Evaluation antimicrobial and antiadhesive properties of the biosurfactant Lunasan produced by Candida sphaerica UCP 0995. Curr Microbiol. 2011;62:1527-1534. [PMID: 21327556 DOI: 10.1007/s00284-011-9889-1]

Antibiofilm and wound healing efficacy of rhamnolipid biosurfactant against pathogenic bacterium Staphylococcus aureus

The present study evaluates the in-vitro antibiofilm activity against the biofilm formed by Staphylococcus aureus, and the wound-healing efficacy of two different types of rhamnolipids produced by Pseudomonas aeruginosa strain JS29 in S.aureus infected wounds. The biosurfactant production was carried out in a mineral salt medium supplemented with 2 % Glucose and 2 % Glycerol individually and thus were designated as RL-Glu and RL-Gly respectively. 0.5 mg/ml of RL-Glu and RL-Gly demonstrated 90 % growth inhibition of S. aureus while exhibiting bactericidal activity at 4 mg/ml of RL-Glu and 1 mg/ml of RL-Gly. Both types of rhamnolipid cause changes in membrane permeability leading to pathogens' non-viability. 90 % inhibition of biofilm formation by S. aureus was observed at 2 mg/ml of RL-Glu and 0.5 mg/ml of RL-Gly, while 0.5 mg/ml of both rhamnolipid disrupted 90 % of the preformed biofilm. 0.5 mg/ml of RL-Glu and RL-Gly decreases the production of exopolysaccharides and also causes structural alteration. 0.5 mg/ml of RL-Glu and RL-Gly were found to exhibit effective wound healing efficacy in S. aureus infected wounds within 7 days of treatment. Histopathological studies of wound sites revealed efficient wound management by both the rhamnolipid. LCMS and GCMS characterization of the biosurfactant revealed that JS29 produces different rhamnolipid congeners when grown on different carbon sources, thereby influencing the antimicrobial, antibiofilm, and wound healing efficacy of rhamnolipid.

Utilizing chitooligosaccharides from shrimp waste biodegradation via recombinant chitinase A: a promising approach for emulsifying hydrocarbon and bioremediation

BACKGROUND

Hydrocarbon pollution stemming from petrochemical activities is a significant global environmental concern. Bioremediation, employing microbial chitinase-based bioproducts to detoxify or remove contaminants, presents an intriguing solution for addressing hydrocarbon pollution. Chitooligosaccharides, a product of chitin degradation by chitinase enzymes, emerge as key components in this process. Utilizing chitinaceous wastes as a cost-effective substrate, microbial chitinase can be harnessed to produce Chitooligosaccharides. This investigation explores two strategies to enhance chitinase productivity, firstly, statistical optimization by the Plackett Burman design approach to  evaluating the influence of individual physical and chemical parameters on chitinase production, Followed by  response surface methodology (RSM) which delvs  into the interactions among these factors to optimize chitinase production. Second, to further boost chitinase production, we employed heterologous expression of the chitinase-encoding gene in E. coli BL21(DE3) using a suitable vector. Enhancing chitinase activity not only boosts productivity but also augments the production of Chitooligosaccharides, which are found to be used as emulsifiers.

RESULTS

In this study, we focused on optimizing the production of chitinase A from S. marcescens using the Plackett Burman design and response surface methods. This approach led to achieving a maximum activity of 78.65 U/mL. Subsequently, we cloned and expressed the gene responsible for chitinase A in E. coli BL21(DE3). The gene sequence, named SmChiA, spans 1692 base pairs, encoding 563 amino acids with a molecular weight of approximately 58 kDa. This sequence has been deposited in the NCBI GenBank under the accession number "OR643436". The purified recombinant chitinase exhibited a remarkable activity of 228.085 U/mL, with optimal conditions at a pH of 5.5 and a temperature of 65 °C. This activity was 2.9 times higher than that of the optimized enzyme. We then employed the recombinant chitinase A to effectively hydrolyze shrimp waste, yielding chitooligosaccharides (COS) at a rate of 33% of the substrate. The structure of the COS was confirmed through NMR and mass spectrometry analyses. Moreover, the COS demonstrated its utility by forming stable emulsions with various hydrocarbons. Its emulsification index remained stable across a wide range of salinity, pH, and temperature conditions. We further observed that the COS facilitated the recovery of motor oil, burned motor oil, and aniline from polluted sand. Gravimetric assessment of residual hydrocarbons showed a correlation with FTIR analyses, indicating the efficacy of COS in remediation efforts.

CONCLUSIONS

The recombinant chitinase holds significant promise for the biological conversion of chitinaceous wastes into chitooligosaccharides (COS), which proved its potential in bioremediation efforts targeting hydrocarbon-contaminated sand.

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.

