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Biosurfactants are amphipathic, surface-active, nontoxic, and biodegradable compounds with wide applications in different industrial preparations. The present study was carried out to identify the biosurfactant-producing bacterial strains and surfactant production optimization with agro-industrial wastes. The potential biosurfactant-producing bacterial strain SS-1 was isolated from industrial effluent, and its surfactant-producing capabilities were determined via drop collapse assay, emulsification index, and reduction in surface tension. 16 S rRNA gene sequencing revealed 99% homology of isolate SS-1 with Alcaligenes sp. Agro-industrial wastes, namely, molasses, whey, and rapeseed cake, were optimized for biosurfactant production by the SS-1 strain, and maximum production was reported with molasses (4%). The present research has also documented an emulsification index of 93.26 ± 0.76% and surface tension reduction up to 35.26 ± 0.70 mN/m with an overall yield of biosurfactant approximately 2.38 g/L using 4% molasses at pH 7 and a temperature of 36 °C by Alcaligenes sp. FT-IR analysis revealed the presence of various functional groups, including O-H, N-H, C = O, C-H, and C-O-C, which suggest the lipopeptide nature of the biosurfactant. This was further validated by the distinctive resonance peaks observed in the NMR spectrum. The molecular mass of the biosurfactant was deduced to be 1382 Da via LC-MS. The partially purified biosurfactant was stable over a wide range of temperatures and pH values, with a maximum emulsification at pH 7 and a temperature of 30 °C. [ABSTRACT FROM AUTHOR]

Antimicrobial drug resistance (AMR) from improper use of antibiotics in various livestock products is a growing hazard for humans worldwide, with current death rate in excess of 700,000 per annum linked to the problem. Microorganisms are a rich source of structurally distinct bioactive compounds designed to protect the microbes and can offset AMR challenge. A study was conducted at Chinhoyi University of Technology to isolate, identify and characterize biosurfactant secreting microbes from broiler bird's gastrointestinal tract. Analysis of variance was performed in Genstat software. 16S rRNA technique was used to identify the DNA of isolates, annotated by similarity using BLASTn analysis against the NCBI nucleotide database. Phylogenetic analysis was performed on the BLASTn outcome to have an appreciation of the evolutionary genetic relationships. Small intestine-derived samples had a wider hemolytic activity of 5.6 mm, with a 39% emulsification index. At 98.29% sequence similarity, the bacterium producing biosurfactants was identified as an Escherichia coli strain similar to the 7.1994/NIST 0056 strain. The biosurfactant substance is a derivative of decane with beta lactams, tetracyclines and sulfa drugs properties which were responsible for the observed antibacterial activity. We recommend endogenous biosurfactant production optimization experiments and in-vivo trials to evaluate the potential impacts of a biosurfactant based feed additive in broilers. [ABSTRACT FROM AUTHOR]

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Biosurfactants are amphiphilic biomolecules with promising tensoative and emulsifying properties that find application in the most varied industrial sectors: environment, food, agriculture, petroleum, cosmetics, and hygiene. In the current work, a 23 full-factorial design was performed to evaluate the effect and interactions of pineapple peel and corncob as substrates for biosurfactant production by Bacillus subtilis LMA-ICF-PC 001. In a previous stage, an alkaline pretreatment was applied to corncob samples to extract the xylose-rich hydrolysate. The results indicated that pineapple peel extract and xylose-rich hydrolysate acted as partial glucose substitutes, minimizing production costs with exogenous substrates. Biosurfactant I (obtained at 8.11% pineapple peel extract, 8.11% xylose-rich hydrolysate from corncob, and 2.8109 g/L glucose) exhibited a significant surface tension reduction (52.37%) and a promising bioremediation potential (87.36%). On the other hand, biosurfactant III (obtained at 8.11% pineapple peel extract, 31.89% xylose-rich hydrolysate from corncob, and 2.8109 g/L glucose) exhibited the maximum emulsification index in engine oil (69.60%), the lowest critical micellar concentration (68 mg/L), and the highest biosurfactant production (5.59 g/L). These findings demonstrated that using pineapple peel extract and xylose-rich hydrolysate from corncob effectively supports biosurfactant synthesis by B. subtilis, reinforcing how agro-industrial wastes can substitute traditional carbon sources, contributing to cost reduction and environmental sustainability. [ABSTRACT FROM AUTHOR]

Background: Ujung Pangkah mangroves are reported to have been contaminated with heavy metals. Such heavy metals can induce microorganisms to produce biosurfactants. Biosurfactants with amphiphilic characteristics can lower surface tension. Biosurfactants can be used as antibacterial, antifungal, and antiviral for biomedical purposes. Purpose: This study aimed to identify and test the activity of biosurfactant isolates of bacteria from Ujung Pangkah Mangrove sediments, Gresik Regency. Methods: Biosurfactant activity test methods include emulsification index, oil spreading, drop collapse, and parafilm test. Results: The results of the identification of bacterial isolates in this study obtained the genus Bacillus sp. because bacterial isolates show rod shape, Gram-positive, aerobic, and have ellipse-shaped endospores on the subterminal. The results of the biosurfactant activity test with the Emulsification index method showed an average result of 54.39% and the results of the biosurfactant activity test with the oil spreading method showed that there was a clear zone. The average result of the clear zone obtained is 54.83 mm. The average result in the parafilm test was 8.02 mm and the drop collapse test showed positive results characterized by falling and spreading of bacterial isolate fermentation broth supernatants.

Bioemulsifier production by Aureobasidium pullulans LB83 from pretreated sugarcane bagasse was evaluated in solid-state fermentation. Alkaline (0.2 mol.L−1 NaOH; 12 min) and hydrodynamic cavitation (0.5 mol.L−1 NaOH, 25 min) pretreatments showed a maximum lignin removal of 55.1 % and 44.7 %, respectively. Pretreatment biomass effectivity was assessed by X-ray diffraction, FT-MIR, FTIR-NIR, and RAMAN techniques. Maximum kerosene emulsification indexes of 65.8 % and 41.3 % were obtained in solid-state fermentation, respectively, for alkaline and hydrodynamic cavitation pretreated sugarcane bagasse. Synthesis of cellulases was observed in fermentation, showing maximum values of endoglucanase and exoglucanase, respectively, of 2.25 U.g−1 and 1.39 U.g−1, for alkaline pretreated sugarcane bagasse, and 2.43 U.g−1 and 1.45 U.g−1, for hydrodynamic cavitation-pretreated sugarcane bagasse. The biomolecule was characterized as a mixture of mannitol and arabitol-type liamocin. Microorganism was able to produce bioemulsifier using sugarcane bagasse as support and carbon source in solid-state fermentation, thus showing the potential of this system to obtain value-added products from this biomass. [ABSTRACT FROM AUTHOR]

