Microbial Biosurfactant: Candida bombicola as a Potential Remediator of Environments Contaminated by Heavy Metals.

Industrial interest in surfactants of microbial origin has intensified recently due to the characteristics of these compounds, such as biodegradability and reduced toxicity, and their efficiency in removing heavy metals and hydrophobic organic compounds from soils and waters. The aim of this study was to produce a biosurfactant using Candida bombicola URM 3712 in a low-cost medium containing 5.0% molasses, 3.0% corn steep liquor and 2.5% residual frying oil for 144 h at 200 rmp. Measurements of engine oil tension and emulsification were made under extreme conditions of temperature (0 °C, 5 °C, 70 °C, 100 °C and 120 °C), pH (2-12) and NaCl concentrations (2-12), demonstrating the stability of the biosurfactant. The isolated biosurfactant was characterized as an anionic molecule with the ability to reduce the surface tension of water from 72 to 29 mN/m, with a critical micellar concentration of 0.5%. The biosurfactant had no toxic effect on vegetable seeds or on Eisenia fetida as a bioindicator. Applications in the removal of heavy metals from contaminated soils under dynamic conditions demonstrated the potential of the crude and isolated biosurfactant in the removal of Fe, Zn and Pb with percentages between 70 and 88%, with the highest removal of Pb being 48%. The highest percentage of removal was obtained using the cell-free metabolic liquid, which was able to remove 48, 71 and 88% of lead, zinc and iron from the soil, respectively. Tests in packed columns also confirmed the biosurfactant's ability to remove Fe, Zn and Pb between 40 and 65%. The removal kinetics demonstrated an increasing percentage, reaching removal of 50, 70 and 85% for Pb, Zn and Fe, respectively, reaching a greater removal efficiency at the end of 24 h. The biosurfactant was also able to significantly reduce the electrical conductivity of solutions containing heavy metals. The biosurfactant produced by Candida bombicola has potential as an adjuvant in industrial processes for remediating soils and effluents polluted by inorganic contaminants.

Oil spills: impacts and perspectives of treatment technologies with focus on the use of green surfactants.

Oil spills into the oceans cause irreparable damage to marine life and harms the coastal population of the affected areas. The main measures to be taken in response to an oil spill are to reduce the impact on marine life, prevent oil from reaching the shore through its recovery, and accelerate the degradation of unrecovered oil. Any environmental damage can be reduced if the spilled oil is removed from the water quickly and efficiently. Therefore, it is essential to know the treatment strategies for spilled oils. Several technologies are currently available, including booms, skimmers, in situ burning, use of adsorbents, dispersants/surfactants, and bioremediation. The selection of the type of treatment will depend not only on the effectiveness of the technique, but mainly on the type of oil, amount spilled, location, weather, and sea conditions. In this review, the characteristics of oil spills, their origin, destination, and impacts caused, including major accidents around the world, are initially addressed. Then, the main physical, chemical, and biological treatment technologies are presented, describing their advances, advantages, and drawbacks, with a focus on the use of green surfactants. These agents will be described in detail, showing the evolution of research, recent studies, patents, and commercialized products. Finally, the challenges that remain due to spills, the necessary actions, and the prospects for the development of existing treatment technologies are discussed, which must be linked to the use of combined techniques.

Removal of heavy oil from contaminated surfaces with a detergent formulation containing biosurfactants produced by Pseudomonas spp.