An insight into the utilization of microbial biosurfactants pertaining to their industrial applications in the food sector

Microbial biosurfactants surpass synthetic alternatives due to their biodegradability, minimal toxicity, selective properties, and efficacy across a wide range of environmental conditions. Owing to their remarkable advantages, biosurfactants employability as effective emulsifiers and stabilizers, antimicrobial and antioxidant attributes, rendering them for integration into food preservation, processing, formulations, and packaging. The biosurfactants can also be derived from various types of food wastes. Biosurfactants are harnessed across multiple sectors within the food industry, ranging from condiments (mayonnaise) to baked goods (bread, muffins, loaves, cookies, and dough), and extending into the dairy industry (cheese, yogurt, and fermented milk). Additionally, their impact reaches the beverage industry, poultry feed, seafood products like tuna, as well as meat processing and instant foods, collectively redefining each sector's landscape. This review thoroughly explores the multifaceted utilization of biosurfactants within the food industry as emulsifiers, antimicrobial, antiadhesive, antibiofilm agents, shelf-life enhancers, texture modifiers, and foaming agents.

Unraveling the mechanistic insights of sophorolipid-capped gold nanoparticle-induced cell death in Vibrio cholerae

IMPORTANCE

Vibrio cholerae, a Gram-negative bacterium, is the causative agent of a fatal disease, "cholera." Prevention of cholera outbreak is possible by eliminating the bacteria from the environment. However, antimicrobial resistance developed in microorganisms has posed a threat and challenges to its treatment. Application of nanoparticles is a useful and effective option for the elimination of such microorganisms. Metal-based nanopaticles exhibit microbial toxicity through non-specific mechanisms. To prevent resistance development and increase antibacterial efficiency, rational designing of nanoparticles is required. Thus, knowledge on the exact mechanism of action of nanoparticles is highly essential. In this study, we explore the possible mechanisms of antibacterial activity of AuNPs-SL against V. cholerae. We show that the interaction of AuNPs-SL with V. cholerae enhances ROS production and membrane depolarization, change in permeability, and leakage of intracellular content. This action leads to the depletion of cellular ATP level, DNA damage, and subsequent cell death.

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.

Pharmaceutical prospects of biosurfactants produced from fungal species

The development of novel types of biogenic surface-active compounds is of greater interest for combating many diseases and infections. In this respect research and development of biosurfactant has gained immense importance. Substantially, biosurfactant is defined as a class of active amphiphilic chemical compounds that comprise hydrophobic and hydrophilic moieties on their surfaces. It is generally known that many kinds of microorganisms can be used to produce these surfactants or surface-active compounds. Hosting interesting features such as biodegradability, emulsifying/de-emulsifying capacity, low toxicity, and antimicrobial activities; these amphiphilic compounds in recent years have flourished as an ideal replacement for the chemically synthesized surfactant, and also have various commercial attractions. Both bacteria and fungi are the producers of these amphiphilic molecules; however, the pathogenicity of certain bacterial strains has caused a shift in interest toward fungi. Therefore, various fungi species have been reported for the production of biosurfactants amongst which Candida species have been the most studied strains. Biosurfactants uphold desired properties like antibacterial, antifungal, antiviral, antiadhesion, and anticancer activity which proves them an ideal candidate for the application in various fields like pharmaceutical, gene therapy, medical insertion safety, immunotherapy to fight against many chronic diseases, and so forth. Hence, this review article discusses the pharmaceutical prospects of biosurfactants produced from different fungal species, providing new directions toward the discovery and development of molecules with novel structures and diverse functions for advanced application in the medical field.

Microbial surfactants: A journey from fundamentals to recent advances

Microbial surfactants are amphiphilic surface-active substances aid to reduce surface and interfacial tensions by accumulating between two fluid phases. They can be generically classified as low or high molecular weight biosurfactants based on their molecular weight, whilst overall chemical makeup determines whether they are neutral or anionic molecules. They demonstrate a variety of fundamental characteristics, including the lowering of surface tension, emulsification, adsorption, micelle formation, etc. Microbial genera like Bacillus spp., Pseudomonas spp., Candida spp., and Pseudozyma spp. are studied extensively for their production. The type of biosurfactant produced is reliant on the substrate utilized and the pathway pursued by the generating microorganisms. Some advantages of biosurfactants over synthetic surfactants comprise biodegradability, low toxicity, bioavailability, specificity of action, structural diversity, and effectiveness in harsh environments. Biosurfactants are physiologically crucial molecules for producing microorganisms which help the cells to grasp substrates in adverse conditions and also have antimicrobial, anti-adhesive, and antioxidant properties. Biosurfactants are in high demand as a potential product in industries like petroleum, cosmetics, detergents, agriculture, medicine, and food due to their beneficial properties. Biosurfactants are the significant natural biodegradable substances employed to replace the chemical surfactants on a global scale in order to make a cleaner and more sustainable environment.

