Lipase-mediated hydrolysis of castor oil on its biotransformation into γ-decalactone by Yarrowia lipolytica

γ-Decalactone is a peach-like flavour compound that can be obtained biotechnologically by the biotransformation of ricinoleic acid. Castor oil is the substrate most usually used in the biotechnological production of γ-decalactone and it needs to be hydrolyzed in order to release ricinoleic acid. That biotransformation can be carried out by various microorganisms, such as the non-conventional yeast Yarrowia lipolytica, considered as non-pathogenic and as GRAS by the FDA. In order to increase the availability of the substrate to the cells for the production of γ-decalactone, castor oil previously hydrolyzed can be used. This hydrolysis may be promoted by enzymatic action, more specifically by lipases. The purpose of this work is to study the influence of the lipases-mediated castor oil hydrolysis, in aroma production, using different commercial lipases and a lipase produced by the yeast. Firstly, the enzymatic hydrolysis of castor oil by different commercial lipases (CALB L, Lipozyme TL IM and Lipolase 100T) was studied, under different operating conditions (pH and temperature) and Lipozyme TL IM was the most adequate enzyme to hydrolyze castor oil, at the optimal operating conditions of pH 8 and 27 ˚C (95.4%). Furthermore, different strategies for γ-decalactone production in flask experiments were also investigated, namely the addition of previously hydrolyzed castor oil to the culture medium, the addition of an immobilized lipase to the biotransformation medium and finally, the pre-addition of an inducer of lipase production (olive oil) to the biotransformation medium. As result, the process was faster when lipase was involved in any form, since the maximum of aroma concentration was attained at 140 h and 185 h of batch process with lipase and without lipase addition, respectively. However, no significant improvements in the γ-decalactone global yields and productivities were obtained (productivities varied from 8 ± 1 mg/L h to 9 ± 1 mg /L h in all conditions tested)

Biotransformation of ricinoleic acid into g-decalactone by Yarrowia lipolytica : bioprocess optimization

