Characterization and properties of the biosurfactant produced by Candida lipolytica UCP 0988

Pseudomonas aeruginosa RTE4: A Tea Rhizobacterium With Potential for Plant Growth Promotion and Biosurfactant Production

Tea is an ancient non-alcoholic beverage plantation crop cultivated in the most part of Assam, India. Being a long-term monoculture, tea plants are prone to both biotic and abiotic stresses, and requires massive amounts of chemicals as fertilizers and pesticides to achieve worthy crop productivity. The rhizosphere bacteria with the abilities to produce phytohormone, secreting hydrolytic enzyme, biofilm formation, bio-control activity provides induced systemic resistance to plants against pathogens. Thus, plant growth promoting (PGP) rhizobacteria represents as an alternative candidate to chemical inputs for agriculture sector. Further, deciphering the secondary metabolites, including biosurfactant (BS) allow developing a better understanding of rhizobacterial strains. The acidic nature of tea rhizosphere is predominated by Bacillus followed by Pseudomonas that enhances crop biomass and yield through accelerating uptake of nutrients. In the present study, a strain Pseudomonas aeruginosa RTE4 isolated from tea rhizosphere soil collected from Rosekandy Tea Garden, Cachar, Assam was evaluated for various plant-growth promoting attributes. The strain RTE4 produces indole acetic acid (74.54 μg/ml), hydrolytic enzymes, and solubilize tri-calcium phosphate (46 μg/ml). Bio-control activity of RTE4 was recorded against two foliar fungal pathogens of tea (Corticium invisium and Fusarium solani) and a bacterial plant pathogen (Xanthomonas campestris). The strain RTE4 was positive for BS production in the preliminary screening. Detailed analytical characterization through TLC, FTIR, NMR, and LCMS techniques revealed that the strain RTE4 grown in M9 medium with glucose (2% w/v) produce di-rhamnolipid BS. This BS reduced surface tension of phosphate buffer saline from 71 to 31 mN/m with a critical micelle concentration of 80 mg/L. Purified BS of RTE4 showed minimum inhibitory concentration of 5, 10, and 20 mg/ml against X. campestris, F. solani and C. invisium, respectively. Capability of RTE4 BS to be employed as a biofungicide as compared to Carbendazim - commercially available fungicide is also tested. The strain RTE4 exhibits multiple PGP attributes along with production of di-rhamnolipid BS. This gives a possibility to produce di-rhamnolipid BS from RTE4 in large scale and explore its applications in fields as a biological alternative to chemical fertilizer.

Process Optimization of Palm Oil Mill Effluent-Based Biosurfactant of Halomonas meridiana BK-AB4 Originated from Bledug Kuwu Mud Volcano in Central Java for Microbial Enhanced Oil Recovery

Biosurfactants are one of the microbial bioproducts that are in most demand from microbial-enhanced oil recovery (MEOR). The production of biosurfactant is still a relatively high cost. Therefore, this study aims to reduce production costs by utilizing palm oil mill effluent (POME) as the main carbon source. This work examines the optimal conditions of biosurfactant production by Halomonas meridiana BK-AB4 isolated from the Bledug Kuwu mud volcano in Central Java Indonesia and studies it for EOR applications. The biosurfactant production stage was optimized by varying POME concentration, incubation time, NaCl concentration, and pH to obtain the maximum oil displacement area (ODA) values. A response surface methodology (RSM) and a central composite design (CCD) were used to identify the influence of each variable and to trace the relationship between variables. Optimum biosurfactant production was found at a POME concentration (v/v) of 16%, incubation (h) of 112, NaCl concentration (w/v) of 4.7%, pH of 6.5, with an oil displacement area of 3.642 cm. The LC-MS and FTIR analysis revealed the functional groups of carboxylic acid or esters, which indicated that the biosurfactant produced belonged to the fatty acid class. The lowest IFT value was obtained at the second and seventh-day observations at a concentration of 500 mg/L, i.e., 0.03 mN/m and 0.06 mN/m. The critical micelle concentration (CMC) of biosurfactant was about 350 mg/L with a surface tension value of about 54.16 mN/m. The highest emulsification activity (E24 = 76%) in light crude oil (naphthenic–naphthenic) and could reduce the interfacial tension between oil and water up to 0.18 mN/m. The imbibition experiment with biosurfactant results in 23.89% additional oil recovery for 60 h of observation, with the highest increase in oil recovery occurring at the 18th hour, which is 2.72%. Therefore, this bacterium and its biosurfactant show potential, and the bacterium are suitable for use in MEOR applications.

Biosurfactant from vaginal Lactobacillus crispatus BC1 as a promising agent to interfere with Candida adhesion

BACKGROUND

Lactobacillus spp. dominating the vaginal microbiota of healthy women contribute to the prevention of urogenital and sexually transmitted infections. Their protective role in the vagina can be mediated by Lactobacillus cells themselves, metabolites or bacterial components, able to interfere with pathogen adhesion and infectivity. Vulvovaginal candidiasis (VVC) is a common genital infection, caused by the overgrowth of opportunistic Candida spp. including C. albicans, C. glabrata, C. krusei and C. tropicalis. Azole antifungal drugs are not always efficient in resolving VVC and preventing recurrent infections, thus alternative anti-Candida agents based on vaginal probiotics have gained more importance. The present work aims to chemically characterize the biosurfactant (BS) isolated from a vaginal Lactobacillus crispatus strain, L. crispatus BC1, and to investigate its safety and antiadhesive/antimicrobial activity against Candida spp., employing in vitro and in vivo assays.