Precipitation of calcium carbonate in the presence of rhamnolipids in alginate hydrogels as a model of biomineralization

This paper reports the effects of rhamnolipids presence in the alginate hydrogel and CO₃^2- solution, on the precipitation of CaCO₃ in the Ca²⁺ loaded alginate hydrogel. Characteristics of the formed particles are discussed. Model conditions containing alginate hydrogel and rhamnolipids were used in order to mimic the natural environment of biomineralization in biofilms. It has been shown that rhamnolipids affect the characteristics of precipitated calcium carbonate effect of using these biosurfactants depends on their concentration as well as whether they are directly present in the hydrogel matrix or the carbonate solution surrounding the hydrogel. The greatest effect compared to the control samples was found for the rhamnolipids in the form of micelles directly present in the hydrogel with the CaCl₂ cross-linked solution at concentration of 0.05 M. These conditions result in the highest increase in vaterite content, specific surface area, and pore volume. The mechanism of CaCO₃ precipitation in alginate hydrogel containing rhamnolipids has been proposed.

Biosurfactant production by halophilic yeasts isolated from extreme environments in Botswana

Nine morphologically distinct halophilic yeasts were isolated from Makgadikgadi and Sua pans, as pristine and extreme environments in Botswana. Screening for biosurfactant production showed that Rhodotorula mucilaginosa SP6 and Debaryomyces hansenii MK9 exhibited the highest biosurfactant activity using Xanthocercis zambesiaca seed powder as a novel and alternative inexpensive carbon substrate. Chemical characterization of the purified biosurfactants by Fourier Transform Infra-Red spectroscopy suggested that the biosurfactant from R. mucilaginosa SP6 was a rhamnolipid-type whereas the biosurfactant from D. hansenii MK9 was a sophorolipid-type. The two biosurfactants exhibited antimicrobial activities against eight pathogenic bacteria and fungal strains (Proteus vulgaris, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Micrococcus luteus, Cryptococcus neoformans, Candida albicans and Aspergilus niger). The sophorolopid-type biosurfactant was found to be the most potent among the antimicrobial drug resistant strains tested. The findings open up prospects for the development of environmentally friendly antimicrobial drugs that use an inexpensive source of carbon to reduce the costs associated with the production of biosurfactants.

Synthesis, characterization, and evaluation of antibacterial efficacy of rhamnolipid-coated zinc oxide nanoparticles against Staphylococcus aureus

The antimicrobial efficacy of rhamnolipid is well established against a wide range of pathogens. However little is known about the enhancement of antimicrobial efficacy of rhamnolipid in the form of nanoparticles. With a curiosity of enhancing antimicrobial activity, a study has been carried out to evaluate the antimicrobial efficacy of rhamnolipid-coated zinc oxide nanoparticles. The zinc oxide nanoparticles were synthesized with rhamnolipid, produced by Pseudomonas aeruginosa JS29. The rhamnolipid-coated zinc oxide nanoparticles were characterized by FTIR, XRD, TGA, TEM, and SAED. The antimicrobial and antibiofilm efficacy of the nanoparticles was evaluated against Staphylococcus aureus MTCC 96. FTIR, XRD, TEM, and SAED analyses confirmed that the nanoparticles contain both rhamnolipid and zinc as constituents and are polycrystalline with sizes ranging from 40 to 50 nm. At a concentration of 250 µg/ml, rhamnolipid-coated zinc oxide nanoparticles exhibited 80% growth inhibition of the pathogen. Again, at the same concentration, the nanoparticle was observed to inhibit 78% of biofilm formation while disrupting 100% of preformed biofilm. The nanoparticles demonstrated an enhanced inhibitory and antibiofilm efficacy against the pathogen compared to the individual effect of both rhamnolipid and zinc oxide nanoparticles. With the established non-toxicity of rhamnolipid-coated zinc oxide nanoparticles in fibroblast cell lines, the nanoparticles could be a promising pharmaceutical alternative.

Influence of Rhamnolipids and Ionic Cross-Linking Conditions on the Mechanical Properties of Alginate Hydrogels as a Model Bacterial Biofilm

The literature indicates the existence of a relationship between rhamnolipids and bacterial biofilm, as well as the ability of selected bacteria to produce rhamnolipids and alginate. However, the influence of biosurfactant molecules on the mechanical properties of biofilms are still not fully understood. The aim of this research is to determine the effect of rhamnolipids concentration, CaCl₂ concentration, and ionic cross-linking time on the mechanical properties of alginate hydrogels using a Box–Behnken design. The mechanical properties of cross-linked alginate hydrogels were characterized using a universal testing machine. It was assumed that the addition of rhamnolipids mainly affects the compression load, and the value of this parameter is lower for hydrogels produced with biosurfactant concentration below CMC than for hydrogels obtained in pure water. In contrast, the addition of rhamnolipids in an amount exceeding CMC causes an increase in compression load. In bacterial biofilms, the presence of rhamnolipid molecules does not exceed the CMC value, which may confirm the influence of this biosurfactant on the formation of the biofilm structure. Moreover, rhamnolipids interact with the hydrophobic part of the alginate copolymer chains, and then the hydrophilic groups of adsorbed biosurfactant molecules create additional calcium ion trapping sites.