Biosurfactants are a class of amphipathic molecules that various microorganisms can produce. Biosurfactants are used as biopesticides and biocontrol agents because they have antimicrobial activity, especially as antifungal agents in several species of fungal pathogens such as Ganoderma boninense and Fusarium sp. that attack crops. This study aims to detect the biosurfactant activity of Bacillus sp. and its potential as an antifungal agent against the fungi Ganoderma boninense and Fusarium sp. Biosurfactants were produced in mineral salt medium (MSM) by harvesting cell-free supernatants. Screening of biosurfactant-producing isolates was carried out using an oil-spreading assay, a hemolysis assay, and an emulsification index. The antifungal activity of the isolates was then tested using the agar diffusion method. The LP04 isolate was closely related to Bacillus thuringiensis with a 99% similarity level. It has the potential to have biosurfactant activity, which is characterized by a positive result on the oil spreading assay test and has an emulsification index of 48.33±2.87%. The cell-free supernatants of the bacterial isolate were able to inhibit the growth of Ganoderma boninense and Fusarium sp. with growth inhibition rates of 51.11% and 56.92%, respectively. [ABSTRACT FROM AUTHOR]

Biosurfactants of microbial origin have wide applicability because of their surface-active potentials. Bacillus thuringiensis c25 isolated from palm oil contaminated soil was used in the production of biosurfactant and the product was screened using emulsification stability test (E24), drop-collapse, oil spreading, blood hemolysis and surface tension tests. The effects of incubation period, temperature, pH, and carbon source on biosurfactant production by B. thuringiensis c25 were investigated with a view to optimizing the production process. The biosurfactant produced was characterized using Fourier Transform Infrared Spectroscopy and Gas Chromatography-Mass Spectrometry. Initial assay showed emulsification index of 57.24 ± 0.25 %, oil displacement of 6.17 ± 0.21 mm and a positive drop-collapse test. Growth of B. thuringiensis at the optimal conditions of temperature 35 ºC, pH 7.0, glucose 10 g/L and yeast extract 1.5 g/L, reduced surface tension to 27.71 ± 0.88 mN/m and increased emulsification index to 84.78 ± 0.44%. Maximum biosurfactant production of 2.70 ± 0.04 g/L was obtained at 72 h. The characterization showed a lipopeptide biosurfactant type. Consequently, the B. thuringiensis of the present study is a good biosurfactant producer.

Abstract Background Screening for biosurfactant-producing microbes involves the process of sampling and isolating bacteria from various environmental sources. Hydrocarbon-contaminated locations are considered ideal sources for isolating bacteria that produce biosurfactants. This is because these microbes have adapted to living in oil-contaminated environments and have developed mechanisms to produce biosurfactants as a means of survival. Therefore, screening microbes from such locations increases the likelihood of finding bacteria capable of producing biosurfactants. Results This investigation aimed to isolate bisurfactant-producing bacteria from oil-contaminated soil samples, with a particular focus on Pseudomonas aeruginosa. Out of the 10 samples collected, four were confirmed to be P. aeruginosa, and all strains showed positive results for antagonistic, hemolytic, and emulsification tests. The strains were effective against B. subtilis, S. aureus, and E. coli but less effective against A. hydrophila. The PS10 strain exhibited the highest emulsification index, while PS08 showed the lowest. Based on microscopic and biochemical examination, P. aeruginosa was identified as the most effective isolate. Conclusion These findings highlight the potential of P. aeruginosa as a biosurfactant producer for industrial and environmental applications. However, further studies are needed to fully understand the biosurfactant production potential of these strains and to optimize the conditions for biosurfactant production.

The elevation of environmental pollution caused by the production and spillage of petroleum hydrocarbons is disastrous. Major compounds in petroleum hydrocarbon such as polycyclic aromatic hydrocarbons (PAHs) are of special concern since their molecules are persistent for a and highly toxic and carcinogenic to the ecosystems and humans. Although a lot of effort had been spent to treat these pollutants, the left-over products are still ubiquitous in the environment although they could be naturally degraded by indigenous microorganisms aided by biosurfactants or bioemulsifiers that they produce during hydrocarbon biodegradation process. Hydrocarbonoclastic bacteria were isolated from petroleum sludge obtained from a waste disposal company in Malaysia and investigated for their potential to produce biosurfactants (i.e., surface tension measurement) and bioemulsifiers (i.e., emulsification assay) together with their ability in total petroleum hydrocarbon (TPH) biodegradation (i.e., gas chromatography- mass spectrometry (GC-MS)). One isolate of potential bioemulsifier producing bacteria (BEP) exhibited emulsification index as high as 72.81% while the rest were between the range of 64%-68%. In addition, one isolate of potential biosurfactant producing bacteria (BSP) recorded a surface tension measurement as low as 18.92 mN/m while the rest were between the range of 45-28 mN/m. Further identification of selected potential isolates by 16s rRNA gene amplification and sequencing revealed their identity as from several genera such as Achromobacter sp., Pseudomonas sp. and Serratia sp. Isolate P15 was found as the best candidate for potential BSP identified as closely related to Pseudomonas stutzeri while isolate P18 which was the best candidate for potential BEP identified as closely related to Serratia marcescens. Biodegradation study conducted for both isolates showed the percentage of TPH loss of approximately 85% by BSP P15 and approximately 78% by BEP P18. Production of biosurfactant and bioemulsifier by both isolates supported by their ability to degrade total petroleum hydrocarbons validate the advantageous features of biosurfactants and bioemulsifiers in hydrocarbon biodegradation and this can be further exploited in designing bioremediation strategies for contaminated environment. [ABSTRACT FROM AUTHOR]

The present study focusses on proving the biosurfactant activity of the 7 isolated bacterial strains. Plants could not absorb enough nutrients as a result of contamination in the soil. This contaminants can be chemical pollutants or oil spillage. By considering the earlier potential applications of biosurfactants, this research was aimed to prove the role of a plant probiotic bacteria as oil degrading bacteria. In order to prove this approach, many screening methods were performed such as drop collapse, oil spreading (mm), emulsification stability testing by calculating emulsification index (E24%), penetration assay etc. Among the 7 selected isolates, isolate KL-015 have shown positive results with all the biosurfactant screening analysis. A unique role was proven by KL-011 isolate as it has shown a high oil degrading zone, i.e., 0.6 mm in diameter as well as the formation of more foam layer or emulsified layer with the emulsification index of 17.39% which indicates its role in having a biosurfactant molecule within it.