RESULTS

BS isolated from vaginal L. crispatus BC1 was characterised as non-homogeneous lipopeptide molecules with a critical micellar concentration value of 2 mg/mL, and good emulsification and mucoadhesive properties. At 1.25 mg/mL, the BS was not cytotoxic and reduced Candida strains' ability to adhere to human cervical epithelial cells, mainly by exclusion mechanism. Moreover, intravaginal (i.va.) inoculation of BS in a murine experimental model was safe and did not perturb vaginal cytology, histology and cultivable vaginal microbiota. In the case of i.va. challenge of mice with C. albicans, BS was able to reduce leukocyte influx.

CONCLUSIONS

These results indicate that BS from vaginal L. crispatus BC1 is able to interfere with Candida adhesion in vitro and in vivo, and suggest its potential as a preventive agent to reduce mucosal damage occasioned by Candida during VVC.

Highlighting the Crude Oil Bioremediation Potential of Marine Fungi Isolated from the Port of Oran (Algeria)

While over hundreds of terrestrial fungal genera have been shown to play important roles in the biodegradation of hydrocarbons, few studies have so far focused on the fungal bioremediation potential of petroleum in the marine environment. In this study, the culturable fungal communities occurring in the port of Oran in Algeria, considered here as a chronically-contaminated site, have been mainly analyzed in terms of species richness. A collection of 84 filamentous fungi has been established from seawater samples and then the fungi were screened for their ability to utilize and degrade crude oil. A total of 12 isolates were able to utilize crude oil as a unique carbon source, from which 4 were defined as the most promising biodegrading isolates based on a screening test using 2,6-dichlorophenol indophenol as a proxy to highlight their ability to metabolize crude oil. The biosurfactant production capability was also tested and, interestingly, the oil spreading and drop-collapse tests highlighted that the 4 most promising isolates were also those able to produce the highest quantity of biosurfactants. The results generated in this study demonstrate that the most promising fungal isolates, namely Penicillium polonicum AMF16, P. chrysogenum AMF47 and 2 isolates (AMF40 and AMF74) affiliated to P. cyclopium, appear to be interesting candidates for bioremediation of crude oil pollution in the marine environment within the frame of bioaugmentation or biostimulation processes.

Production of biosurfactant using the endemic bacterial community of a PAHs contaminated soil, and its potential use for PAHs remobilization

Biosurfactants are surface-active agents produced by microorganisms whose use in soil remediation processes is increasingly discussed as a more environmentally friendly alternative than chemically produced surfactants. In this work, we report the production of a biosurfactant by a bacterial community extracted from a polluted soil, mainly impacted by PAHs, in order to use it in a soil-washing process coupled with bioremediation. Nutrient balance was a critical parameter to optimize the production. Best conditions for biosurfactant production were found to be 20 g/L of glucose, 2 g/L of NH₄NO₃, and 14.2 g/L of Na₂HPO₄, corresponding to a C/N/P molar ratio equal to 13/1/2. Purification of the produced biosurfactant by acidification and double extraction with dichloromethane as a solvent allowed measuring the Critical Micellar Concentration (CMC) as equal to 42 mg/L. The capacity of the purified biosurfactant to increase the apparent solubility of four reference PAHs (naphthalene, phenanthrene, pyrene and benzo[a]pyrene) was completed. The solubilisation ratios, in mg of PAH/g of biosurfactant for phenanthrene, pyrene and benzo[a]pyrene are 0.214, 0.1204 and 0.0068, respectively. Identification of the bacteria found in the colony producing the biosurfactant showed the presence of bacteria able to produce biosurfactant (Enterobacteriaceae, Pseudomonas), as well as, others able to degrade PAHs (Microbacterium, Pseudomonas, Rhodanobacteraceae).

A novel fatty alkene from marine bacteria: A thermo stable biosurfactant and its applications

In this study, a novel thermo stable biosurfactants, 1-Pentanonacontene (C₉₅H₁₉₀) a fatty alkene and 3-Hydroxy-16-methylheptadecanoic acid (C₁₈H₃₆O₃) were isolated from a marine isolate SGD-AC-13. Biosurfactants were produced using 1% yeast extract in tap water as production medium at 24 h in flask and 12 h in bioreactor. Using 16S rRNA gene sequence (1515 bp) and BCL card (bioMérieux VITEK^®), strain was identified as Bacillus sp. Crude biosurfactant reduced the surface tension of distilled water to 31.32 ± 0.93 mN/m with CMC value of 0.3 mg/ml. Cell free supernatant showed excellent emulsification and oil displacement activity with stability up to 160 °C, pH 6-12 and 50 g/L NaCl conc. Biosurfactants were characterized using FTIR, TLC, HPLC LC-MS and NMR spectroscopy. Cell free supernatant reduced the contact angle of distilled water droplet from 117° to 52.28° and of 2% pesticide from 78.77° to 73.42° while 750 μg/ml of crude biosurfactant reduced from 66.06° to 56.33° for 2% pesticide and recovered 35% ULO and 12% HWCO from the contaminated sand. To our best of knowledge, this is the first report of thermo stable fatty alkene as a biosurfactant and is structurally different from previously reported, with having potential application in agriculture, oil recovery and bioremediation.