Doctoral Dissertation for PhD degree in Chemical and Biological EngineeringThe biotechnological production of γ-decalactone (a peach-like aroma compound) by biotransformation of ricinoleic acid carried out by microorganisms is an interesting process to produce the aroma with a “natural” label, which is valuable, considering the preference of consumers. Although there are many works described in the literature about this subject, several factors in the process remain to fully understand and, consequently, to optimize. One of these factors is the effect of oxygen in the overall process. Thus, this work initially aimed to study the oxygen mass transfer phenomenon from gas to the biotransformation medium, an oil-in-water emulsion stabilized by a non-ionic surfactant, Tween 80. The oil is simultaneously the substrate of the process and it works as an oxygen carrier, since the solubility of this compound is higher in the oil than in the aqueous phase. The influence of each operation parameter (aeration rate and presence and concentration of surfactant agent and organic phase) on the variables involved in the oxygen transfer (gas-liquid interfacial area, a; liquid-side mass transfer coefficient, kL; and volumetric mass transfer coefficient, kLa) was analyzed in a bubble column and in an airlift reactor. Results demonstrated that in the bubble column the increase of aeration rates is positive for both gas-liquid interfacial area and mass transfer due to the increase of turbulence and gas hold-up. The surfactant concentration had a positive effect on the interfacial area since it reduced the gas bubbles size and it had a negative effect upon kL because its molecules are located at the gas-liquid interface, obstructing the oxygen mass transfer. Regarding the oil concentration, it had a negative effect upon the interfacial area but it improved kL, since it causes a new distribution of surfactant in the medium, decreasing its concentration in the gas-liquid interface. The overall result was a negative effect of the organic phase upon kLa. In the airlift reactor, it was observed that the increase of the aeration rates had a negative effect on kL. This was attributed to differences in the liquid distribution inside the airlift reactor. Since the main goal of this work was to optimize the production of γ-decalactone, two different ricinoleic acid sources (methyl ricinoleate, MR, and castor oil, CO) were tested, in different concentrations, as substrates of the process. Moreover, different cell inoculation strategies were attempted, differing among each other in the washing or not of the cells. The results revealed that the use of non-washed cells is more beneficial for the aroma production, independently of the substrate used; and a concentration of 30 g L-1 MR was the most adequate among the range tested, since it allowed the highest γ-decalactone productivity (14.9 mg L-1 h-1). This substrate revealed also to be a lipase inducer. The use of CO as substrate of the process allowed to achieve almost 2 g L-1 of aroma but the process was rather slow, resulting in low productivities. It was then hypothesized an insufficient oil hydrolysis and an enzymatic hydrolysis was attempted with different commercial enzymes and operating conditions (temperature and pH). Lipozyme TL IM, pH 8 and 27 °C were selected as the most efficient lipase and operating conditions, respectively, to hydrolyze CO. The results obtained using CO previously hydrolyzed by the selected lipase were compared with the results obtained in experiments in which the enzymatic hydrolysis occurred during the biotransformation and in experiments without adding lipase, indicating that the process was faster when lipase was involved in any form, but the aroma concentrations were lower, resulting in similar productivities. The droplets size of both oils was characterized by laser granulometry in emulsions with different oil concentrations. The impact of the presence of cells on droplets size was also analyzed as well as the relevance of washing inoculum cells. The granulometry of emulsions was related with γ-decalactone production and it was observed that, in the presence of non-washed cells, the smaller droplets disappeared, with both oils, which increased γ-decalactone concentration, suggesting that the access of cells to the substrate occurs by their adhesion around larger oil droplets. Experiments in a stirred bioreactor using 30 g L-1 MR (concentration at which the highest aroma productivity was achieved) and different aeration and agitation rates demonstrated the direct influence of oxygen transfer rate on the production of γ-decalactone and of another compound, 3-hydroxy-γ-decalactone, that can also accumulate in the medium. The accumulation of this compound indicates a deviation in the metabolic pathway of γ-decalactone production, decreasing its yields. A response surface methodology was used to optimize pH (6.17) and dissolved oxygen concentration (44.4%) for the aroma production. These operating conditions were applied in two fed-batch strategies: with constant medium feeding rate and with intermittent feeding. Both strategies were compared with the traditional batch mode in terms of overall productivity and yield in respect to the substrate. Although the productivity was considerably higher in the batch mode, the level of substrate conversion to both lactones was greater in the intermittent fed-batch, allowing the accumulation of high aroma concentrations (6.8 g L-1 γ-decalactone and 10.0 g L-1 3-hydroxy-γ-decalactone). Finally, the production of aroma was attempted in an airlift bioreactor due to the advantages of this type of bioreactor, mainly in terms of high power economies, the non-mechanical agitation which avoids damage to cells and the higher mass transfer coefficients