Biosurfactants are produced by a variety of microorganisms most of which are bacteria. Their ability to reduce surface and interfacial tensions makes them suitable for environmental applications where hydrophobic compounds are concerned. The biodegradability and lower toxicity of biosurfactants compared to chemical surfactants is ecologically valuable. Four biosurfactant producing bacteria (Alcanivorax borkumensis DSM 11573, Bacillus subtilis DSM 3256, Bacillus licheniformis RS1, and Rhodococcus ruber DSM 43338) were investigated in this study. Their growth and biosurfactant producing profiles were studied. The Bacillus species produced exogenous biosurfactants which were extracted and identified as surfactin and lichenysin. The other isolates produced cell bound biosurfactants and were therefore selected for augmentation in hydrocarbon degradation. Bacterial bioluminescent biosensor derived quantitative structure activity relationships were employed as a tool to validate the suitability of the extracted biosurfactants as solvents for ecotoxicity assessment of hydrophobic organic compounds. The relationships obtained in biosurfactants and water did not differ (p > 0.05) and suggests that the biosurfactants did not compromise the performance of the biosensors. Remediation of diesel hydrocarbons by degraders in the presence of Alcanivorax borkumensis or Rhodococcus ruber was tested. Degradation was 5 and 3 times more effective with respiration rates 20 and 5 times higher in the presence of A. borkumensis and R. ruber respectively. The effect of biosurfactants on bioactivity in historically contaminated soils was evaluated using the extracted lichenysin. Bioactivity was improved in the presence of the biosurfactant. Bioactivity was correlated to biodegradation of hydrocarbons in a crude oil impacted soil amended with degraders, biosurfactant producers and a chemical dispersant (p < 0.001). The lowest CFU counts for heterotrophs and degraders were observed for the chemical dispersant. The results from this study further highlight the value of biosurfactants for environmental application. Improvement in production is necessary to encourage widespread commercial application of biosurfactants.

By using standard isolation procedures 55 microbial isolates were successfully obtained from a number of oil-contaminated sources. These microbial isolates, along with a further 17 obtained from the University culture collection were screened for their ability to degrade hexadecane. Of these, all but two strains were able to utilise hexadecane as their sole carbon and energy source. One isolate, JP1, demonstrated outstanding growth on liquid hexadecane media (final cell-density equal to 1.9 x 10 10 CFU ml -1). A number of techniques were implemented in the screening of the 70 microorganisms for the ability to produce biosurfactants. These methods were based upon the ability of a surfactant to emulsify hexadecane. However, all proved to be unsuccessful methods of detection due to limits of quantification. Surface-tension measurement of the cell-free broth of each isolate was deemed to be the most successful detection method of all those attempted. This technique was selected on the basis of its simplicity, rapidity and reproducibility. On the basis of surface-tension measurements, isolate JP1 demonstrated the greatest reduction to 30 dynes cm "1. On the basis of surface-tension measurements JP1 was deemed the best biosurfactant producer and was selected for further investigations. An absence of suitable quantitative surfactant assays led to the need for the development of such a technique. Two spectrophotometric assays were investigated, the first based upon a surfactants ability to disrupt a liposomal suspension and the second based upon the ability to induce blood haemolysis. Both assays were successfully developed using Triton X-100, a known biological surfactant. Limitations of the liposomal assay were identified when the cell-free broth of JP 1 was introduced into the system. The blood haemolysis assay was successfully implemented to determine biosurfactant production by JP I during a fourteen day fermentation period. The influence of media formulation on biosurfactant production by JP1, demonstrated that maximum production was achieved with a2% (v/v) hexadecane medium incorporating a nitrogen concentration of 0.351 g 1.1 and a phosphorus concentration of 1.218 g 1-1. These concentrations corresponded to a C: N ratio of 48: 1 and a C: P ratio of 14: 1. The biosurfactant exhibited some secondary metabolite characteristics and attained its maximum production during stationary phase. To enable a suitable downstream processing method to be selected for the harvest of the biosurfactant, the nature of the biosurfactant was elucidated. Analytical techniques identified the compound responsible for the surface-tension reducing abilities of the cell-free broth as a glycolipid (30 dynes cm "1). It was demonstrated that the lipid was not responsible for the emulsification abilities of the cell-free broth. Further analytical methods identified the bioemulsifier as a protein with a molecular weight of 14 KDa

No description available.

