Eco-Friendly Bioemulsifier Production by Mucor circinelloides UCP0001 Isolated from Mangrove Sediments Using Renewable Substrates for Environmental Applications.

The successful production of a biosurfactant is dependent on the development of processes using low cost raw materials. In the present work, an economically attractive medium composed of corn steep liquor and waste cooking oil was formulated to maximize the production of bioemulsifier by Mucor circinelloides UCP0001. A central rotational composite design was applied to statistical validation of the production. The emulsifying properties, stability under extreme conditions, its toxicity character, and the characterization of the bioemulsifier were determined. The best condition for biomolecule synthesis occurred in the assay 2 containing 4% of corn steep liquor and 3% waste soybean oil and exhibited 100% emulsification index for canola oil and petroleum, as well as excellent emulsifying activity for canola oil and burned engine oil. The nutritional factors studied showed statistical relevance, since all linear, quadratic effects and their interactions were significant. The bioemulsifier showed 2.69 g/L yield and the chemical character of the molecule structure was identified by FT-IR (Fourier Transform Infrared) spectroscopy. The bioemulsifier showed no toxicity to Artemia salina and Chlorella vulgaris. Stable emulsions were obtained under extreme conditions of temperature, pH, and salinity. These findings contribute to understanding of the relationship between production, physical properties, chemical composition, and stability of bioemulsifier for their potential applications in biotechnology, such as bioremediation of hydrocarbon-contaminated soil and water.

Conversion of renewable substrates for biosurfactant production by Rhizopus arrhizus UCP 1607 and enhancing the removal of diesel oil from marine soil

BACKGROUND: The use of agro-industrial wastes to produce high value-added biomolecules such as biosurfactants is a promising approach for lowering the total costs of production. This study aimed to produce biosurfactants using Rhizopus arrhizus UCP 1607, with crude glycerol (CG) and corn steep liquor (CSL) as substrates. In addition, the biomolecule was characterized, and its efficiency in removing petroderivatives from marine soil was investigated. RESULTS: A 22 factorial design was applied, and the best condition for producing the biosurfactant was determined in assay 4 (3% CG and 5% CSL). The biosurfactant reduced the surface tension of water from 72 to 28.8 mN/m and produced a yield of 1.74 g/L. The preliminary biochemical characterization showed that the biosurfactant consisted of proteins (38.0%), carbohydrates (35.4%), and lipids (5.5%). The compounds presented an anionic character, nontoxicity, and great stability for all conditions tested. The biomolecule displayed great ability in dispersing hydrophobic substrates in water, thereby resulting in 53.4 cm2 ODA. The best efficiency of the biosurfactant in removing the pollutant diesel oil from marine soil was 79.4%. CONCLUSIONS: This study demonstrated the ability of R. arrhizus UCP1607 to produce a low-cost biosurfactant characterized as a glycoprotein and its potential use in the bioremediation of the hydrophobic diesel oil pollutant in marine soil

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.

Cadmium Removal from Aqueous Solutions by Strain of Pantoea agglomerans UCP1320 Isolated from Laundry Effluent.

BACKGROUND: Cadmium (Cd), which is a deadly heavy metal of work-related and environmental concern, has been recognized as a substance that is teratogenic and carcinogenic for humans. Therefore, the need to develop low-cost adsorbents to remove heavy metals from aqueous solution has greatly increased. Adsorbents such as Pantoea agglomerans biomass have been used. AIMS: We investigated the biotechnological potential of Pantoea agglomerans for the biosorption of cadmium from aqueous solution. PATIENTS AND METHODS: Pantoea agglomerans UCP1320 isolated from the effluent of a laundry industry was used to remove cadmium from aqueous solutions. Two approaches were compared using active or thermally inactivated biomass. Three different cadmium concentrations of 1, 10 and 100 ppm were used under constant stirring at temperatures of 25°C and 35°C as was pH of 3.0, 5.0 and 7.0. Variable incubation times of 1, 6, and 24h were also studied. RESULTS: The results showed that the temperature did not influence the uptake of metal by living cells nor by inactive bacterial biomass. However, increasing the pH had a positive effect on removing intermediate concentrations of cadmium. Low concentrations of cadmium were completely removed by both live and inactive biomass. CONCLUSION: Pantoea agglomerans biomass was shown to have a promising performance for the biotechnological removal of cadmium which had been dissolved in aqueous solution.