A total of seventy-one bacteria were isolated from crude oil-contaminated soil samples. The isolates were screened for biosurfactant production by applying various methods, including determination of hemolytic, lipolytic, and esterolytic activities, oil displacement, parafilm M, drop-collapse, CTAB-methylene blue agar tests, determination of emulsification index (E24) and reduction in surface tension. Thirteen isolates were selected and further subjected to molecular identification. 16S rRNA gene sequencing analysis indicated that the isolates belong to Pseudomonas (Pseudomonas sp., P. balearica, and P. aeruginosa), Acinetobacter (A. radioresistens, A. baumanni), Bacillus (Bacillus sp.) and Priestia (Priestia sp.) genera. The largest spreading zone diameter (6.5 cm) and the highest enzymatic activity index (EAI) for lipolytic (5.4) and esterolytic (2.7) activities were demonstrated by P. aeruginosa strain TBA-B58. Surface tension analysis by the Du Noüy tensiometer confirmed that the glycolipid-type biosurfactant obtained from P. aeruginosa strain TBA-B58 achieved the highest reduction in surface tension with a value of 31.5 ± 0.5 mN m−1. Notable E24 values, superior to the synthetic surfactant sodium dodecyl sulfate, were recorded by the cell-free supernatants obtained from A. baumanni TBA-B45 (66%) and TBA-B56 (65%) against toluene and benzene, respectively. Based on the results of the present study, two biosurfactant/bioemulsifier-producing strains belonging to Pseudomonas and Acinetobacter genera demonstrated significant surface and interfacial activities, which might find applications in the bioremediation of crude oil hydrocarbons. [ABSTRACT FROM AUTHOR]

Low-temperature laundry washing prompted the formulation of a new biobased detergent that meets sustainability criteria. A soapnut extract conferred good cleaning performance on the standard soiling agents EMPA 101 and EMPA 114 but showed rather weak performance on EMPA 116 and EMPA 160. The results indicated the good disinfection properties of the soapnut extract–Carvacrol emulsion (>6 log CFU/carriers), whereas the commercial detergent and sole soapnut extract were less effective. Comparable results were observed for cross-contamination assessment and wash water, whereas total elimination was achieved only for the soapnut extract–Carvacrol emulsion. We demonstrated significantly decreased water surface tension for all three compounds. The microorganism cell membrane integrity assessment showed the highest number of dead cells on cotton carriers washed with the soapnut extract–Carvacrol emulsion. All this indicated that the newly formulated biobased laundry detergent made of soapnut extract and Carvacrol could effectively remove standard soiling agents and ensure good disinfection. [ABSTRACT FROM AUTHOR]

Biosurfactants of microbial origin have wide applicability because of their surface-active potentials. Bacillus thuringiensis c25 isolated from palm oil contaminated soil was used in the production of biosurfactant and the product was screened using emulsification stability test (E24), drop-collapse, oil spreading, blood hemolysis and surface tension tests. The effects of incubation period, temperature, pH, and carbon source on biosurfactant production by B. thuringiensis c25 were investigated with a view to optimizing the production process. The biosurfactant produced was characterized using Fourier Transform Infrared Spectroscopy and Gas Chromatography-Mass Spectrometry. Initial assay showed emulsification index of 57.24 ± 0.25 %, oil displacement of 6.17 ± 0.21 mm and a positive drop-collapse test. Growth of B. thuringiensis at the optimal conditions of temperature 35 °C, pH 7.0, glucose 10 g/L and yeast extract 1.5 g/L, reduced surface tension to 27.71 ± 0.88 mN/m and increased emulsification index to 84.78 ± 0.44%. Maximum biosurfactant production of 2.70 ± 0.04 g/L was obtained at 72 h. The characterization showed a lipopeptide biosurfactant type. Consequently, the B. thuringiensis of the present study is a good biosurfactant producer. [ABSTRACT FROM AUTHOR]

Microbial bioemulsifiers are molecules of amphiphilic nature and high molecular weight that are efficient in emulsifying two immiscible phases such as water and oil. These molecules are less effective in reducing surface tension and are synthesized by bacteria, yeast and filamentous fungi. Unlike synthetic emulsifiers, microbial bioemulsifiers have unique advantages such as biocompatibility, non-toxicity, biodegradability, efficiency at low concentrations and high selectivity under different conditions of pH, temperature and salinity. The adoption of microbial bioemulsifiers as alternatives to their synthetic counterparts has been growing in ongoing research. This article analyzes the production of microbial-based emulsifiers, the raw materials and fermentation processes used, as well as the scale-up and commercial applications of some of these biomolecules. The current trend of incorporating natural compounds into industrial formulations indicates that the search for new bioemulsifiers will continue to increase, with emphasis on performance improvement and economically viable processes. [ABSTRACT FROM AUTHOR]

Recently, the use of biosurfactants has been suggested for oil spill clean-up from seawater, but the major challenge in biosurfactant production is the high cost of large-scale production. The lack of appropriate criteria to scale-up properly for biosurfactants production has led to the failure of commercial production. This research focuses on strategies to optimize process parameters for the maximum productivity of rhamnolipid in bench scale production for crude oil spill clean-up. For large-scale economic production, small-scale optimization is required. The effect of incubation time, sunflower oil, and nitrogen source based on single-factor experiments and then C/N, rpm, and, inoculum size for rhamnolipid production from Pseudomonas aeruginosa PTCC 1340 by the RSM were investigated. The maximum production (10.13 g/L) was achieved under the optimum conditions (144 h, 80 g/L sunflower oil, NaNO3 as a nitrogen source, 7% (v/v) inoculum, C/N ratio 200, and 200 rpm) that was higher than the results of other studies. A 50% reduction in production time has occurred compared to the results. Rhamnolipid production was confirmed by FTIR, 1HNMR, and TLC, and its performance was explored by CMC, dynamic surface tension (ST), E24%, oil spreading, and foam stability experiments. The rhamnolipid reduced the ST from 72 to 30 mN/m at 35 mg/L (CMC). The foam stability was also better than SLS as a commercial surfactant. The E24 for crude and sunflower oil was 100 and 55%, respectively. The visual oil spill clean-up test indicated that the crude oil layer was completely removed from the water surface. [ABSTRACT FROM AUTHOR]

