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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.How to cite: Pele MA, Ribeaux DR, Vieira ER, et al. Conversion of renewable substrates for biosurfactant production by Rhizopus arrhizus UCP 1607 and enhancing the removal of diesel oil from marine soil. Electron J Biotechnol 2019;38. https://doi.org/10.1016/j.ejbt.2018.12.003. Keywords: Agro-industrial wastes, Biomolecules, Biosurfactant, Corn steep liquor, Crude glycerol, Diesel oil, Marine soil, Mucoralean fungus, Removing hydrophobic compound, Rhizopus, Tensioactive agent

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. Electronic supplementary material The online version of this article (10.1186/s12934-018-1046-0) contains supplementary material, which is available to authorized users.

We investigated the influence of corn steep liquor (CSL) and cassava waste water (CWW) as carbon and nitrogen sources on the morphology and production of biomass and chitosan by Mucor subtilissimus UCP 1262 and Lichtheimia hyalospora UCP 1266. The highest biomass yields of 4.832 g/L (M. subtilissimus UCP 1262) and 6.345 g/L (L. hyalospora UCP 1266) were produced in assay 2 (6% CSL and 4% CWW), factorial design 22, and also favored higher chitosan production (32.471 mg/g) for M. subtilissimus. The highest chitosan production (44.91 mg/g) by L. hyalospora (UCP 1266) was obtained at the central point (4% of CWW and 6% of CSL). The statistical analysis, the higher concentration of CSL, and lower concentration of CWW significantly contributed to the growth of the strains. The FTIR bands confirmed the deacetylation degree of 80.29% and 83.61% of the chitosan produced by M. subtilissimus (UCP 1262) and L. hyalospora (UCP 1266), respectively. M. subtilissimus (UCP 1262) showed dimorphism in assay 4&ndash, 6% CSL and 8% CWW and central point. L. hyalospora (UCP 1266) was optimized using a central composite rotational design, and the highest yield of chitosan (63.18 mg/g) was obtained in medium containing 8.82% CSL and 7% CWW. The experimental data suggest that the use of CSL and CWW is a promising association to chitosan production.

Surfactants are amphipathic molecules of petrochemical origin used in various industrial segments, mainly in the petroleum industry. However, they are toxic and produced from non-renewable sources. Biosurfactants are natural, biodegradable and less toxic molecules synthesized by bacteria, yeast, and filamentous fungi, however, their cost of production is still high. In the present study, agro-industrial by-products were used as renewable sources to evaluate their influence on the production of biosurfactant by Penicillium sclerotiorum UCP1361. A central composite rotated design (CCRD) 2² was performed to optimize the concentrations of milk whey and barley on the synthesis of biosurfactant. The filamentous fungus P. sclerotiorum was inoculated in the assays according to the experimental design and incubated in orbital agitation at 150 rpm, pH 5.0 for 96 h at 28 °C. Then, the cell-free metabolic liquid was obtained and the surface tension was measured. The emulsification index was also analyzed with different hydrophobic substrates. The dispersing capacity of the biosurfactant and its viscosity were tested on burnt engine oil. The extraction of the biomolecule was performed using chloroform and methanol as solvent system. The results showed that the biosurfactant reduced the surface tension from 72 to 27 mN/m and the emulsification index was 68% with burnt engine oil. The dispersing capacity detected was 33.15 cm2 and further reduced the oil viscosity from 279.6 to 48.5 cP. This study indicated that the biosurfactant produced by P. sclerotiorum may be promising as a bioremediation agent in oil spilled sites.

Microbial surfactants are amphipathic molecules mainly produced by submerged fermentation, and capable of decreasing the surface and interfacial tension between two immiscible phases. However, their obtention by solid state fermentation (SSF) has gained attention due to the less complex equipment involved, less energy demand, low volumes of water and requirement of less solvent for extraction. Hence, the aim of this study was to evaluate the ability of Candida tropicalis UCP 1613 to produce biosurfactant through solid-state fermentation and determine its stability under different environmental conditions. A factorial design 24 was performed to determine the influence of four variables, which were inoculum size, temperature, and particle size and inductor volume on the surface tension. In addition, the stability of the biomolecule was analysed in different pH, temperature and salinity ranges. The results showed that yeast synthesized biosurfactant under all conditions tested. From the statistical analysis, it was bserved that all variables except the inductor concentration had a significant influence on the surface tension decrease. The lowest value 25.8 mN/m was detected at condition 8 (10-6 cells/mL; 31 °C; 32 mesh and 0 mL of the inductor). The biosurfactant displayed a good performance when analysing its activity in different temperature, salinity and pH ranges. The study showed the feasibility of the solid-state fermentation to obtain a biosurfactant with excellent activity produced by a yeast. At the same time this is the first report of its kind in the literature.