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.

Biosurfactant-and-bioemulsifier produced by a promising Cunninghamella echinulata isolated from Caatinga soil in the northeast of Brazil.

A Mucoralean fungus was isolated from Caatinga soil of Pernambuco, Northeast of Brazil, and was identified as Cunninghamella echinulata by morphological, physiological, and biochemical tests. This strain was evaluated for biosurfactant/bioemulsifier production using soybean oil waste (SOW) and corn steep liquor (CSL) as substrates, added to basic saline solution, by measuring surface tension and emulsifier index and activity. The best results showed the surface water tension was reduced from 72 to 36 mN/m, and an emulsification index (E24) of 80% was obtained using engine oil and burnt engine oil, respectively. A new molecule of biosurfactant showed an anionic charge and a polymeric chemical composition consisting of lipids (40.0% w/w), carbohydrates (35.2% w/w) and protein (20.3% w/w). In addition, the biosurfactant solution (1%) demonstrated its ability for an oil displacement area (ODA) of 37.36 cm², which is quite similar to that for Triton X-100 (38.46 cm²). The stability of the reduction in the surface water tension as well as of the emulsifier index proved to be stable over a wide range of temperatures, in pH, and in salt concentration (4%-6% w/v). The biosurfactant showed an ability to reduce and increase the viscosity of hydrophobic substrates and their molecules, suggesting that it is a suitable candidate for mediated enhanced oil recovery. At the same time, these studies indicate that renewable, relatively inexpensive and easily available resources can be used for important biotechnological processes.

Effects of 7-hydroxycalamenene isolated from Croton cajucara essential oil on growth, lipid content and ultrastructural aspects of Rhizopus oryzae.

The leaves and bark of Croton cajucara, a shrub from the Amazon region, have been used in folk medicine to treat diabetes, malaria, and gastrointestinal and liver disorders. The essential oil from the leaves, rich in linalool, presented antileishmanial and antimicrobial activities. A chemotype of this species was found with an essential oil rich in 7-hydroxycalamenene. During our studies of the C. cajucara essential oil, we isolated 7-hydroxycalamenene at > 98 % purity. The minimum inhibitory concentration of 7-hydroxycalamenene against Absidia cylindrospora, Cunninghamella elegans, Mucor circinelloides, Mucor circinelloides f. circinelloides, Mucor mucedo, Mucor plumbeus, Mucor ramosissimus, Rhizopus microsporus, Rhizopus oryzae, and Syncephalastrum racemosum ranged from 19.53 to 2500 µg/mL. The reference drug used, amphotericin B, presented a minimum inhibitory concentration ranging from 0.085 µg/mL to 43.87 µg/mL. 7-Hydroxycalamenene also altered spore differentiation and total lipid content. Ultrastructural analysis by transmission electron microscopy showed significant alterations in the cellular structure of R. oryzae.

Production of heterologous cutinases by E. coli and improved enzyme formulation for application on plastic degradation

Background: The hydrolytic action of cutinases has been applied to the degradation of plastics. Polyethylene terephthalate (PET) have long half-life which constitutes a major problem for their treatment as urban solid residues. The aim of this work was to characterize and to improve stable the enzyme to optimize the process of degradation using enzymatic hydrolysis of PET by recombinant cutinases. Results: The wild type form of cutinase from Fusarium solani pisi and its C-terminal fusion to cellulose binding domain N1 from Cellulomonas fimi were produced by genetically modified Escherichia coli. The maximum activity of cutinases produced in Lactose Broth in the presence of ampicillin and isopropyl β-D-1-thiogalactopyranoside (IPTG) was 1.4 IU/mL. Both cutinases had an optimum pH around 7.0 and they were stable between 30 and 50ºC during 90 min. The addition of glycerol, PEG-200 and (NH4)2SO4 to the metabolic liquid, concentrated by ultra filtration, stabilized the activity during 60 days at 28ºC. The treatment of PET with cutinases during 48 hrs led to maxima weight loss of 0.90%. Conclusions: Recombinant microbial cutinases may present advantages in the treatment of poly(ethylene terephthalate) PET through enzymatic treatments.