The present study focusses on proving the biosurfactant activity of the 7 isolated bacterial strains. Plants could not absorb enough nutrients as a result of contamination in the soil. This contaminants can be chemical pollutants or oil spillage. By considering the earlier potential applications of biosurfactants, this research was aimed to prove the role of a plant probiotic bacteria as oil degrading bacteria. In order to prove this approach, many screening methods were performed such as drop collapse, oil spreading (mm), emulsification stability testing by calculating emulsification index (E24%), penetration assay etc. Among the 7 selected isolates, isolate KL-015 have shown positive results with all the biosurfactant screening analysis. A unique role was proven by KL-011 isolate as it has shown a high oil degrading zone, i.e., 0.6 mm in diameter as well as the formation of more foam layer or emulsified layer with the emulsification index of 17.39% which indicates its role in having a biosurfactant molecule within it. [ABSTRACT FROM AUTHOR]

Biosurfactant are surface active compounds (SAC), amphiphilic in nature consisting of hydrophobic (long chain fatty acids) and hydrophilic domain (amino acid, protein, carbohydrate). Classification of this compound is based on molecular weight, mode of action and physico-chemical structure. Biosurfactant are being utilized in laundry formulation, house hold cleaning products, as antimicrobial agents, in detergents, pesticides, food and pharmaceutical industries. Various type of microorganism has been studied capable of synthesizing wide range biosurfactant by utilizing hydrocarbon compounds as source of carbon and energy. Present study aims to isolate biosurfactant producing bacteria from different waste sources. In this study among twenty-one isolated microbial cultures from different waste samples were screened for biosurfactant production using methods like hemolytic activity, blue gar assay, hydrocarbon tolerance assay, oil spread test, Emulsification index (E24%).

Microorganisms producing extracellular polymeric substances (EPS) are of great potential in numerous environmental applications. The present study explores the production and properties of extracellular polymeric substances (EPS) from Amphora coffeiformis diatom strain and their potential applications in environmental remediation. EPS were composed of a complex mixture of polysaccharides, proteins, humic substances and nucleic acids, with polyanionic characteristics as revealed by FTIR, Raman and zeta potential analyses. EPS showed high flocculation efficiency against kaolin clay at low dosages (5 mg/L) through a charge neutralization mechanism involving both polysaccharides and proteins. EPS also exhibited strong emulsification activity for various nonpolar substrates, mainly olive oil, corn oil, soybean oil, essence and diesel, with emulsification indexes above 80%. The emulsions were stable for 72 h under different NaCl concentrations (1-10% w/v). Moreover, EPS demonstrated remarkable adsorption capacity for lead, reaching a maximum of 1699.33 ± 89.61 mg/g under optimized conditions using Box-Behnken design. The adsorption mechanism involved multiple functional groups such as hydroxyl, carbonyl, carboxyl, phosphoric and sulfhydryl. Therefore, EPS from A. coffeiformis are a promising candidate for restoring environments contaminated by heavy metals., Competing Interests: Declarations. Conflict of interest: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2025. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Mineral lubricating oils are widely used in various industrial sectors for their applications in maintenance and functioning of machineries. However, indiscriminate dumping of these used oils have resulted in polluting the natural reservoirs which subsequently destroys ecological balance. Bacteria can emulsify or lower surface tension between phases of immiscible substrates and can acquire them as their carbon and energy sources. Such a phenomenon is mediated by production of extracellular polymers which can function as eminent surface active compounds based on their surfactant or emulsifying nature. The comparison between bacterial strains (Gram-positive Bacillus stratosphericus A15 and Gram-negative Ochrobactrum pseudintermedium C1) on utilization of pure straight chain hydrocarbons, waste mineral lubricating oils as sole carbon source and chemical characterization of the synthesized surface active compounds were studied. Characterization analysis by Ultraviolet Visible spectrophotometry, Fourier transform infrared spectroscopy, Nuclear Magnetic Resonance spectroscopy, Carbon–Hydrogen–Nitrogen analysis has given detailed structural elucidation of surface active compounds. The contrasting nature of bacterial strains in utilization of different hydrocarbons of waste mineral lubricating oils was observed in Gas Chromatography-Mass Spectroscopy analysis. The variation between both strains in utilization of hydrocarbons can be manifested in chemical structural differences and properties of the produced surface active compounds. Scanning Electron Microscopy has given detailed insight into the microstructural difference of the compounds. The utilization of lubricating oils can address waste disposal problem and offer an economical feasible approach for bacterial production of surface active compounds. Our results suggest that these surface active compounds can maneuver applications in environmental bioremediation and agriculture, pharmaceuticals and food as functional biomaterials. [ABSTRACT FROM AUTHOR]

Biosurfactants are surface-active agents produced by a variety of microorganisms. To make biosurfactant production economically feasible, several alternative carbon sources have been proposed. This study describes biosurfactant production by strains of Pseudomonas aeruginosa and Burkholderia gladioli isolated from mangrove sediments in Northeastern Brazil and cultured in mineral media enriched with waste cooking oil. The biosurfactants were tested for drop collapse, emulsion formation and stability and surface tension. P. aeruginosa performed better both at lowering the surface tension (from 69 to 28 mN/m) and at forming stable emulsions (approximately 80%) at 48 hours of culture. The strains tested in this study were found to be efficient biosurfactant producers when cultured on substrates enriched with vegetable oil. DOI: http://dx.doi.org/10.17807/orbital.v8i5.771

Increasing environmental concerns have brought natural surfactant produced by microorganisms into limelight due to their lesser toxicity, biodegradable nature, and retention of activity at extreme conditions. In the present investigation, the surfactant production perspective of capsulated Gram-negative bacilli Klebsiella pneumoniae ssp. ozaenae BK34 was explored. It was identified on the basis of PCR amplification of conserved region of 16SrRNA using species specific primers. Highest oil displacement and emulsification (E24) index of 6.8 cm and 20% along with 4.38-fold increase in biomass were attained using olive oil (2% (v/v)) as substrate. Incorporation of urea at 0.5% (w/v) concentration increased the oil displacement, E24 index, and drop diameter to 9.2 cm, 77.50%, and 0.80 cm, respectively, accompanied by 5.38-fold increase in biomass production. Biosurfactant level was recorded maximum at 30 °C as apparent from the oil displacement of 9.3 cm and E24 index of 75%. Reduction in incubation temperature to 25 °C abated oil displacement (5.2 cm) and E24 index (17.66%). Biosurfactant production was also appeared to be pH sensitive as shifting pH from 7.0 to 6.0 or 8.0 reduced the E24 index from 75 to 35% and 25%, respectively. Inoculum of stationary phase bacterial biomass at the proportion of 0.05% (w/v) was found adequate in triggering maximum biosurfactant production while the log phase biomass delayed the production significantly. Acid precipitation method was able to yield 7 g/L biosurfactant at pH 2. The surfactant was allocated to glycolipopeptide class on the basis of FTIR spectroscopy. [ABSTRACT FROM AUTHOR]

