Isolation and characterization of biosurfactant-producing microbes isolated from the gastrointestinal system of broiler birds fed a commercial diet.

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

γ-Cyclodextrin-based metal-organic frameworks for lactonic sophorolipid application in enhanced oil recovery.

Lactonic sophorolipid (LSL) exhibits numerous surfactant activities, such as emulsification, wetting action, dispersion effect, and oil-washing activities. Nevertheless, LSLs have poor water solubility, which restrains their application in the petroleum industry. In this research, a new compound, lactonic sophorolipid cyclodextrin metal-organic framework (LSL-CD-MOFs), was obtained by loading LSL into γ-cyclodextrin metal-organic frameworks (γ-CD-MOFs). The LSL-CD-MOFs were characterized by N2 adsorption analysis, X-ray powder diffraction analysis, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Loading LSL into γ-CD-MOFs significantly increased the apparent water solubility of LSL. However, the critical micelle concentration of LSL-CD-MOFs was similar to that of LSL. Furthermore, LSL-CD-MOFs effectively reduced the viscosities and improved the emulsification indices of oil-water mixtures. Oil-washing tests, which were conducted using oil sands, revealed that the LSL-CD-MOFs yielded an oil-washing efficiency of 85.82 % ± 2.04 %. Overall, γ-CD-MOFs are promising carriers for LSL, and LSL-CD-MOFs are a potential, low-cost, new, green surfactant for enhanced oil recovery.

Sustainable production of bioemulsifiers, a critical overview from microorganisms to promising applications.

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

Anti-oxidative property of xylolipid produced by Lactococcus lactis LNH70 and its potential use as fruit juice preservative.

In the present study, 20 lactic acid bacteria (LAB) were isolated from different fruit juices, milk, and milk products. Based on preliminary screening methods like emulsification index, oil displacement method, hemolysis, and reduction in surface tension, strain LNH70 was selected for further studies. Further, it was evaluated for preliminary probiotic characteristics, identified by 16 s rRNA sequencing as Lactococcus lactis, submitted to NCBI, and an accession number was obtained (MH174454). In addition, LNH70 was found to tolerate over wide range of temperatures (10-45 °C), pH (3-10), NaCl (up to 9%), bile (0.7%), and phenol (0.1%) concentrations. Further, optimization studies at flask level revealed that lactose as carbon source, peptone as organic nitrogen, and inorganic nitrogen (ammonium sulfate) enhanced biosurfactant production. Chemical composition of purified biosurfactant obtained from LNH70 was characterized by various physico-chemical analytical techniques and identified as xylolipid. Xylolipid biosurfactant exhibited anti-adhesion activity against food borne pathogens in in vitro conditions. Its anti-oxidative property by 1, 1-diphenyl-2-picrylhydrazyl (DPPH), 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS), and ferric reducing antioxidant power (FRAP) radical scavenging activity was found in range of 60.76 ± 0.5 to 83.50 ± 0.73%. Furthermore, xylolipid (0.05, 0.1, 0.3 mg/mL) when used for its potential as orange and pineapple juices preservation revealed miniature changes in the physico-chemical parameters evaluated in this study. However, the microbial population slightly lowered when xylolipid was used at 0.3 mg/mL after 5th day. Hence, this study supports the potential use of biosurfactant from L. lactis for its application as food preservative.

A comparative study on chemical characterization and properties of surface active compounds from Gram-positive Bacillus and Gram-negative Ochrobactrum strains utilizing pure hydrocarbons and waste mineral lubricating oils.

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

Biosurfactant production prospects of a Gram-negative bacterium-Klebsiella pneumoniae ssp. ozaenae BK34.

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

Characterization of a potent biosurfactant produced from Franconibacter sp. IITDAS19 and its application in enhanced oil recovery.