Advances on research in the use of agro-industrial waste in biosurfactant production

Biosurfactants are amphiphilic molecules produced by a variety of microorganisms, including bacteria, yeast and filamentous fungi. Unlike chemically synthesized surfactants, biosurfactants present advantages, such as biodegradability, low toxicity, high selectivity and activity under extreme temperature, pH and salinity conditions, as well as a low critical micelle concentration. Moreover, they can be produced from agro-industrial waste and renewable sources. Their structural diversity and functional properties mean that they have potential applications in various industrial processes as wetting agents, dispersants, emulsifiers, foaming agents, food additives and detergents, as well as in the field of environmental biotechnology. However, opportunities for their commercialization have been limited due to the low yields obtained in the fermentation processes involved in their production as well as the use of refined raw materials, which means higher cost in production. In an attempt to solve these limitations on the commercialization of biosurfactants, various research groups have focused on testing the use of inexpensive alternative sources, such as agro-industrial waste, as substrates for the production of different biosurfactants. In addition to enabling the economical production of biosurfactants, the use of such waste aims to reduce the accumulation of compounds that cause environmental damage. This review shows advances in biosurfactant production carried out using different waste materials or by-products from agro-industrial activities.

Simultaneous Application of Biosurfactant and Bioaugmentation with Rhamnolipid-Producing Shewanella for Enhanced Bioremediation of Oil-Polluted Soil

In the present study, a combined treatment strategy involving the addition of rhamnolipid, rhamnolipid-producing bacteria (Shewanella sp. BS4) and a native soil microbial community for the remediation of hydrocarbon-contaminated soil under pilot-scale conditions was adopted. The isolate BS4 (rhl+), demonstrating the highest emulsification activity and surface tension reduction efficiency, was identified based on 16 S rDNA sequencing as Shewanella sp. strain. Growth conditions for rhamnolipid production were optimized based on Central Composite Design (CCD) as 2.9% crude oil, a 54 × 106 CFU g−1 inoculation load of soil, a temperature of 30.5 °C, and a pH of 6.7. In situ bioremediation experiments, conducted using hydrocarbon-contaminated soil treated with the combination of rhamnolipid and rhamnolipid-producing bacteria, showed that the inoculated Shewanella sp. BS4, along with the indigenous soil microbial community, supported the highest hydrocarbon-degrading bacterial population and soil respiration activity, and this treatment resulted in 75.8% hydrocarbon removal efficiency, which was higher compared to contaminated soil devoid of any treatment.

Effect of biosurfactant derived from Vibrio natriegens MK3 against Vibrio harveyi biofilm and virulence

Vibrio harveyi is a marine luminous pathogen, which causes biofilm-mediated infections, pressures the search for an innovative alternate approach to strive against vibriosis in aquaculture. This study anticipated to explore the effect of glycolipid biosurfactant as an antipathogenic against V. harveyi to control vibriosis. In this study, 27 bacterial strains were isolated from marine soil sediments. Out of these, 11 strains exhibited surfactant activity and the strain MK3 showed high emulsification index. The potent strain was identified as Vibrio natriegens and named as V. natriegens MK3. The extracted biosurfactant was purified using high-performance liquid chromatography and it was efficient to decrease the surface tension of the growth medium up to 21 mN/m. The functional group and composition of the biosurfactant were determined by Fourier-transform infrared spectroscopy and nuclear magnetic resonance spectroscopy spectral studies and the nature of the biosurfactant was identified as glycolipid. The surfactant was capable of reducing the biofilm formation, bioluminescence, extracellular polysaccharide synthesis, and quorum sensing in marine shrimp pathogen V. harveyi. The antagonistic effect of biosurfactant was evaluated against V. harveyi-infected brine shrimp Artemia salina. This study reveals that biosurfactant can be considered for the management of biofilm-related aquatic infections.

Biosurfactant production by yeasts from different types of soil of the South Shetland Islands (Maritime Antarctica)

AIM

To screen and identify a potential biosurfactant-producing yeast strain isolated from Antarctic soil and to evaluate the fermentation process kinetics of the most promising strain on biosurfactant production using glycerol as carbon source.

METHODS AND RESULTS

From the 68 isolated yeast strains, 11 strains were able to produce biosurfactants after Emulsification Index (E.I.) and Drop Collapse tests, reaching an E.I. higher than 10%. Strain 1_4.0 was the best producer, identified as Candida glaebosa based on molecular analysis. Yeast was cultivated in a medium composed of glycerol supplemented with yeast extract for 120 h to determine the process kinetics. The increased C/N ratio affected yeast growth and biosurfactant production. Biosurfactant release was associated with the end of exponential and beginning of the stationary growth phases. Results indicated an E.I. of 30% at the end of the fermentation.

CONCLUSIONS

The feasiability of C. glaebosa to produce biosurfactant from a low-cost medium cultivation shows a great impact on the development of bioresource in the Antarctica terrestrial environment.

