroxidase (Lip) with 24.44 U/L of laccase and 281.69 U/L of Lip in 100 ppm BPA and 344 U/L Lip in 50 ppm TCS supplemented medium compared to their respective controls (without EDC). Biodegradation was also found to be correlated with lowering of surface tension from 57.02 mN/m (uninoculated control) to 44.16 mN/m in case of BPA and 38.49 mN/m in TCS, indicative of biosurfactant (BS) production. FTIR, GC-MS, and LC-ESI/MSMS confirmed the presence of surfactin lipopeptide isoforms. The WRF also displayed positive plant growth promoting traits as production of ammonia, indole acetic acid, siderophores, Zn solubilization, and 1-1-aminocyclopropane-1-carboxylate (ACC) deaminase activity, reflecting its soil restoration ability. The combined traits of biosurfactant production, EDC degradation and plant growth promotion displayed by WRF will help in emulsifying the hydrophobic pollutants favoring their fast degradation along with restoration of contaminated soil in natural conditions.

Influence of chirality and sequence in lysine-rich lipopeptide biosurfactants and micellar model colloid systems

Lipopeptides can self-assemble into diverse nanostructures which can be programmed to incorporate peptide sequences to achieve a remarkable range of bioactivities. Here, the influence of peptide sequence and chirality on micelle structure and interactions is investigated in a series of lipopeptides bearing two lysine or D-lysine residues and tyrosine or tryptophan residues, attached to a hexadecyl lipid chain. All molecules self-assemble into micelles above a critical micelle concentration (CMC). Small-angle x-ray scattering (SAXS) is used to probe micelle shape and structure from the form factor and to probe inter-micellar interactions via analysis of structure factor. The CMC is obtained consistently from surface tension and electrical conductivity measurements. We introduce a method to obtain the zeta potential from the SAXS structure factor which is in good agreement with directly measured values. Atomistic molecular dynamics simulations provide insights into molecular packing and conformation within the lipopeptide micelles which constitute model self-assembling colloidal systems and biomaterials.

Production of Lipopeptide Biosurfactant Using Wastewater from Parboiled Paddy Rice and Evaluation of Antifungal Property of the Biosurfactant Against Two Dermatophyte Fungi.

A previously isolated lipopeptide biosurfactant-producing bacterium Bacillus licheniformis SCV1 was investigated for the production of the biosurfactant using wastewater from parboiled paddy rice. The biosurfactant thus produced was evaluated for its antifungal property against dermatophyte fungi Trichophyton ajelloi and Microsporum fulvum. Results revealed that the bacterial strain reduced surface tension of the media from 56.16 ± 1 mN/m to 35 ± 0.9 mN/m within 12h, which further shrank to 29.3 ± 1 mN/m in 24h of incubation. The yield of the biosurfactant was 3.15 ± 0.25g/L at 48h of incubation. The obtained biosurfactant exhibited efficient emulsifying activity against a wide range of hydrophobic substrates such as crude oil, olive oil, engine oil, and kerosene oil used in the study. The critical micelle concentration of the biosurfactant was found to be 80mg/L. Structural characterization using FT-IR and TLC revealed that the biosurfactant produced by the strain in the wastewater is a lipopeptide consisting of surfactin and iturin. LCMS analysis revealed that the surfactin homologs range from C12 to C17-surfactin while the iturin contains C13 to C17-iturin homologs. It also revealed an in vitro study that the biosurfactant has antifungal properties against dermatophyte fungi Trichophyton ajelloi and Microsporum fulvum. Microscopic observation of the hyphae of the treated dermatophyte revealed disruption and fissure of the mycelia. The chemical composition of the wastewater revealed that it contains adequate nutritional composition and micronutrients to support bacterial growth. This is the first report that the wastewater of parboiled paddy could be used as a low-cost substrate for the production of lipopeptide biosurfactant, and the biosurfactant could be used for preventing dermatophytes fungi.