Thesis (M App Sc) -- University of South Australia, 1992

No description available.

Thesis (MTech (Environmental Health))--Cape Peninsula University of Technology, 2016. / Environmental remediation of organic and inorganic contaminants such as hydrocarbons has been a research focus area of interest. Chemical surfactants have been extensively used for the remediation of contaminated sites for immobilisation of hydrocarbons from environmental matrices. The focus has been on the impact of chemical surfactants on the environment. These petroleum-based chemical surfactants have raised serious environmental concerns as: 1) they are toxic, 2) they deteriorate the environment owing to their non-biodegradability, 3) they are costly, and 4) most are not intended for environmental applications. As such, alternatives had to be found to mitigate concerns associated with the application of such synthetic surfactants in bioremediation. Biosurfactants produced by microorganisms are a potential alternative to these synthetic surfactants. They have minimal environmental impact, are biodegradable and can withstand extreme conditions. However, biosurfactants are associated with high production costs and low production yield. Currently, large-scale production of biosurfactants cannot be achieved. Most research focuses on improving production yield which will contribute to the reduction in production costs. A lichenysin lipopeptide biosurfactant producing Bacillus sp., which grew exclusively on Beta vulgaris agrowaste, was identified. The microorganism was found to be an effective emulsifier for high molecular weight hydrocarbons such as, lubricant oil and diesel. The aim of this study was to improve biosurfactant production yield from this Bacillus sp., including emulsification efficacy by optimising fermentation conditions by supplementing the broth with biocompatible nanoparticles synthesised using a green chemistry approach with B. vulgaris (B. vulgaris) extracts. This study also aimed at reducing production costs by using B. vulgaris agrowaste exclusively as the production medium, both for the biosurfactant and the nanoparticles.

The purpose of this dissertation was two-fold: 1) explore the micelle structure and microenvironment of monorhamnolipids (mRL), produced by Pseudomonas aeruginosa ATCC 9027, and their mixtures with synthetic surfactants in order to postulate possible applications of these materials in industrial products and 2) examine the effects of mRL on commercial metal oxide nanoparticle (NP) aqueous dispersion behavior to reveal the potential impact of microbial secondary metabolites on NP fate and transport in the environment. The mixing behavior of mRL with cetylpyridinium chloride (CPC) was measured using surface tensiometry. Electrostatics resulted in cooperative enhancement in mixture properties, but were not significant until α(CPC) ≥ 0.25. Steady-state and time resolved fluorescence quenching measurements in mRL micelles revealed that quenching proceeded via a combined static and dynamic mechanism. Static quenching was preferred in mRL illustrating the reactants form a globular micelle. Changing the structure of the reactants displayed changes in the degree and mechanism of quenching further supporting this aggregate model. Fluorescence measurements on mRL-Tween 20 micelles supported that a geometrically-driven shape transition occurs as mRL decreases. The corresponding decrease in probe lifetime indicated the polarity of the micelle was decreasing. Tween "sealed" the mRL micelles making them less susceptible to water penetration. The effect of mRL on metal oxide NP dispersions was evaluated on adsorption strength, NP aggregate size and stability, and zeta potential under different conditions. Silica NPs showed little adsorption of mRL and was impervious to all variables in altering the solution stable aggregate size. NP aggregate size decreased at very high mRL concentrations due to osmotic and electrosteric repulsions of mRL micelles in solution. Titania, despite expectations, indicated fairly low adsorption of mRL and displayed similar aggregate dispersion stability as that of silica. Spectroscopic investigations exposed that the commercial titania NPs were contaminated with silica altering NP surface properties. Zinc oxide (ZnO) dispersions were substantially affected by the adsorption of mRL. Without mRL, ZnO NPs were unstable independent of pH. The addition of mRL stabilized the ZnO dispersions and lowered the zeta potentials. Furthermore, mRL coating prevented the dissolution of ZnO, the major factor implicated in ZnO toxicity.