Enhancement of Cunninghamella elegans UCP/WFCC 0542 biomass and chitosan with amino acid supply.

Studies were carried out with Cunninghamella elegans UCP/WFCC 0542 to evaluate the effects of an abundant supply of amino acids, asparagine and corn steep liquor associated with sucrose on the production of biomass and chitosan by submerged fermentation. The concentrations of the components of the culture medium which were determined by a 2³ full factorial design evaluated the interactions and effects of the independent variables of the sucrose, asparagine and corn steep liquor in relation to carbon and nitrogen sources, on the production of chitosan regarding biomass. The best results were observed at the central point [asparagine 0.025%, sucrose 0.15% and 0.45% of corn steep liquor, ratio C:N=2:6], and produced maximum yields of 16.95 g/L biomass and 2.14 g/L chitosan, after 96 h of submerged fermentation. However, the lowest level of sucrose, asparagine and corn steep liquor produced a low amount of biomass (10.83 g/L) and chitosan (0.60 g/L). The infrared spectrum absorption of the chitosan produced by C. elegans showed bands regarding OH-axial stretching between 3406 and 3432 cm⁻¹, superimposed on the NH stretching band with axial deformation of the amide C=O group at about 1639 cm⁻¹, NH angular deformation at approximately 1560 cm⁻¹; axial deformation of amide-CN at around 1421 cm⁻¹, symmetrical angular deformation in CH3 at 1379 cm⁻¹, -CN axial deformation of amino groups from 1125 to 1250 cm⁻¹ and polysaccharide structure bands in the range of between 890-1150 cm⁻¹. The crystallinity index of chitosan was 60.92%, and its degree of deacetylation was 75.25%. A low percentage of a supply of sucrose and asparagine with corn steep liquor offered higher yields of biomass and chitosan production at low cost.

Eco-friendly chitosan production by Syncephalastrum racemosum and application to the removal of acid orange 7 (AO7) from wastewaters.

Due to the existence of new methodologies that have reduced the production costs of microbiological chitosan, this paper puts forward the use of agro-industrial residues in order to produce microbiological chitosan and to apply chitosan as an innovative resource for removing acid orange 7 (AO7) from wastewaters. The best culture conditions were selected by a full 24 factorial design, and the removal of the dye was optimized by a 23 central composite rotational design. The results showed that corn steep liquor (CSL) is an agro-industrial residue that can be advantageously used to produce microbiological chitosan with yields up to 7.8 g/kg of substrate. FT-IR spectra of the product showed typical peak distributions like those of standard chitosan which confirmed the extracted product was chitosan-like. The efficiency of removing low concentrations of AO7 by using microbiological chitosan in distilled water (up to 89.96%) and tap water (up to 80.60%) was significantly higher than the efficiency of the control (chitosan obtained from crustaceans), suggesting that this biopolymer is a better economic alternative for discoloring wastewater where a low concentration of the dye is considered toxic. The high percentage recovery of AO7 from the microbiological chitosan particles used favors this biopolymer as a possible bleaching agent which may be reusable.

Antioxidant and antimicrobial activities of 7-hydroxy-calamenene-rich essential oils from Croton cajucara Benth.