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 (30g/L), temperature (34°C), pH (7.2), stirring (239rpm), and aeration (0.775vvm) in a 5-L bioreactor. Maximum BSFs production reached 1527.6mg/L of surfactins and 176.88mg/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.

Biological Activities, Biosorption of Heavy Metals, and Stability of Lipopeptide Biosurfactant Produced by the Alcaligenes aquatilis Bacterium YGD-2906

Background: Biosurfactants are natural products produced by microorganisms. This study examined the antioxidant activity, biosorption of heavy metals, and stability of lipopeptide biosurfactant (BLA 2906) produced by the Alcaligenes aquatilis bacterium YGD-2906. Methods: Biosurfactant production was determined by using four techniques: hemolytic test, emulsion indices, oil spreading test, and drop collapse test. The biosorption capacity of our biosurfactant to chelate the different heavy metals. The antioxidant activity was evaluated by the reducing power, phosphomolybdate tests, and DPPH•, ABTS•+ radical scavenging assays and in the end, the stability of this biosurfactant was studied. objective: Study of the heavy metal biosorption, antioxidant activity, and stability study of lipopeptide biosurfactant BLA 2906 produced by Alcaligenes aquatilis YGD-2906. Results: A negative hemolytic test, emulsion indices of 63.11 % with crude oil, 23.66 mm of oil spreading test, and a positive drop collapse test. The lipopeptide biosurfactant BLA 2906 demonstrated its ability to chelate different heavy metals at pH = 7.2, which gave biosorption capacities of Cu (II), Fe (II), Pb (II), Cd (II), and Zn (II) of 43.34, 43.60, 50.00, 20.08 and 22.48 mg /g of BLA 2906, respectively. The total antioxidant capacity of BLA 2906 presented a value of 0.84 mg Eq Trolox / g DM for the reducing power. On the other hand, the result for the phosphomolybdate test showed a value of 1029.00 ± 3.66 μg / mL to cause a 50 % reduction of the reducing activity of the phosphomolybdenum for the BLA 2906. The result of ABTS+• scavenging activity was 10.46 %. DPPH radical-scavenging effects and BHA at varying concentrations showed that concentrations required to cause 50 % inhibition were 705.48 ± 3.89 μg / ml and 7.61 ± 0.11 μg / ml for this biosurfactant and BHA, respectively. The BLA 2906 showed high stability at different temperatures, pH, and salinity in terms of emulsification activity. Conclusion: The results obtained by the lipopeptide biosurfactant BLA 2906 are attractive to invest in future applications in different fields such as industry, environment and biotechnology.

Heavy metal application of response surface optimized-lipopeptide biosurfactant produced by Pseudomonas aeruginosa strain CGA-02 in low-cost substrate

Cost-effective methods of biosurfactant production with minimal environmental impact are needed as global demand continues to increase. This study evaluated lipopeptide biosurfactant production in a Pseudomonas aeruginosa strain CGA-02 using a low-cost carbon substrate. The structural properties of the biosurfactant and applicability of the biosurfactant in heavy metal removal were evaluated. Response surface methodology (RSM) involving central composite design (CCD) was used to optimize process parameters to maximize biosurfactant production. The study identified sugar cane molasses and sodium nitrate as carbon and nitrogen sources of choice for bacterial growth and biosurfactant production, with a relatively 2.64-fold increase in biosurfactant yield under optimized conditions. Analysis of the biosurfactant measured a surface tension reduction of water from 72.2 ± 0.26 to 30.5 ± 0.2 mN/m at 40 mg/L critical micelle concentration. GC–MS and FTIR analysis revealed structural properties of the lipopeptide biosurfactant, with fatty acid components predominantly 9-octadecenoic acid (oleic acid), n-hexadecanoic acid, cyclotetrasiloxane and trimyristin, and infrared peaks belonging to amine, carboxyl, nitrile, alkanol, ether and carbonyl groups. Capture of heavy metals using the biosurfactant was evaluated in soil microcosms. Removal rates of 80.47, 100, 77.57, 100, and 97.57% were recorded for As, Pb, Hg, Cd and Cr respectively after 12 weeks of incubation. There was no significant difference (p < 0.05) in the removal efficiency of the biosurfactant and an analogous chemical surfactant, sodium dodecyl sulphate. First and second-order kinetic models described heavy metal removal rates by the biosurfactant. We demonstrate the production of a useful biosurfactant using low-cost waste carbon.