Orientador: Glaucia Maria Pastore / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-08T11:37:31Z (GMT). No. of bitstreams: 1 Barros_FranciscoFabioCavalcante_M.pdf: 816271 bytes, checksum: 1ac93e87eef201f2b03cad5fc4da0cac (MD5) Previous issue date: 2007 / Resumo: A bactéria Bacillus subtilis tem a capacidade de produzir biossurfactantes do grupo dos lipopeptídeos, dentre os quais, o que mais se destaca é a surfactina, um dos que possui maior atividade superficial. Esse composto é capaz de reduzir a tensão superficial da água a 20°C de 72 para 27 mN/m em concentrações menores que 20 _M. A aplicação de resíduos industriais como substrato para produção de biossurfactante de Bacillus subtilis tem sido estudada como forma de reduzir custos associados à produção destes. A manipueira, que é o resíduo líquido da produção de farinha e fécula, tem sido apontada como potencial meio de cultura para processos biotecnológicos, incluindo produção de biossurfactantes. Esse uso tem significativa relevância quando se consideram os resultados de redução de tensão superficial e de produtividade obtidos. Este trabalho estudou o processo produtivo, as propriedades e a estabilidade de biossurfactante produzido pela linhagem LB5a de Bacillus subtilis em escala piloto utilizando manipueira como substrato. O composto produzido foi capaz de reduzir a tensão superficial da água de 72 para 27 mN/m além de apresentar concentração micelar crítica de 12 mg/l. Manteve estabilidade frente à temperatura de 100°C por 140 minutos e 121°C por 60 minutos. Também foi estável na faixa de pH de 6 a 10 e suportou concentrações salinas testadas (de até 20%). A eficiência da extração primária realizada através da coleta de espuma mostrou bons resultados, sendo perfeitamente aplicável ao processo. Além disso, os parâmetros envolvidos no preparo da manipueira foram otimizados visando um melhor aproveitamento do substrato. Os resultados apontam temperatura de aquecimento ótima de 95°C (máxima temperatura testada), tempo de aquecimento de 1 minuto, a aceleração centrífuga de 17,85 G x 103 e o tempo de centrifugação de 14,86 minutos. Os resultados apresentados são bastante animadores em relação à possibilidade de aplicações do biossurfactante produzido em diversos setores. Além de permitir um melhor aproveitamento da manipueira / Abstract: The bacteria Bacillus subtilis is well known by their capacity of production surfactants lipopeptides. Among these, the most studied is surfactin, a powerfull surfactant that reduces the superficial tension of the water from 72 to 27 mN/m in concentrations less than 20_M. The application of industrial wastewaters as substrate for production of biosurfactant by Bacillus has been studied in order to reduce manufacturing costs. Manipueira is the residue from cassava industrialization process to the production of flour and starch. It has been pointed as potential culture medium for biotechnological processes, including production of biosurfactants. This work studied the productive process, the properties and the stability of biosurfactant produced by Bacillus subtilis strain LB5a in pilot scale using manipueira as substrate. The produced compounds were capable of reducing the superficial tension of the water from 72 to 27 mN/m beyond presenting critical micelar concentration of 12 mg/l. It remaing stable on temperature of 100°C during 140 minutes and 121°C during 60 minutes. It was also stabile in the range of pH from 6 to 10 and in saline concentrations (until 20%). The efficiency of the primary extration by foam collection showed good results, being perfectly applicable to the process. Moreover, the involved parameters in the preparation of the manipueira has been optimized with the objective of better using of the substrate. The results presented the optimal points of heating temperature was 95°C (maximum tested temperature), warm up time of 1 minute, the acceleration centrifugal of 17,85 G x 103 and the centrifugalization time of 14,86 minutes. The results showed that the biosurfactant produced have potential applications in several industrial sectors, beyond allowing one better exploitation of the manipueira / Mestrado / Mestre em Ciência de Alimentos