Biosurfactants are surface-active molecules produced from microorganisms either on the cell surface or secreted extracellularly. Several biosurfactant producing microorganisms have been isolated to date, but they differ in their efficacy towards different types of hydrocarbons. Here, we report the isolation and characterization of a biosurfactant producing bacterium Franconibacter sp. IITDAS19 from crude oil contaminated soil. The biosurfactant was isolated, purified and characterized. It was identified as a glycolipid. It was found to be very stable at wide range of temperatures, pH and salt concentrations. It could reduce the surface tension of the water from 71 mN/m to 31 mN/m. IITDAS19 showed very high efficacy towards both aliphatic and aromatic hydrocarbons. It resulted in about 63% recovery of residual oil in a sand pack column. Our results suggested that the produced biosurfactant can be used for enhanced oil recovery. To our knowledge, this is the first report demonstrating the detailed characterization of a biosurfactant from Franconibacter spp.

Bioremediation of motor oil-contaminated soil and water by a novel indigenous Pseudomonas otitidis strain DU13 and characterization of its biosurfactant.

Production of biosurfactant by a novel indigenous isolate Pseudomonas otitidis strain DU13 and its role in bioremediation of petroleum hydrocarbon is reported. The identity of the isolate was confirmed by 16S rDNA gene sequencing analysis (Genbank accession: MK177190). The biosurfactant produced by the isolate could reduce the surface tension of petroleum supplemented medium by 46% just after 7 days of treatment. The emulsification index (E 24 ) of the surfactant was found 37, 35, and 20%, respectively, against used motor oil, diesel, and kerosene. The FTIR spectrum of the crude biosurfactant showed the presence of υC-H stretch, υCH2, υ-C=C stretch and υC-H bonding. The isolated strain could degrade 26% of TPH content of used motor oil in liquid culture. Whereas, ex situ pilot-scale field trial demonstrated very high bioremediation potential of the isolate in terms of germination rate of Vigna radiata and Cicer arietinum seeds and plant growth just after 20 days of treatment.

Statistical optimization of medium components for biosurfactant production by Pseudomonas guguanensis D30.

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

Effect of gelatinization degree on emulsification capacity of corn starch esterified with octenyl succinic acid.

Normal corn starch (∼26% amylose content) was subjected to different degrees of extrusion-based pregelatinization (55, 75, and 95%) to improve the efficiency of octenyl succinic anhydride (OSA) esterification. The partial disruption of the native semi-crystalline structure was verified with X-ray diffraction and Fourier transform infrared analysis. It was found that partial gelatinization (pregelatinization) reduced the relative crystallinity, which is an effect that was magnified by OSA esterification. Polarized and scanning electron microscopies revealed gradual destruction of the starch granules, yielding a fraction of insoluble remnants for high gelatinization degrees. The emulsification index showed a marked increase of about 18% by single extrusion treatment. However, fully stable emulsions (emulsification index = 1.0) were obtained by dual extrusion-esterification treatment. The hardness of hydrogels was reduced by pregelatinization. Principal component analysis revealed that most starch characteristics were mutually interdependent and that the impact of gelatinization degree was independent of the impact of OSA esterification.

Isolation and characterization of biosurfactant producing bacteria from Mile 2 and Ologe Lagoons, Nigeria

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

Production optimization, stability and oil emulsifying potential of biosurfactants from selected bacteria isolated from oil-contaminated sites.

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

Isolation, screening and molecular characterization of biosurfactant producing bacteria from soil samples of auto repair shops.

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

Production and potential biotechnological applications of microbial surfactants: An overview.

Microbial surfactants are amphipathic molecules that consist of hydrophilic and hydrophobic domains, which allow partition of two fluid phases of varying degree of polarity. They are classified into two main groups: bioemulsifier and biosurfactant, depending on their molecular weight. Microbial surfactants occur in various categories according to their chemical nature and producing organisms. These biomolecules are produced by diverse groups of microorganisms including fungi, bacteria, and yeasts. Their production is significantly influenced by substrate type, fermentation technology and microbial strains. Owing to inherent multifunctional properties and assorted synthetic aptitude of the microbes, microbial surfactants are mostly preferred than their chemical counterparts for various industrial and biomedical applications including bioremediation, oil recovery; as supplements in laundry formulations and as emulsion-stabilizers in food and cosmetic industries as well as therapeutic agents in medicine. The present review discusses on production of microbial surfactants as promising and alternative broad-functional biomolecules for various biotechnological applications.