Biosurfactants and bioemulsifiers (BS/BE) are naturally synthesized molecules, which can be used as alternatives to traditional detergents. These molecules are commonly produced by microorganisms isolated from hydrocarbon-rich environments. Gordonia alkanivorans strain 1B was originally found in such an environment, however little was known about its abilities as a BS/BE producer. The goal of this work was to access the potential of strain 1B as a BS/BE producer and perform the initial characterization of the produced compounds. It was demonstrated that strain 1B was able to synthesize lipoglycoprotein compounds with BS/BE properties, both extracellularly and adhered to the cells, without the need for a hydrophobic inducer, producing emulsion in several different hydrophobic phases. Using a crude BS/BE powder, the critical micelle concentration was determined (CMC = 16.94 mg/L), and its capacity to reduce the surface tension to a minimum of 35.63 mN/m was demonstrated, surpassing many commercial surfactants. Moreover, after dialysis, emulsification assays revealed an activity similar to that of Triton X-100 in almond and sunflower oils. In benzene, the E24 value attained was 83.45%, which is 30% greater than that of the commercial alternative. The results obtained highlight for the presence of promising novel BS/BE produced by strain 1B. [ABSTRACT FROM AUTHOR]

In the present work, the relationship between structural characteristics and functional performance in polyglycerol polyricinoleate (PGPR) stabilised water-in-oil (W/O) emulsions was investigated. Novel W/O emulsions with a PGPR concentration of 4%, and oil volume fractions (fO) of 0.7 and 0.8 showed the smallest mean droplet size (~5 µm) and highest emulsification index (~97%). Both W/O emulsions showed shear-thinning and elasticdominant properties with a weak frequency dependence. Both W/O emulsions possessed superior thixotropic recovery properties with recovery percentages of 131.26% (fO = 0.7) and 114.56% (fO = 0.8). The thermo-responsive properties could be closely related to the PGPR aggregation induced by hydrophobic interaction and interfacial rearrangement. The present work helped to design and develop functional W/O emulsions as alternatives to butter spreads, bio-lubricants, and other thermo-responsive delivery systems. [ABSTRACT FROM AUTHOR]

Biosurfactant are surface active compounds (SAC), amphiphilic in nature consisting of hydrophobic (long chain fatty acids) and hydrophilic domain (amino acid, protein, carbohydrate). Classification of this compound is based on molecular weight, mode of action and physico-chemical structure. Biosurfactant are being utilized in laundry formulation, house hold cleaning products, as antimicrobial agents, in detergents, pesticides, food and pharmaceutical industries. Various type of microorganism has been studied capable of synthesizing wide range biosurfactant by utilizing hydrocarbon compounds as source of carbon and energy. Present study aims to isolate biosurfactant producing bacteria from different waste sources. In this study among twenty-one isolated microbial cultures from different waste samples were screened for biosurfactant production using methods like hemolytic activity, blue gar assay, hydrocarbon tolerance assay, oil spread test, Emulsification index (E24%). [ABSTRACT FROM AUTHOR]

In situ biosurfactant production by hydrocarbon degrader microorganisms is an attractive approach in the bioremediation of oil contamination because of their compatibility, biodegradability, environmental safety, and stability under extreme environmental conditions. Given the high efficiency of bacteria in degrading petroleum hydrocarbons, the present work studied the detection and characterization of a biosurfactant-producing hydrocarbon degrader, Roseomonas aestuarii NB833. This strain was able to synthesize a biosurfactant during the biodegradation of crude oil, which reduced the surface tension of the aqueous system from 70 to 34 mN m -1 , with a critical micelle concentration of 200 mg L -1 . The emulsification ability of the biosurfactant was sustained at various temperatures, pH values, and salinities. The biosurfactant chemical structure was identified via FT-IR, LC-MS, and NMR analyses. These analyses confirmed the production of surfactin-C14 with a molecular mass of 1007 g mol -1 . These results revealed the high potential of R. aestuarii NB833 as an in situ surfactin-producing bacteria for bioremediation applications under extreme environmental conditions., (© 2024 Wiley‐VCH GmbH.)

Production of biosurfactant by a novel indigenous isolate Pseudomonas otitidis strain DU13 and its role in bioremediation of petroleum hydrocarbon is reported. The identity of the isolate was confirmed by 16S rDNA gene sequencing analysis (Genbank accession: MK177190). The biosurfactant produced by the isolate could reduce the surface tension of petroleum supplemented medium by 46% just after 7 days of treatment. The emulsification index (E24) of the surfactant was found 37, 35, and 20%, respectively, against used motor oil, diesel, and kerosene. The FTIR spectrum of the crude biosurfactant showed the presence of υC–H stretch, υCH2, υ-C=C stretch and υC–H bonding. The isolated strain could degrade 26% of TPH content of used motor oil in liquid culture. Whereas, ex situ pilot-scale field trial demonstrated very high bioremediation potential of the isolate in terms of germination rate of Vigna radiata and Cicer arietinum seeds and plant growth just after 20 days of treatment. [ABSTRACT FROM AUTHOR]

Biosurfactant production by Pseudomonas guguanensis D30 was reported using mineral oil in submerged condition. Twelve medium components were tested at two levels by Plackett–Burman design, among them, mineral oil, yeast extract, peptone, MgSO4, and CaCl2 found significant on the basis of emulsification index. These five significant components were further optimized through central composite design (CCD). The experimental design was successfully used for regression analysis and the significant model suggested the solution of 10% (v/v) mineral oil, 3.0 g/L (w/v) yeast extract and 0.2 g/L (w/v) peptone for 13.14 g/L predicted biosurfactant production. We kept the suggested concentrations of medium components and got 13.34 ± 0.08 g/L biosurfactant production, which is almost double the conventional one-factor-at-a-time production (7.126 ± 0.12 g/L). It reduced the surface tension of the medium up to 28 ± 1.2 mN/m. We found ethyl acetate a suitable solvent for biosurfactant extraction amongst methanol, chloroform, and methanol:chloroform. The partially purified biosurfactant was chemically characterized as lipopeptide by Fourier transform infrared spectroscopy (FT-IR). [ABSTRACT FROM AUTHOR]