Croton cajucara is a shrub native to the Amazon region locally known as "sacaca". Two morphotypes are known: white and red "sacaca". The essential oils (EO) obtained by hydrodistillation from leaves of the red morphotype were, in general, rich in 7-hydroxycalamenene (28.4%-37.5%). The effectiveness of these EO regarding the antimicrobial activity against pathogenic microorganisms was initially investigated by the drop test method, showing significant inhibition zones. Among the microorganisms tested, the essential oils rich in 7-hydroxycalamenene were more effective against methicillin resistant Staphylococcus aureus (MRSA), Enterococcus faecalis, Mycobacterium tuberculosis, M. smegmatis, Mucor circinelloides and Rhizopus oryzae. The minimum inhibitory concentrations (MIC) of the oils were determined using the broth dilution assay. It was possible to observe that 7-hydroxycalamenene-rich oils presented high antimicrobial activity, with MIC of 4.76 × 10⁻³ µg/mL for MRSA, 4.88 µg/mL for M. tuberculosis, 39.06 µg/mL for M. smegmatis, and 0.152 µg/mL for R. oryzae and 3.63 × 10⁻8 µg/mL for M. circinelloides. The antioxidant activity of this EO suggests that 7-hydroxycalamenene provides more antioxidant activity according with EC(50) less than 63.59 µg/mL. Considering the bioactive potential of EOs and 7-hydroxycalamenene could be of great interest for development of antimicrobials for therapeutic use in treatment of bacterial and fungal infections in humans and/or veterinary practice.

Physicochemical characterization of tensio-active produced by Geobacillus stearothermophilus isolated from petroleum-contaminated soil.

Biosurfactants are surface-active agents of microbial origin, and have a property of lowering the interfacial tension between two liquids. They act on the interface and are amphiphathic molecules; in with both hydrophilic and hydrophobic portions are present in the same molecule. However, the economics of producing biosurfactant has limited its commercial applications, and the costs can be reduced using cheap substrates or industrial waste. The present study showed the biosurfactant production using corn steep liquor and palm oil as carbon and nitrogen sources for reduction the costs of production. The biosurfactant production by Geobacillus stearothermophilus UCP 986 was carried out using optimized culture medium constituted by palm oil (7.5%) and corn steep liquor (4.5%) using Bioflo fermentor, at temperature of 45°C, during 32 h and agitation of 300 rpm. The biosurfactant showed a reduction of the water surface tension of 72-31 mN/m and interfacial tension of 0.3 mN/m. The biosurfactant was obtained from the net metabolic liquid by acetone precipitation corresponding to the yield of 2.3g/L. The isolate biosurfactant showed a CMC of 2.5% and non-ionic profile. The best emulsification index (E(24)) obtained was 87% using motor oil burned. The biosurfactant solution (2.5%) used in oil spreading test increases the viscosity of engine burning oil of 149.2% and 138.2% to vegetable fat post-frying, respectively. The gas chromatography-mass spectrometer indicated at 29.52 min a molecular weight of 207 Da and eight peaks by FT-IR identified the chemical structure of the biosurfactant produced by G. stearothermophilus.

An improved method for removal of azo dye orange II from textile effluent using albumin as sorbent.

Azo dyes are generally resistant to biodegradation due to their complex structures. Acid orange II is one of the most widely used dyes in the textile industry. The influence of bovine serum albumin (BSA) in different concentrations, pH, and time of contact on Orange II was investigated using kinetics and adsorption-isotherm experiments. The results showed that the maximum colour removed from dye/albumin was 99.50% and that a stable dye-protein complex had been formed at pH 3.5 and in a proportion of 1:3 (v/v), respectively. The synthetic effluent did not show toxicity to the microcrustacean Artemia salina, and showed a CL50 equal to 97 µg/mL to azo dye orange II. Additionally, the methodology was effective in removing the maximum of orange II using BSA by adsorption at pH 3.5 which mainly attracted ions to the azo dye during the adsorption process. This suggests that this form of treatment is economical and easy to use which potentially could lead to bovine serum albumin being used as a sorbent for azo dyes.

Oxidation of dibenzothiophene (DBT) by Serratia marcescens UCP 1549 formed biphenyl as final product.