Preparation and Physicochemical Properties of a Thermosensitive Hydrogel-based Lipopeptide Biosurfactant

Background: Temperature-sensitive (thermo-sensitive) formulations are a novel drug delivery dosage form that shows bio-inspired behavior in various applications. The structure and properties of a thermosensitive polymer are critical in designing an intelligent biometric polymer that contains lipopeptide biosurfactants. Objectives: In this study, thermo-sensitive hydrogels with lipopeptide biosurfactants as a potential wound dressing dosage form were formulated and examined regarding physicochemical properties. Methods: The lipopeptide biosurfactants were isolated from the Acinetobacter junni B6 bacterial strain and loaded on a formulation of poloxamer 407® and carboxymethyl cellulose as a gelling agent. Numerous experiments were carried out to evaluate the physicochemical properties of these formulations, such as the stability, spreadability, release profile, and kinetic. Results: The formulation (Poloxamer 407® (19% w/v), carboxymethyl cellulose (2% w/v), lipopeptide biosurfactants (5mg/mL), benzyl alcohol (1% v/v), and 0.1mL polyethylene glycol 400) was select as the optimum formulation. The selected formulation released 26.9% of the lipopeptide biosurfactants with anomalous transport kinetics after 10 hours. Conclusions: The results showed that a thermo-sensitive formulation could help achieve a sustained release of lipopeptide biosurfactants and potentially be used as a dressing formulation for wounds in future studies.

Lipopeptide biosurfactant as a potential root canal irrigation agent: Antimicrobial and anti-biofilm evaluation

ObjectivesLipopeptide Biosurfactant (LB) is a bacteria derived compound able to reduce surface tension between water and hydrophobic substances and exhibit antimicrobial and anti-biofilm properties. This study aimed to investigate the antimicrobial and anti-biofilm effect of a Lipopeptide Biosurfactant (LB) on Enterococcus faecalis, and its potential use in root canal treatment, either as a standalone irrigation solution or in conjunction with sodium hypochlorite (NaOCl). MethodsLB was extracted from Bacillus clausii isolate and the dry extract was diluted in deionized water. The antimicrobial effect of LB against planktonic E. faecalis was evaluated by determining the Minimal Inhibitory Concentration (MIC50). The anti-biofilm effect was evaluated by Minimal Biofilm Inhibitory Concentration (MBIC50) and Minimal Biofilm Eradication Concentration (MBEC50) assays on biofilm grown on dentin specimen surface. To evaluate the effectiveness of LB as a single irrigation solution and as a pre-irrigation prior to NaOCl, live and dead bacterial cells were quantified using Confocal Laser Scanning Microscopy (CLSM), and cell biomass was assessed. ResultsLB exhibited an MIC50 and MBIC50 of 100 ppm, with an MBEC50 of 1000 ppm, resulting in 52.94 % biofilm inhibition and 60.95 % biofilm eradication on dentin specimens. The effectiveness was concentration-dependent, at 500 ppm, LB demonstrated comparable antimicrobial efficacy to 2.5 % NaOCl. Pre-irrigation with LB resulted in lower biofilm biomass compared to NaOCl alone. ConclusionPre-irrigation with LB enhanced the antimicrobial effect when followed by NaOCl irrigation. Consequently, LB shows promise as both a standalone root canal irrigation solution and as an adjunct to NaOCl in root canal treatment. Clinical significanceThe study highlights the potential of Lipopeptide Biosurfactant (LB) as an environmentally friendly irrigation solution for root canal treatment, demonstrating potent antimicrobial and anti-biofilm properties against Enterococcus faecalis. LB exhibits concentration-dependent efficacy comparable to 2.5 % NaOCl and can be used as a standalone irrigation solution or in conjunction with NaOCl.