SIGNIFICANCE AND IMPACT OF THE STUDY

Although the diversity of psychrophilic/psychrotolerant micro-organisms from Antarctica has been the preferred subject of study by microbiologists, terrestrial microfungal communities are scarcely investigated and literature about the biotechnological potential of such micro-organisms should cover important biomolecules in addition to cold-adapted enzymes. In the present study, for the first time, the Maritime Antarctica environment was screened as a novel source of biosurfactants produced by micro-organisms.

Fast Biodegradation of Diesel Hydrocarbons at High Concentration by the Sophorolipid-Producing Yeast KP324968

In the last decades, biodegradation as an environmentally friendly approach has raised interest in connection with the removal of hydrocarbon pollutants. Its capacity for removing pollutants strongly depends on the type of living cell and environmental conditions. The degradative activity of a new sophorolipid-producing yeast, <i>Candida catenulata</i> KP324968, in the removal of high concentrations of diesel from effluents was statistically evaluated considering the initial pH, the agitation speed, and the initial diesel concentration. The optimal setting of the operational variables at an initial pH of 4.7, an agitation speed of 204 rpm, and an initial diesel concentration of 93.4 g L^–1 resulted in the highest total petroleum hydrocarbon removal efficiency: about 82.1% after 6 days (biodegradation rate: 0.378 g g_cell^–1 h^–1). During the cell growth phase, the emulsification index in the medium increased and reached its highest level at 64.6% after 48 h. Further tests indicated that the emulsification capacity was obtained by in situ production of two sophorolipid molecules with an m/z of 533 and 583. In summary, its effective diesel removal and high emulsification capacity makes <i>C. catenulata</i> KP324968 an attractive candidate yeast for the degradation of hydrocarbons from aqueous environments.

Genomic Insights of Halophilic Planococcus maritimus SAMP MCC 3013 and Detail Investigation of Its Biosurfactant Production

Moderate halophilic bacteria thrive in saline conditions and produce biosurfactant (BS) which facilitates the oil scavenging activity in the oil polluted surroundings. Production of such unusual bioactive molecules plays a vital role for their survival in an extreme and adverse environment. Current research deals with isolation of Planococcus maritimus strain SAMP MCC 3013 from Indian Arabian coastline sea water for BS production. The bacterium tolerated up to 2.7 M NaCl demonstrating osmotic stress bearable physiological systems. We used integrated approach to explore the genomic insight of the strain SAMP and displayed the presence of gene for BS biosynthesis. The genome analysis revealed this potential to be intrinsic to the strain. Preliminary screening techniques viz., surface tension (SFT), drop collapse (DC) and oil displacement (OD) showed SAMP MCC 3013 as a potent BS producer. BS reduced SFT of phosphate buffer saline (PBS) pH: 7.0 from 72 to 30 mN/m with a critical micelle concentration (CMC) value of 1.3 mg/mL. Subsequent investigation on chemical characterization, using thin layer chromatography (TLC), Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (1H NMR and 13C NMR) and liquid chromatography mass spectrometry (LC-MS) revealed terpene containing BS having sugar, lipid moieties. The genomic sequence analysis of P. maritimus SAMP showed complete genes in the pathway for the synthesis of terpenoid. Probably terpenoid is the accountable backbone molecule for the BS production, but the later stages of terpenoid conversion to the BS could not be found. Moreover, it is important to highlight that till today; no single report documents the in-detailed physico-chemical characterization of BS from Planococcus sp. Based on genomic and functional properties, the term terpene containing BS is denoted for the surfactant produced by P. maritimus.

Sustainable biosurfactant produced by Serratia marcescens UCP 1549 and its suitability for agricultural and marine bioremediation applications

BACKGROUND

Biosurfactants are surface-active agents produced by microorganisms that have higher efficiency and stability, lower toxicity and higher biocompatibility and biodegradability than chemical surfactants. Despite its properties and potential application in a wide range of environmental and industrial processes, biosurfactants are still not cost-competitive when compared to their synthetic counterparts. Cost effective technologies and renewable raw substrates as agro-industrial and regional waste from northeast of Brazil as cassava flour wastewater, supplemented with lactose and corn oil are mainly the chemically media for growing microorganism and in turn the production of the biosurfactant of quality. This study aimed to obtained biosurfactant by Serratia marcescens UCP 1549 containing cassava flour wastewater (CWW), by application of a full-factorial design, as sustainable practices in puts the production process in promising formulation medium. The characterization of the biomolecule was carried out, as well as the determination of its stability and toxicity for cabbage seeds. In addition, its ability to stimulate seed germination for agriculture application and oil spill bioremediation were investigated.

RESULTS

Serratia marcescens showed higher reduction of surface tension (25.92 mN/m) in the new medium containing 0.2% lactose, 6% cassava flour wastewater and 5% corn waste oil, after 72 h of fermentation at 28 °C and 150 rpm. The substrate cassava flour wastewater showed a promising source of nutrients for biosurfactant production. The isolate biosurfactant exhibited a CMC of 1.5% (w/v) and showed an anionic and polymeric structure, confirmed by infrared spectra. The biomolecule demonstrated high stability under different temperatures, salinity and pH values and non-toxicity against to cabbage seeds. Thus, exploring biosurfactant their potential role in seeds germinations and the promotion and agricultural applications was investigated. In addition, the effectiveness of biosurfactant for removal burned motor oil adsorbed in sand was verified.