Industrial plants powered by heavy oil routinely experience problems with leaks in different parts of the system, such as during oil transport, the lubrication of equipment and mechanical failures. The surfactants, degreasing agents and solvents that make up detergents commonly used for cleaning grease-covered surfaces are synthetic, non-biodegradable and toxic, posing risks to the environment as well as the health of workers involved in the cleaning process. To address this problem, surfactant agents of a biodegradable nature and low toxicity, such as microbial surfactants, have been widely studied as an attractive, efficient solution to replace chemical surfactants in decontamination processes. In this work, the bacterial strains Pseudomonas cepacia CCT 6659, Pseudomonas aeruginosa UCP 0992, Pseudomonas aeruginosa ATCC 9027 and Pseudomonas aeruginosa ATCC 10145 were evaluated as biosurfactant producers in media containing different combinations and types of substrates and under different culture conditions. The biosurfactant produced by P. aeruginosa ATCC 10145 cultivated in a mineral medium composed of 5.0% glycerol and 2.0% glucose for 96 h was selected to formulate a biodetergent capable of removing heavy oil. The biosurfactant was able to reduce the surface tension of the medium to 26.40 mN/m, with a yield of approximately 12.00 g/L and a critical micelle concentration of 60.00 mg/L. The biosurfactant emulsified 97.40% and dispersed 98.00% of the motor oil. The detergent formulated with the biosurfactant also exhibited low toxicity in tests involving the microcrustacean Artemia salina and seeds of the vegetable Brassica oleracea. The detergent was compared to commercial formulations and removed 100% of the Special B1 Fuel Oil (OCB1) from different contaminated surfaces, demonstrating potential as a novel green remover with industrial applications.

Production of green surfactants: market prospects

Science has greatly contributed to the advancement of technology and to the innovation of production processes and their applications. Cleaning products have become indispensable in today's world, as personal and environmental hygiene is important to all societies worldwide. Such products are used in the home, in most work environments and in the industrial sectors. Most of the detergents on the market are synthesised from petrochemical products. However, the interest in reducing the use of products harmful to human health and the environment has led to the search for detergents formulated with natural, biodegradable surfactant components of biological (plant or microbiological) origin or chemically synthesised from natural raw materials usually referred to as green surfactants. This review addresses the different types, properties, and uses of surfactants, with a focus on green surfactants, and describes the current scenario as well as the projections for the future market economy related to the production of the different types of green surfactants marketed in the world.

Biosorption of heavy fuel oil from aqueous solution by Eichhornia crassipes (Mart.) Solms in natura.

This work investigated the efficiency of bioremediation of heavy fuel oil (HFO) in aqueous solutions by living Eichhornia crassipes (Mart.) Solms, also known as water hyacinth. Possibility of using post-biosorption macrophytes to produce briquettes was also studied. HFO was characterized by its density, viscosity, and Fourier-transform infrared spectroscopy. Water hyacinth was characterized by scanning electron microscope, pH of zero point of charge, buoyancy, and wettability. Experiments were performed to evaluate effects of contact time and initial oil concentration on biosorption. E. crassipes presented a hydrophobic nature, ideal for the treatment of oily effluents. Hollow structures in macrophytes were also identified, which favor capillary rise and retention of oils of high density and viscosity. Biosorption efficiency of HFO reached 94.8% in tests with initial concentration of 160 mg.L-1. A calorific value of 4022 kcal.kg-1 was obtained in briquettes made of water hyacinth post-biosorption. These results reinforce the great potential of E. crassipes as a sustainable and efficient alternative for treatment of oily effluents.

Production of cupcake-like dessert containing microbial biosurfactant as an emulsifier.

This work describes the application of the biosurfactant from Candida bombicola URM 3718 as a meal additive like cupcake. The biosurfactant was produced in a culture medium containing 5% sugar cane molasses, 5% residual soybean oil and 3% corn steep liquor. The surface and interfacial tension of the biosurfactant were 30.790 ± 0.04 mN/m and 0.730 ± 0.05 mN/m, respectively. The yield in isolated biosurfactant was 25 ± 1.02 g/L and the CMC was 0.5 g/L. The emulsions of the isolated biosurfactant with vegetable oils showed satisfactory results. The microphotographs of the emulsions showed that increasing the concentration of biosurfactant decreased the oil droplets, increasing the stability of the emulsions. The biosurfactant was incorporated into the cupcake dessert formulation, replacing 50%, 75% and 100% of the vegetable fat in the standard formulation. Thermal analysis showed that the biosurfactant is stable for cooking cupcakes (180 °C). The biosurfactant proved to be promising for application in foods low in antioxidants and did not show cytotoxic potential in the tested cell lines. Cupcakes with biosurfactant incorporated in their dough did not show significant differences in physical and physical-chemical properties after baking when compared to the standard formulation. In this way, the biosurfactant has potential for application in the food industry as an emulsifier for flour dessert.