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Os biossurfactantes formam molÃculas anfipÃticas, que possuem em sua estrutura quÃmica segmentos hidrofÃbicos e hidrofÃlicos, espacialmente separados que auxiliam a formaÃÃo de emulsÃes e disponibilizam compostos à cÃlula microbiana. Em funÃÃo dessas caracterÃsticas, os emulsificantes reduzem a tensÃo superficial na interface das fases imiscÃveis, permitindo, portanto, que elas se misturem, formando a emulsÃo. Com isso, este trabalho foi dividido em seis etapas: a primeira tendo como objetivo avaliar a produÃÃo de biossurfactante a partir da glicerina, proveniente da produÃÃo do biodiesel de soja, pela cepa comercial de Bacillus subtilis ATCC 6633, possÃvel produtora de biossurfactante que foi selecionada devido a sua habilidade em sintetizar biossurfactantes a partir de diferentes fontes de carbono; a segunda, resolveu-se avaliar o potencial de produÃÃo de surfactina por cepas de Bacillus sp. nÃo patogÃnicas isoladas da EstaÃÃo de Tratamento de Efluentes da Universidade Federal do CearÃ, com propÃsito de avaliar o maior potencial de produÃÃo do biossurfactante; a terceira, avaliar e otimizar experimentalmente a produÃÃo de biossurfactante em mesa agitadora, utilizando a cepa selecionada durante o screening; a quarta, produÃÃo do biossurfactante utilizando biorreator de 4 L; a quinta, caracterizar o biossurfactante produzido, determinando os grupos funcionais, os estudos de conformaÃÃo e estrutura dos compostos; a sexta, estudar o poder de emulsificaÃÃo do biossurfactante atravÃs da construÃÃo de diagramas de fases para uma posterior aplicaÃÃo do emulsificante. Inicialmente, foi analisada uma cepa produtora de biossurfactante de Bacillus subtilis (ATCC 6633), cultivada em meio de cultura contendo glicerina, um resÃduo da indÃstria do biodiesel, como fonte de carbono e energia, a fim de avaliar a viabilidade desta matÃria-prima na sÃntese de biossurfactante. Uma concentraÃÃo mÃxima de surfactina de 158,14 mg.L-1 foi obtida. Posteriormente, um screening com sete cepas isoladas de Bacillus sp. foi realizado quanto ao crescimento e produÃÃo de biossurfactante a partir da glicerina. Apenas duas cepas (LAMI005 e LAMI009) foram selecionadas atravÃs de dois mÃtodos indiretos, quanto a reduÃÃo da tensÃo superficial e a capacidade de emulsionar trÃs fontes hidrofÃbicas (querosene, Ãleo de soja e n-hexadecano). Foi avaliada a cinÃtica de crescimento e a produÃÃo de biossurfactante para as cepas selecionadas e o melhor resultado em frascos de Erlenmeyer foi realizado com Bacillus subtilis LAMI005, com concentraÃÃo de surfactina de 441,06 mg.L-1 e tensÃo superficial que manteve-se numa faixa estÃvel de 28,8  0,05 mN.m-1 com uma concentraÃÃo micelar crÃtica (CMC) de 19,8 mg.L-1. Posteriormente, ensaios foram realizados em biorreator de 4L, porÃm nÃo se atingiu a concentraÃÃo de surfactina produzida em mesa agitadora, devido, provavelmente, a condiÃÃes de aeraÃÃo, que nÃo foi monitorada quando os ensaios foram realizados em frascos agitados. A surfactina produzida em biorreator foi submetida a anÃlises de espectroscopia vibracional no infravermelho com transformada de Fourier (FTIR), atravÃs destes espectros foi confirmado que o biossurfactante produzido tinha caracterÃsticas similares a surfactina padrÃo da Sigma. O comportamento dos diagramas de fases demonstrou o potencial de emulsificaÃÃo do biossurfactante produzido nestes experimentos, que à bastante positivo em relaÃÃo à possibilidade de aplicaÃÃes do biossurfactante analisado em diversos setores industriais. / Biosurfactants are amphipathic molecules, which possess in their chemical structure hydrophobic and hydrophilic segments, separated spatially, that favor the formation of emulsions and improve the availability of compounds to microbial cell. Given these characteristics, emulsifiers reduce surface tension at the interface of immiscible phases, thereby allowing them to blend in, forming an emulsion. Thus, this study was divided into six stages: the first stage aimed at studying the biosurfactant producers using glycerol, a co-product of biodiesel production from soybean oil, the commercial strain of Bacillus subtilis ATCC 6633, a known biosurfactant-producing was selected due their ability to synthesize biosurfactants from different carbon sources; the second stage aimed at studying the potential of Bacillus sp. strains, isolated from the tank of chlorination, at the Wastewater Treatment Plant on the âCampus do Piciâ (WWTP-PICI), at the Federal University of CearÃ, in producing biosurfactants; the third step was to experimentally evaluate and optimize the production of biosurfactant in shaker, using the strains selected during the screening; the fourth step was the process by using a 4 L batch bioreactor; the fifth step was to characterize the biosurfactant produced by determining the functional groups through studies of conformation and structure of compounds; and the sixth, to study the emulsifying power of the biosurfactant produced by the construction of phase diagrams for a subsequent application of the surfactant. Initially, a biosurfactant-producing strain of Bacillus subtilis (ATCC 6633) was cultived in a culture medium containing glycerin, a residue of the biodiesel industry, as carbon and energy source, in order to evaluate the viability of this raw material in the synthesis of biosurfactants. A maximum concentration of surfactin of 158.14 mg. L-1 was achieved. Next, a screening with seven strains of Bacillus sp. was performed aiming to study growth and biosurfactant production from glycerin. Only two strains (LAMI005 and LAMI009) were selected through two indirect methods, surface tension reduction and the ability to emulsify three hydrophobic sources (kerosene, soybean oil and n-hexadecane). Kinetics of growth and biosurfactant production was evaluated for the selected strains and best results in Erlenmeyer flasks was achieved with Bacillus subtilis LAMI005, 441.06 mg.L-1 of surfactin concentration and the surface tension remained stable in the range of 28.8  0.05 mN.m-1 with a critical micelle concentration (CMC) of 19.8 mg.L-1. Later, tests were conducted in 4L bioreactor, but the concentration of surfactin obtained during grothw in shaker flasks were not achieved probably due to different aeration condition. The surfactin produced in bioreactor was subjected to analysis of the vibrational spectroscopy of Fourier transform infrared (FTIR), the spectra confirmed that the biosurfactant produced had similar characteristics to a standard of surfactin from Sigma. The behavior of phase diagrams showed the potential of the biosurfactant produced for emulsification, which is very encouraging regarding the possibility of biosurfactant applications in many industrial sectors.