CONCLUSIONS

The use of medium containing CWW not only reduces the cost of process of biosurfactant production, but also the environmental pollution due to the inappropriate disposal of this residue. This fact, added to the high stability and non-toxicity of the biosurfactant produced by S. marcescens UCP 1549, confirms its high environmental compatibility, make it a sustainable biocompound that can be replace chemical surfactants in diverse industries. In addition, the effectiveness of biosurfactant for stimulate seed germination and removing burned motor oil from sand, suggests its suitability for agriculture and bioremediation applications.

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.

Biosurfactant production by Trametes versicolor grown on two-phase olive mill waste in solid-state fermentation

Biosurfactants are amphiphilic compounds of microbial origin which exhibit better properties than their chemically derived counterparts. They are usually produced in submerged fermentation by different types of bacteria. However, biosurfactant production by fungi, particularly of the white-rot type, has been scarcely studied. In this work, and for the first time, we report the production of biosurfactants by the white-rot fungus Trametes versicolor, which was grown on two-phase olive mill waste (TPOMW) in a solid-state fermentation system. The effect of the composition of the culture medium on biosurfactant production was also studied. The highest biosurfactant production (373.6 ± 19.4 mg in 100 g of culture medium) was achieved with a medium containing 35% (w/w) of TPOMW, the highest concentration used, 10% of wheat bran and 55% of olive stones. Interestingly, no inhibition of biosurfactant production by TPOMW was detected within the concentration range used (5-35% w/w). The biosurfactant produced by T. versicolor was able to reduce the surface tension of an aqueous extract of the culture medium up to 34.5 ± 0.3 mN m^-1. A preliminary study of the chemical structure of the biosurfactant indicated that it contains both lipid and protein fractions. The simultaneous production of lignin-degrading enzymes was also assessed.

Biosurfactant production by fungi as a sustainable alternative

ABSTRACT: A wide variety of bacteria is far more exploited than fungi as biosurfactants (BS) or bioemulsifiers (BE), using renewable sources. BS are considered to be environmentally safe and offer advantages over synthetic surfactants. However, the BS yield depends largely on the metabolic pathways of the microorganisms and the nutritional medium. The production of BS or BE uses several cultural conditions, in which a small change in carbon and nitrogen sources affects the quantity of BS or BE produced. The type and quantity of microbial BS or BE produced depend mainly on the producer organism, and factors such as carbon and nitrogen sources, trace elements, temperature and aeration. The diversity of BS or BE makes it interesting to apply them in the pharmaceutical and cosmetics industries, agriculture, public health, food processes, detergents, when treating oily residues, environmental pollution control and bioremediation. Thus, this paper reviews and addresses the biotechnological potential of yeasts and filamentous fungi for producing, characterizing and applying BS or BE.

Recovery of contaminated marine environments by biosurfactant-enhanced bioremediation

The need to remediate areas contaminated by petroleum products has led to the development of novel technologies for treating such contaminants in a non-conventional manner, that is, without the use of chemical or physical methods. Biosurfactants are amphipathic biomolecules produced by microorganisms that can be used in bioremediation processes in environments contaminated by petroleum products due to their excellent tensioactive properties. The aim of the present study was to produce a biosurfactant from Pseudomonas aeruginosa UCP 0992 cultivated in 0.5% corn steep liquor and 4.0% vegetable oil residue in a 1.2-L bioreactor employing a central composite rotatable design to optimize the cultivation conditions for maximum yield. The best results were achieved with aeration rate of 1.0 vvm and 3.0% inoculum at 225 rpm for 120 h, resulting in a surface tension of 26.5 mN/m and a biosurfactant yield of 26 g/L. Kinetic and static assays were then performed with the biosurfactant for the removal of motor oil adsorbed to sand, with removal rates around 90% and 80%, respectively, after 24 h. Oil degradation experiments with the bacterium and the combination of the bacterium and biosurfactant were also conducted to simulate the bioremediation process in sand and seawater samples (duration: 75 and 30 days, respectively). In both cases, oil degradation rates were higher than 90% in the presence of the biosurfactant and the producing species, indicating the potential of the biomolecule as an adjuvant in petroleum decontamination processes in the marine environment.

Enhancement of Paenibacillus sp. D9 Lipopeptide Biosurfactant Production Through the Optimization of Medium Composition and Its Application for Biodegradation of Hydrophobic Pollutants