Optimization of Lipopeptide Biosurfactant Production with Anti-Inflammatory and Antimicrobial Activities

Background:: Biosurfactants are very important amphiphile compounds due to their interesting advantages such as low toxicity, biodegradability and also their many biological properties. Methods:: In the present study, antimicrobial and anti-imflammatory activities were evaluated to determine the biological proprieties of biosurfactant BLA 2906 produced by Alcaligenes aquatilis YGD 2906 using different assays. Screening and optimization component concentrations in the medium were investigated using PBD and SRM to increase surfactant yield in term emulsification activity value (E24%). Results:: The halos of antifungal activity presented a mean value of 12.33 mm to 17.67 mm. For antibacterial activity, the diameter varied from 10.33 to 12.67 mm with a very important antiinflammatory activity using a protein denaturation method that showed a maximum inhibition of 92.79%. Conclusion:: These results suggest that BLA 2906 may be used as a new therapeutic and antiinflammatory agent. The PBD selected 7 significant components out of the 14 screened. The RSM resulted in the production in terms of emulsification activity of 68.37% in the optimized medium.

Characterization, production optimization and ecotoxicity of a lipopeptide biosurfactant by Pseudomonas citronellolis using oily wastewater

Considering both fundamental principles and application perspectives, it is imperative to characterize biosurfactants (BSFs) for replacing their synthetic counterparts. In this study, a BSF produced by the Pseudomonas citronellolis 620 C bacterium, using oily wastewater, was identified as a lipopeptide based on ultraviolet spectroscopy, thin layer chromatography, high-pressure liquid chromatography and nuclear magnetic resonance spectroscopy. The latter detected the lactone ring at the 5.1–4.9 ppm region, suggesting it as a cyclic lipopeptide (CLP). Gas chromatography/mass spectrometry detected high percentage of C16:0, C18:0 fatty acids, and aliphatic amino acids. A novel CLP is here proposed. To reduce its bioprocess costs, different nitrogen (N)-sources were tested using oily wastewater as the main nutrient source. Ammonium sulfate was the best N-source for the bacterium, reaching BSF production of 556 mg/L, at 10/2 C/N ratio. The BSF ecotoxicity for Aliivibrio fischeri, expressed as effective concentration (EC), was 0.45 and 3.04 g/L as EC20 and EC50, respectively. For Daphnia magna, the EC50 at 24 h and 48 h were 0.980 and 0.936 g/L, respectively. The lipopetide had no estrogenic activity up to 8 g/L. These data make the novel lipopeptide suitable for agriculture, environmental restoration, as dispersant in waste(water) biodisposal and life sciences applications.

Lipopeptide Biosurfactant Produced by Acinetobacter junii B6 Attenuates Lung Inflammatory, Oxidative, and Histopathological Alterations due to Asthma in Rats

Lipopeptide Biosurfactant Produced by Acinetobacter junii B6 Attenuates Lung Inflammatory, Oxidative, and Histopathological Alterations due to Asthma in Rats

Characterization and performance of a new lipopeptide biosurfactant producing strain Bacillus Subtilis R1-2

Biosurfactants produced by native microorganisms have excellent surface activity and ideal environmental compatibility, and the mining of the biosurfactant-producing strains has become a key focus in the field of applied and environmental biotechnology. In this paper, we report a new lipopeptide-producing strain isolated from the production water of Daqing oilfield in China and identified as Bacillus Subtilis R1-2 based on 16S rRNA gene sequence analyses. A combination of ESI-MS and FT-IR analyses revealed that the strain R1-2 produced the surfactin family containing four members of the C12-surfactin, C13-surfactin, C14-surfactin and C15-surfactin, which is a representative family of the lipopeptide biosurfactants. The lipopeptide biosurfactant produced by the strain R1-2 exhibits excellent surface activity and good thermal stability over a temperature range between 20°C and 100°C and pH range between 3 and 14, and has a strong salt tolerance to NaCl concentration up to 140 g/L. In addition, the lipopeptide biosurfactant demonstrates significant properties in changing the contact angles of oil reservoir core slices from 86.2° to 39.0° and the wettability from strong oil-wet to strong water-wet, and therefore, resulted in a good oil removing ability with an efficiency of 64.84%, suggesting that the lipopeptide-producing strain R1-2 is promising in applications in environmental bioremediation and enhanced oil recovery.