Accumulation of oily sludge in the petroleum industry causes various environmental problems. In this research, a biosurfactant obtained by Pseudomonas aeruginosa PTCC 1340 was characterized. The biosurfactant can reduce the surface tension and promote the formation of oil/water emulsions facilitating oily sludge removal. For biosurfactant production, sunflower oil as a carbon source was used. Glycerol was also used as a comparative carbon source. The use of sunflower oil as a carbon source for biosurfactant production showed higher rhamnolipid production, expressed by rhamnose (2.09 g/L). The yields of rhamnolipid per sunflower oil (YRL/S) and rhamnolipid per biomass (YRL/X) in shake flask were 0.14 and 2.63 g/g, respectively. After 5 d of incubation, the rhamnolipid reduced the surface tension of cell-free broth from 70 to 26.8 mN/m. The critical micelle concentration was 0.123 g/L. The usage of the small volume of cell-free culture broth to remove sticky oily sludge may be an environmentally friendly and cost-efficient usable technology. Cell-free broth containing biosurfactant was able to produce high emulsification index (EI24) values for oily sludge (66 to 99%). The process proved to be highly effective for the removal of sticky oily sludge from oil-contaminated vessels and resulted in a 100% reduction in sludge volume. [ABSTRACT FROM AUTHOR]

Aims: This study was aimed to isolate and characterize biosurfactant producing bacteria from Mile 2 and Ologe Lagoon which are sinks for domestic and industrial waste waters and potential source of value added bioresources such as biosurfactants, hydrocarbon degraders and organisms with potential for biotechnological applications. Methodology and results: Physicochemical parameters of the two lagoon waters were analyzed using standard procedures. Bacteria were isolated using enrichment techniques on 1% Escravos light crude oil, palm oil and groundnut oil on mineral salt medium (MSM). Biosurfactant production by the isolates was assayed by hemolytic activity, oil spread test, blue agar test and emulsification activity. Isolates were identified using their colony morphologies and biochemical characteristics, while the antibiotic susceptibility of the isolates was determined using multidisc. The physicochemistry of the lagoon water showed high nitrate content of 15.7 mg/L and 19.6 mg/L for Mile 2 and Ologe Lagoon, respectively. Total hydrocarbon content (THC) of both lagoon waters was low, with values 0.53 mg/L for Mile 2 Lagoon and 0.44 mg/L for Ologe Lagoon. The predominant genera of bacteria identified include Micrococcus, Bacillus, Pseudomonas, Acinetobacter, Stomatococcus and Moraxella. A total of 23 bacterial isolates were tested for hemolytic activity, of which 13 showed β-hemolysis which is presumptive for biosurfactant production, 5 showed α-hemolysis and the remaining 5 exhibited γ-hemolysis. Majority of the isolates were positive for oil spread assay and blue agar test (19) indicating production of anionic biosurfactant. The isolates showed good emulsification activity; AGG3 (67.7%), AGG1 (62.3%), AGG2 (60%), AGG4 (60%), MTP2 (56%), AGC4 (54%) and the least emulsification value of 23.3% for strain AGP1. Most of the isolates were susceptible to ciprofloxacin, perfloxacin and showed resistance to septrin and erythromycin. Conclusion, significance and impact of study: This study showed that Mile 2 and Ologe Lagoon are a potential source of biosurfactant producers with diverse emulsification properties and prospective industrial applications. This would have implication for economic empowerment, as well as sustainable and environmentally friendly clean-up technology in both locally and globally. [ABSTRACT FROM AUTHOR]

Bio-surfactants are surface-active molecules which are produced by the wide range of microbes including bacteria, fungi, moulds, and yeast. This study was conducted to identify bio-surfactants by Bacillus subtilis combined with use of cheap substrates and industrial wastes (Mustard cake, Whey and Soya cake) which are found locally in Nepal. Bacillus subtilis, one of the most potential bio-surfactants producer; was isolated from soil sample of hydrocarbon contaminated site. Isolates were grown in a Minimal Salt Media (MSM) with 10% (v/v) mustard oil cake, whey and soya cake separately. The presence and potential of surfactant was determined by the oil spreading technique, emulsification index (%E24) and surface tension measurement. It was revealed that the surface tensions of cell free extract were 54.41, 60.02 and 56.64 mN/m for from mustard cake, whey and soya cake respectively as compared to distilled water (72.09) at 25oC. The emulsification index values was found to be highest in engine oil from the bio-surfactant extracted from mustard cake, soya cake and whey respectively. Similarly, mustard oil showed the lowest value of emulsification index. The highest emulsification activity was shown in mustard oil i.e. 1.13 from the cell free extract from mustard oil and lowest in engine oil i.e., 0.07, by the extract from soya cake medium, when measured in spectrophotometer at 540 nm. In conclusion, strain of Bacillus subtilis was found to be the potential surface active agent producers on the mustard oil cake, which can be useful medium for various environmental, food, medicinal and industrial processes. [ABSTRACT FROM AUTHOR]

Oil pollution is of increasing concern for environmental safety and the use of microbial surfactants in oil remediation has become inevitable for their efficacy and ecofriendly nature. In this work, biosurfactants of bacteria isolated from oil-contaminated soil have been characterized. Four potent biosurfactant-producing strains (SD4, SD11, SD12 and SD13) were selected from 27 isolates based on drop collapse assay and emulsification index, and identified as species belonging to Bacillus, Burkholderia, Providencia and Klebsiella, revealed from their 16S rRNA gene-based analysis. Detailed morphological and biochemical characteristics of each selected isolate were determined. Their growth conditions for maximum biosurfactant production were optimized and found quite similar among the four isolates with a pH of 3.0 and temperature 37°C after 6 or 7 days of growth on kerosene. The biosurfactants of SD4, SD11 and SD12 appeared to be glycolipids and that of SD13 a lipopeptide. Emulsification activity of most of the biosurfactants was stable at low and high temperatures (4–100°C), a wide range of pH (2–10) and salt concentrations (2–7% NaCl). Each biosurfactant showed antimicrobial activity against two or more pathogenic bacteria. The biosurfactants were well-capable of emulsifying kerosene, diesel and soya bean, and could efficiently degrade diesel.