attained. The highest γ-decalactone production was obtained at an air flow-rate of 1 L min-1. The aeration rate increase of 5-fold lead to lower aroma concentrations. However, the time needed to reach the peak of production was also reduced, resulting in higher productivities.A produção biotecnológica de γ-decalactona (composto com aroma a pêssego) através da biotransformação de ácido ricinoleico por microrganismos é um processo interessante para produzir o aroma com um rótulo de “natural”, o que é uma mais-valia, considerando as actuais preferências dos consumidores. Embora existam muitos trabalhos na literatura sobre este tema, vários factores do processo ainda permanecem por compreender totalmente e, consequentemente, por optimizar. Um desses factores é o efeito do oxigénio no processo global. Assim, este trabalho teve inicialmente como objectivo estudar o fenómeno de transferência de O2 do gás para o meio de biotransformação, uma emulsão do tipo óleo-em-água estabilizada pelo surfactante não-iónico Tween 80. O óleo é simultaneamente o substrato do processo e actua também como transportador de O2, uma vez que a solubilidade deste composto no óleo é maior do que na fase aquosa. A influência de cada parâmetro de operação (arejamento, presença e concentração de surfactante e fase orgânica) nas variáveis envolvidas na transferência de O2 (área interfacial gás-líquido, a; coeficiente de transferência de O2 na fase líquida, kL; e coeficiente volumétrico de transferência de massa, kLa) foi analisada numa coluna de bolhas e num reactor airlift. Os resultados demonstraram que na coluna de bolhas o aumento da taxa de arejamento é positivo tanto para a área interfacial como para a transferência de massa devido ao aumento da turbulência e do gás hold-up. A concentração de surfactante teve um efeito positivo na área interfacial, uma vez que reduziu o tamanho das bolhas de gás e teve um efeito negativo no kL porque as suas moléculas localizam-se na interface gás-líquido, dificultando a transferência de O2. Relativamente à concentração de óleo, esta teve um efeito negativo na área interfacial mas melhorou o kL, uma vez que provocou uma nova distribuição do surfactante no meio, diminuindo a sua concentração na interface gás-líquido. O resultado global foi um efeito negativo da fase orgânica no kLa. No reactor airlift, observou-se que o aumento do arejamento produziu um efeito negativo no kL. Este resultado foi atribuído às diferenças na distribuição do líquido dentro do reactor airlift. Como o principal objectivo deste trabalho era optimizar a produção O uso de OR como substrato do processo permitiu obter quase 2 g L-1 de aroma mas o processo foi bastante lento, resultando em baixas produtividades. Hipotetizou-se então uma insuficiente hidrólise do óleo e testou-se uma hidrólise enzimática com diferentes enzimas comerciais e condições operatórias (temperatura e pH). Lipozyme TL IM, pH 8 e 27 °C foram seleccionadas, respectivamente, como a enzima e as condições operatórias mais eficientes na hidrólise do OR. Os resultados obtidos usando OR previamente hidrolisado pela enzima seleccionada foram comparados com os resultados obtidos em ensaios em que a hidrólise enzimática ocorreu durante a biotransformação e em ensaios em que não se adicionou lipase, indicando que o processo foi mais rápido quando a lipase esteve envolvida de alguma forma, mas as concentrações de aroma foram inferiores, resultando em produtividades idênticas. O tamanho das gotas de ambos os óleos em emulsões com diferentes concentrações de óleo foi caracterizado por granulometria laser. O impacto da presença de células no tamanho das gotas também foi analisado, assim como a relevância de se lavarem as células do inóculo. A granulometria das emulsões foi relacionada com a produção de γ-decalactona e observou-se que, na presença de células não lavadas, as gotas mais pequenas desapareceram, com ambos os óleos, aumentando a produção do aroma e sugerindo que o acesso das células ao substrato ocorre pela sua adesão à volta das gotas de óleo de maior tamanho. Ensaios num bioreactor agitado com 30 g L-1 RM (concentração à qual se obteve a maior produção de aroma) e diferentes arejamentos e agitações demonstraram a directa influência da taxa de transferência de oxigénio na produção de γ-decalactona e de outro composto, a 3-hidroxi-γ-decalactona, que também pode acumular no meio. A acumulação deste composto indica um desvio na via metabólica de produção de γ- decalactona, diminuindo o rendimento. A metodologia de superfície de resposta foi utilizada para optimizar o pH (6.17) e a concentração de O2 dissolvida no meio (44.4%) na produção do aroma. Estas condições foram aplicadas em duas estratégias semi-contínuas: com alimentação contínua de meio e com alimentação intermitente. Ambas as estratégias foram comparadas com o modo descontínuo tradicional em termos de produtividade global e rendimento em relação ao substrato. Embora a produtividade fosse consideravelmente superior no modo descontínuo, o nível de conversão de substrato em lactonas foi superior na estratégia semi-contínua intermitente, acumulando-se elevadas concentrações de aroma (6.8 g L-1 γ-decalactona e 10.0 g L-1 3-OH-γ-decalactona). Por fim, a produção de aroma foi testada num bioreactor airlift devido às vantagens deste tipo de reactor, nomeadamente no que diz respeito à poupança energética, à agitação não mecânica que evita danos nas células e aos elevados coeficientes de transferência de massa que se obtêm. A maior produção de γ- decalactona foi obtida com um caudal de arejamento de 1 L min-1. O aumento do caudal de arejamento em 5 vezes resultou numa diminuição da concentração do aroma. Porém, o tempo necessário para se atingir o pico de produção também foi reduzido, resultando em produtividades mais elevadas