Biosurfactant synergized with marine bacterial DNase disrupts polymicrobial biofilms

Globally, the occurrence of biofilm associated infection has become an alarming menace to the medical fraternity because the thick exopolysaccharide layer encasing the biofilms makes the biofilm producing pathogens inherently resistant to antibiotics. Candida albicans, the most common pathogen among Candida spp. is the causative agent for superficial and invasive candidiasis. The morphological phase switching from yeast to hyphal form is one of the virulent traits of C. albicans critical for its pathogenicity. Owing to the emergence of antifungal resistance among this opportunistic fungus, there is a dire need for improvised alternative antifungal agents. In the present study, we have evaluated a biosurfactant from a marine bacterium for its biofilm disruption ability against C. albicans. This biosurfactant had the potential to disrupt biofilms as well as to inhibit the morphological transition from yeast to hyphae. In addition, this biosurfactant showed enhance disruption of mixed species biofilms of C. albicans and Staphylococcus epidermidis when combined with DNase isolated from marine bacteria. From the results obtained, it is evident that the biosurfactant could act as a potential antibiofilm agent against drug resistant C. albicans strains.

Valorization of biodiesel side stream waste glycerol for rhamnolipids production by Pseudomonas aeruginosa RS6

Biodiesel side stream waste glycerol was identified as a cheap carbon source for rhamnolipids (RLs) production which at the same time could improve the management of waste. The present study aimed to produce RLs by using Pseudomonas aeruginosa RS6 utilizing waste glycerol as a substrate and to evaluate their physico-chemicals properties. Fermentation conditions such as temperature, initial medium pH, waste glycerol concentration, nitrogen sources and concentrations resulted in different compositions of the mono- and di-RLs produced. The maximum RLs production of 2.73 g/L was obtained when P. aeruginosa RS6 was grown in a basal salt medium supplemented with 1% waste glycerol and 0.2 M sodium nitrate at 35 °C and pH 6.5. At optimal fermentation conditions, the emulsification index (E₂₄) values of cooking oil, diesel oil, benzene, olive oil, petroleum, and kerosene were all above E₂₄₌50%. The surface tension reduction obtained from 72.13 mN/m to 29.4-30.4 mN/m was better than the surface activity of some chemical-based surfactants. The RLs produced possessed antimicrobial activities against Gram-negative and Gram-positive bacteria with values ranging from 37% to 77% of growth inhibition when 1 mg/mL of RLs was used. Concentrations of RLs below 1500 μg/mL did not induce phytotoxicity effects on the tested seeds (Vigna radiata) compared to the chemical-based- surfactant, SDS. Furthermore, RLs tested on zebrafish (Danio rerio) embryos only exhibited low acute toxicity with an LC₅₀ value of 72.97 μg/mL at 48 h of exposure suggesting a green and eco-biochemical worthy of future applications to replace chemical-based surfactants.

Production and potential biotechnological applications of microbial surfactants: An overview

Microbial surfactants are amphipathic molecules that consist of hydrophilic and hydrophobic domains, which allow partition of two fluid phases of varying degree of polarity. They are classified into two main groups: bioemulsifier and biosurfactant, depending on their molecular weight. Microbial surfactants occur in various categories according to their chemical nature and producing organisms. These biomolecules are produced by diverse groups of microorganisms including fungi, bacteria, and yeasts. Their production is significantly influenced by substrate type, fermentation technology and microbial strains. Owing to inherent multifunctional properties and assorted synthetic aptitude of the microbes, microbial surfactants are mostly preferred than their chemical counterparts for various industrial and biomedical applications including bioremediation, oil recovery; as supplements in laundry formulations and as emulsion-stabilizers in food and cosmetic industries as well as therapeutic agents in medicine. The present review discusses on production of microbial surfactants as promising and alternative broad-functional biomolecules for various biotechnological applications.

A novel sophorolipid-producing Candida keroseneae GBME-IAUF-2 as a potential agent in microbial enhanced oil recovery (MEOR)

The biosurfactants have extensive applications in food and petroleum microbiology. The aims of this research were isolation and characterization of thermo-tolerant biosurfactants from highly producing yeast strains. The Bushnell Hass medium was used for screening the biosurfactant-producing yeasts. Biosurfactant presence was evaluated using oil displacement assay and surface tension test. The best biosurfactant-producing strain was named Candida keroseneae GBME-IAUF-2 and its 5.8s-rDNA sequence was deposited in GenBank, NCBI, under the accession number MT012957.1. The thin layer chromatography and Fourier-transform infrared spectroscopy analysis confirmed that the extracted biosurfactant was sophorolipid with a significant surface activity. The purified sophorolipid decreased the surface tension of water from 72 to 29.1 mN/m. Its maximum emulsification index, E24%, was recorded as 60% and preserved 92.06-97.25% of its original activity at 110-120°C. It also preserved 89.11% and 84.73% of its original activity in pH of 9.3 and 10.5, respectively. It preserved 96.66-100% of its original activity in saline extreme conditions. This is the first report of sophorolipid production by the yeast C. keroseneae. According to the high thermal, pH and saline stability, the sophorolipid produced by C. keroseneae GBME-IAUF-2 could be highly recommended for applications in microbial enhanced oil recovery as well as food industries as an excellent emulsifying agent.