Biosurfactants: Production and application prospects in the food industry.

There has been considerable interest in the use of biosurfactants due to the diversity of structures and the possibility of production from a variety of substrates. The potential for industrial applications has been growing, as these natural compounds are tolerant to common processing methods and can compete with synthetic surfactants with regards to the capacity to reduce surface and interfacial tensions as well as stabilise emulsions while offering the advantages of biodegradability and low toxicity. Among biosurfactant-producing microorganisms, some yeasts present no risks of toxicity or pathogenicity, making them ideal for use in food formulations. Indeed, the use of these biomolecules in foods has attracted industrial interest due to their properties as emulsifiers and stabilizers of emulsions. Studies have also demonstrated other valuable properties, such as antioxidant and antimicrobial activity, enabling the aggregation of greater value to products and the avoidance of contamination both during and after processing. All these characteristics allow biosurfactants to be used as additives and versatile ingredients for the processing of foods. The present review discusses the potential application of biosurfactants as emulsifying agents in food formulations, such as salad dressing, bread, cakes, cookies, and ice cream. The antioxidant, antimicrobial and anti-adhesive properties of these biomolecules are also discussed, demonstrating the need for further studies to make the use of the natural compounds viable in this expanding sector.

Treatment of oily effluent using a low-cost biosurfactant in a flotation system.

Fuel and lubricating oil leaks produce an oily wastewater that creates an environmental problem for industries. Dissolved air flotation (DAF) has been successfully employed for the separation of oily contaminants. Collectors constitute an auxiliary tool in the DAF process that enhances the separation efficiency by facilitating the adhesion of the contaminant particles. The use of biosurfactants as collectors is a promising technology in flotation processes, as these biomolecules are biodegradable and non-toxic. In the present study, a biosurfactant was produced from the bacteria Pseudomonas aeruginosa UCP 0992 cultivated in 0.5% corn steep liquor and 4.0% vegetable oil residue in a bioreactor at 225 rpm for 120 h, resulting in a surface tension of 26.5 mN/m and a yield of 26 g/L. The biosurfactant demonstrated stability when exposed to different temperatures, heating times, pH values and salt and was characterised as a glycolipid with a critical micelle concentration of 600 mg/L. A central composite rotatable design was used to evaluate the effect of the crude biosurfactant added to a laboratory DAF prototype on the removal efficiency of motor oil. The isolated and formulated forms of the biosurfactant were also tested in the prototype after the optimisation of the operational conditions. The results demonstrated that all forms of the biosurfactant increased the oil separation efficiency of the DAF process by 65 to 95%. In conclusion, the use of biosurfactants is a promising alternative as an auxiliary tool in flotation processes for the treatment of oily waters generated by industrial activities.

The potential application of biosurfactant produced by Pseudomonas aeruginosa TGC01 using crude glycerol on the enzymatic hydrolysis of lignocellulosic material.

The production of biosurfactant by Pseudomonas aeruginosa TGC01 using crude glycerol and sodium nitrate as the sole substrate and nitrogen source, respectively, was investigated using two mineral culture media. Two inoculum sizes (5 and 10% v/v) and two volumes of the culture medium (50 and 100 mL) in 500 mL Erlenmeyer flask also were used. Enzymatic hydrolyses of waste office paper (WOP), newspaper (NP) and eucalyptus wood chips (EWC) were carried out using the biosurfactant from P. aeruginosa TGC01. The decrease in volume of the culture medium increased the production of rhamnolipid by 500% in relation to concentration obtained when higher volume of culture medium was used. High quantity biosurfactant was recovered (11 g/L) with desired surface active properties after extraction using chloroform:methanol (v/v). The biosurfactant was able to reduce the water surface tension from 72 to 27 mN/m with a critical micelle concentration (CMC) of 100 mg/L and a stable emulsion index (above 60%) in the enzymatic hydrolysis (pH 4.8 and 50 °C for 4 h). Biosurfactant increased the glucose released in the enzymatic hydrolysis in relation to control (without tensoactive) when WOP (19% increase) and NP (113% increase) were used. The process for NP (18% lignin) was economical, given that the biosurfactant present made a delignification process unnecessary.