Efeito do oxigénio na biotransformação de lípidos em aromas pela levedura Yarrowia lipolytica

Dissertação de mestrado em Biotecnologia.Vários processos biotecnológicos baseiam-se no desenvolvimento de microrganismos num meio bifásico formado por uma emulsão do tipo óleo-em-água. Um exemplo deste sistema consiste no meio utilizado na biotransformação de ricinoleato de metilo em γ-decalactona, pela levedura Yarrowia lipolytica. A γ-decalactona é um composto aromático de interesse industrial, que resulta da ß-oxidação peroxisomal do ricinoleato de metilo. A concentração de oxigénio dissolvido no meio é um factor interveniente na via metabólica implicada na biotransformação. Assim, a caracterização da capacidade de transferência de massa de oxigénio do ar para o meio bifásico reveste-se de grande importância para a optimização do processo em bioreactor. Neste trabalho foi desenvolvida uma correlação empírica para prever o KLa em função das condições de operação (agitação e arejamento) e da composição do meio de biotransformação em fracções orgânicas de óleo e de surfactante, no biorreactor. Isto permitiu seleccionar condições de operação para estudar o efeito do KLa na produção de γ-decalactona. Apesar de se verificar que o kLa influencia a produção de γ-decalactona não foi possível estabelecer uma relação directa entre estas duas variáveis. Foi igualmente objectivo deste trabalho avaliar a sensibilidade de Yarrowia lipolytica a concentrações elevadas de oxigénio, com o intuito de averiguar a possibilidade de aplicação de ar hiperbárico como forma de melhorar a capacidade de transferência de oxigénio para o meio. Verificou-se que a aplicação de pressões de ar de 0.5 MPa na fase de crescimento da levedura estimula o crescimento celular. Porém, na fase de biotransformação, a aplicação de pressões de ar acrescidas não favorece o processo. A acumulação de γ-decalactona pode variar muito com as actividades das enzimas da ß-oxidação que degradam o seu precursor directo, o ácido 4-hidroxidecanoico. Essas actividades são influenciadas pelas condições de pressão e oxigénio aplicadas na biotransformação. A maior produção de γ-decalactona (328 mg.L-¹) foi obtida no biorreactor Parr, aplicando pressões de 0.1 MPa durante as fases de crescimento e biotransformação, com uma agitação e arejamento de 400 rpm e 0.9 vvm, respectivamente.The dissolved oxygen concentration in the medium is an intervening factor in the metabolic pathway involved in the biotransformation. Therefore, the characterization of oxygen mass transfer capacity from air to biphasic medium is very important to optimize the process within the bioreactor. In this work, an empirical correlation was developed to predict KLa as a function of operating conditions (agitation and aeration) and of organic and surfactant fractions in the biotransformation medium, within the bioreactor. This enabled then to select operating conditions to study the effect of KLa on γ-decalactone production. Although KLa influenced γ-decalactone production, it was impossible to establish a direct correlation between these two variables. Another aim of this work, was to evaluate the sensibility of Yarrowia lipolytica at high oxygen concentrations, with the purpose of checking the possibility of using hyperbaric air to enhance the oxygen mass transfer capacity into the medium. It was observed that hyperbaric air applications of 0.5 MPa during the yeast growth phase, improved the cellular growth. However, the use of hyperbaric air during the biotransformation did not improve the process. γ-Decalactone accumulation can vary a lot with the activities of the peroxisomal ß-oxidation enzymes, that degrade its direct precursor, 4-hidroxydecanoic acid. Those activities are influenced by pressure and oxygen conditions applied in the biotransformation. The highest production of γ-decalactone (328 mg.L-¹) was obtained in the Parr bioreactor, using a pressure of 0.1 MPa during the growth and biotransformation phases, with agitation and aeration conditions of respectively 400 rpm and 0.9 vvm

Fed-batch versus batch cultures of Yarrowia lipolytica for γ-decalactone production from methyl ricinoleate

Constant medium feeding rate and intermittent fed-batch fermentation strategies were investigated aiming to increase the yields of γ-decalactone production by Yarrowia lipolytica, using methyl ricinoleate as substrate and ricinoleic acid source. The accumulation of another compound, 3-hydroxy-γ-decalactone, was also analyzed since it derives from the direct precursor of γ-decalactone thereby providing information about the enzymatic activities of the pathway. Both strategies were compared with the traditional batch mode in terms of overall productivity and yield in respect to the substrate. Although the productivity of γ-decalactone was considerably higher in the batch mode (168 mg l−1 h−1), substrate conversion to lactone (73 mg γ-decalactone g−1) was greater in the intermittent fed-batch giving 6.8 g γ-decalactone l−1. This last strategy therefore has potential for γ-decalactone production at an industrial level.The authors acknowledge Fundacao para a Ciencia e Tecnologia (FCT) for the financial support provided (SFRH/BD/28039/2006)

Avaliação do conhecimento de jovens adultos sobre o vírus do papiloma humano e cancro do colo do útero