Eco-friendly biosurfactant from Wickerhamomyces anomalus CCMA 0358 as larvicidal and antimicrobial

Kitchen waste oil (KWO) was evaluated as a substrate for production of biosurfactant by Wickerhamomyces anomalus CCMA 0358 and was tested against Aedes aegypti larvae, the mosquito causing neglected diseases, such as dengue fever, Zika, and Chikungunya, achieving 100 % mortality in the lowest concentration (6.25 %) evaluated in 24 h. Furthermore, possible applications of this compound were evaluated as antibacterial, antiadhesive, and antifungal. At a concentration of 50 %, the biosurfactant was found to inhibit the growth of Bacillus cereus, showing high inhibitions levels against Salmonella Enteritidis, Staphylococcus aureus, and Escherichia coli. The antifungal activity was evaluated against Aspergillus, Cercospora, Colletotrichum, and Fusarium, obtaining results of up to 95 % inhibition. In addition to these promising results, the yeast W. anomalus produced the biosurfactant from an inexpensive substrate, which increases the possibility of its application in several industries owing to the low cost involved.

Evaluation of Salmonella bongori derived biosurfactants and its extracellular protein separation by SDS-PAGE using petridishes: A simply modified approach

Presently, through the preliminary screening assays, the Salmonella bongori BH11 was found to be an effective biosurfactants (BSFs) producer. The secreted BSFs were extracted using methanol: chloroform and characterized through FTIR, TLC, HPLC and GCMS analyses. Further, the extracellular protein was extracted (TCA/acetone method), estimated (Lowry's method) and separated (standard and modified SDS-PAGE). Through the obtained characteristic FTIR peaks (1107.09cm^-1), its content was presumed to be glycolipids and as rhamnose/rhamnolipids through the TLC-R_f value. GCMS revealed 6 compounds, in which Toluene (32%) and 5-(2-Thienyl) pentanoic acid (23%) are the major ones. The crude BSFs exhibited preponderant antibacterial effects on Staphylococcus aureus and Serratia marcescens. Also, it inhibited the biofilm formation of S. aureus, Pseudomonas aeruginosa, P. fluorescens and S. marcescens. Considerably, 76% mortality of IV instar larvae of Culex quinquefasciatus was recorded from BSFs, when compared to SDS. The presently followed protein separation technique using two petridishes might attract the attention of the researchers, as it would emerge as a standard procedure in future. This is the first report on the screening of BSFs from Salmonella bongori that showed antagonistic property, larvicidal potentials and the presently followed modified SDS-PAGE protein separation technique is a simple, reliable and cost effective one.

Evaluating rhamnolipid-enhanced washing as a first step in remediation of drill cuttings and petroleum-contaminated soils

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Soil washing is an innovative approach to treatment of waste streams.

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Temperature has a significant effect on rhamnolipid enhanced soil washing.

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Drill cuttings and petroleum-impacted soil show similar optimum washing conditions.

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Maximum total petroleum hydrocarbon reduction in drill cuttings was 76.8%.

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Maximum total petroleum hydrocarbon reduction in soil was 58.5%.

Environmental pollution by petroleum hydrocarbons (PHCs) is a severe and widespread problem impacting human health and the environment. To combat this issue, innovative and sustainable treatment methods are required. This research study investigated rhamnolipid-enhanced washing of drill cuttings and petroleum-contaminated soil obtained from northeastern British Columbia in Canada. The efficiency of PHC reduction was analysed and quantified via a Gas Chromatography equipped with a Flame Ionization Detector. Optimum washing conditions for both drill cuttings and petroleum-contaminated soil were temperature of ∼23.5 °C (room temperature), rhamnolipid concentration of 500 mg/L, and a washing time of 30 min. The optimum stirring speed and solution-to-sample ratio for drill cuttings and petroleum-contaminated soil were 100 rpm; 1:1, and 200 rpm; 4:1 respectively. The maximum PHC reduction recorded for total petroleum hydrocarbon and PHC fractions – F2, F3 and F4 were 76.8%, 85.4%, 71.3% and 76.9% respectively for drill cuttings and 58.5%, 48.4%, 63.5% and 59.8% respectively for petroleum-contaminated soil. The results strongly suggest that soil washing is an effective step in the reduction of PHC and can be used as a first step in the treatment of drill cuttings and petroleum-contaminated soils.