Evaluation of biosurfactant production potential of Lysinibacillus fusiformis MK559526 isolated from automobile-mechanic-workshop soil.

BACKGROUND: Biosurfactants are amphipathic biological compounds with surface active potential and are produced by many microorganisms. Biosurfactant production by Lysinibacillus fusiformis MK559526 isolated from automobile-mechanic-shop soil was investigated with a view to assessing its potential for production and potential for optimization. MATERIALS AND METHODS: Effects of carbon and nitrogen sources, pH, temperature and incubation periods on biosurfactant production were evaluated with a view to optimizing the processes. Fourier Transform Infra-Red absorption peaks and Gas chromatography mass spectrometry were used to determine the functional groups of the chemical make-up and the chemical profile of the biosurfactant respectively. RESULTS: Lysinibacillus fusiformis surfactant had emulsification index of 65.15 ± 0.35 %, oil displacement of 2.7 ± 0.26 mm, zone of haemolysis of 7.3 ± 0.16 mm and a positive drop collapse test. Optimized culture conditions for biosurfactant production: temperature, 35 ºC; pH, 7.0; starch solution, 40 g/L and urea, 1.5 g/L showed a reduction in surface tension to 28.46 ± 1.11 mN/m and increased emulsification index to 93.80 ± 0.41 %. Maximum biosurfactant production of 2.92 ± 0.04 g/L was obtained after 72 h. The biosurfactant contained peptides and fatty acids. The predominant fatty acid was 9-Octadecenoic acid (80.80%). CONCLUSIONS: The above results showing high emulsification potential and remarkable reduction in the surface tension are good biosurfactant attributes. Consequently, Lysinibacillus fusiformis MK559526 is a good candidate for biosurfactant production.

Use of Spondias Mombin fruit pulp as a substrate for biosurfactant production.

In this study, we explored the possibility of utilizing the succulent pulp of Spondias mombin (SM) as feedstock for the synthesis of biosurfactants by Pseudomonas spp. The cultures were composed of basic mineral medium amended with SM, SM + glucose, glucose (GLC), and nutrient broth (NB) as carbon sources. Biosurfactant production was determined by surface-active properties such as hemolysis, emulsification index (E24), drop collapse, oil-spreading assays, and reduction of surface tension. The stability of the biosurfactants was monitored across different temperature and pH regimes while chemical components of the extracted biosurfactants were determined by thin-layer chromatography. Biosurfactants synthesized from SM as sole substrate showed the highest emulsification index (56.35%), oil-spreading capacity (4.4 ± 1.31 cm), hemolysis (3.10 ± 0.02 cm), the shortest time for drop collapse (30 s), and surface tension reduction (24 mN/m). Biosurfactant concentrations ranged from 0.07 ± 0.01 in the NB to 2.08 ± 0.01 g/L in the media amended with SM. Chemical characterization revealed significant concentrations of carbohydrates and lipids in the biosurfactant produced from SM (1.2 ± 0.17 and 0.88 ± 0.04 g/L, respectively) when compared to SM + glucose (0.92 ± 0.05, and 0.62 ± 0.02 g/L, respectively), glucose (0.35 ± 0.04 and 0.13 ± 0.02 g/L, respectively), and nutrient broth (0.06 ± 0.03 and 0.01 ± 0.01 g/L, respectively). The biosurfactants were stable over a wide range of temperature while E24 increased with pH. Our results show the viability of SM fruit pulp as low-cost feedstock for industrial-scale production of biosurfactants using Pseudomonas spp.

Production, functional stability, and effect of rhamnolipid biosurfactant from Klebsiella sp. on phenanthrene degradation in various medium systems.