Introdução: O cancro do colo do útero (CCU) é a quarta neoplasia mais frequente em mulheres mundialmente, sendo que cerca de 95% dos casos de cancro do colo do útero devem-se ao vírus do papiloma humano (HPV). O nível de conhecimento da população é essencial para planear a melhor estratégia de intervenção com vista à redução da prevalência da infeção e, consequentemente, da incidência e mortalidade por CCU. Assim, pretende-se com este trabalho determinar o nível de conhecimento de jovens adultos, de ambos os sexos, sobre infeção por HPV e CCU e verificar se o sexo, escolaridade e orientação sexual dos utentes influencia o seu nível de conhecimento. Metodologia: Trata-se de um estudo observacional, transversal e analítico, tendo sido aplicado um questionário a uma amostra de 274 jovens adultos, de ambos os sexos, entre os 18 e 26 anos de idade. O tratamento de dados e análise estatística foram realizados com recurso aos softwares Microsoft Excel® e SPSS® v. 28.0. Resultados: Verificou-se que 72% (n = 198) dos inquiridos já tinham ouvido falar de HPV e CCU. Destes, 56% (n = 111) tinham conhecimento da existência de vacinas contra o HPV. Foram calculadas pontuações médias de conhecimento sobre HPV, CCU e vacinação. Verificou-se que, de uma forma geral, o sexo feminino demonstrou ter maior conhecimento sobre HPV e CCU, havendo diferenças estatisticamente significativas no nível de conhecimento entre os dois sexos. No que diz respeito à influência do nível de escolaridade no conhecimento sobre HPV e CCU, não foram encontradas diferenças estatisticamente significativas entre o nível superior de ensino e níveis de ensino até ao 12º ano. Relativamente à orientação sexual, verificou-se que os indivíduos heterossexuais possuem maior conhecimento sobre HPV relativamente aos homossexuais ou bissexuais. No entanto, não foram encontradas diferenças entre estes dois grupos, a nível de conhecimento sobre CCU. Com exceção das respostas fornecidas pelo sexo feminino, o nível de conhecimento global sobre HPV e CCU foi considerado insuficiente (< 50% respostas corretas). No que diz respeito ao conhecimento sobre vacinação contra o HPV, verificou-se um nível suficiente, não existindo diferenças significativas entre os vários grupos analisados. Conclusão: Embora grande parte da população estudada já tenha ouvido falar em HPV e CCU, os seus conhecimentos sobre a temática são insuficientes, tornando-se imperativo delinear estratégias de educação para a saúde, no sentido da prevenção da infeção e consequente redução do número de casos de cancro do colo do útero.Introduction: Cervical cancer (CC) is the fourth most common cancer in women worldwide, with around 95% of cervical cancer cases being due to the human papillomavirus (HPV). The level of knowledge of the population is essential to design the best intervention strategy aiming to reduce the prevalence of the infection and, consequently, the incidence and mortality due to CC. Therefore, the aim of this work is to determine the level of knowledge of young adults, of both sexes, about HPV infection and CC and to verify whether the sex, education and sexual orientation influence their level of knowledge. Methodology: This is an observational, cross-sectional and analytical study, with a questionnaire applied to a sample of 274 young adults of both sexes, between 18 and 26 years of age. Data processing and statistical analysis were carried out using Microsoft Excel® and SPSS® v. 28.0. Results: It was found that 72% (n = 198) of respondents had already heard of HPV and CC. Of these, 56% (n = 111) were aware of the existence of HPV vaccines. Mean knowledge scores on HPV, CC and vaccination were calculated. It was found that, in general, females demonstrated greater knowledge about HPV and CC, with statistically significant differences in the level of knowledge between both sexes. Regarding the influence of education level on knowledge about HPV and CC, no statistically significant differences were found between higher education and education levels up to the 12th grade. Regarding sexual orientation, it was found that heterosexual individuals have greater knowledge about HPV compared to homosexuals or bisexuals. However, no differences were found between these two groups in terms of knowledge about CC. Apart from the answers provided by females, the overall level of knowledge about HPV and CC was considered insufficient (< 50% correct answers). Regarding knowledge about HPV vaccination, there was a sufficient level, with no significant differences between the various groups analyzed. Conclusion: Although a large part of the analyzed population has already heard of HPV and CC, their knowledge on the subject is insufficient, making it mandatory to outline health education strategies, aiming at preventing the infection and consequently reducing the number of cases of cervical cancer

Hyperbaric bioreactors use with Yarrowia lipolytica cultures : cellular adaptation to hyperbaric conditions