Interests in biosurfactant in industrial and environmental applications have increased considerably in recent years, owing to their potential benefits over synthetic counterparts. The present study aimed at analyzing the stability and oil removal efficiency of a new lipopeptide biosurfactant produced by Paenibacillus sp. D9 and its feasibility of its use in biotechnological applications. Paenibacillus sp. D9 was evaluated for optimal growth conditions and improved production yield of lipopeptide biosurfactant with variations in different substrate parameters such as carbon (C), nitrogen (N), C:N: ratio, metal supplements, pH, and temperature. Enhanced biosurfactant production was observed when using diesel fuel and ammonium sulfate as carbon and nitrogen source respectively. The maximum biosurfactant yield of 4.11 g/L by Paenibacillus sp. D9 occurred at a C/N ratio of 3:1, at pH 7.0, 30 °C, 4.0 mM MgSO₄, and 1.5% inoculum size. The D9 biosurfactant was found to retain surface-active properties under the extreme conditions such as high thermal, acidic, alkaline, and salt concentration. The ability to emulsify further emphasizes its potential usage in biotechnological application. Additionally, the lipopeptide biosurfactant exhibited good performance in the degradation of highly toxic substances when compared with chemical surfactant, which proposes its probable application in biodegradation, microbial-enhanced oil recovery or bioremediation. Furthermore, the biosurfactants were effective in a test to stimulate the solubilization of hydrophobic pollutants in both liquid environments removing 49.1 to 65.1% diesel fuel including hydrophobic pollutants. The study highlights the usefulness of optimization of culture parameters and their effects on biosurfactant production, high stability, improved desorption, and solubilization of hydrophobic pollutants.

Biosurfactant-induced remediation of contaminated marine sediments: Current knowledge and future perspectives

The contamination of marine sediments is widespread in coastal regions of the world and represents a major concern for the potential detrimental consequences on ecosystems' health and provision of goods and services for human wellbeing. Thus, there is an urgent need to find sustainable and eco-compatible solutions for the remediation of contaminated sediments. Bioremediation is a low cost and environmental-friendly strategy with a high potential for the remediation of contaminated marine sediments. Here we review the potential application of biosurfactants produced by microbial taxa for the remediation of contaminated marine sediments and we discuss future research needs to develop efficient and eco-sustainable biosurfactant-based strategies for the recovery of contaminated marine sediments, in view of large-scale applications.

Culture Medium Development for Microbial-Derived Surfactants Production-An Overview

Surfactants are compounds that can reduce the surface tension between two different phases or the interfacial tension of the liquid between water and oil, possessing both hydrophilic and hydrophobic moieties. Biosurfactants have traits that have proven to be advantageous over synthetic surfactants, but these compounds do not compete economically with synthetic surfactants. Different alternatives increase the yield of biosurfactants; development of an economical production process and the usage of cheaper substrates during process have been employed. One of the solutions relies on the suitable formulation of a production medium by including alternative raw materials sourced from agro-wastes, hydrocarbons, or by-products of a process might help in boosting the biosurfactant production. Since the nutritional factors required will be different among microorganisms, the establishment of a suitable formulation for biosurfactant production will be challenging. The present review describes various nutrients and elements considered in the formulation of a production medium with an approach focusing on the macronutrient (carbon, nitrogen source, and C/N ratio), minerals, vitamins, metabolic regulators, and salinity levels which may aid in the study of biosurfactant production in the future.

New lipopeptide produced by Corynebacterium aquaticum from a low-cost substrate

Conventional biosurfactants have high production costs. Therefore, the use of low-cost carbon sources for their production is attractive for industry. The ability to remain stable under various environmental conditions further extends industrial application. Here we aimed to evaluate the stability of a new lipopeptide produced by Corynebacterium aquaticum using fish residue as an unconventional energy source. The biosurfactant was produced using 3% fish residue, 2% of the microorganism, and mineral medium. Biosurfactant characterization was performed by thin layer chromatography (TLC), as well as by testing its infrared, surface tension, emulsifying activity, and ionic character. The stability of the biosurfactant was evaluated by testing its surface tension at a range of temperatures, pH, and saline concentrations, as well as after 6 months of storage. The biosurfactant was characterized as a lipopeptide due to its retention time, which was coincident with the amino acid and lipid chains obtained in the TLC analysis, being confirmed by some regions of absorption verified in the infrared analysis. The surface tension and emulsifying activity of the biosurfactant were 27.8 mN/m and 87.6%, respectively, and showed anionic character. The biosurfactant was stable at temperatures of 20 to 121 °C, in saline concentrations of 1 to 7%, and at pH close to neutrality. Based on our findings, it is possible to use unconventional sources of energy to produce a lipopeptide biosurfactant that can act under various environments.

Production and characterization of a biosurfactant produced by Streptomyces sp. DPUA 1559 isolated from lichens of the Amazon region

Surfactants are amphipathic compounds containing both hydrophilic and hydrophobic groups, capable to lower the surface or interfacial tension. Considering the advantages of the use of biosurfactants produced by microorganisms, the aim of this paper was to develop and characterize a biosurfactant produced by Streptomyces sp. DPUA1559 isolated from lichens of the Amazon region. The microorganism was cultured in a mineral medium containing 1% residual frying soybean oil as the carbon source. The kinetics of biosurfactant production was accompanied by reducing the surface tension of the culture medium from 60 to values around 27.14 mN/m, and by the emulsification index, which showed the efficiency of the biosurfactant as an emulsifier of hydrophobic compounds. The yield of the isolated biosurfactant was 1.74 g/L, in addition to the excellent capability of reducing the surface tension (25.34 mN/m), as observed from the central composite rotational design when the biosurfactant was produced at pH 8.5 at 28°C. The critical micelle concentration of the biosurfactant was determined as 0.01 g/mL. The biosurfactant showed thermal and pH stability regarding the surface tension reduction, and tolerance under high salt concentrations. The isolated biosurfactant showed no toxicity to the micro-crustacean Artemia salina, and to the seeds of lettuce (Lactuca sativa L.) and cabbage (Brassica oleracea L.). The biochemistry characterization of the biosurfactant showed a single protein band, an acid character and a molecular weight around 14.3 kDa, suggesting its glycoproteic nature. The results are promising for the industrial application of this new biosurfactant.