Application of biosurfactants and chitosan in toothpaste formulation.

The aim of the present study was to formulate toothpastes containing biosurfactants and either fungal chitosan or sodium fluoride and evaluate the cytotoxicity, antimicrobial action and inhibition potential against biofilm formed by Streptococcus mutans. Chitosan was extracted from the biomass of the fungus Mucorales. We tested biosurfactants produced by Pseudomonas aeruginosa UCP 0992 (PB), Bacillus metylotrophicus UCP 1616 (BB) and Candida bombicola URM 3718 (CB). Fractional inhibitory concentration analysis was performed to determine the type of interaction between the compounds. Six toothpaste were prepared, the active ingredients of which were the biosurfactants, chitosan or sodium fluoride. The cytotoxicity tests were performed using the 3-[4,5-dimethyl-2-thiazolyl]-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay for the L929 (mouse fibroblast) and RAW 264.7 (mouse macrophage) cell lines. The toothpastes were tested with regard to pH, consistency and foaming capacity. The inhibition of biofilm was investigated by applying the toothpaste to biofilm formed in modified artificial saliva for 24 h at 37 °C in anaerobiosis. All substances had a minimum inhibitory concentration (MIC) for S. mutans. The combinations of CB and PB with chitosan had an additive effect against S. mutans, whereas BB combined with chitosan had an indifferent effect. The toothpastes were non-toxic. The formulations had pH around 9, spreading capacity between 8 and 17 mm and foaming capacity between 63 and 95%. All formulations inhibited the cellular viability of S. mutans in the biofilm, with similar results compared to the commercial toothpaste tested. The present results show that the formulations suggested are promising when compared to a commercial tooth paste.

Production and formulation of a new low-cost biosurfactant to remediate oil-contaminated seawater.

The aim of the present study was to produce biosurfactants using three bacterial strains (Pseudomonas cepacia CCT6659, Bacillus methylotrophicus UCP 1616 and Bacillus cereus UCP 1615) cultivated in mineral medium containing different carbon (glucose, sucrose, molasses and waste frying oil) and nitrogen [NH4NO3, (NH4)2SO4, peptone, yeast extract and corn steep liquor] sources. B. cereus stood out as the best biosurfactant producer when inoculated with a 1.5% cell suspension and cultivated at 28 °C and 200 rpm in 2.0% molasses and 1.0% corn steep liquor for 48 h. Under these conditions, medium surface tension was reduced to 26.2 ± 0.2 mN/m, and biosurfactant concentration achieved 2.05 ± 0.32 g/L. The biosurfactant showed a critical micelle concentration of 0.90 ± 0.05 g/L, proved to be highly stable in wide ranges of pH, salt concentration and heating temperature, and exerted low toxicity to larvae of Artemia salina as a marine environmental bioindicator. Structural characterisation of biosurfactant suggested a lipopeptide composition. The biotensioactive agent was shown to effectively remove motor oil adsorbed to marine rock (91.0 ± 0.4%) and to disperse it in seawater (70.0 ± 0.4%). The biosurfactant formulated with 0.2% potassium sorbate demonstrated considerable potential for application in the petroleum industry, where it could be successfully used as a commercial product to mobilize oil in marine environments.

Mouthwash containing a biosurfactant and chitosan: An eco-sustainable option for the control of cariogenic microorganisms.

The aim of the present study was to determine the antimicrobial action and toxicity of mouthwashes formulated with a biosurfactant, chitosan of a microbial origin and peppermint (Mentha piperita) essential oil (POE). Chitosan was extracted from the biomass of a fungus from the order Mucorales grown in yam bean broth. Three biosurfactants produced by Pseudomonas aeruginosa UCP 0992 (PB), Bacillus cereus UCP 1615 (BB) and Candida bombicola URM 3718 (CB) were tested. Six mouthwashes were prepared, the active ingredients of which were the biosurfactant, chitosan and POE. The minimum inhibitory concentration (MIC) was determined for the test substances separately, in combinations and in the mouthwash formulas. The toxicity of the mouthwashes was tested using MTT (3-(4,5-dimethylthiazole-2-il)-2,5-diphenyltetrazolium bromide) for the L929 (mouse fibroblast) and RAW 264.7 (mouse macrophage) cell lines. All substances tested had a MIC for cariogenic microorganisms. The combinations of the CB and PB biosurfactants with chitosan demonstrated an additive effect on the majority of microorganisms tested. The toxicity of the mouthwashes was significantly lower than that of the commercial mouthwash. The present findings demonstrate that mouthwashes containing natural products constitute a safe, effective, natural alternative to commercially available mouthwashes for the control of oral microorganisms.