Soil pollution in recent years has emerged as an issue of great environmental concern. Contamination of soil by improper disposal or spillage of petrochemicals and products containing petroleum hydrocarbons is one of such pollution cases highly reported. To remediate petroleum contaminated soil, A DC powered electrokinetic reactor was used with biosurfactants as an enhancement for the remediation process. To begin with, studies were made under voltage variations of 10 V and 30 V with an electrode spacing of 185 mm. Biosurfactant with its producing microbes and biosurfactant free cells were introduced in the soil chamber after which the reactor was left to run for 10 days under the electric field. The technology was able to achieve the highest oil recovery of 75.15 % from the soil in 96 hours at 30 V. With other factors remaining constant, the reactor was also operated under a constant voltage of 30 V with configurations of fixed electrodes spacings of 335 mm, 260 mm,185 mm and continuous approaching electrodes at 335 mm, 260 mm and 185 mm. The current in the electrolyte was highest with the least electrode distance of 185 mm. The increase in current led to a direct proportional increase in the electroosmotic flow towards the cathode leading to increased coalescence of the oil from the soil as compared to the other electrode distances. The analysis of the results showed reduction in the total carbon content in the soil with viable oil recovery rates for all the electrode distances with 185 mm being the most effective in both oil recovery and degradation. The reactor was further operated with amended biosurfactant concentrations of 28 g/L, 56 g/L and 84 g/L to enhance the recovery of oil from the soil and aid in biodegradation of the remaining oil by hydrocarbon degrading microbes. The highest oil recovery of 83.15 % was obtained with the biosurfactant concentration of 56 g/L showing that the hyper increase in concentration of the biosurfactants is not necessary to have an efficient process. In all experiments the microorganisms were able to survive under the electro-halo-thermal environment in the reactor and degraded the remaining hydrocarbons to acceptable amounts in the environment. The bacteria were however affected by the constantly changing pH in all experiments. The presence of biosurfactants was so significant in aiding oil recovery and increasing bioavailability of hydrocarbons to the microbes. Production of biosurfactants in the reactor followed up by kinetic suggestions of the processes in the bioelectrokinetic reactor should be studied in future. / Dissertation (MEng (Environmental Engineering))--University of Pretoria, 2019. / Chemical Engineering / MEng (Environmental Engineering) / Unrestricted