Yeasts and bacterial biosurfactants as demulsifiers for petroleum derivative in seawater emulsions

Oil sludge or waste generated in transport, storage or refining forms highly stable mixtures due to the presence and additives with surfactant properties and water forming complex emulsions. Thus, demulsification is necessary to separate this residual oil from the aqueous phase for oil processing and water treatment/disposal. Most used chemical demulsifiers, although effective, are environmental contaminants and do not meet the desired levels of biodegradation. We investigated the application of microbial biosurfactants as potential natural demulsifiers of petroleum derivatives in water emulsions. Biosurfactants crude extracts, produced by yeasts (Candida guilliermondii, Candida lipolytica and Candida sphaerica) and bacteria (Pseudomonas aeruginosa, Pseudomonas cepacia and Bacillus sp.) grown in industrial residues, were tested for demulsification capacity in their crude and pure forms. The best results obtained were for bacterial biosurfactants, which were able to recover about 65% of the seawater emulsified with motor oil compared to 35–40% only for yeasts products. Biosurfactants were also tested with oil-in-water (O/W) and water-in-oil (W/O) kerosene model emulsions. No relationship between interfacial tension, cell hydrophobicity and demulsification ratios was observed with all the biosurfactants tested. Microscopic illustrations of the emulsions in the presence of the biosurfactants showed the aspects of the emulsion and demulsification process. The results obtained demonstrate the potential of these agents as demulsifiers in marine environments.

Using Odd-Alkanes as a Carbon Source to Increase the Content of Nutritionally Important Fatty Acids in Candida krusei, Trichosporon cutaneum, and Yarrowia lipolytica

We investigated the possibility of utilizing unusual carbon sources by three yeast strains: Candida krusei DBM 2136, Trichosporon cutaneum CCY 30-5-10, and Yarrowia lipolytica CCY 30-26-36. These strains are characterized by high biomass yield, ability to accumulate high amounts of lipids, and their potential as producers of dietetically important fatty acids. The aim of this work was the production of nutritionally important fatty acids by utilization of n-alkanes with an odd number of carbon atoms, alone and in combination with glucose and subsequent analysis of microbial lipids accumulation and fatty acid profile. All three yeast strains were able to grow and produce high amounts of the fatty acids of interest. Yarrowia lipolytica was found as the most suitable strain for the growth on n-alkanes (n-pentadecane and n-heptadecane) as the only source of carbon. The addition of biosurfactants rhamnolipids into the cultivation increased the ratio of heptadecenoic acid (up to 17.9% of total FAs in Y. lipolytica CCY 30-26-36, 14.9% in T. cutaneum CCY 30-5-10, and 17.5% in C. krusei DBM 2136) and the total biomass yield. The results show that, by manipulation of the initial cultivation conditions, the ratio of important fatty acids may be increased.

Biosurfactant production by Mucor circinelloides on waste frying oil and possible uses in crude oil remediation

Biosurfactants are biocompatible surface active agents which many microorganisms produce. This study investigated the production of biosurfactants by Mucor circinelloides. The effects of different factors on biosurfactant production, including carbon sources and concentrations, nitrogen sources, and iron (II) concentration, were studied and the optimum condition determined. Finally, the strain's ability to remove the crude oil and its relationship with biosurfactant production was evaluated. The results showed that M. circinelloides could reduce the surface tension of the culture medium to 26.6 mN/m and create a clear zone of 12.9 cm diameter in an oil-spreading test. The maximum surface tension reduction was recorded 3 days after incubation. The optimum condition for biosurfactant production was achieved in the presence of 8% waste frying oil as a carbon source, 2 g/L yeast extract as a nitrogen source, and 0.01 mM FeSO₄. M. circinelloides could consume 8% waste frying oil in 5 days of incubation, and 87.6% crude oil in 12 days of incubation. A direct correlation was observed between oil degradation and surface tension reduction in the first 3 days of fungal growth. The results showed that the waste frying oil could be recommended as an inexpensive oily waste substance for biosurfactant production, and M. circinelloides could have the potential to treat waste frying oil. According to the results, the produced crude biosurfactant or fungal strain could be directly used for the mycoremediation of crude oil contamination in oil fields.

Candida lipolytica UCP0988 Biosurfactant: Potential as a Bioremediation Agent and in Formulating a Commercial Related Product

The aim of the present study was to investigate the potential application of the biosurfactant from Candida lipolytica grown in low-cost substrates, which has previously been produced and characterized under optimized conditions as an adjunct material to enhance the remediation processes of hydrophobic pollutants and heavy metals generated by the oil industry and propose the formulation of a safe and stable remediation agent. In tests carried out with seawater, the crude biosurfactant demonstrated 80% oil spreading efficiency. The dispersion rate was 50% for the biosurfactant at a concentration twice that of the CMC. The biosurfactant removed 70% of motor oil from contaminated cotton cloth in detergency tests. The crude biosurfactant also removed 30-40% of Cu and Pb from standard sand, while the isolated biosurfactant removed ~30% of the heavy metals. The conductivity of solutions containing Cd and Pb was sharply reduced after biosurfactants' addition. A product was prepared through adding 0.2% potassium sorbate as preservative and tested over 120 days. The formulated biosurfactant was analyzed for emulsification and surface tension under different pH values, temperatures, and salt concentrations and tested for toxicity against the fish Poecilia vivipara. The results showed that the formulation had no toxicity and did not cause significant changes in the tensoactive capacity of the biomolecule while maintaining activity demonstrating suitability for potential future commercial product formulation.

