Production of Biosurfactants by Ascomycetes

Surfactants are utilized to reduce surface tension in aqueous and nonaqueous systems. Currently, most synthetic surfactants are derived from petroleum. However, these surfactants are usually highly toxic and are poorly degraded by microorganisms. To overcome these problems associated with synthetic surfactants, the production of microbial surfactants (called biosurfactants) has been studied in recent years. Most studies investigating the production of biosurfactants have been associated mainly with bacteria and yeasts; however, there is emerging evidence that those derived from fungi are promising. The filamentous fungi ascomycetes have been studied for the production of biosurfactants from renewable substrates. However, the yield of biosurfactants by ascomycetes depends on several factors, such as the species, nutritional sources, and environmental conditions. In this review, we explored the production, chemical characterization, and application of biosurfactants by ascomycetes.

Examining effects of surfactants on particle clearance rate and capture efficiency of the blue mussel Mytilus edulis

Suspension-feeding bivalve molluscs perform important ecological roles by coupling pelagic and benthic systems during their feeding activities. Particle capture, and thus feeding, is dependent on particle encounter and retention on the gill filaments, with several factors influencing this process. Over the past 30 yr, different types of synthetic microspheres have been used to examine aspects of particle capture and ingestion by bivalves. Critics of this work have posited that manufactured particles may contain surfactants, chemicals commonly used in manufacturing to reduce surface tension, that could produce spurious capture and ingestion rates. The goal of this work was to experimentally assess whether the presence of different types of surfactants on manufactured polystyrene particles can result in instantaneous effects on particle capture by the blue mussel Mytilus edulis. The effects of 3 different types of common surfactants (sodium dodecyl sulfate, benzalkonium chloride, Triton-X) on clearance rates (CR) and capture efficiencies (CE) were tested. Results indicated that none of the surfactant treatments had an effect on CR. Treatment with one of the surfactants (Triton-X) significantly lowered CE for 3 µm sized spheres compared to the control spheres (Milli-Q treated). None of the other tested surfactants significantly affected CE when compared to the control treatment. These data add to an understanding of particle handling by bivalves, and suggest that concentrations of surfactants found on commercially available microspheres used for experiments or found in the environment have little immediate effect on feeding processes.

BIOREMEDIATION OF CRUDE OIL CONTAMINATED SEAWATER WITH THE APPLICATION OF BIOSURFACTANT AND BIOSTIMULATION

Marine oil spills have bad impacts on the marine biota. Oil spill mitigation that is currently safe, effi cient, relatively cheap and easy to implement is bioremediation, that is degradation of oil spills biologically using microorganisms. Petroleum will be more easily dispersed in water when surfactants are added. The surfactants have the ability to increase the bioavailability of petroleum to facilitate bacteria contact with carbon sources as their feed. This study was intended to test the effect of addition of diethanolamide (DEA) surfactants to improve the ability of bacteria to degrade hydrocarbon compound in the seawater media. The biodegradation experiment was conducted in 8-liter seawater media and the ability of DEA surfactants to reduce surface tension, oil content, pH and nutrients on days 0, 1, 3, 6 and 10 were observed. GC-MS analysis was conducted to detect chemical component changes in petroleum. A bacterial consortium of Enterobacter sp., Pseudomonas sp., and Raoultella sp. was utilized. The oil was degraded up to 65.52% with biodegradation rate k = -0.1054 t in the media added with DEA surfactants. The aliphatic fraction detected was C17-C31 n-alkane compound and after biodegradation it became C20- C31. The results showed that DEA surfactants were able to improve the ability of bacterial consortium to degrade petroleum.

EFFECT OF DIETANOLAMIDE (DEA) SURFACTANT ADDITION AND DEEP-SEA BACTERIA ACTIVITIES ON THE BIODEGRADABILITY OF ARTIFICIAL OILY WASTEWATER IN SEAWATER MEDIA

Marine oil spills have bad impacts on the marine biota. Oil spill mitigation that is currently safe, effi cient, relatively cheap and easy to implement is bioremediation, that is degradation of oil spills biologically using microorganisms. Petroleum will be more easily dispersed in water when surfactants are added. The surfactants have the ability to increase the bioavailability of petroleum to facilitate bacteria contact with carbon sources as their feed. This study was intended to test the effect of addition of diethanolamide (DEA) surfactants to improve the ability of bacteria to degrade hydrocarbon compound in the seawater media. The biodegradation experiment was conducted in 8-liter seawater media and the ability of DEA surfactants to reduce surface tension, oil content, pH and nutrients on days 0, 1, 3, 6 and 10 were observed. GC-MS analysis was conducted to detect chemical component changes in petroleum. A bacterial consortium of Enterobacter sp., Pseudomonas sp., and Raoultella sp. was utilized. The oil was degraded up to 65.52% with biodegradation rate k = -0.1054 t in the media added with DEA surfactants. The aliphatic fraction detected was C17-C31 n-alkane compound and after biodegradation it became C20- C31. The results showed that DEA surfactants were able to improve the ability of bacterial consortium to degrade petroleum.

Lipid polarity gradient formed by ω-hydroxy lipids in tear film prevents dry eye disease

Meibum lipids form a lipid layer on the outermost side of the tear film and function to prevent water evaporation and reduce surface tension. (O-Acyl)-ω-hydroxy fatty acids (OAHFAs), a subclass of these lipids, are thought to be involved in connecting the lipid and aqueous layers in tears, although their actual function and synthesis pathway have to date remained unclear. Here, we reveal that the fatty acid ω-hydroxylase Cyp4f39 is involved in OAHFA production. Cyp4f39-deficient mice exhibited damaged corneal epithelium and shortening of tear film break-up time, both indicative of dry eye disease. In addition, tears accumulated on the lower eyelid side, indicating increased tear surface tension. In Cyp4f39-deficient mice, the production of wax diesters (type 1ω and 2ω) and cholesteryl OAHFAs was also impaired. These OAHFA derivatives show intermediate polarity among meibum lipids, suggesting that OAHFAs and their derivatives contribute to lipid polarity gradient formation for tear film stabilization.