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

Butter whey and corn steep liquor as sole raw materials to obtain a bioemulsifier from Yarrowia lipolytica for food oil-in-water emulsions / Soro de manteiga e milhocina como únicas matérias primas para obter bioemulsificante de Yarrowia lipolytica para emulsões óleo-em-água alimentícias

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

RESUMO: O meio sintético contendo glicose, glicerol, extrato de levedura (YE) e sulfato de amônio (AS) foi comparado a meios de baixo custo para produzir alto índice de emulsificação (EI). Para este fim, os subprodutos agroindustriais foram rastreados quanto à produção de bioemulsificante por Yarrowia lipolytica. A análise estatística mostrou que EI de meios contendo óleo de fritura residual de óleo de palma (RFO_palm) ou óleo de soja (RFO_soy), líquido residual da produção de manteiga (soro de manteiga, BWhey) ou da produção de queijo (soro de queijo, CWhey), suplementado com YE e AS foram semelhantes ao EI do meio sintético. A substituição do YE por milhocina (CSL) também resultou em EI semelhante, exceto no RFO_soy. O BWhey foi testado com CSL sem AS e EI semelhante (66,8%) foi detectado em comparação com o mesmo meio com AS (66,3%). O meio isento de células obtido após o crescimento de Y. lipolytica no meio BWhey + CSL foi utilizado com sucesso para obter emulsões de óleo vegetal em água, indicando sua potencial aplicação em produtos alimentícios.

A novel sophorolipid-producing Candida keroseneae GBME-IAUF-2 as a potential agent in microbial enhanced oil recovery (MEOR).

The biosurfactants have extensive applications in food and petroleum microbiology. The aims of this research were isolation and characterization of thermo-tolerant biosurfactants from highly producing yeast strains. The Bushnell Hass medium was used for screening the biosurfactant-producing yeasts. Biosurfactant presence was evaluated using oil displacement assay and surface tension test. The best biosurfactant-producing strain was named Candida keroseneae GBME-IAUF-2 and its 5.8s-rDNA sequence was deposited in GenBank, NCBI, under the accession number MT012957.1. The thin layer chromatography and Fourier-transform infrared spectroscopy analysis confirmed that the extracted biosurfactant was sophorolipid with a significant surface activity. The purified sophorolipid decreased the surface tension of water from 72 to 29.1 mN/m. Its maximum emulsification index, E24%, was recorded as 60% and preserved 92.06-97.25% of its original activity at 110-120°C. It also preserved 89.11% and 84.73% of its original activity in pH of 9.3 and 10.5, respectively. It preserved 96.66-100% of its original activity in saline extreme conditions. This is the first report of sophorolipid production by the yeast C. keroseneae. According to the high thermal, pH and saline stability, the sophorolipid produced by C. keroseneae GBME-IAUF-2 could be highly recommended for applications in microbial enhanced oil recovery as well as food industries as an excellent emulsifying agent.

Process parameters for biosurfactant production using yeast Meyerozyma guilliermondii YK32.

Microbially produced biosurfactants are fast catching up due to their environment-friendly approach over chemical surfactants. But their commercial production is restricted due to poor economy of the production process which could be improved by using high yielding microbial strains and optimizing the process parameters. The present research was directed to optimize the biosurfactant production monitored in terms of oil displacement and emulsification (E24) index, using a promising yeast Meyerozyma guilliermondii YK32. Maximum oil displacement equaling 7.5 cm was obtained with olive oil at 8% (v/v) concentration as carbon source under shaking conditions (150 rpm). Diesel being a complex hydrocarbon was not utilized easily by yeast and showed poor biosurfactant production. Yeast extract at 1.5% (w/v) concentration yielded maximum biosurfactant as evident from maximum oil displacement and E24 index equal to 8.1 cm and 52.6%, respectively. Sodium chloride at the rate of 3% (w/v) supported maximum oil displacement (8.8 cm) using the production broth containing optimized carbon and nitrogen sources. Any increase beyond this level negatively influenced the biosurfactant production. The yield was at its maximum at 30 °C as a shift in temperature either to 35 °C or 25 °C decreased the oil displacement from 8.8 to 5.2 or 7.6 cm, respectively. At 40 °C, oil displacement was decreased to 2.5 cm. Biosurfactant production appeared to be sensitive to varying pH as evident from the E24 index as high as 67.3% at pH 6.0 as compared with 60.2%, 60.1%, and 52.4% at pH 5.0, 5.5, and 7.0, respectively. Yeast biomass yield equivalent to 10.3 g/L and 8.3 g/L was recorded at pH 6 and 7, respectively, during the production process. Elimination of shaking reduced the E24 index from 67.3 to 34.8% under optimized conditions.