A total of 107 bacterial strains were isolated from used motor oil contaminated soil samples from auto-repair shops. The isolates were evaluated for their biosurfactant production abilities by employing a series of screening techniques, including hemolytic assay, oil displacement assay, drop-collapse assay, and parafilm M test. The potential biosurfactant producers were characterized by 16S rDNA-based molecular tools and were identified as Proteus mirabilis, Klebsiella pneumoniae, Enterobacter cloacae, Micrococcus sp., Citrobacter sp., and Bacillus sp. The widest clearing zone with a diameter of 6.5 cm was observed upon the addition of cell-free supernatant (CFS) from P. mirabilis SLM-B52 as assayed by the oil displacement test. Remarkable emulsification indexes, equivalent to 42% (against kerosene), 53% (against xylenes), and 50% (against benzene and toluene), were recorded by the CFSs of Micrococcus sp. SLM-B28, P. mirabilis SLM-B85, and K. pneumoniae SLM-B46, respectively. Du Noüy tensiometer analysis showed that biosurfactant produced by P. mirabilis SLM-B52 has the highest surface tension reduction capacity with a value of 30.5 mN m−1. The emulsifying activity of a CFS from P. mirabilis was also described in this study for the first time. Taking together, biosurfactants from promising bacterial strains have potential application in microorganism-based biodegradation processes of hydrocarbons which cause detrimental effects on the environment. [ABSTRACT FROM AUTHOR]

A wide range of microorganisms can produce biosurfactants with attractive properties. Fifteen bacterial isolates have been collected (9 isolates from soil and 6 from water). The isolates characterized morphological 10 were gram-negative, and 5 were positive. All isolates were screened to perform their ability to produce biosurfactants (hemolysis and drop collapsing, emulsification, oil spreading, and foam production tests). The screening results for isolates' ability to produce biosurfactants showed that the highest value of the drop-collapsing test was recorded for the isolates F4, F5, F9, and F10. In contrast, isolate F13 recorded the highest value for the emulsification test. F11 had the highest value for the oil-spreading test, and the isolate F7 recorded the highest value for the foam test, while none of the isolates recorded hemolysis activity. The biosurfactant production of F9 and F6 show the highest yield 0.955 g/L and 0.68 g/L for the two isolates, respectively, is the highest compared with other isolates. The present study included five samples from each soil and water contaminated with petroleum hydrocarbons. [ABSTRACT FROM AUTHOR]

A synthetic medium containing glucose, glycerol, yeast extract (YE), and ammonium sulfate (AS) was compared to several low-cost media in their ability to produce high emulsification index (EI). The goal was to reduce the production costs of an emulsifier with application in food oil-in-water emulsions. To this end, agro-industrial by-products were screened for bioemulsifier production from Yarrowia lipolytica. The statistical analysis showed that the EIs of media containing residual frying oil from palm oil (RFO_palm) or soybean oil (RFO_soy), residual liquid from butter production (butter whey, BWhey) or cheese production (cheese whey, CWhey), supplemented with YE and AS were similar to the EI of the synthetic medium. The replacement of YE by corn steep liquor (CSL) also resulted in similar EI, except for RFO_soy. BWhey was tested with CSL without AS and similar EI (66.8%) was detected in comparison to that of the same medium with AS (66.3%). The cell-free broth obtained after Y. lipolytica growth in BWhey+CSL was successfully used to obtain vegetable oil-in-water emulsions indicating its potential application in food products. [ABSTRACT FROM AUTHOR]

The present study investigated the stability and efficacy of a biosurfactant produced by Klebsiella sp. KOD36 under extreme conditions and its potential for enhancing the solubilization and degradation of phenanthrene in various environmental matrices. Klebsiella sp. KOD36 produced a mono-rhamnolipids biosurfactant with a low critical micelle concentration (CMC) value. The biosurfactant was stable under extreme conditions (60 °C, pH 10 and 10% salinity) and could lower surface tension by 30% and maintained an emulsification index of > 40%. The emulsion index was also higher (17–43%) in the presence of petroleum hydrocarbons compared to synthetic surfactant Triton X-100. Investigation on phenanthrene degradation in three different environmental matrices (aqueous, soil-slurry and soil) confirmed that the biosurfactant enhanced the solubilization and biodegradation of phenanthrene in all matrices. The high functional stability and performance of the biosurfactant under extreme conditions on phenanthrene degradation show the great potential of the biosurfactant for remediation applications under harsh environmental conditions.

Biosurfactants play an important role in bioremediation of organic pollutants such as petroleum hydrocarbon. The unique properties of biosurfactants make them possible to be used in the remediation of hydrocarbon contaminated sites. Therefore, the existence of indigenous microorganisms that have the ability to consume petroleum hydrocarbon as carbon source and simultaneously produce biosurfactants in order to facilitate the hydrocarbon metabolism can be manipulated for bioremediation purposes. In this study, isolation and screening of potential biosurfactant-producing bacteria from two sampling points in Kuantan Port seawater were successfully done. Amongst the isolates, 4 out of 7 isolates from Point A were Gram negative bacteria and 2 out 5 isolates from Point B were Gram negative bacteria. The positive oxidase test resulted for all isolates from Point A and only B5 from Point B produced negative result. Catalase test conducted produced positive results on isolates from Point A (A3, A5, A6& A7) and Point B (B1, B2, B4 & B5).The highest percentage emulsification index measured belonged to isolate B4 and B5 which are 67%, thus make these isolates to be the most promising biosurfactant producers. Further identification by 16S rRNA gene found that isolates were closely related to Rhodococcus erythropolis (A1), Psedomonas stutzeri (A2), Pseudoalteromonas lipolytica (A3, A6 and B4), Vibrio brasiliensis (A4 and B2), Vibrio tubiashii (B1), Marinobacter salsuginis (A5), Labrenzia aggregate (A7), Marinococcus halophilus (B3) and Thalassospira xianmenensis(B5). Hence, through biosurfactant activities exhibited by isolates, B4 and B5 were the most potential isolates to produce biosurfactant. Therefore, these isolates can potentially be exploited to aid in bioremediation of petroleum hydrocarbon contaminated sites and would also be useful to enhance oil recovery in petroleum industry.