Therapeutic potential of lipopeptide biosurfactant-fabricated copper oxide nanoparticles: Mechanistic insight into their biocompatibility using zebra fish

Nanoscale copper oxide (CuO NPs) with diameters in the 80–150 nm range has been biosynthesized using lipopeptide biosurfactant derived from Bacillus vallismortis and characterized by XRD and FE-SEM. The CuO NPs could be introduced as nanocarrier systems for combination therapy and a potential candidate for antibacterial, antioxidant, anticancer, and anti-diabetic activity. The antibacterial activity of CuO NPs was studied by incorporating the nanoparticles with fluorescent antibiotic Ciprofloxacin HCL (CIP) to form CIP@CuO NPs and tracked inside HEK-293 cell lines. The MIC values of CIP@CuO NPs against 1 × 106 CFU ml−1Pseudomonas aeruginosa was determined to be 76 µg ml−1and 69 µg ml−1 against 1 × 106 CFU ml−1Staphylococcus aureus. The CuO NPs were conjugated with the anticancer drug Doxorubicin (DOX) to form DOX@CuONPs, improving delivery toward cancer (HeLa) cells. The intracellular uptake of the drug-loaded CuO NPs was confirmed from confocal micrographs. Finally, the in vitro anti-diabetic activity of lipopeptide-coated CuO NPs was confirmed by the inhibitory activity of α-amylase. In contrast, the in vivo anti-diabetic efficacy of CuO NPs was validated by a significant reduction in blood glucose and glutathione levels. The CuO NPs positively affected the histopathological changes of the pancreas in induced diabetic mice. Cytotoxicity testing with Zebrafish demonstrated abnormal organ development with varying viability and hatching rates at 72 and 96 hpf, with an LC50 of 45 µg/l. Aside from the various potential medicinal characteristics, the study provided valuable information on cytotoxic impact, which can be used in future investigations of their eco-toxicological impacts.

Copper and chromium removal from industrial sludge by a biosurfactant-based washing agent and subsequent recovery by iron oxide nanoparticles

Industrial wastewater treatment generates sludge with high concentrations of metals and coagulants, which can cause environmental problems. This study developed a sequential sludge washing and metal recovery process for industrial sludge containing > 4500 mg/kg Cu and > 5000 mg/kg Cr. The washing agent was formulated by mixing glycolipid, lipopeptide, and phospholipid biosurfactants from Weissella cibaria PN3 and Brevibacterium casei NK8 with a chelating agent, ethylenediaminetetraacetic acid (EDTA). These biosurfactants contained various functional groups for capturing metals. The optimized formulation by the central composite design had low surface tension and contained relatively small micelles. Comparable Cu and Cr removal efficiencies of 37.8% and 38.4%, respectively, were obtained after washing the sludge by shaking with a sonication process at a 1:4 solid-to-liquid ratio. The zeta potential analysis indicated the bonding of metal ions on the surface of biosurfactant micelles. When 100 g/L iron oxide nanoparticles were applied to the washing agent without pH adjustment, 83% Cu and 100% Cr were recovered. In addition, X-ray diffraction and X-ray absorption spectroscopy of the nanoparticles showed the oxidation of nanoparticles, the reduction of Cr(V) to the less toxic Cr(III), and the absorption of Cu. The recovered metals could be further recycled, which will be beneficial for the circular economy.

Do biosurfactants as anti-biofilm agents have a future in industrial water systems?