Application of a low-cost biosurfactant in heavy metal remediation processes.

The industrial interest in microbial surfactants has intensified in recent years due to the characteristics of these compounds, such as biodegradability, low toxicity, and effectiveness in removing heavy metals and hydrophobic organic compounds from soil and water. This paper describes the production of a biosurfactant by the yeast Candida tropicalis grown in distilled water with 2.5% molasses, 2.5% frying oil and 4% corn steep liquor. The production of the biosurfactant reached 27 g/l in a 50-l bioreactor with a surface tension of 30 mN/m. Surface tension and engine oil emulsification assays demonstrated the stability of biosurfactant under extreme conditions of temperature and pH as well as in the presence of NaCl. Chemical structures of the biosurfactant were identified using GC-MS and NMR. The isolated biosurfactant was characterised as an anionic molecule capable of reducing the surface tension of water from 70 to 30 mN/m at 0.5% of the critical micelle concentration, with no toxic effects on plant seeds or brine shrimp. In tests involving both the crude and isolated biosurfactant for the removal of heavy metals from contaminated sand under dynamic conditions, the removal rates for Zn and Cu ranged from 30 to 80%, while the best removal rate for Pb was 15%. Tests in packed columns also confirmed the ability of biosurfactant to remove Cu and Zn at rates ranging from 45 to 65%. However, lead was not removed under static conditions. The removal kinetics demonstrated that 30 min was sufficient for the removal of metals and a single washing with the biosurfactant achieved greater removal efficiency. The use of the biosurfactant led to a significant reduction in the electrical conductivity of solutions containing heavy metals. The present findings as well as a brief economic analysis suggest the great potential of this agent for industrial remediation processes of soil and water polluted with inorganic contaminants.

Dyeing of bacterial cellulose films using plant-based natural dyes.

The aim of this work was to test the use of plant-based natural dyes on bacterial cellulose (BC) to add aesthetic value to dyed pellicles while maintaining the mechanical properties. Natural pigments from Clitoria ternatea L. and Hibiscus rosa-sinensis were tested. The commercial ARAQCEL RL 500 was also used for comparison purposes. The behavior of biocellulose regarding dye fixation, rehydration, tensile strength, and elasticity was evaluated in comparison to the dried biomaterial, showing that dyeing is a process that can be performed on hydrated BC. Dyeing the BC films through an innovative process maintained the crystallinity, thermal stability and mechanical strength of the BC and confirmed the compatibility of the membrane with the dyes tested, from the observed Scanning Electron Microscopy (SEM) morphology of nanofibers. Dyed biomaterial can be applied to various products, as confirmed by the results of the mechanical tests. As environmental awareness and public concern regarding pollution increase, the combination of natural dyes and BC pellicles can produce an attractive new material for the textile industry.

Production of a biosurfactant from Bacillus methylotrophicus UCP1616 for use in the bioremediation of oil-contaminated environments.

The aim of the present study was to produce a microbial biosurfactant for use in the bioremediation of environments contaminated with petroleum products. Bacillus methylotrophicus was isolated from seawater taken from a port area and cultivated using industrial waste as substrate (corn steep liquor and sugarcane molasses [both at 3%]). Surface tension measurements and motor oil emulsification capacity were used for the evaluation of the production of the biosurfactant, which demonstrated stability in a broad range of pH and temperature as well as a high concentration of saline, with the reduction of the surface tension of water to 29 mN/m. The maximum concentration of biosurfactant (10.0 g/l) was reached after 144 h of cultivation. The biosurfactant was considered to be a lipopeptide based on the results of proton nuclear magnetic resonance and Fourier transformed infrared spectroscopy. The tests demonstrated that the biosurfactant is innocuous and has potential for the bioremediation of soil and water contaminated by petroleum products. Thus, the biosurfactant described herein has a low production cost and can be used in environmental processes.