Characterization and application of a biosurfactant isolated from Candida utilis in salad dressings

This study aimed at characterizing a biosurfactant from Candida utilis, and use it in the preparation of salad dressings. The biosurfactant was produced in mineral medium supplemented with 6% glucose and 6% waste frying canola oil. The crude biosurfactant was then tested for stability in different conditions of pH, salt concentration, heating time and temperature. The critical micelle dilution, chemical composition, and structural analysis were determined. The compound was resistant to extreme conditions and presented stable surface tension and emulsification activity in alkaline pH and was characterized as a carbohydrate-lipid-protein complex showing the best formulation and consistency at 0.7% (w/v) with guar gum indicating potential applicability in food emulsions.

The Role of Biosurfactants in the Continued Drive for Environmental Sustainability

Biosurfactants are microbial products that have been increasingly researched due to their many identified advantages, such as low toxicity and high activity at extreme temperatures, but more importantly, they are biodegradable and compatible with the environment. Biosurfactants are versatile products with vast applications in the clean-up of environmental pollutants through biodegradation and bioremediation. They also have applications in the food, pharmaceutical, and other industries. These advantages and wide range of applications have led to the continued interest in biosurfactants. In particular, there is a growing discussion around environmental sustainability and the important role that biosurfactants will increasingly play in the near future, for example, via the use of renewable by-products as substrates, waste reduction, and potential reuse of the treated waste. This has resulted in increased attention on these microbial products in industry. Research highlighting the potential of biosurfactants in environmental sustainability is required to drive efforts to make biosurfactants more viable for commercial and large-scale applications; making them available, cheaper and economically sustainable. The present review discusses the unique relationship between biosurfactants and environmental sustainability, especially the role that biosurfactants play in the clean-up of environmental pollutants and, therefore, increasing environmental protection.

Penile prosthesis biofilm formation and emerging therapies against them

Infections are among the most feared and devastating complications of penile prosthesis infections, often requiring surgical exploration and explantation are prosthesis infections. While the rate of infections have decreased due to antibiotic prophylaxis, antiseptic device preparation, increased sterility in implantation techniques and device modifications, infections still occur at a rate of 1-3%. This article reviews the formation of biofilms on penile prostheses and novel, experimental methods to prevent and eradicate them.

Bioemulsifiers Derived from Microorganisms: Applications in the Drug and Food Industry

Emulsifiers are a large category of compounds considered as surface active agents or surfactants. An emulsifier acts by reducing the speed of chemical reactions, and enhancing its stability. Bioemulsifiers are known as surface active biomolecule materials, due to their unique features over chemical surfactants, such as non-toxicity, biodegradability, foaming, biocompatibility, efficiency at low concentrations, high selectivity in different pH, temperatures and salinities. Emulsifiers are found in various natural resources and are synthesized by Bacteria, Fungi and Yeast. Bioemulsifier’s molecular weight is higher than that of biosurfactants. Emulsion’s function is closely related to their chemical structure. Therefore, the aim of this paper was to study the various bioemulsifiers derived from microorganisms used in the drug and food industry. In this manuscript, we studied organisms with biosurfactant producing abilities. These inexpensive substrates could be used in environmental remediation and in the petroleum industry.

Interactions between surfactants and the skin - Theory and practice

One of the primary causes of skin irritation is the use of body wash cosmetics and household chemicals, since they are in direct contact with the skin, and they are widely available and frequently used. The main ingredients of products of this type are surfactants, which may have diverse effects on the skin. The skin irritation potential of surfactants is determined by their chemical and physical properties resulting from their structure, and specific interactions with the skin. Surfactants are capable of interacting both with proteins and lipids in the stratum corneum. By penetrating through this layer, surfactants are also able to affect living cells in deeper regions of the skin. Further skin penetration may result in damage to cell membranes and structural components of keratinocytes, releasing proinflammatory mediators. By causing irreversible changes in cell structure, surfactants can often lead to their death. The paper presents a critical review of literature on the effects of surfactants on the skin. Aspects discussed in the paper include the skin irritation potential of surfactants, mechanisms underlying interactions between compounds of this type and the skin which have been proposed over the years, and verified methods of reducing the skin irritation potential of surfactant compounds. Basic research conducted in this field over many years translate into practical applications of surfactants in the cosmetic and household chemical industries. This aspect is also emphasized in the present study.