BACKGROUND: The desulphurization of dibenzothiophene (DBT), a recalcitrant thiophenic fossil fuel component by Serratia marcescens (UCP 1549) in order for reducing the Sulphur content was investigated. The Study was carried out establishing the growth profile using Luria Bertani medium to different concentrations of DBT during 120 hours at 28°C, and orbital Shaker at 150 rpm. RESULTS: The results indicated that concentrations of DBT 0.5, 1.0 and 2.0 mM do not affected the growth of the bacterium. The DBT showed similar Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MCB) (3.68 mM). The desulphurization of DBT by S. marcescens was used with 96 hours of growth on 2 mM of DBT, and was determined by gas chromatography (GC) and GC-mass spectrometry. In order to study the desulphurization process by S. marcescens was observed the presence of a sulfur-free product at 16 hours of cultivation. CONCLUSIONS: The data suggests the use of metabolic pathway "4S" by S. marcescens (UCP 1549) and formed biphenyl. The microbial desulphurization process by Serratia can be suggest significant reducing sulphur content in DBT, and showed promising potential for reduction of the sulfur content in diesel oil.

Microbial enhance of chitosan production by Rhizopus arrhizus using agroindustrial substrates.

This study investigated the potential of Rhizopus arrhizus UCP 402 for producing chitosan using corn steep liquor and honey as agroindustrial nitrogen and carbon sources. A complete factorial design was used to assess the improved biomass and chitosan production. The results were evaluated using Pareto charts (Statistica 7.0 software). The chitosan obtained was characterized by X-ray diffraction. The cristallinity index (I(C)), and infrared spectroscopy (FTIR) were used to evaluate the degree of deacetylation (DD %). The morphological aspects of the R. arrhizus were evaluated by measuring the diameter of the colonies by light microscopy. The results obtained showed higher biomass and chitosan yields (20.61 g/L and 29.3 mg/g), respectively, in the selected assays. The characterization of the macromolecular arrangement of chitosan showed a crystallinity index compatible with the literature, and the infrared peaks confirmed a degree of 86%. The experimental data obtained suggest that adding honey to corn steep liquor is a promising way to improve microbiological chitosan production.

A biosorption isotherm model for the removal of reactive azo dyes by inactivated mycelia of Cunninghamella elegans UCP542.

The biosorption of three reactive azo dyes (red, black and orange II) found in textile effluents by inactive mycelium of Cunninghamella elegans has been investigated. It was found that after 120 hours of contact the adsorption led to 70%, 85%, 93% and 88% removal of reactive orange II, reactive black, reactive red and a mixture of them, respectively. The mycelium surface was found to be selective towards the azo dyes in the following order: reactive red > reactive black > orange II. Dye removal from a mixture solution resulted in 48.4 mg/g retention by mycelium and indicated a competition amongst the dyes for the cellular surface. A Freundlich adsorption isotherm model exhibited a better fit, thus suggesting the presence of heterogeneous binding sites. Electrondense deposits observed on the mycelium ultrastructure suggest that the dyes are mainly retained under the cellular surface of the inactive biomass of C. elegans.

Physico-chemical characteristics and functional properties of chitin and chitosan produced by Mucor circinelloides using yam bean as substrate.

Microbiological processes were used for chitin and chitosan production by Mucor circinelloides (UCP 050) grown in yam bean (Pachyrhizus erosus L. Urban) medium. The polysaccharides were extracted by alkali-acid treatment and structural investigations by X-ray diffraction, Fourier transform IR analysis, viscosity and thermal analysis by TG, DTG, and DTA were done. The highest biomass yield (20.7 g/L) was obtained at 96 hours. The highest levels of chitosan (64 mg/g) and chitin (500 mg/g) were produced at 48 and 72 hours, respectively. It was demonstrated that yam bean shows great potential as an economic medium and it is possible to achieve a good yield of chitosan with chemical properties that enable its use in biotechnological applications.

Economic optimized medium for tensio-active agent production by Candida sphaerica UCP0995 and application in the removal of hydrophobic contaminant from sand.