Increase air pressure for aeration of microbial cell cultures can prevent oxygen limitation but cause oxidative stress and consequently affect cell physiology. A pressurized bioreactor was used for Y. lipolytica batch cultivation under increased air pressure up to 6 bar and no inhibition of cell growth was observed. Moreover, an increase of 6-fold led to a 3.4-fold increase in specific growth rate under atmospheric pressure. The antioxidant enzyme superoxide dismutase was induced by the air pressure raise, which indicates that the defensive mechanisms of the cells were effective and cells could cope with increased pressure. The extracellular lipase activity increased from 22.3 to 43.7 U/l using a 5-bar air pressure instead of air at 1 bar pressure

UV-NIR efficiency of the refractive index matching mechanism on colorectal muscle during treatment with different glycerol osmolarities

The evaluation of the optical clearing mechanisms in tissues provides information about the efficiency of the clearing treatment. One of such mechanisms is the refractive index matching, which is created by the partial replacement of tissue water by an optical clearing agent with higher refractive index, better matched to the index of tissue scatterers. With the objective of evaluating the refractive index matching mechanism for a wide spectral range and comparing its magnitude between treatments with different clearing agent osmolarities, thickness and collimated transmittance measurements were obtained from human colorectal muscle samples under treatment with 20%-, 40% and 60%-glycerol. Such measurements were used in a calculation model to obtain the refractive index kinetics for the interstitial fluid and for the whole tissue. The calculation results show that the refractive index matching has a stronger effect in the ultraviolet and that such matching is more effective for higher agent concentrations in the treating solutions.This research was supported by the Portuguese Grant FCT UIDB/04730/2020. VVT was supported by the grant of the Russian Foundation of Basic Research #18-29-02060 MK.info:eu-repo/semantics/publishedVersio

Empirical modelling as an experimental approach to optimize lactone production

The biotransformation of ricinoleic acid, carried out by Yarrowia lipolytica, leads to the formation of gama-decalactone, a well-known peach-like aroma compound, interesting to produce and to use in the flavouring industry, reason why it is imperative to define the most appropriate conditions for its production. Thus, the aim of this work is the optimization of operating conditions for this lactone. However, as the accumulation of another compound, namely 3-hydroxy-g-decalactone (the precursor of two other aromatic compounds, dec-2-enolide and dec-3-enolide), may also occur simultaneously in the biotransformation medium, and since this compound may as well be of interest for the flavouring industry, the operating conditions for its production were also a focus of attention. Therefore, a 3^2 level full-factorial design was used to determine the effect of pH and dissolved oxygen concentration (DO) on the production of gama-decalactone and 3-hydroxy-gama-decalactone. Since both factors were found to influence the two lactones production, a response surface methodology (RSM) analysis was also applied to identify the optimal conditions for the production of those two compounds. The statistical model pointed out pH = 6.17 and DO = 44.4% as the best conditions optimizing gama-decalactone production. Using these optimalconditions, the maximal gama-decalactone concentration achieved was 680.9 mg/L, which was quite similar to the predicted value of 718.7 mg gama-decalactone per liter. Among the range of operating conditions tested, no optimization was possible for 3-hydroxy-gama-decalactone production, since all possible solutions corresponded to operating conditions not analyzed.The authors aknowledge Fundacao para a Ciencia e Tecnologia (FCT) for the financial support provided (SFRH/BD/28039/2006) and Hector Ruiz for the help provided with MATLAB

Oxygen effect in γ-decalactone production through biotransformation of ricinoleic acid

γ-Decalactone can be produced biotechnologically from the degradation of ricinoleic acid by yeasts, namely Yarrowia lipolytica. Preliminary studies using two different ricinoleic acid sources (methyl ricinoleate and castor oil) at different concentrations were tested as substrates, in flask experiments. Although high amounts of γ-decalactone (up to 2 g L-1) were achieved with oil concentrations of 3% and 5% (v/v) for each substrate, the productivity of the process was small (10 to 14.5 mg L-1 h-1). In order to increase these values, essays were conducted in a 2-L bioreactor, with 3% (v/v) methyl ricinoleate at different aeration and agitation rates, in the herein presented work. Under these conditions, the highest amount of γ-decalactone achieved was lower (approximately 1 g L-1). However, the productivity of the process was much higher: 87 mg L-1 h-1. Furthermore, another compound derived from the direct precursor of γ-decalactone, 3-hydroxy-γ-decalactone, was detected in large amounts (up to 8 g L-1), which implies a change in the metabolic pathway control