Biofilms are bacterial communities embedded in exopolymeric substances that form on the surfaces of both man-made and natural structures. Biofilm formation in industrial water systems such as cooling towers results in biofouling and biocorrosion and poses a major health concern as well as an economic burden. Traditionally, biofilms in industrial water systems are treated with alternating doses of oxidizing and non-oxidizing biocides, but as resistance increases, higher biocide concentrations are needed. Using chemically synthesized surfactants in combination with biocides is also not a new idea; however, these surfactants are often not biodegradable and lead to accumulation in natural water reservoirs. Biosurfactants have become an essential bioeconomy product for diverse applications; however, reports of their use in combating biofilm-related problems in water management systems is limited to only a few studies. Biosurfactants are powerful anti-biofilm agents and can act as biocides as well as biodispersants. In laboratory settings, the efficacy of biosurfactants as anti-biofilm agents can range between 26% and 99.8%. For example, long-chain rhamnolipids isolated from Burkholderia thailandensis inhibit biofilm formation between 50% and 90%, while a lipopeptide biosurfactant from Bacillus amyloliquefaciens was able to inhibit biofilms up to 96% and 99%. Additionally, biosurfactants can disperse preformed biofilms up to 95.9%. The efficacy of antibiotics can also be increased by between 25% and 50% when combined with biosurfactants, as seen for the V9T14 biosurfactant co-formulated with ampicillin, cefazolin, and tobramycin. In this review, we discuss how biofilms are formed and if biosurfactants, as anti-biofilm agents, have a future in industrial water systems. We then summarize the reported mode of action for biosurfactant molecules and their functionality as biofilm dispersal agents. Finally, we highlight the application of biosurfactants in industrial water systems as anti-fouling and anti-corrosion agents.

Fabrication and characterization of lipopeptide biosurfactant-based electrospun nanofibers for use in tissue engineering

Nanofibers are a class of nanomaterial with specific physicochemical properties and characteristics making them quite sought after and investigated by researchers. Lipopeptide biosurfactant (LPB) formulation properties were previously established in wound healing. LPB were isolated from in vitro culture of Acinetobacter junii B6 and loaded on nanofibers formulation produced by electrospinning method with different ratios of carboxymethylcellulose (CMC), polyvinyl alcohol (PVA), and Poloxamer. Numerous experimental control tests were carried out on formulations, including physicochemical properties which were evaluated by using dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), morphology study by scanning electron microscopy (SEM), and thermal stability. The best nanofibers formulation was obtained by the electrospinning method, with a voltage of 19.8 volts, a discharge capacity of 1cm/h, a cylindrical rotating velocity of 100rpm, and a needle interval of 7cm from the cylinder, which continued for 7hours. The formulation contained 2% (w/v) CMC, 10% (w/v) poloxamer, 9% (w/v) PVA, and 5% (w/v) LPB. This formula had desirable physicochemical properties including spreadability, stability, and uniformity with the particle size of about 590nm.

Fundamental study of pyrite flotation using eco-friendly surfactin as collector

The drive towards cost-effective and environmentally friendly reagents has led to a significant increase in investigations into microorganisms and metabolites as potential collectors in froth flotation. The primary goal of this study was to develop a fundamental understanding of the interaction between surfactin, a cyclic lipopeptide biosurfactant which shows excellent surface activity even at very low concentrations, and pyrite. Surfactin adsorption on pyrite was confirmed through zeta potential and FTIR analysis and indicated a greater interaction in the neutral and alkaline pH ranges, signifying that ionisation of the surfactin carboxylic groups plays a significant role in adsorption. The attachment mechanism of surfactin onto the surface of pyrite was potentially chemisorption to either Fe-hydroxide sites or interaction of the amide groups with sulphur on the pyrite surface. Surfactin demonstrated a cleaning effect on pyrite (removal of hydrophilic species), which may contribute to increased hydrophobicity on the mineral and showed collecting abilities for pyrite at most operating conditions. Generally, surfactin performance was observed to be more effective in the alkaline pH range.