Recovery of contaminated marine environments by biosurfactant-enhanced bioremediation.

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

Use of bacterial biosurfactants as natural collectors in the dissolved air flotation process for the treatment of oily industrial effluent.

The aim of the present study was to investigate the separation of oil from water using a bench-scale DAF prototype with the addition of biosurfactants isolated from Pseudomonas cepacia CCT6659 and Bacillus cereus UCP1615. The best operating conditions for the DAF prototype were determined using a central composite rotatable design. The results demonstrated that the biosurfactants from P. cepacia and B. cereus increased the oil separation efficiency from 53.74% (using only microbubbles) to 94.11 and 80.01%, respectively. The prediction models for both DAF-biosurfactant systems were validated, showing an increase in the efficiency of the DAF process from 53.74% to 98.55 and 70.87% using the formulated biosurfactants from P. cepacia and B. cereus, respectively. The biosurfactant from P. cepacia was selected as the more promising product and used for the treatment of oily effluent from a thermoelectric plant, achieving removal rates ranging between 75.74 (isolated biosurfactant) and 95.70% (formulated biosurfactant), respectively.

Saponins and microbial biosurfactants: Potential raw materials for the formulation of cosmetics.

The cosmetic industry is currently one of the fasting growing sections of the economy in many countries. The recent tendency toward the use of cosmetics of a natural origin has driven the industry to seek alternatives to synthetic components in the formulation of products. Biosurfactants are natural compounds that have considerable potential for application in the formulation of safe, effective cosmetics as a replacement for commonly used chemical tensioactive agents. The present review provides essential information on the physicochemical and biological properties of saponins and microbial biosurfactants employed in cosmetic products, with a focus on the use of these natural compounds in shampoos, addressing the current state of research and patents involving biosurfactants for this purpose. The challenges and prospects of this cosmetic application are also discussed. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:1482-1493, 2018.

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

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

Production of Bacterial Cellulose by Gluconacetobacter hansenii Using Corn Steep Liquor As Nutrient Sources.

Cellulose is mainly produced by plants, although many bacteria, especially those belonging to the genus Gluconacetobacter, produce a very peculiar form of cellulose with mechanical and structural properties that can be exploited in numerous applications. However, the production cost of bacterial cellulose (BC) is very high to the use of expensive culture media, poor yields, downstream processing, and operating costs. Thus, the purpose of this work was to evaluate the use of industrial residues as nutrients for the production of BC by Gluconacetobacter hansenii UCP1619. BC pellicles were synthesized using the Hestrin-Schramm (HS) medium and alternative media formulated with different carbon (sugarcane molasses and acetylated glucose) and nitrogen sources [yeast extract, peptone, and corn steep liquor (CSL)]. A jeans laundry was also tested. None of the tested sources (beside CSL) worked as carbon and nutrient substitute. The alternative medium formulated with 1.5% glucose and 2.5% CSL led to the highest yield in terms of dry and hydrated mass. The BC mass produced in the alternative culture medium corresponded to 73% of that achieved with the HS culture medium. The BC pellicles demonstrated a high concentration of microfibrils and nanofibrils forming a homogenous, compact, and three-dimensional structure. The biopolymer produced in the alternative medium had greater thermal stability, as degradation began at 240°C, while degradation of the biopolymer produced in the HS medium began at 195°C. Both biopolymers exhibited high crystallinity. The mechanical tensile test revealed the maximum breaking strength and the elongation of the break of hydrated and dry pellicles. The dry BC film supported up to 48 MPa of the breaking strength and exhibited greater than 96.98% stiffness in comparison with the hydrated film. The dry film supported up to 48 MPa of the breaking strength and exhibited greater than 96.98% stiffness in comparison with the hydrated film. The values obtained for the Young's modulus in the mechanical tests in the hydrated samples indicated low values for the variable rigidity. The presence of water in the interior and between the nanofibers of the hydrated BC only favored the results for the elasticity, which was 56.37% higher when compared to the dry biomaterial.