Statistical experimental designs and response surface methodology were employed to optimize the concentrations of agroindustrial residues as soybean oil (SORR) from refinery, and corn steep liquor (CSL) from corn industry, for tensio-active agent produced by Candida sphaerica UCP 0995. Three 2(2) full factorial design were applied sequentially to investigate the effects of the concentrations and interactions of soybean oil refinery residue and corn steep liquor on the surface tension of free-cell culture broth for 144 h. Two 2(2) central composite designs and response surface methodology were adopted to derive a statistical model to measure the effect of SORR and CSL on the surface tension of the free-cell culture broth for 144 h. The regression equation obtained from the experimental data using a central composite design was solved, and by analyzing the response surface contour plots, the optimal concentrations of the constituents of the medium were determined: 8.63% v/v (≅9% v/v) of SORR and 8.80% v/v (≅9% v/v) CSL. The minimum surface tension predicted and experimentally confirmed was 25.25 mN/m. The new biosurfactant, denominated Lunasan, recovered 95% of motor oil adsorbed in a sand sample, thus showing great potential for use in bioremediation processes, especially in the petroleum industry.

Chromium (VI) ion adsorption features of chitosan film and its chitosan/zeolite conjugate 13X film.

This research evaluated the importance of the adsorption properties of chitosan a chitosan/zeolite conjugate film for the removal of Cr(VI) ions from solutions in the 5-260 mg/L concentration range, when the pH was adjusted to 4.0 and 6.0. The uptake capacities of the films formed by chitosan and by the chitosan/zeolite conjugate were calculated by mass balance. The equilibrium isotherms were fitted to the Langmuir, Freundlich and Redlich-Peterson models. The chitosan film seems to be a good sorbent for Cr(VI) at pH 4, but its physical instability suggests the need for a more resilient support. Due to this fact zeolite was added to the chitosan matrix in solution and a chitosan/zeolite (CS/Zeo) film was thus formed. The solubility of the film and the characterization of the different matrices by FTIR, TGA and X-Ray showed that a cross-linked structure was formed between the chitosan and zeolite and the solubility of the film increased. In this study, the low manufacturing cost of the CS/Zeo matrix, the good uptake of Cr(VI) at acidic pH (17.28 mg/g) and the non desorption of Cr(VI) from the film in water suggests this combination should be tested in industrial environment.

Evaluation antimicrobial and antiadhesive properties of the biosurfactant Lunasan produced by Candida sphaerica UCP 0995.

Different groups of biosurfactants exhibit diverse properties and display a variety of physiological functions in producer microorganisms; these include enhancing the solubility of hydrophobic/water-insoluble compound, heave metal binding, bacterial pathogenesis, cell adhesion and aggregation, quorum sensing and biofilm formation. Candida sphaerica was grown in a low cost medium, consisting of distilled water supplemented with 9% refinery residue of soybean oil and 9% corn steep liquor, for 144 h at 28°C and 150 rpm. The cell-free supernatant obtained at the end of the experiments was submitted to extraction, and afterward the biosurfactant was isolated using methanol with a yield of 9 g l(-1). The critical micelle concentration of the biosurfactant was found to be 0.25 mg ml(-1) with a surface tension of 25 mN m(-1). Several concentrations of the biosurfactant (0.625-10 mg ml(-1)) were used to evaluate its antimicrobial and antiadhesive activities against a variety of microorganisms. The biosurfactant showed antimicrobial activity against Streptococcus oralis (68%), Candida albicans (57%), and Staphylococcus epidermidis(57.6%) for the highest concentration tested. Furthermore, the biosurfactant at a concentration of 10 mg ml(-1) inhibited the adhesion between 80 and 92% of Pseudomonas aeruginosa, Streptococcus agalactiae, Streptococcus sanguis12. Inhibition of adhesion with percentages near 100% occurred for the higher concentrations of biosurfactant used. Results gathered in this study point to a potential use of the biosurfactant in biomedical applications.