Biosurfactants are considered a good alternative to highly-polluting petroleum-based surfactants that are toxic and non-biodegradable in nature. However, the high production cost of biosurfactants limits its potential for commercialization. The use of a highly efficient biosurfactant-producing actinomycetes isolate, combined with the utilization of low-cost substrates such as agroindustrial wastes, may aid in lowering the overall production cost. In this study, twenty-eight (28) actinomycetes isolated from distillery wastes and soil samples were screened for the production of extracellular biosurfactants. Based on the preliminary screening experiment, isolate CGS B11 -- molecularly identified as Streptomyces angustmyceticus -- produced the biosurfactant with the highest emulsification activity (E24). Subsequently, the best alternative carbon and nitrogen sources, salt supplement, and pH level were determined using one-factor-at-a-time (OFAT) experiments. The highest measured biosurfactant activity was observed in the medium containing molasses, spent yeast autolysate, and NaCl, and a pH level ranging from 6.0-7.0. Biosurfactant production was observed to be growth associated with maximum emulsification activity achieved after 4 d of fermentation (late log phase). FTIR (Fourier transform infrared) spectra and biochemical composition analyses of the S. angustmyceticus CGS B11 biosurfactant suggest that it belongs to the lipopeptide type of biosurfactants. S. angustmyceticus CGS B11 biosurfactant also showed resistance and high stability on a wide range of temperature, pH, and salinity, and the ability to form stable and dense emulsions with various oils tested. It has great potential for various applications such as in the food and pharmaceutical industries, and in oil recovery and bioremediation. The results of this study will hopefully serve as a basis for large-scale production of biosurfactants utilizing agro-industrial wastes in the country. [ABSTRACT FROM AUTHOR]

• Interfacial activity of biosurfactants produced by P. syringae pv. tabaci. • Chemical characterization revealed that the sample mostly consists of lipopeptides. • Water surface tension of 29 mN/m was reached in presence of 5 % w/w of NaCl. • Emulsifying activity comparable or even superior to that of commercial bioemulsifiers. • Emulsions resulted to be little affected by different operational conditions. In recent years, worldwide awareness about environmental concerns has led to an extensive searching for products of natural origin. Biosurfactants (BS), are an attractive alternative to the chemical counterparts. In these sense, this works evaluate for the first time the emulsifying and surface activity of biosurfactants produced by P. syringae pv. tabaci. Chemical characterization revealed that the produced BS extract mostly consisted in a mixture of syringopeptins and arthrofactins. Besides, this sample was able to reduce water surface tension up to 36.89 mN/m. This activity was improved by modifying conditions of pH, temperature and salinity. For instance, the surface tension was reduced up to 29 mN/m when using NaCl 5 % w/w. The BS also exhibited a high emulsifying activity, this being comparable or even superior to that of commercial bioemulsifiers such xanthan, tara and guar gums. A notorious emulsification index, close to 90 %, was exhibited by BS in coconut oil/water mixtures. Moreover, emulsifying activity resulted to be little affected by different operational conditions, thus retaining about 80 % of its emulsificant index in presence of 20 % w/w of NaCl at 80 °C. These findings are indicative of the BS promising properties and its potential as additive in a variety of industrial applications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Rhodococcus is a genus of Gram-positive bacteria that are widely distributed in soil, water, and plants. They have a versatile metabolism that produces different kinds of compounds like biosurfactants, lipids and carotenoids, and therefore are promising for biotechnological applications. In this work, we aimed to characterize the ability of the strain Rhodococcus ALDO1 isolated from alperujo, a complex residue from the olive oil industry, to produce biosurfactants. Growing was determined by counting the number of cells and by dry weight determination Biosurfactant production was followed by xylose equivalents (μg/ml Xylose Eq.), the perimeter obtained in the oil spreading assay and the emulsification index at 24 h (E24). We found that this strain grew in different media like glucose, oil, and glycerol, and produced a biosurfactant of a glycolipid nature as suggested by FT-IR spectrum. The maximal amount of biosurfactant (18.8 ± 2.0 μg/ml Xylose Eq., perimeter = 4.17 ± 0.17 cm, and E24 = 63.1 ± 4.1 %) was obtained when Rhodococcus ALDO1 grew in the media with oil 3% + glucose 1 %. Glycerol was also a suitable substrate for biosurfactant production (8.3 ± 1.0 μg/ml Xylose Eq., perimeter = 2.84 ± 0.07 cm, and E24 = 35.7 ± 2.9 %). The biosurfactant activity is stable at salt concentrations up to 5 g/L, temperatures up to 60 °C and pHs above 9. The thermal degradation started at 220 °C which suggested that the biosurfactant is suitable for various industrial applications. These results indicated that Rhodococcus ALDO1 is a strain to be considered as a source of biocompounds with possible industrial applications obtained from cheap substrates. • Rhodococcus ALDO1 isolated from olive-mill wastes produces a biosurfactant. • The biosurfactant could be obtained from cheap substrates like glycerol and oil. • The glycolipid biosurfactant has a remarkably low critical micelle concentration. • The activity is stable at high pHs, salt concentrations and temperatures. [ABSTRACT FROM AUTHOR]

In this paper, biosurfactant production by free and immobilized cells of Ochrobactrum intermedium has been studied. This bacterium strain was isolated from an Algerian crude oil-contaminated soil; hexadecane was used for the production as the sole carbon and energy source. The process was monitored by measuring the surface tension and emulsification index E24 for one week at 37 °C and neutral pH. For the production by immobilized cells, the concentrations of sodium alginate, calcium chloride and biomass were optimized. Results showed that O. intermedium entrapped in calcium alginate beads is able to preserve its viability and produce biosurfactants but with an effect on the production kinetics due to diffusional limitations of the alginate beads with greater stability with up to 75%. The product biosurfactant reduced the surface tension below 33 and emulsification index were 68%–93% after 48 and 72 h with free and immobilized cells, respectively. Also, the product belongs to the family of glycolipids and showed stability in a wide range of pH (2–12), temperature (25–120 °C), and to high salinity. Both products by strain O. intermedium, based on spectral features, have a chemical structure identical to that of glycolipids. The production yield of biosurfactant versus concentration of the hexadecane is 1292 g/g. Second, the surfactants are able to promote the solubility of polycyclic aromatic hydrocarbons (PAHs). Results show that the use of biosurfactant, produced by the isolated bacterial strain O. intermedium, obtained a better solubility of naphthalene and phenanthrene.

The Marinobacter hydrocarbonoclasticus ST1, isolated from soil contaminated with palm oil from palm oil mill factories in southern Thailand, was evaluated as a potential biosurfactant with effective emulsifying property. This strain was able to produce biosurfactant with the maximum emulsification activity of 81% and emulsification index of 60% after 60 h of cultivation under the optimized cultivation conditions. The yield of biosurfactant obtained by chloroform:methanol (2 : 1, vol/vol) extraction was 1.85 g/L. The stability of the biosurfactant was effective over a wide range of pH, temperature and salinity. The high thermostability of the biosurfactant was assessed by simultaneous thermal analyzer. In addition, a preliminary chemical characterization using FT-IR, 1H-NMR and 13C-NMR indicated that it is glycolipid biosurfactant. The features of this biosurfactant make it a promising product for many industrial applications involving to extreme conditions. [ABSTRACT FROM AUTHOR]