Improvement of biosurfactant production by Wickerhamomyces anomalus CCMA 0358 and its potential application in bioremediation

In this work, biosurfactant production by Wickerhamomyces anomalus CCMA 0358 was increased through the development of an optimized culture medium using response surface methodology. The optimized culture medium contained yeast extract (4.64 g/L), ammonium sulfate (4.22 g/L), glucose (1.39 g/L) and olive oil (10 g/L). Biosurfactant production using this medium was validated both in flasks and bioreactor, and the surface tension was reduced from 49.0 mN/m up to 31.4 mN/m and 29.3 mN/m, respectively. In both cases, the highest biosurfactant production was achieved after 24 h of growth. W. anomalus CCMA 0358 demonstrated to be a fast biosurfactant producer (24 h) as compared to other yeast strains previously reported (144-240 h). The produced biosurfactant remained stable at high temperature (121 °C), NaCl concentrations as high as 300 g/L, and pH values between 6 and 12. The crude biosurfactant allowed the recovery of 20% of crude oil from contaminated sand, being a promising candidate for application in bioremediation or in the petroleum industry.

Response Surface Methodology for Optimizing the Production of Biosurfactant by Candida tropicalis on Industrial Waste Substrates

Biosurfactant production optimization by Candida tropicalis UCP0996 was studied combining central composite rotational design (CCRD) and response surface methodology (RSM). The factors selected for optimization of the culture conditions were sugarcane molasses, corn steep liquor, waste frying oil concentrations and inoculum size. The response variables were surface tension and biosurfactant yield. All factors studied were important within the ranges investigated. The two empirical forecast models developed through RSM were found to be adequate for describing biosurfactant production with regard to surface tension (R² = 0.99833) and biosurfactant yield (R² = 0.98927) and a very strong, negative, linear correlation was found between the two response variables studied (r = −0.95). The maximum reduction in surface tension and the highest biosurfactant yield were 29.98 mNm⁻¹ and 4.19 gL⁻¹, respectively, which were simultaneously obtained under the optimum conditions of 2.5% waste frying oil, 2.5%, corn steep liquor, 2.5% molasses, and 2% inoculum size. To validate the efficiency of the statistically optimized variables, biosurfactant production was also carried out in 2 and 50 L bioreactors, with yields of 5.87 and 7.36 gL⁻¹, respectively. Finally, the biosurfactant was applied in motor oil dispersion, reaching up to 75% dispersion. Results demonstrated that the CCRD was suitable for identifying the optimum production conditions and that the new biosurfactant is a promising dispersant for application in the oil industry.

Biosurfactants in cosmetic formulations: trends and challenges

Cosmetic products play an essential role in everyone's life. People everyday use a large variety of cosmetic products such as soap, shampoo, toothpaste, deodorant, skin care, perfume, make-up, among others. The cosmetic industry encompasses several environmental, social and economic impacts that are being addressed through the search for more efficient manufacturing techniques, the reduction of waste and emissions and the promotion of personal hygiene, contributing to an improvement of public health and at the same time providing employment opportunities. The current trend among consumers is the pursuit for natural ingredients in cosmetic products, as many of these products exhibit equal, better or additional benefits in comparison with the chemical-based products. In this sense, biosurfactants are natural compounds with great potential in the formulation of cosmetic products given by their biodegradability and impact in health. Indeed, many of these biosurfactants could exhibit a "prebiotic" character. This review covers the current state-of-the-art of biosurfactant research for cosmetic purposes and further discusses the future challenges for cosmetic applications.

Influence of micelle formation on the adsorption capacity of a biosurfactant extracted from corn on dyed hair

Biosurfactants obtained from corn steep liquor were applied to dyed hair and showed good adsorption while maintaining the dyed hair structure in a good state.

Current status in biotechnological production and applications of glycolipid biosurfactants

Biosurfactants are natural compounds with surface activity and emulsifying properties produced by several types of microorganisms and have been considered an interesting alternative to synthetic surfactants. Glycolipids are promising biosurfactants, due to low toxicity, biodegradability, and chemical stability in different conditions and also because they have many biological activities, allowing wide applications in different fields. In this review, we addressed general information about families of glycolipids, rhamnolipids, sophorolipids, mannosylerythritol lipids, and trehalose lipids, describing their chemical and surface characteristics, recent studies using alternative substrates, and new strategies to improve of production, beyond their specificities. We focus in providing recent developments and trends in biotechnological process and medical and industrial applications.

Waste Soybean Oil and Corn Steep Liquor as Economic Substrates for Bioemulsifier and Biodiesel Production by Candida lipolytica UCP 0998