This study screened four Rhizopus species as biosurfactant producers using different markers. First of all, Rhizopus spp. UCP 1607 was identified as Rhizopus arrhizus by morphological and molecular methods. The production of biosurfactant/bioemulsifier was investigated by submerged fermentation using soybean post-frying oil (5% v/v) and sodium glutamate (1% w/v) medium. The primary markers’ hemolysis and parafilm M tests showed that R. arrhizus UCP1607 strain exhibited higher hemolytic activity (49 mm of clear zone) on sheep blood agar and a larger drop diameter (12 mm) on parafilm hydrophobic surface. The experimental results showed the most promising biosurfactant production by R. arrhizus UCP 1607 strain led to a reduction of surface tension (31.8 mN/m) and the diameter of the oil-spreading covered an area of 66.4 cm2. The strains Rhizopus microsporus var. chinensis UCP1296, R. microsporus var. microsporus UCP1304, and R. arrhizus UCP1607 were capable of forming stable emulsions corresponding to 91.7, 94.8, and 82.6%, respectively in crude oil. Key words: Tensio-active agent, bioemulsifier, screening of Rhizopus strains, submerged fermentation.

The current work aimed to use agro-industrial wastes as a strategy to obtain biosurfactant from a new Candida tropicalis UCP 1613 isolated from mangrove sediments of Rio Formoso, Pernambuco State, Brazil. The yeast was identified based on 18S rRNA sequencing method and blast homology search. The promising strain showed the ability to use an optimal composition of a cheap medium containing whey (3%), cassava wastewater (7%) and soybean post frying oil (10%) during 96h which reduced significantly the surface tension from 70 to 28.8 mN/m. The yield of the biosurfactant obtained was 4.9 g/L and the minimum value of critical micelle concentration was 1.5%. In addition, this was isolated and characterized as an anionic polymeric molecule, composed of proteins (51%), lipids (37%) and carbohydrates (11%), and confirmed by Fourier transform infrared spectroscopy (FTIR) analysis. Also, biosurfactant was capable in forming stable emulsions at different ranges of temperature, pH and salinity. Alternatively, the biosurfactant displayed no toxicity against the different vegetable evaluated seeds Brassica oleracea, Lactuca sativa L. and Solanum lycopersicum. The antimicrobial activity of this biosurfactant was verified showing the main efficacy against Gram-positive bacteria besides inhibiting the antifungal activity against the yeast tested. The results obtained suggest its potential application to pharmaceutical, as well as environmental area. Key words: Candida tropicalis, mangrove sediment, oil dispersion, biosurfactant.

Additional file 1: Table S1. Average of chemical composition of cassava wastewater. Table S2. Application of biosurfactant produced by Serratia marcescens UCP 1549 in removal of burned motor oil from contaminated marine soil. Figure S1. Growth profile of Serratia marcescens UCP 1549 on Luria Bertani (LB) medium, during 144 h at 28 °C and 150 rpm.

This research aims to study the production of chitosan from shrimp shell (Litopenaeus vannamei) of waste origin using two chemical methodologies involving demineralization, deproteinization, and the degree of deacetylation. The evaluation of the quality of chitosan from waste shrimp shells includes parameters for the yield, physical chemistry characteristics by infrared spectroscopy (FT-IR), the degree of deacetylation, and antibacterial activity. The results showed (by Method 1) extraction yields for chitin of 33% and for chitosan of 49% and a 76% degree of deacetylation. Chitosan obtained by Method 2 was more efficient: chitin (36%) and chitosan (63%), with a high degree of deacetylation (81.7%). The antibacterial activity was tested against Gram-negative bacteria (Stenotrophomonas maltophiliaandEnterobacter cloacae) and Gram-positiveBacillus subtilisand the Minimum Inhibitory Concentrations (MIC) and the Minimum Bactericidal Concentration (MBC) were determined. Method 2 showed that extracted chitosan has good antimicrobial potential against Gram-positive and Gram-negative bacteria and that the process is viable.

A biosurfactant was produced fromCunninghamella echinulatausing sustainable technology for cleaning and degreasing of cotton fabric impregnated with burned motor oil. The surface tension was 32.4 mN/m on a medium containing instant noodle waste (2%), corn steep liquor (2%), and postfrying oil (0.5%) with a carbon/nitrogen ratio of 30 : 1, yield of 6.0 g·L−1, emulsifier index of 81.4%, and dispersant property of 32.15 cm2. The biosurfactant produced is a glycolipid constituted by carbohydrate (47.7%) and lipids (50.0%). The structure was confirmed by GC-MS (stearic acid in predominance with mass of 298 m/z), FTIR spectroscopy (polysaccharides in bands between 1025 and 1152 cm−1and fatty acids in bands between 2057 and 3100 cm−1), 1H NMR, and 13C NMR spectrum (carbohydrates in signal of 4.38 ppm and 77.0 ppm). The properties of cleaning and degreasing of burned engine oil in cotton fabric by biosurfactant ofC. echinulatawas evidenced by removal of 86% of oil. After use of the biosurfactant, the fibers were not damaged, which is important for structural integrity of cotton fabric after the wash. In addition, the biosurfactant did not show toxic effect. This study suggests that the biosurfactant fromC. echinulatacan be used in formulation of textile detergents, in particular for removal of hydrophobic residues from the automobile industry.

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.