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.

Monitoring surfactant mediated defence of gastrointestinal Proteus mirabilis DMTMMK1 against pathogenic consortia of Vibrio cholerae

Schematic representation of the biosurfactant production and evaluation of anti-pathogenic potential.

Biosurfactants: Promising Molecules for Petroleum Biotechnology Advances

The growing global demand for sustainable technologies that improves the efficiency of petrochemical processes in the oil industry has driven advances in petroleum biotechnology in recent years. Petroleum industry uses substantial amounts of petrochemical-based synthetic surfactants in its activities as mobilizing agents to increase the availability or recovery of hydrocarbons as well as many other applications related to extraction, treatment, cleaning, and transportation. However, biosurfactants have several potential applications for use across the oil processing chain and in the formulations of petrochemical products such as emulsifying/demulsifying agents, anticorrosive, biocides for sulfate-reducing bacteria, fuel formulation, extraction of bitumen from tar sands, and many other innovative applications. Due to their versatility and proven efficiency, biosurfactants are often presented as valuable versatile tools that can transform and modernize petroleum biotechnology in an attempt to provide a true picture of state of the art and directions or use in the oil industry. We believe that biosurfactants are going to have a significant role in many future applications in the oil industries and in this review therefore, we highlight recent important relevant applications, patents disclosures and potential future applications for biosurfactants in petroleum and related industries.

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.

Antifungal activity of rhamnolipids against dimorphic fungi

In this paper, rhamnolipids are investigated, for the first time, for their feasibility for inhibiting dimorphic fungi. Rhamnolipids were found to effectively inhibit a dimorphic fungus isolated from tomato plants which was identified as Mucor circinelloides according to characterizations by morphologies as well as 28S rDNA sequences. Rhamnolipids markedly reduced growth of this fungus in both the yeast-like form and the filamentous form. Such an inhibitive effect was similarly obtained with Verticillium dahliae, a representative member of dimorphic fungi, confirming the effectiveness of rhamnolipids in the two growth forms of dimorphic fungi. Interestingly, rhamnolipids showed a greater inhibitive function in the case of the pathogenic growth mode of dimorphic fungi, such as the mycelium growth for M. circinelloides and the yeast-like growth for V. dahliae, than their non-pathogenic modes. The use of rhamnolipids might greatly reduce the frequently-reported drugresistance to the common anti-fungal agents by deterring the possible switch between the two modes of dimorphic fungi. Overall, rhamnolipids as environment-friendly biocontrol agents have a potential use in protecting plants from dimorphic fungi infections, and could also offer guidance toward future research into controlling dimorphic disease infection in humans.

Chlorpyrifos-methyl solubilisation by humic acids used as bio-surfactants extracted from lignocelluloses and kitchen wastes

Chlorpyrifos-methyl (CLP-m) is a widely used organophosphate insecticide that can accumulate in soil and become toxic to humans. CLP-m can be removed from soil by its solubilisation using synthetic surfactants. However, synthetic surfactants can accumulate in soil causing contamination phenomena themselves. Bio-surfactants can be used as an alternative to synthetic ones, reducing costs and environmental issues. In this work, humic acid (HA) extracted from raw biomasses, i.e. lignocelluloses (HAL) and lignocelluloses plus kitchen food waste (HALF), corresponding composts (C) (HALC and HALFC) and leonardite (HAc), were tested in comparison with commercial surfactants, i.e. SDS, Tween 20 and DHAB, to solubilize CLP-m. Results obtained indicated that only biomass-derived HA, composted biomass-derived HA, and SDS solubilized CLP-m: SDS = 0.006; HAL = 0.007; HALC = 0.009 g; HALF = 0.025; HALFC = 0.024) (g CLP-m g(-1) surfactant). Lignocelluloses HAs (HAL, HALF) solubilized CLP-m just as well as SDS while lignocellulosic plus kitchen food waste HA (HALF, HALFC) showed a three times higher CLP-m solubilisation capability. This difference was attributed to the higher concentration of alkyl-Carbon that creates strong links with CLP-m in the hydrophobic micelle-core of the surfactants.

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.

Lipopeptide surfactants: Production, recovery and pore forming capacity

Lipopeptides are microbial surface active compounds produced by a wide variety of bacteria, fungi and yeast. They are characterized by highly structural diversity and have the ability to decrease the surface and interfacial tension at the surface and interface, respectively. Surfactin, iturin and fengycin of Bacillus subtilis are among the most studied lipopeptides. This review will present the main factors encountering lipopeptides production along with the techniques developed for their extraction and purification. Moreover, we will discuss their ability to form pores and destabilize biological membrane permitting their use as antimicrobial, hemolytic and antitumor agents. These open great potential applications in biomediacal, pharmaceutic and agriculture fields.