Almost all oleaginous microorganisms are available for biodiesel production, and for the mechanism of oil accumulation, which is what makes a microbial approach economically competitive. This study investigated the potential that the yeast Candida lipolytica UCP0988, in an anamorphous state, has to produce simultaneously a bioemulsifier and to accumulate lipids using inexpensive and alternative substrates. Cultivation was carried out using waste soybean oil and corn steep liquor in accordance with 2² experimental designs with 1% inoculums (10⁷ cells/mL). The bioemulsifier was produced in the cell-free metabolic liquid in the late exponential phase (96 h), at Assay 4 (corn steep liquor 5% and waste soybean oil 8%), with 6.704 UEA, IE₂₄ of 96.66%, and showed an anionic profile. The emulsion formed consisted of compact small and stable droplets (size 0.2–5 µm), stable at all temperatures, at pH 2 and 4, and 2% salinity, and showed an ability to remove 93.74% of diesel oil from sand. The displacement oil (ODA) showed 45.34 cm² of dispersion (central point of the factorial design). The biomass obtained from Assay 4 was able to accumulate lipids of 0.425 g/g biomass (corresponding to 42.5%), which consisted of Palmitic acid (28.4%), Stearic acid (7.7%), Oleic acid (42.8%), Linoleic acid (19.0%), and γ-Linolenic acid (2.1%). The results showed the ability of C. lipopytica to produce both bioemulsifier and biodiesel using the metabolic conversion of waste soybean oil and corn steep liquor, which are economic renewable sources.

Inhibitory Effect of Sophorolipid on Candida albicans Biofilm Formation and Hyphal Growth

Candida albicans causes superficial and life-threatening systemic infections. These are difficult to treat often due to drug resistance, particularly because C. albicans biofilms are inherently resistant to most antifungals. Sophorolipid (SL), a glycolipid biosurfactant, has been shown to have antimicrobial and anticancer properties. In this study, we investigated the effect of SL on C. albicans biofilm formation and preformed biofilms. SL was found to inhibit C. albicans biofilm formation as well as reduce the viability of preformed biofilms. Moreover, SL, when used along with amphotericin B (AmB) or fluconazole (FLZ), was found to act synergistically against biofilm formation and preformed biofilms. Effect of SL on C. albicans biofilm formation was further visualized by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM), which revealed absence of hyphae, typical biofilm architecture and alteration in the morphology of biofilm cells. We also found that SL downregulates the expression of hypha specific genes HWP1, ALS1, ALS3, ECE1 and SAP4, which possibly explains the inhibitory effect of SL on hyphae and biofilm formation.

Biosurfactants: Multifunctional Biomolecules of the 21st Century

In the era of global industrialisation, the exploration of natural resources has served as a source of experimentation for science and advanced technologies, giving rise to the manufacturing of products with high aggregate value in the world market, such as biosurfactants. Biosurfactants are amphiphilic microbial molecules with hydrophilic and hydrophobic moieties that partition at liquid/liquid, liquid/gas or liquid/solid interfaces. Such characteristics allow these biomolecules to play a key role in emulsification, foam formation, detergency and dispersal, which are desirable qualities in different industries. Biosurfactant production is considered one of the key technologies for development in the 21st century. Besides exerting a strong positive impact on the main global problems, biosurfactant production has considerable importance to the implantation of sustainable industrial processes, such as the use of renewable resources and "green" products. Biodegradability and low toxicity have led to the intensification of scientific studies on a wide range of industrial applications for biosurfactants in the field of bioremediation as well as the petroleum, food processing, health, chemical, agricultural and cosmetic industries. In this paper, we offer an extensive review regarding knowledge accumulated over the years and advances achieved in the incorporation of biomolecules in different industries.

Role of quorum sensing in bacterial infections

Quorum sensing (QS) is cell communication that is widely used by bacterial pathogens to coordinate the expression of several collective traits, including the production of multiple virulence factors, biofilm formation, and swarming motility once a population threshold is reached. Several lines of evidence indicate that QS enhances virulence of bacterial pathogens in animal models as well as in human infections; however, its relative importance for bacterial pathogenesis is still incomplete. In this review, we discuss the present evidence from in vitro and in vivo experiments in animal models, as well as from clinical studies, that link QS systems with human infections. We focus on two major QS bacterial models, the opportunistic Gram negative bacteria Pseudomonas aeruginosa and the Gram positive Staphylococcus aureus, which are also two of the main agents responsible of nosocomial and wound infections. In addition, QS communication systems in other bacterial, eukaryotic pathogens, and even immune and cancer cells are also reviewed, and finally, the new approaches proposed to combat bacterial infections by the attenuation of their QS communication systems and virulence are also discussed.

Applications of biosurfactants in the petroleum industry and the remediation of oil spills

Petroleum hydrocarbons are important energy resources. However, petroleum is also a major pollutant of the environment. Contamination by oil and oil products has caused serious harm, and increasing attention has been paid to the development and implementation of innovative technologies for the removal of these contaminants. Biosurfactants have been extensively used in the remediation of water and soil, as well as in the main stages of the oil production chain, such as extraction, transportation, and storage. This diversity of applications is mainly due to advantages such as biodegradability, low toxicity and better functionality under extreme conditions in comparison to synthetic counterparts. Moreover, biosurfactants can be obtained with the use of agro-industrial waste as substrate, which helps reduce overall production costs. The present review describes the potential applications of biosurfactants in the oil industry and the remediation of environmental pollution caused by oil spills.