Biosynthesis of rhamnolipid by a Marinobacter species expands the paradigm of biosurfactant synthesis to a new genus of the marine microflora

Background In comparison to synthetically derived surfactants, biosurfactants produced from microbial culture are generally regarded by industry as being more sustainable and possess lower toxicity. One major class of biosurfactants are rhamnolipids primarily produced by Pseudomonas aeruginosa. Due to its pathogenicity rhamnolipid synthesis by this species is viewed as being commercially nonviable, as such there is a significant focus to identify alternative producers of rhamnolipids. Results To achieve this, we phenotypically screened marine bacteria for biosurfactant production resulting in the identification of rhamnolipid biosynthesis in a species belonging to the Marinobacter genus. Preliminary screening showed the strain to reduce surface tension of cell-free supernatant to 31.0 mN m−1. A full-factorial design was carried out to assess the effects of pH and sea salt concentration for optimising biosurfactant production. When cultured in optimised media Marinobacter sp. MCTG107b produced 740 ± 28.3 mg L−1 of biosurfactant after 96 h of growth. Characterisation of this biosurfactant using both HPLC–MS and tandem MS showed it to be a mixture of different rhamnolipids, with di-rhamnolipid, Rha-Rha-C10-C10 being the most predominant congener. The strain exhibited no pathogenicity when tested using the Galleria mellonella infection model. Conclusions This study expands the paradigm of rhamnolipid biosynthesis to a new genus of bacterium from the marine environment. Rhamnolipids produced from Marinobacter have prospects for industrial application due to their potential to be synthesised from cheap, renewable feed stocks and significantly reduced pathogenicity compared to P. aeruginosa strains.

Identifikasi Kandungan Saponin dalam Ekstrak Kamboja Merah (Plumeria rubra L.) dan Daya Surfaktan dalam Sediaan Kosmetik

Saponin is a group of compounds contained in natural materials that have amphiphilic properties and can reduce surface tension. The reduction of surface tension caused by a soap compound (Latin = sapo) that can disrupt hydrogen bonds in water. Red frangipani plant (Plumeria rubra) is known to have saponin content. The research objectives were to identify the saponin content of red frangipani plant extract (Plumeria rubra) which could reduce the surface tension. Part of red frangipani plant (flowers, leaves and stems) was extracted using five kinds of solvents. Each of the extracts obtained was then tested for saponin content qualitatively. Extract from each part of the plant (flower, leaf, and stem) which has the highest foam was selected then tested surface tension using surface tensionmat equipment. The result of qualitative saponin test showed that flower, stem and flower extract of red frangipani with aqua demineralisata solvent had the highest saponin content compared to extract with other solvent. The content of saponins in plumeria rubra extract either from the leaves, stems or flowers could decrease the surface tension with the best results obtained from the flower extract with 8,61% of Critical Micelle Concentration (CMC).

Evolution and mechanics of mixed phospholipid fibrinogen monolayers

All mammals depend on lung surfactant (LS) to reduce surface tension at the alveolar interface and facilitate respiration. The inactivation of LS in acute respiratory distress syndrome (ARDS) is generally accompanied by elevated levels of fibrinogen and other blood plasma proteins in the alveolar space. Motivated by the mechanical role fibrinogen may play in LS inactivation, we measure the interfacial rheology of mixed monolayers of fibrinogen and dipalmitoylphosphatidylcholine (DPPC), the main constituent of LS, and compare these to the single species monolayers. We find DPPC to be ineffective at displacing preadsorbed fibrinogen, which gives the resulting mixed monolayer a strongly elastic shear response. By contrast, how effectively a pre-existing DPPC monolayer prevents fibrinogen adsorption depends upon its surface pressure. At low DPPC surface pressures, fibrinogen penetrates DPPC monolayers, imparting a mixed viscoelastic shear response. At higher initial DPPC surface pressures, this response becomes increasingly viscous-dominated, and the monolayer retains a more fluid, DPPC-like character. Fluorescence microscopy reveals that the mixed monolayers exhibit qualitatively different morphologies. Fibrinogen has a strong, albeit preparation-dependent, mechanical effect on phospholipid monolayers, which may contribute to LS inactivation and disorders such as ARDS.

Effect of adjuvants on the amount of air included in droplets generated by spray nozzles

The air included in droplets generated by spray nozzles directly int0erferes in transport, deposition and retention of the droplets after its impact on the target. The objective of this study was to analyze the interference of adjuvants in the amount of air included in droplets generated by spray nozzles. The treatments were composed by four spray solutions containing mineral oil, vegetable oil, surfactant and water, and three spray nozzles, two air induction type and one pre-orifice. The air included was calculated by the difference between the volume of spray mix (air plus liquid) and only the liquid, which was made by means of sprayed samples captured in a funnel and collected in a graduated cylinder. The surface tension was estimated by the gravimetric method using a precision scale and a graduated pipette. The surfactant provided the largest percentage of air included in the spray. For the surface tension, the mineral oil and the surfactant had the lowest values. It was concluded that the use of adjuvants had a direct influence on the percentage of air included. In addition, products with greater ability to reduce surface tension and to form homogeneous solutions provided the increase in the percentage of air included in the droplet.